ATA5279P-PLQW 19 - Atmel - Product.Network

Features

•Six Connections for Series-resonant LF Coil Antennas

•Drives up to 1A Peak Current on the First Three Channels and up to 700mA Peak on the

Second Three, Largely Independent of the Battery Voltage

•On-off-keyed Data Modulation with up to 5.7kbit/s (Manchester Coded)

•Sinusoidal-like Output Signal for Superior EMC Behavior

•20 Selectable Steps for Current Regulation for Field Strength Measurement (RSSI)

•Output Driver Stages are Protected Against Electrical and Thermal Overload

•Very Low Power-down Current Consumption

•SPI Interface for Easy Microcontroller Bus Connection

•LF Data Buffer to Minimize Microcontroller’s CPU Load During a Data Transmission

•Small Outline Package: QFN48, 7mm ×7mm

1. Description

The Atmel® ATA5279 is an LF coil driver IC intended for passive entry/-go (PEG) sys-

tems. It can drive up to six low-frequency-antennas (i.e., coils) to provide a wake-up

and initialization channel to the key fob.

Figure 1-1. Block Diagram

Oscillator Internal Supply

POR, BG, UV/OV

Control Logic

Communication

Protocol Handling

Boost

Controller

LF Data BufferSPI

PGND VDS

A4P

A6P

A5P

A1P

A3P

A2P

A1N

A3N

A2N

VLVCC

IRQ

BCNT

MACT

NRES

VIF

MISO

MOSI

S_CLK

S_CS

OSCO

OSCI

RGND VSHSCINTAGND

Reference

Sine Wave

Generator

Driver Stage

Control

Zero Cross

Detector

Return Line

Driver

HP 1-3

Integrator

Sample

and Hold

LP 1-3

A4N

A6N

VSHF

A5N

Antenna Driver

for Multiple

Antennas

Atmel ATA5279

Atmel ATA5279C

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Atmel ATA5279

2. Pin Configuration

Figure 2-1. Pinning QFN48

A3N2

A2N1

A2N2

VDS1

A1N1

A4N2

A4N1

A5N1

VSHF2

A5N2

A6N2

A3N1

Atmel

ATA5279

VL3

PGND3

VL2

PGND2

VL1

PGND1

VDS3

IRQ

NRES

S_CLK

S_CS

MOSI

RGND

CINT

VCC

VSHS

VIF

OSCI

BCNT

VSHF1

A6N1

MACT

OSCO

VDS2

A4P

A2P

AGND2

A6P

AGND3

MISO

A3P

A5P

AGND1

A1P

A1N2

1314 15 16 19

17 20 21 22 2324

424344

4546474841 40 3938 37

Table 2-1. Pin Description

Pin Symbol Function Pin Group

Heat Slug PGND Backside ground connection -

1 VS Battery supply pin -

2 RGND Reference ground -

3 CINT Integration capacitor connection -

4 VCC Analog 5V stabilization capacitor connection -

5 VSHS Shunt resistor voltage sense input -

6 VIF Digital supply voltage input -

7 OSCI Oscillator input pin CSP

8 OSCO Oscillator output pin CSP

9 MACT Modulator active indicator output pin DO

10 BCNT LF-bit counter output pin DO

11 VSHF1 Shunt resistor driving pin 1 RLO

12 A6N1 Coil 6 negative connection line pin 1 LRL

13 A6N2 Coil 6 negative connection line pin 2 LRL

14 A3N1 Coil 3 negative connection line pin 1 HRL

15 A3N2 Coil 3 negative connection line pin 2 HRL

16 A5N1 Coil 5 negative connection line pin 1 LRL

17 A5N2 Coil 5 negative connection line pin 2 LRL

18 VSHF2 Shunt resistor driving pin 2 RLO

19 A2N1 Coil 2 negative connection line pin 1 HRL

20 A2N2 Coil 2 negative connection line pin 2 HRL

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21 VDS1 Driver supply pin 1 DS

22 A4N1 Coil 4 negative connection line pin 1 LRL

23 A4N2 Coil 4 negative connection line pin 2 LRL

24 A1N1 Coil 1 negative connection line pin 1 HRL

25 A1N2 Coil 1 negative connection line pin 2 HRL

26 A1P Coil 1 positive connection line pin HDL

27 VDS2 Driver supply pin 2 DS

28 AGND1 Driver ground pin 1 -

29 A4P Coil 4 positive connection line pin LDL

30 A2P Coil 2 positive connection line pin HDL

31 AGND2 Driver ground pin 2 -

32 A5P Coil 5 positive connection line pin LDL

33 A3P Coil 3 positive connection line pin HDL

34 A6P Coil 6 positive connection line pin LDL

35 AGND3 Driver ground pin 3 -

36 MISO Master-In-Slave-Out SPI output pin DO

37 MOSI Master-Out-Slave-In SPI input pin DI

38 S_CS SPI chip select pin DI

39 S_CLK SPI clock input pin DI

40 NRES Chip reset input pin DI

41 IRQ Interrupt request output pin DO

42 VDS3 Driver supply pin 3 DS

43 PGND1 Boost converter low-side switch output 1 -

44 VL1 Boost converter low-side switch input 1 BLS

45 PGND2 Boost converter low-side switch output 2 -

46 VL2 Boost converter low-side switch input 2 BLS

47 PGND3 Boost converter low-side switch output 3 -

48 VL3 Boost converter low-side switch input 3 BLS

Table 2-1. Pin Description (Continued)

Pin Symbol Function Pin Group

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3. Functional Description

3.1 Operation Modes

Atmel® ATA5279 features five operation modes. They are:

• Power-down mode (reset state)

• Idle mode

• Operating mode

• Shutdown mode

• Diagnosis mode

Power-down mode is active after supply voltages have been applied to the chip. No internal

circuitry is active in this mode and as such power consumption is minimal. If no operation of

the chip is demanded, it should be kept in this state. To enter power-down mode, a negative

pulse on the NRES pin for at least tNRES,min is required.

After wake-up from power-down mode by a logic high signal at the S_CS pin, the chip is in idle

mode. That is, the oscillator is running and the control logic waits for commands coming from

the serial interface. Furthermore, the selected output driver stage is ready for operation (the

voltage on the corresponding output pin AxP is approximately half the battery supply voltage).

The current consumption of the chip is now mainly defined by the cross current through the

active driver stage (please refer also to Section 3.2 “Coil Driver Stage” on page 5).

When processing coil driving commands, the chip is in operation mode. From the interface

point of view, there is no difference from the idle mode; however, current consumption is now

higher as the output driver stages are operating and, depending on the selected output cur-

rent, the DC-DC converter is also operating.

If a connection failure (short circuit on any of the coil connection lines) is detected, the

ATA5279 enters the shutdown mode to protect itself from damage. In this mode, the interface

operates in idle mode but with all power stages shutdown and no LF transmission command

processing. This mode should be exited using the Reset Fault Status command (see below),

however, it can also be exited by resetting the chip.

In diagnosis mode, the output driver stages are also disabled. In their place, high-ohmic cur-

rent sources are activated that can be programmed via the serial interface in order to check

the coil connection lines for failures. This mode can be exited by an appropriate SPI command

or by resetting the chip.

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3.2 Coil Driver Stage

The driver stage for each coil consists of two N-channel DMOS transistors. The low-side tran-

sistor is in Darlington configuration to maintain a source-follower characteristic.

Figure 3-1. Principle Driver Stage Setup

In the graphic above, the names of internal pins have a grey shaded background, and the

hatched area is not part of the driver stage itself but only used in diagnostic mode (please refer

to the Diagnosis Block description for further information on this topic).

The driver stages are supplied by the three VDS pins, which are tied together inside the chip.

A quiescence current regulation ensures low cross current while in idle state. The output tran-

sistors are monitored for current and temperature to protect them from damage caused by

irregular load conditions or too high ambient temperatures.

The driving stage is optimized for signal quality to ensure low harmonic distortions.

Two groups of driver stages are integrated: the first group is intended for high-current coils,

whereas the second group drives low-current coils. Note that there are certain coil impedance

ranges for each driver group. If the connected load exceeds this range, proper current regula-

tion and/or data modulation is not guaranteed.

While in idle mode and especially during a transmission, the driver stages of the five inactive

(i.e., not selected) coils are switched to high-side outputs, i.e., the positive coil connection

lines are tied to the VDS potential. The same applies to the return line inputs AxN. These mea-

sures ensure minimum parasitic currents in the disabled coils while the selected coil is

operating.

VSin_pre

Internal nodes

AxP

Ax_State

Diag Enable

VDS

HSDiag

Diag Enable

mirr

LSDiag

mirr2

mirr1

pwr

GND

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3.3 Sine Wave Generator

The sinusoidal coil-driving signal is internally generated. Its amplitude is dependant on the

measured coil current, and the frequency is derived from the oscillator stage. In conjunction

with the output driver stages, the generated signal is optimized for low harmonic distortions.

The peak-to-peak amplitude of the sinusoidal signal is directly defined by the voltage on the

external integration capacitor connected to the CINT pin. This voltage, with an offset sub-

tracted, is internally used to generate a low-voltage sine wave signal, which is in turn amplified

and level-shifted up to the desired output level.

The output signal itself has a DC offset close to the half of the supply voltage, and the maxi-

mum possible amplitude has about 3V distance to each of the supplies. Figure 3-2 illustrates

this.

Figure 3-2. Maximum Possible Coil Driving Signal for a Given Supply Voltage VDS

Table 3-1. States of Driver Outputs within Operation Modes

Mode Operation/

Transmission Mode

Entering by SPI cmd

Shutdown Mode

Fault has detected

Idle Mode

Entering by S_CS

Power Down/Reset

Entering by NRES or

POC

Diagnosis Mode

Entering by SPIOutput

AxP

Selected driver active

others are on High Level

(VDS)

All high impedance

Selected driver stays on

Vbatt /2 ready for

Operation

Others are on High Level

High impedance

(Diagnosis current

sources programmable)

AxN

Selected driver stays on

l o w l e v e l

Others are on High Level

All high impedance

Selected driver stays on

l o w l e v e l

Others are on High Level

High impedance

(Diagnosis current

sources programmable)

OUT,min

OUT,max

0.5

VDS

GND

VDS

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In application, the output coil current is the fixed valued (selectable via SPI). Hence, the

required output voltage is calculated as follows:

Here, ZCoil is the complex impedance of the coil, RDSon,HRS/LRS is the on-resistance of the

appropriate return line current selector (see also Section 8. “Functional Parameters” on page

32) and RShunt is the resistance of the externally applied current sense shunt resistor (typ. 1Ω,

see also Section 4. “Application” on page 27).

3.4 Boost Converter

The coil driver stage can be supplied by a DC-DC converter in boost configuration. Together

with an externally applied choke, freewheeling diode and capacitor, the battery voltage can be

brought up to the required value, which is dependant on the coil's impedance and the selected

current. The converter is only enabled during an active transmission. The peak current

through the low-side switch IVL and the output voltage VVDS are measured to shut down the

converter operation in case one of the values exceeds its upper limit.

Note: There is no dedicated temperature monitoring for the boost converter low-side switch. For fur-

ther details, please refer to Section 4.1 “Application Hints” on page 28.

The switching frequency is, like the coil driving signal, derived from the oscillator stage and

125kHz in value when using an 8MHz input clock. The least possible time the boost converter

takes to generate the maximum possible output voltage from the minimum possible input volt-

age is dependant on several parameters. The values of the external components (choke

inductance, charge capacitance and CINT integration capacitance) greatly effects this time.

3.5 Coil Current Sensing (Zero Cross, Sample and Hold, Integrator)

The coil current flows through an external shunt resistor, causing a current-dependant voltage,

which is fed into the IC via the VSHS pin. By monitoring the zero crossing events of this signal,

the phase of the coil current is known and hence the positive peak value can be sampled.

The peak coil current is then subtracted from an internal reference voltage that is dependant

on the selected coil current, which results in the regulation difference.

An amplifier stage converts this difference into a current, which is then fed into an externally

applied integration capacitor connected to the CINT pin. The resulting voltage on this capaci-

tor directly influences the amplitude of the sine wave signal. It also determines the supply

voltage generated by the boost converter, if the necessary coil supply voltage exceeds the

actual supply voltage level. Note that during an active transmission, this voltage is internally

limited to VCINT,max.

Note that in idle mode, the voltage on the integration capacitor is kept at a value that corre-

sponds to the battery supply voltage. This ensures that the boost converter, if needed, always

performs a soft start from the battery voltage level on.

The desired current can be selected via the SPI. A total of 20 predefined steps are available,

divided into the following sections:

• The lower four steps (50mA to 200mA) are intended for the low-current coils only

• The next ten steps (250mA to 700mA) are intended for both types of coils

• The upper six steps (750mA to 1A) are intended only for the high-current coils

VOut,p ICoil,p ZCoil RDSon,HRS/LRS RShunt

++()×=

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The IC allows the use of a current step not intended for a particular driver group; however, in

this case, full functionality, especially a stabilized coil current, cannot be guaranteed. See also

the Control Logic block description for an overview over the commands.

3.6 Diagnosis

The diagnosis stage monitors both the positive (AxP) and negative (AxN) connection lines of

the six coils. If one of these lines is shorted to battery supply or to ground, the following mea-

sures are taken for protection and diagnostic reasons:

• All coil driver stages are shut down, i.e., put into high impedance state

• The shunt resistor is disconnected from the coil return lines

• The reason for the fault shutdown is stored in the fault register

• An interrupt request is triggered (see also control logic block)

In addition to short circuits, a disconnected coil (i.e., open load) or an excessive junction tem-

perature can also lead to such a fault shutdown.

Note that this type of diagnosis is carried out continuously during normal operation of the IC to

protect both the IC and the peripherals from damage.

It must be avoided to design the system's load profile in such a way that the protection fea-

tures of the chip are triggered under normal operating conditions. Consecutive triggering of the

overtemperature shutdown may lead to a reduced lifetime.

In the event of such a fault shutdown, the IC can be brought back to operation by resetting its

fault register with the appropriate SPI command (please refer also to the Section 3.9.2 “Gen-

eral Command Description” on page 21 later in this document). As a result, transmission on

non- faulty coils is still possible even if there is a failure of one coil.

Beyond this, the diagnosis of all connected coil lines is a very useful tool for maintenance rea-

sons. The Atmel® ATA5279 has implemented test structures that can be activated and read

out via SPI commands, so that the microcontroller can be programmed to detect most of the

possible faults, for example, shorts between different coil connection lines and multiple shorts

in one pair of lines.

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3.6.1 Functional Description of Diagnosis Mode

In this diagnosis mode, the coil-line drivers themselves are switched to high impedance.

Hence, only the test structure at every coil connection (both at the positive outputs AxP of the

drivers and at the negative outputs AxN) is present and can directly test the status of the line.

Figure 3-3 illustrates this:

Figure 3-3. Base Structure of the Diagnosis Module of One Output Channel

The structure above can be found in each of the six channels of the Atmel® ATA5279. As soon

as the diagnosis mode is engaged, all channels are operated in this way. On the channel that

is actually selected, the setting of the switches can be changed with the Set Coil Current com-

mand and the status of the two connection lines can be checked with the Get Driver Setup

command.

The two switches in the P line driver are controlled with one bit. That means, either the

high-side (S_HxP) or the low-side (S_LxP) switch is closed. The same is true for the N line

driver (S_HxN, S_LxN). The controlling bits c0 and c1 are taken from the coil current selection

Note that the setting of the switches is latched. That means, if the setting on the switches of

the selected driver is changed, the setting on the five other channels remains unchanged.

By a combination of test structures, many different faults, even between the coils, can be

detected.

As described in the principle schematic of a driver stage above, a test structure consists of two

switchable current sources (one to VDS and one to GND) and a comparator that converts the

voltage level on the line into a digital signal. The switches for the current sources can only be

controlled in diagnosis mode, with the corresponding coil being selected (see also Driver

Command description). Note that one switch is always closed, either the high-side or the

low-side switch of one test structure. These structures are independent, i.e., they can be set

up for each line individually and at the same time.

The status of the connection lines of the selected coil can be read out with a SPI command.

VDS

AGND

Driver x select

Latch

c0 bit

c0, 1 bits

c1 bi

VDS

AGND

S_HxN

c1 = '1'

S_LxN

c1 = '0'

AxNAxP

S_HxP

c0 = '1'

S_LxP

c0 = '0'

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In the following example, there is a short circuit between the positive coil connections of coil 1

and 2.

Figure 3-4. Example 1, Using the Diagnosis Mode

Taking the circuit situation shown above, the test run starts with both S_L1P and S_L2P

switches closed (default state when entering the diagnosis mode for the first time). The

read-back of the line state result in both times 0, which is not unexpected. However, the result

does not change when either altering the channel 1 or the channel 2 switch setting. That can

be caused both by the failure shown above and by short-circuits of both lines to ground. The

final diagnosis can be identified by changing both channels to the high-side switches (S_H1P

and S_H2P). In this case, the two status lines both return 1s – which eliminates the possibility

of two short-circuits to ground.

Table 3-2 summarizes this test sequence.

GND

VDS

S_L1P

S_H1P

Short

Status_1

S_L2P

S_H2P

Status_2

A1P A2P

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The suggested waiting time is calculated as follows:

The sequence above is an example of how the failure illustrated in Figure 3-4 on page 10

could be detected. Depending on the grade of detection detail that is required, a matrix for the

test sequence should be set up to find the most effective way of programming and testing. For

more details on the commands, please refer also to Section 3.9.2 “General Command

Description” on page 21.

Table 3-2. Sequence for Example 1, Using the Diagnosis Mode

Step Command I/O Coding Actions/Remarks

1 Select Driver I 00101001 – 29h Selects driver 1 with Diagnosis Mode enabled

2Get Driver Setup

01101000 – 68h

00000001 – 01h

Reads back active driver info:

Channel 1 active, both lines return a 0

3 Select Driver I 00101010 – 2Ah Selects driver 2 with Diagnosis Mode enabled

4Get Driver Setup

01101000 – 68h

00000010 – 02h

Reads back active driver info:

Channel 2 active, both lines return a 0

5 Set Coil Current I 10100001 – A1h Closes test switches S_H2P and S_L2N

Note: S_L2P and S_H2N are then open

6 - no command - Wait for the test structures to stabilize in the new setting, see

below

7Get Driver Setup

01101000 – 68h

00000010 – 02h

Reads back active driver info:

Channel 2 active, but both lines return a 0

8 Select Driver I 00101001 – 29h Selects driver 1 with Diagnosis Mode enabled

9 Set Coil Current I 10100001 – A1h Closes test switches S_H1P and S_L1N (Note: S_L1P and

S_H1N are then open)

10 - no command - Wait for the test structures to stabilize in the new setting, see

below

11 Get Driver Setup I

01101000 – 68h

00001001 – 09h

Reads back active driver info:

Channel 1 active and A1P returns a 1

12 Select Driver I 00101010 – 2Ah Selects driver 2 with Diagnosis Mode enabled

13 Set Coil Current I 10100000 – A0h Closes test switches S_L2P and S_L2N

Note: S_H2P and S_H2N are then open

14 - no command - Wait for the test structures to stabilize in the new setting, see

below

15 Get Driver Setup I

01101000 – 68h

00000010 – 02h

Reads back active driver info:

Channel 2 active and A2P returns a 1

Note: Steps 6, 10 and 14 are wait states, as the test structures need some time to stabilize in their new setting. This depends mainly

on the externally applied capacitors on the AxP and the AxN pins.

tdiag,wait

×CeCant

+()×

300 µA

------------------------------------------------------=

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Atmel ATA5279

The second example circuit has two faults in the circuitry.

Figure 3-5. Example 2, Using the Diagnosis Mode

If channel four is activated in normal operation, a fault shutdown will occur. The reason for this

shutdown (i.e., the entry in the fault register) could either be an overload on the A4P line (here

a short circuit to VS) or a short-circuit on the A4N line to VS. In any case, the IC protects itself

and the external components from damage; however, the fact that there is more than one fail-

ure in the wiring cannot be discovered.

In diagnosis mode, by testing the A4P line with S_H4P and S_L4P, the short circuit to VS

could be found first. The same result would be found when testing the return line switch 4

accordingly, so the presence of more than one fault on coil 4 is determined. The precise fault

cannot be found though. The diagnosis result would be the same both for the above shown cir-

cuit and for the A4N line being directly shorted to VS (without the failure in the coil module,

here RShunt2) and for the combination of the two.

A4NA4P

VDS

GND

S_L4N

S_H4N

S_L4P

S_H4P

RShort1

RShort2

Status_4NStatus_4

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Again, this is only an example of how the diagnosis system can be used. Generally, a more

systematic approach is suggested in order to efficiently test all connection lines used.

Note: To exit the diagnosis mode correctly, two SPI commands have to be sent: the first is the Select

Driver command with the DM bit set to 0 and the second is a Reset Fault Status command. See

also SPI Command Description.

3.7 SPI

The SPI is used to select the required coil and its current, to provide LF data to the IC, to

select and start an LF transmission, and to read out status information. It is equipped with a

chip select input to enable or disable communication. When disabled, the data output of the IC

is in high impedance mode, so other devices may communicate on the same bus.

The interface is configured as a slave device, always requiring a master (e.g., a microcon-

troller) for operation. The maximum input clock frequency is 1/4 of the system clock present at

the OSCI pin, resulting, for example, in a maximum signal speed of 2 Mbit/s when using a typ-

ical 8MHz input clock. The SPI features four different operation modes, which only differ in the

relationship between the clock signal (S_CLK) and the data I/Os.

Both the SPI itself and the corresponding I/O lines are supplied by the application-provided

logic supply voltage connected to the VIF pin. This ensures that the controller (master) and the

IC (slave) operate with the same voltage levels.

In total, four modes of operations are possible, each differing in clock polarity and phase.

Figure 3-7 and Figure 3-8 illustrate this.

Table 3-3. Sequence for Example 2, Using the Diagnosis Mode

Step Command I/O Coding Actions / Remarks

1 Select Driver I 00101101 – 2Dh Selects driver 4 with Diagnosis Mode enabled

2Get Driver Setup

01101000 – 68h

00011101 – 15h

Reads back active driver info:

Channel 4 active, A4N returns a 1

3 Set Coil Current I 10100010 – A2h Closes test switches S_L4P and S_H4N

Note: S_H4P and S_L4N are open then

4 - no command - Wait for the test structures to stabilize in the new setting, see

first example

5Get Driver Setup

01101000 – 68h

00011101 – 1Dh

Reads back active driver info:

Channel 4 active, both lines return a 1

6 Set Coil Current I 10100000 – A0h Closes test switches S_L4P and S_L4N

Note: S_H4P and S_H4N are open then

7 - no command - Wait for the test structures to stabilize in the new setting, see

first example

8Get Driver Setup

01101000 – 68h

00010101 – 15h

Reads back active driver info:

Channel 4 active and A4N returns a 1

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Figure 3-6. SPI Operation in POL = 1 and PHA = 1 Mode (Default Mode after Reset)

Figure 3-7. SPI Operation in POL = 0 and PHA = 0 Mode

Figure 3-8. SPI Operation in POL = 1 and PHA = 0 Mode

Sample

Setup

XX LSB MSB12345 X6X

Z ZX

S_CS

MOSI

MISO

S_CLK

Sample

Setup

LSB MSB12345 X6

ZXZ

S_CS

MOSI

MISO

S_CLK

XXX

Sample

Setup

LSB MSB12345 X6

ZXZ

S_CS

MOSI

MISO

S_CLK

XXX

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Figure 3-9. SPI Operation in POL = 0 and PHA = 1 Mode

The configuration mode can be selected with the appropriate SPI command (see Section 3.9.2

“General Command Description” on page 21). Note that after power-up or a reset, the IC is

always in its default configuration (POL = 1, PHA = 1), which must be used to alter the config-

uration. At the end of the SPI configuration-changing command, the new configuration is

activated with the falling edge of the S_CS signal.

3.7.1 Timing

Figure 3-10 illustrates the timing parameters of the SPI communication.

Figure 3-10. Timing Parameters of the SPI Communication

Note: The diagram above is using POL = 0 and PHA = 0 as a setup for the SPI. The values are also

valid for the other three configurations. The limits for the timing values shown above can be

found in Section 8. “Functional Parameters” on page 32.

Sample

Setup

XX LSB MSB12345 X6X

Z ZX

S_CS

MOSI

MISO

S_CLK

LSB 1 6 MSB

S_CS

tIo

thi

tsetup thold

tCS,set tSPIoff

tSPI tout,valid

tCShold

MOSI

MISO

S_CLK

XXX

tMISOoff tMISOon

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3.8 Command Buffer

This buffer is a First-In-First-Out (FIFO)-type buffer, located between the SPI and the modula-

tor stage. The microcontroller can write coil-driving related commands and data with full SPI

speed to keep the CPU and bus load low.

3.8.1 Structure

The buffer can store up to 128bits, organized in 16 words, each eight bit in size. Hence, each

data word from the SPI that contains a control command for the driver stages (i.e., select a

certain driver, select a certain current, transmit LF-data bits and transmit a constant wave) is

stored in a buffer word. Figure 3-11 outlines this.

Table 3-4. States of Control I/Os

Name Pin # Direction

Operation/

Transmission Mode

Entering by SPI cmd

Shutdown Mode

Fault has detected

Idle Mode

Entering by S_CS

Power Down/Reset

Entering by NRES or

POC

S_CS 38 Input Weak-pull-down Weak-pull-down Weak-pull-down Weak-pull-down

S_CLK 39 Input High impedance High impedance High impedance High impedance

MOSI 37 Input High impedance High impedance High impedance High impedance

MISO 36 Push-pull

output

Tristate (S_CS = low)

Low/High (S_CS = high)

Tristate (S_CS = low)

Low/High (S_CS = high)

Tristate (S_CS = low)

Low/high (S_CS = high)

Tristate (S_CS = low)

Low/high (S_CS = high)

VIF 6 Input Supply current Supply current Supply current Supply current

NRES 40 Input Weak-pull-up Weak-pull-up Weak-pull-up Weak-pull-up

IRQ 41 Push-pull

output Low/high(1) Low/high(1) Low/high(1) High

BCNT 10 Push-pull

output Low/high(1) Low Low Low

MACT 9 Push-pull

output High Low Low Low

Note: 1. State dependant on modulation, chip state or SPI data

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Figure 3-11. Structure of 128-bit FIFO Command Buffer

The read pointer indicates the next word to be processed by the Modulator Stage, whereas

the write pointer indicates the next free location for data from the SPI. These pointers are con-

trolled by the internal logic to enable the first-in-first-out functionality.

3.8.2 Usage

After wake-up from power-down, the buffer is empty and ready to receive commands and LF

data. Any LF command and data is fed into the buffer via the SPI. The buffer can be filled even

during an active data modulation, i.e., when some LF data and/or commands remain in the

buffer while waiting to be processed. This increases the independency of the coil driver from

the microcontroller. An interrupt request (IRQ) is triggered when the fill state of the buffer

drops below 25% or if too many words are sent and a FIFO overflow occurs.

Seamless data processing is an important feature of the command buffer. LF data intended for

the same coil and the same current step can be distributed to several commands without the

risk of having unwanted gaps in the LF telegram. This allows protocols to have any length and

is usable both with the Send LF-data and the Send Carrier command. Refer also to the Sec-

tion 3.9.1 “Modulator Stage” on page 18 for further details.

128 bit FIFO buffer

From SPI

Modulator Stage

Read Pointer

General Command

Processing

Write Pointer

Data

Selector

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3.9 Control Logic

The internal control logic handles all information coming from the SPI and controls the power

stages. Diagnostic information is also collected and evaluated here.

3.9.1 Modulator Stage

The modulator stage controls the coil drivers. It gets all necessary information from the com-

mand buffer. That is:

• Which coil to drive

• Which current to maintain in this coil/which diagnosis switch to close (in diagnosis mode)

• Which baud rate to use for LF data transmission

• What kind of transmission (i.e., data or carrier)

• LF data itself (respectively the on-time when a carrier is to be transmitted)

When a modulator operation is started by an SPI command, the data in the buffer is processed

in the order it arrives via SPI, command by command. The time for this data processing

depends on the command itself and, if LF transmissions are involved, the amount and length

of the data bits.

Table 3-5 lists the timings for the driver-related commands.

Note: Table 3-5 lists the duration of command execution for the different commands and not the

decoding or processing time. This is done simultaneous, so that two commands can be exe-

cuted seamlessly.

Table 3-5. Execution Durations of Driver-related Commands

Command Dur. [LF per.] Comment

Select Driver 64

During the first 32 periods, the actual driver is stopped in order

to decay any oscillation in the coil. Then the switching itself is

performed and another 32 periods waiting time is started in

order to wait for the new driver to reach its operation point

Select Coil Curr. < 1

The switching time of internal references takes less than 1LF

period. Note that there will always be an interruption in a

telegram if the coil current is changed between two transmission

commands

Send LF Data N × 2 × {32 / 22}

The duration of this command depends on the selected data

rate (3.9kbit/s, i.e. 32 periods/LF bit, or 5.7kbit/s, i.e.,

22 periods/LF bit) and the amount of nibbles N (2LF data bits) to

be transmitted

Send LF Carrier T × (32 / 22) The duration of this command depends on the selected data

rate (see also above) and the carrier duration T

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LF data is transmitted on-off-keyed (OOK). “1” enables the field, whereas “0” disables it. Note

that the field generation strongly depends on the bandwidth (the Q factor) of the coil. If it is too

narrow, the receiver might not be able to decode the data correctly. Figure 3-12 shows the sig-

nal path from the modulator stage to the receiver.

Figure 3-12. Example for OOK-data Modulation with Atmel ATA5279

Coils with high Q values need more periods to reach the desired field strength and hence

appropriate detection level thresholds in the receiver. So the Q factor must be adapted in

order to ensure proper data communication. For example, the thresholds here are chosen at

70% of the required output current for a 0 to 1 and at 30% for a 1 to 0 detection.

The IC supports two data rates: standard, which is 3.9kbit/s (or 32LF periods), and high

speed, rated with 5.7kbit/s (or 22LF periods). Note that this refers to the encoded (net) data

rate. The minimum length of an active field (e.g., the time for the first 1 in Figure 3-12), is 16LF

periods in standard and 11LF periods in high speed mode (i.e., gross data rate).

Another aspect of the LF data transmission is that current regulation can only be done roughly,

as the measurement must be interrupted over and over again. At a 0 to 1 transition, the cur-

rent measurement will not start until the 5th period, and there will not be any measurement

during a 0-transmission. The regulation precision that is achieved during carrier transmission

is not valid here.

As described in Section 3.8 “Command Buffer” on page 16, data is processed seamlessly to

avoid gaps in longer LF telegrams. The following example illustrates this feature.

Assume that following data words have been written into the command buffer via the SPI:

1. Send 2LF bits (SPI data 00h 05h)

2. Send carrier with a length of 24 data bits (SPI data 98h)

11 110 0off

Receiver Threshold

Detection

11 110

Current

Envelope

off

Transmitter Coil Current

Receiver Data

Modulator Data

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In this example, the output signal of the modulator resembles the illustration below.

Figure 3-13. Example of Data Transmission of Two Consecutive Commands

The value for tdata depends on the speed setting of the modulator (32LF periods in standard

and 22 periods in high speed mode, with one period being 8µs when operating with 125kHz

output frequency and therefore 8MHz system clock).

The least amount of data that can be processed by the modulator stage is four LF bits or two

(e.g. Manchester-encoded) data bits. The first command in the upper example is a mini-

mum-length LF data command.

To ensure the traceability of the LF protocol, two pins are provided, which indicate an active

data transmission (MACT) and the change of an LF bit (BCNT). Figure 3-12 illustrates the

function of these two signals:

Figure 3-14. LF Transmission Tracing Signals

The MACT signal can be used to start a timer whereas BCNT can be used as input signal to a

counter. Note that for carrier transmissions, only the MACT signal is active. There are not any

pulses on the BCNT line.

26 × tdata

24 × tdata

2 × tdata

BCNT Signal

Modulator Data

First Command Second Command

11 1 110 0

Current Envelope

offoff

Transmitter Coil Current

MACT Signal

BCNT Signal

Modulator Data

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3.9.2 General Command Description

The following commands are directly processed by the control logic, i.e., they are not fed into

the data buffer:

Refer to Section 3.7 “SPI” on page 13 for bit direction definitions.

• Get Status Info:

This command delivers the general IC status information back to the microcontroller (via

the SPI bus). One part of the return word is the interrupt request source. If such a request

is active (i.e., the IRQ line is high), the source for it is coded here.

• Possible sources include the diagnosis block to indicate a driver stage fault (bit F), a

general reset (either triggered externally by the NRES pin or internally by the power-on

reset structure, bit R), an overtemperature of the chip (bit T), or the FIFO buffer indicating

that the fill state has dropped to 25% or below (i.e., only four words are left, bit BU), or the

fill state exceeds the upper limit of 16 bytes (bit BO). The IRQ signal is reset with this

command. Additionally, the operability flag of the IC (bit Op) is returned in the word. Note

that only if no fault is stored in the fault register and all operation voltages are present and

valid, the operability is given (indicated by a 1 in the Op bit). Otherwise, Atmel® ATA5279

will not process any driver-related command. Finally, the LF speed mode bit returned here

indicates the current speed state of the modulator stage (bit S, 0 for normal speed, 1 for

high speed).

bit R: Chip reset - either triggered externally by the NRES pin or internally by the

power on reset structure

bit F: Indicator for a driver stage fault

bit BO: The FIFO buffer fill state exceeds the upper limit of 16 bytes

bit BU: The FIFO buffer fill state drops to 25% or below, i.e., only 4 words are left

bit T: Chip overtemperature indicator

bit S: LF modulator speed mode indicator

bit Op LF driver stage operability indicator

Table 3-6. Bit Definitions of the General SPI Commands

Command

Input Word (MOSI Data) Output Word (MISO Data)

MSB

654321

LSB

MSB

654321

LSB

Get status info 0

Get driver setup 0

Get fault info 0

F03

F02

F01

F00

Reset fault status 01000000XXXXXXXX

Set SPI config 010010POPHXXXXXXXX

Halt operation 01010000XXXXXXXX

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• Get Driver Setup:

This command returns the actual setup of the driver stage, i.e., the selected coil, encoded

in the bits DG,D1..0, and the selected current, which can be found in the bits C4..0 (see also

“Select Driver” and “Set Coil Current” command description below for details on bit coding).

This command is also used in diagnosis mode to fetch the state of the coil connection lines.

• Get Fault Info:

This command returns the content of the driver stage fault register back to the

microcontroller via the SPI bus. The register contains both the code for the detected fault

and the number of the driver stage that was active when the fault occurred. Refer also to

the Section 3.9.4 “Status Monitor” on page 25 for further details.

• Reset Fault Status:

This command clears the content of the driver stage fault register and sets the operability

bit in the general state register if all supply voltages are present and valid. This command is

necessary to resume normal operation following the occurrence and subsequent removal

of a fault. Please note that prior to this command, the active channel should be switched to

a line that is not faulty. Otherwise, the internal logic might get corrupted and must then be

reset with a negative pulse on the NRES line.

Note that this command is also required to bring the Atmel ATA5279 back into operation

mode once the diagnosis mode was active and was then cleared by a Select Driver

command.

• Set SPI Config:

This command changes the two configuration bits PO(L) and PH(A). These bits are

responsible for the serial data processing of the SPI.

Default: PO = 1, PH = 1

• Halt Operation:

As this command is processed immediately, it is not written to the FIFO buffer even if it is a

driver-related command. The effect of this command is that the content of the FIFO buffer

is cleared, hence no new LF data is available, and if any driver is active it will be stopped.

Note that such stops are only carried out at the end of an LF period (i.e., when the

sinusoidal output signal reaches half of the supply voltage).

3.9.3 Driver-related Command Description

Following commands are processed via the LF data buffer:

Table 3-7. Bit Definitions of the Driver-Related SPI Commands

Command

Input Word Output Word

MSB

654321

LSB

MSB

654321

LSB

Select driver 0 0 1 BR DM DGD1D0XXXXXXXX

Select coil current 1 0 1 C4C3C2C1C0XXXXXXXX

Send LF data

L 7

L 6

L 5

L 4

L 7

L 6

L 5

L 4

N 3

N 2

N 1

N 0

Send LF carrier 1 0 0 T4T3T2T1T0XXXXXXXX

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• Select Driver:

This command selects the coil that is to be driven or tested next. The BR-bit indicates the

modulation speed (0 for 3.9kbit/s, i.e., 32LF periods and 1 for 5.7kbit/s, i.e., 22LF periods).

•The D

G,1..0 bits indicate the channel number to be activated. DG selects the driver group (0

for high-current driver 1..3, 1 for low-current driver 4..6) and D1..0 the required driver in the

group (01 for driver 1 / 4, 11 for driver 3 / 6). For connection line diagnosis, the diagnosis

mode can be enabled by setting the DM-bit to 1.

bit BR: LF modulator speed (0 for 3.9kbit/s, i.e., 32LF periods and 1 for 5.7kbit/s,

i.e., 22 LF periods, referred to Manchester coding)

bit DM: Diagnosis mode selector (0: Normal LF operation mode, 1: Coil connection

diagnosis mode)

Notes: 1. If set, all coil connections are switched to this mode. Normal operation is not possible. (i.e.,

LF transmission). The same works for the opposite way: once a Select Driver command is

received with the DM-bit at 0, all connection lines are switched back to normal operation

mode.

2. For a proper operation after a diagnosis run, a Reset Fault Status command also needs to

be sent.

bits DG,1..0: Active channel indicator

bit DG: Driver group selector (0 for high-current driver 1..3, 1 for low-current driver

4..6)

bits D1..0: Driver selector, i.e. 01 is driver 1 (DG=0) / 4 (D

G= 1), 11 is driver 3

(DG= 0) / 6 (DG=1).

Default: DG,1..0 = [001], DM = 0, BR = 0 --> Channel 1, diagnosis mode off and normal LF

speed selected.

• Select Coil Current

This command defines the current to be established for the next LF transmissions.

bits C4..0: Contain the step number in the range of 0 to 19 (00hex to 13hex)

bits C1..C0: Are used in diagnosis mode, to control the test switches of the activated

connection line

whereas …

bit C0: The low/high-side switch of the AxP line

bit C1: The low/high-side switch of the AxN line)

Default: C4..0 = [00000] --> 50 mA coil current selected.

• Send LF Data:

This command must be used to start an LF data telegram on the selected coil. The bits

N3..0 contain the amount of nibbles to be transferred into the LF data buffer of the Atmel

ATA5279. This amount has to be coded as follows:

N3..0 = (nNibbles – 1)

Hence, a maximum of 16 nibbles or eight words and a minimum of one nibble can be

written into the buffer using one command.

Note also that this command uses one more word of space in the buffer, as the header

word is also stored. So for example, if the LF telegram consists of four words, the required

space in the LF data buffer is five words (four words of pure data and one word for the

command header).

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It is important that the amount of nibbles passed in the header word matches the number of

words transferred afterwards to the IC, as no data consistency checking can be carried out

here. If an odd number of nibbles is to be transferred, the data word on the SPI has to be

completed with dummy data in the upper nibble, as the SPI always requires complete data

words on the bus. The FIFO buffer is also only filled with complete words.

For an example, if seven nibbles of LF data (i.e., 14LF data bits) are to be sent by the

Atmel® ATA5279 via the LF channel, the Send LF Data command consists of five words,

the header word (here 06h) and four LF data words, whereas the last word contains only

four bits (the four least significant) of the LF data.

For an additional example, see Figure 3-15, which illustrates how LF transmission data is

processed in ATA5279.

Figure 3-15. LF Data Processing

• Send LF Carrier:

This command should be used when a carrier shall be transmitted on the LF channel via

the selected coil. The current will be regulated by ATA5279 to the value selected with the

last Select Coil Current command (resp. the default value of 50mA). See also Section 3.5

“Coil Current Sensing (Zero Cross, Sample and Hold, Integrator)” on page 7 for further

details.

The duration of this carrier can be defined by the T4..0 bits. Note that the time unit here is

one LF data bit, i.e., 32LF periods in normal- and 22LF periods in high-speed mode. That

leads to a maximum definable carrier time per command of 31 ×0.256ms = 7.936ms when

using an 8MHz system clock.

However, when the T4..0-value is set to 0, an endless carrier transmission with the actually

selected current on the actually active coil is started. This can be used for long-term

measurements or for energy-coupling purposes. Be aware that long-term transmissions

can produce a huge amount of heat in the driver, dependant on the selected coil current

and the properties of the coil itself. It is therefore strongly recommended to use this feature

only with a maximum current settings of 100mA; otherwise, the chip temperature might

reach excessive values.

LF Telegram

MACT Signal

BCNT Signal

SPi Data String (bin)

SPi Data String (hex)

0000 0010

02h 35h 04h

01 1010 101000

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3.9.4 Status Monitor

The status monitor holds all information from the diagnosis stage. In case of an existing fault,

all power stages are disabled. As soon as a fault is stored, an interrupt request (IRQ) to the

microcontroller is generated. This signal is persistent until the status info is polled by the

microcontroller. The entry in the fault register can only be cleared by the Reset Fault com-

mand or a global reset.

There are two different status registers:

• A general IC status register (requestable by the Get Status Info command)

• A coil-driver related fault register (requestable by the Get Fault Info command)

The fault register is encoded as follows:

The meaning of the bits is described below:

•D

G, D1..0: The driver group and number that was active when the fault occurred. Only a

selected driver can be affected by external faults. Therefore, it is sufficient to store the type

of failure and the corresponding driver number. Refer to Section 3.9.3 “Driver-related

Command Description” on page 22 for further details on the coding of these bits.

• T: A temperature shutdown has occurred. Note that there is not necessarily a link between

the driver number and this fault, as all sensor signals of the chip are OR’ed together.

However, in general, it can be assumed that the last active driver also caused the

overtemperature condition.

•F

03: This bit indicates a missing return line signal during modulation. That means that the

current detection unit was not able to find a sinusoidal signal on the VSHS pin although the

LF coil was driven. The reason for this can either be an open load condition or a

short-circuit on the AxN pin towards ground.

•F

02: This bit indicates an excessive positive voltage on the VSHS pin. In normal

applications, this is only the case if there is a high current flowing through the shunt

resistor. The typical reason for this is a short-circuit on the AxN line towards battery.

Another possible reason could be a shorted LF coil.

•F

01: This bit indicates an excessive current through the high-side transistor that drives the

AxP line. The most typical reason for this is a short-circuit towards ground.

•F

00: This bit indicates an excessive current through the low-side transistor that drives the

AxP line. The most typical reason for this is a short-circuit towards battery.

Table 3-8. Fault Assignment between Driver Stages and the Fault Registers

MSB LSB

Fault Register DGD1D0TF

03 F02 F01 F00

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3.10 Oscillator

This block provides the clock signals internally needed for control logic, the LF driver stage,

and the boost converter. The oscillator requires an external clock source, which can either be

an active signal from a microcontroller for example, or a passive oscillation device like a crys-

tal or a ceramic resonator. As the LF carrier frequency is directly derived from this clock, the

(resonance) frequency of the clock source must be chosen to match the desired LF frequency.

Possible values range from 6.4MHz to 9.6MHz, where 8MHz is the typical value resulting in an

LF frequency of 125kHz.

Note that during start-up (i.e., as long as no stable oscillation can be detected), the driving cur-

rent for the crystal is increased to shorten the start-up delay. Furthermore, the IC is only

functional if the oscillator is working properly. That means, during start-up after a power-down

phase, no communication and no operation of the IC is possible until the oscillator reaches its

operation point.

If an external clock source such as a microcontroller is to be used, the logic-level clock signal

must be applied at the OSCI pin, and the OSCO pin must be left open. Note that the chip pro-

tection features, need a clock signal present at the OSCI pin; without this, the chip is not fully

protected. Therefore, if the chip is in any mode but in power-down (reset), a clock signal is

needed.

The oscillator block is, like the control logic and the SPI, supplied by the application-provided

logic supply voltage connected to the pin VIF.

3.11 Internal Supply

The internal power supply stage provides all internally needed BIAS currents and reference

voltages. An integrated one-time-programming (OTP) structure is used to adjust internal set-

tings. This ensures parameter stability over the production process.

The internal supply block performs monitoring functions to reset or shut down the IC in case of

supply shortages or during power-up. A power-management minimizes current consumption

during power-down mode of the IC.

Another part of this block is the internal 5V voltage regulator. It is supplied by the VS pin, i.e.,

the battery supply connection. This voltage is used for all internal analog functions and driving

processes. It is active as long as the IC is not in power-down mode. To increase stability and

quality of this supply line, it is externally available (pin VCC) for connection to a ceramic

capacitor for filtering and buffering. Note that no loads must be connected to this pin.

As with the oscillator, this supply voltage must settle in its operation point prior to any opera-

tion. The control logic checks the status of this voltage and inhibits operation until it reaches

the required level. Furthermore, the driver supply voltage present on the VDSx pins is also

monitored. If the level falls below VVDS,min, the operability flag of the chip is cleared (bit Op in

the Status Register) and driver-related commands cannot be processed. Once the voltage

level is valid again, the Op bit is set again, and operability is restored.

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4. Application

Find below a typical application schematic for the Atmel® ATA5279.

Figure 4-1. Application Schematic for the Atmel ATA5279

Notes: 1. A negative current on pin MISO that causes the voltage to drop below –0.6V with respect to

ground might lead to a chip reset, comparable to a logic low on the NRES pin.

2. For applications with > 6 antennas please refer to the application note “Atmel ATA5279

Antenna Driver Extension”.

3. R1 ≥1Ω for proper operation.

4. No pull-up resistance (by means of resistor or microcontroller pull-up) allowed.

VBATT

Oscillator Internal Supply

POR, BG, UV/OV

Control Logic

Communication

Protocol Handling

Boost

Controller

LF Data BufferSPI

µC voltage supply line (VDD)

µC connection

PGND VDS

A4P

A6P

A5P

A1P

A3P

A2P

A1N

A3N

A2N

VLVCC

IRQ

BCNT

MACT

NRES

VIF

MISO(4)

MOSI

S_CLK

S_CS

OSCO

OSCI

RGND VSHSCINTAGND

R1(3)

Reference

Sine Wave

Generator

Driver Stage

Control

Ant1

Zero Cross

Detector

Return Line

Driver

HP 1-3

Integrator

Sample

and Hold

LP 1-3

Ant2

Ant3

Ant4

Ant5

PCB car

Ant6

A4N

A6N

VSHF

A5N

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4.1 Application Hints

An important application aspect is the thermal budget. Under certain conditions, high power

dissipations can occur during operation of the chip. The Atmel® ATA5279's power dissipation

mainly depends on the supply voltage and the selected antenna output current. Under worst

case conditions (e.g., low supply voltage and maximum antenna power) the power dissipation

increases exponentially and may rise to values exceeding 10W. It must be avoided under all

circumstances to exceed the specified maximum average junction temperature. Therefore, the

thermal aspects of the entire application, along with the electrical design, are essential.

The thermal resistance between the IC and the ambient has to be designed according to the

specific application requirements. It is mandatory to solder the exposed die pad to the PCB.

As many vias as possible must be provided between the top and the bottom layer (soldering

side to the PCB's backside). This copper plane is able to store and dissipate the heat. It must

be electrically connected to ground, and an appropriate heat transfer away from the chip must

be ensured. In addition, multi-layer-PCBs (more than two layers) are recommended.

The ATA5279's power dissipation depends on the supply voltage, the selected antenna

current, the antenna's impedance and further parameters such as the external components

used for the DC-DC converter. Background information, design hints and an example are

given in the application note “LF Antenna Driver ATA5279 – Thermal Considerations and PCB

Design Hints”.

It is strongly recommended to measure the power dissipation in the target application during

the design phase to verify the system's thermal budget. One option is to calculate the differ-

ence between input and output power.

Table 4-1. Bill of Materials (BOM) for Typical Application Circuit

Part Value Description

R1 1ΩShunt resistor, ±1% tolerance

C1 220µF/50V Supply line input filter and stabilizing cap

C2 100nF cer. Supply line input filter cap

C3 4.7µF/50V tant. Boost converter storage cap, low ESR

C4 100nF cer. Boost converter filter cap (+ESD clamp)

C5 100nF cer. Internal 5V supply line stabilizing cap

C6 33nF cer. Integration cap for current regulation loop

C7 100nF cer. Filter cap for µC supply line

D1 50V/3A Rectifying diode

D2 50V/3A/50ns High-speed freewheeling diode

L1 150µH Supply line input filter choke, Isat > 3A

L2 82µH Boost converter charging choke, Isat > 3A

X1 8MHz Crystal or resonator

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See the following description for details:

Mean value measured during an LF carrier transmission with the desired output current.

Pdiss,ext is the sum of power dissipated by the external components.

Alternative formula for calculating the output power.

Note: The output power can either be calculated by using the impedance of the antenna or by mea-

suring the peak-to-peak amplitude of the sinusoidal voltage applied to the antenna. As the

impedance may change under load conditions, it is recommended to use the formula with the

peak-to-peak antenna voltage.

The input power determination should be done by transmitting a single LF carrier burst with a

length of for example 8ms. The required electrical data needs to be recorded with a digital

sampling oscilloscope (DSO) and a current probe. Note that the start-up phase of the LF field

must not be used for reading out the data.

Figure 4-2. Power Dissipation on Chip Measured at Application Board ATAB5279

Note: If the VDS output voltage regulation fails due to too high input currents or too high output volt-

age, the power dissipation increases up to 40%

The power dissipation of the external components depends on their parameters and the sup-

ply current. Regarding choke L2, it is the DC resistance, regarding the freewheeling diode D2,

it is the forward biasing voltage. In addition, the equivalent series resistance (ESR) of the

charging capacitor C3 is important. The devices' names refer to the application schematic (see

Figure 4-1 on page 27).

Pdiss,tot Pin Pout

–=

Pin UVS IVBATT

×=

Pout

IAnt,p

-------------

⎝⎠

⎛⎞

2ZAnt Pdiss,ext

+×=

Pout

IAnt,p

-------------

⎝⎠

⎛⎞

UAnt,pp

22×

------------------Pdiss,ext

+×=

2.00

4.00

6.00

8.00

10.00

12.00

14.00

8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0

Supply Voltage VS (V)

IC Power Dissipation (W)

Z(Ant) = 12.5Ω

I(Ant) = 700 mAp

Z(Ant) = 12.5Ω

I(Ant) = 1000 mAp

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Atmel ATA5279

Note: To define the operation limits, the static thermal resistance of the PCB must be known (see the

measurement hints in the application note). The Atmel® ATAB5279 application board features a

total thermal resistance of 42K/W.

Under worst case conditions, e.g., low supply voltage and high antenna impedance, the maxi-

mum antenna current might not be reached.

A “static” operation of ATA5279 is not allowed for typical transmit currents of several hundreds

of mAs. Typical applications are operated with a temporary LF field, resulting in an on/off oper-

ation mode of the chip. A suitable on/off duty cycle nduty reduces the average power

dissipation and keeps the thermal budget of the system. Therefore, following equation needs

to be fulfilled:

with

Tamb the application’s maximum ambient temperature

Pdiss,tot the total power dissipation of the chip

nduty Operation duty cycle‚On-time during period, t1/tper

Note: It must be avoided to design the system's load profile in such a way that the protection features

of the chip are triggered under normal operating conditions. If the output voltage reaches the

upper shutdown limit, the power dissipation of the DC-DC converter increases significantly.

Consecutive triggering of the overtemperature shutdown may lead to a reduced lifetime.

In addition to the average junction temperature Tj,max, the maximum peak temperature during

a transmission must not be exceeded. The equation to be met is as follows:

with:

Tpeak maximum peak temperature = 200°C

Rthca Thermal resistance case-to-ambient (PCB)

t1Transmission on-time, 10 ms ≤ t

1 ≤ 1sec

tauPCB Thermal time constant of PCB (Rthca × Cthca)

nduty Operation duty cycle

Note: Application Note “LF Antenna Driver ATA5279 – Thermal Considerations and PCB Design

Hints” available

Tamb RthJA Pdiss,tot nduty Tj,max

<××+

Tpeak Pdiss Rthjc Rthca 1e

τPCB

--------------

–

⎝⎠

⎜⎟

⎛⎞

×+nduty Pdiss Rthjc Rthca

+()Tamb

+××+×≥

9125L–RKE–03/11

Atmel ATA5279

5. Absolute Maximum Ratings

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating

only and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of this

specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Parameters Symbol Min. Max. Unit

Voltage range on pin VS VVS –0.3 40 V

Voltage range on pins VDSx, VLx VVDS,max –0.3 46 V

Voltage range on pins AxP VAxP,max –0.3 VVDS + 0.3 V

Voltage range on pins VSHFx, VSHS VVSHF,max –3 VVCC + 0.3 V

Voltage range on pins AxNx VAxNx,max V

VSHF – 0.3 46 V

Voltage range on pins VCC, VIF VDIGSUP,max –0.3 +5.5 V

Voltage on pins RGND, PGNDx VGND,max –0.3 +0.3 V

Voltage range on pins NRES, S_CS, S_CLK, MOSI,

OSCI, MACT, BCNT, IRQ, MISO, OSCO VIO,max –0.3 VVIF + 0.3 V

Voltage range on pin CINT VCINT,max –0.3 VVCC + 0.3 V

ESD Voltage Ratings

- HBM (MIL-STD-883F, M. 3015.7) VESD 2kV

Count of peaks over lifetime:

Number of events

Peak junction temperature

Tj.max 500,000 at

200 °C

Note: All voltages refer to the AGND pins.

6. Thermal Resistance

Parameters Symbol Value Unit

Thermal resistance junction to case RthJC 10 K/W

Thermal resistance junction to ambient(1) RthJA 35 K/W

Note: 1. Value that can be achieved when providing sufficient thermal vias and heat dissipation area

7. Operating Range

Parameters Symbol Min. Max. Unit

Junction temperature range(1)(2)(3) Tj–40 +145 °C

Note: 1. For details see Section 5. “Absolute Maximum Ratings” on page 31

2. Triggering the overtemperature switch off mode as described in item 6.5 in Section 8. “Functional Parameters” on page

32 is not recommended for standard application. Note: The permanent use of overtemperature switch off will reduce the

life time of the IC.

3. For more details in terms of thermal considerations please refer to the application note “Thermal Considerations and PCB

Design Hints”.

9125L–RKE–03/11

Atmel ATA5279

8. Functional Parameters

All parameters valid for 7.0V ≤VS ≤16.5V and –40°C ≤Ta ≤105°C unless otherwise noted.

No. Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Type*

1Power Supply

1.1 VS-pin power-down

mode supply current VVS ≤14V 1 IVSpd 5.5 10 µA A

1.2 VS-pin idle mode

supply current VVS = 16.5V 1 IVS,idle 3.5 5 mA A

1.3

Internal VCC voltage

- idle

- load

7V ≤ VS ≤ 28V

IVCC = 0

IVCC = 5mA

VCC,0

VVCC,1

4.8 5.05 5.3 V A

1.4 VS voltage clamp VS = 28V

VS = 40V 1IVS,C28

IVS,C40

1.5

180

400

4.5

µA

mA A

1.5 VCC power-on reset

threshold 4V

PORVCC 4.1 4.8 V A

1.6 VDS operation

threshold VS = 16.5V DS VVDS,min 5.1 5.15 6 V A

1.7 Battery supply range for

normal operation Idle mode 1 VVS 7 16.5 V D

1.8 VDS power-down mode

supply current VVDS = 28V DS IVDS,0 0 0.12 1.4 µA A

1.9 VDS fault-shutdown

mode supply current VVDS = 16.5V DS IVDS,FS 0.85 2.45 mA A

1.10 Battery supply range for

Jump start operation Idle mode 1 VVS 7 26.5 V D

1.11 VCC power-up time 4 tVCC 200 µs D

1.12 Minimum VS voltage

level for VCC operation 1V

VS,min 6VD

2Boost Converter

2.1 Overvoltage shut-down

level DS VVDSmax 40 42 44 V A

2.2 Switch overcurrent

shutdown level BLS IVLmax 2.9 3.2 4 A A

2.3 Switch on-state

resistance IVL = 500mA BLS RDSon,VL 0.5 ΩA

2.4 Max duty cycle (ton / T) BLS DBoost 0.875 - A

2.5 Switch leakage current VVL = 38V BLS IVL,leak 500 nA A

2.6 Switch fall time IVL = 200mA BLS tVL,f 50 200 ns A

2.7 Switch rise time IVL = 200mA BLS tVL,r 50 200 ns A

3 Oscillator

3.1 External clock source

frequency range CSP fOSC 6.4 8 9.6 MHz D

3.2

Driver output sink

resistance during

startup

IOSCO = 100µA CSP ROSC,L1 0.9 2.2 kΩA

*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter

Notes: 1. In this column, pin group names are given. Please refer to Section 2. “Pin Configuration” on page 2 in this document for

more details.

2. Operation of coils with higher impedance than the given value is possible but functional limitations might occur (inability to

reach to configured coil current). Coils with lower impedance should not be used as they might be detected as faulty.

9125L–RKE–03/11

Atmel ATA5279

3.3

Driver output sink

resistance during

operation

IOSCO = 100µA CSP ROSC,L1 1.8 4.4 kΩA

3.4

Driver output source

resistance during

startup

IOSCO = –100µA CSP ROSC,L1 0.9 2.2 kΩA

3.5

Driver output source

resistance during

operation

IOSCO = –100µA CSP ROSC,L1 1.8 4.4 kΩA

3.6 Feedback resistance VOSCI, OSCO = 5V CSP RFB,OSC 220 360 kΩA

3.7 Clock input low-to-high

detection threshold CSP VLH,OSC 0.45 ×

VIF

0.55 ×

VIF A

3.8 Power-down input

pull-down resistance

VOSCI = 5V

VVIF = 5V 7R

OSCI,0 36kΩA

4 High-current Driver Stage (A1P, A2P, A3P)

4.1 Sourcing current limit

(RMS) Idle mode, DC ramping HDL IHP,HSCL –1.7 –0.88 A B

4.2 Sinking current limit

(RMS) Idle mode, DC ramping HDL IHP,LSCL 1.1 2 A B

4.3 Signal difference carrier

to harmonics 2, 3, 4, 5

VAxP,pp = 30V

Icoil,p = 200mA

fOSCI = 8MHZ

HDL DSig –34 dB A

4.4

Load imped. range

(amount of complex

impedance)(2) Icoil,pp = 2App HDL

HRL ZCoil,HP 212ΩD

4.5 Min. output voltage IAxP = 200mA

Tj ≅ 30°C HDL VOHP,min 2.5 4.3 V A

4.6 Max. output voltage IAxP = –200mA

Tj ≅ 30°C HDL VOHP,max VDS – 4.5 VDS –

2.5 VA

4.7 Idle mode cross current VVDS = 16.5V DS IAxPH,CC 35 50 68 mA A

4.8 Idle mode output

voltage

VVDS = 20V

IAxP = 0

IAxP = ±200mA

Tj ≅ 30°C

HDL VAxPH,dile 911VA

4.9 Inactive pull-up current

VVDS = 20V

IAxP = –100µA

Tj ≅ 30°C

HDL RAxPH,PU 11.5 27 kΩB

4.10 Diagnosis mode pull-up

current

VVDS = 16.5V

VAxP = 0V IPU,Diag –150 –100 µA A

4.11 Diagnosis mode

pull-down current

VVDS = 16.5V

VAxP = 16.5V IPD,Diag 170 260 µA A

8. Functional Parameters (Continued)

All parameters valid for 7.0V ≤VS ≤16.5V and –40°C ≤Ta ≤105°C unless otherwise noted.

No. Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Type*

*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter

Notes: 1. In this column, pin group names are given. Please refer to Section 2. “Pin Configuration” on page 2 in this document for

more details.

2. Operation of coils with higher impedance than the given value is possible but functional limitations might occur (inability to

reach to configured coil current). Coils with lower impedance should not be used as they might be detected as faulty.

9125L–RKE–03/11

Atmel ATA5279

5 Low Current Driver Stage (A4P, A5P, A6P)

5.1 Sourcing current limit

(RMS) Idle mode, DC ramping LDL ILP,HSCL –1.2 –0.55 A B

5.2 Sinking current limit

(RMS) Idle mode, DC ramping LDL ILP,LSCL 0.9 1.7 A B

5.3 Signal difference carrier

to harmonics 2, 3, 4, 5

VAxP,pp = 30V

Icoil,p = 200mA

fOSCI = 8MHZ

LDL DSig –34 dB A

5.4

Load imped. range

(amount of complex

impedance)(2)

LDL

LRL ZCoil,LP 10 25 ΩD

5.5 Min. output voltage IAxP = 200mA

Tj ≅ 30°C LDL VOLP,min 2.5 4.3 V A

5.6 Max. output voltage IAxP = –200mA

Tj ≅ 30°C LDL VOLP,max VDS – 4.5 VDS –

2.5 VA

5.7 Idle mode cross current VVDS = 16.5V DS IAxPL,CC 28 40 53 mA A

5.8 Idle mode output

voltage

VVDS = 20V

IAxP = 0

IAxP = ±200mA

Tj ≅ 30°C

HDL VAxPL,dile 911VA

5.9 Inactive pull-up current

VVDS = 20V

IAxP = –100µA

Tj ≅ 30°C

HDL RAxPL,PU 11.5 27 kΩB

5.10 Diagnosis mode pull-up

current

VVDS = 16.5V

VAxP = 0V

HDL

LDL IPU,Diag –150 –100 µA A

5.11 Diagnosis mode

pull-down current

VVDS = 16.5V

VAxP = 16.5V

HDL

LDL IPD,Diag 170 260 µA A

6 Coil Return Line and Diagnosis Stage (A1N … A6N)

6.1 Return line switch

on-state resistance

IHPS = 0.3A

ILPS = 0.22A

HRL

LRL

RDS,onHPS

RDS,onLPS

1.05

1.2 Ω

ΩA

6.2

Return line switch

overcurrent shutdown

threshold

RShunt = 1Ω

Ch. 1-3 selected

Ch. 4-6 selected

RLO IShunt,max 1.25

0.875

1.75

1.225

6.3 Diagnosis mode pull-up

current

VVDS = 16.5V

VAxP/N = 0V

HRL

LRL IPU,Diag –150 –100 µA A

6.4 Diagnosis mode

pull-down current

VVDS = 16.5V

VAxP/N = 16.5V

HRL

LRL IPD,Diag 170 260 µA A

6.5 Overtemperature

shutdown threshold TOTsdwn 145 170 °C B

6.6

Open load and short

circuit detection AxN to

GND

HRL

LRL tOLdet 115 215 µs A

8. Functional Parameters (Continued)

All parameters valid for 7.0V ≤VS ≤16.5V and –40°C ≤Ta ≤105°C unless otherwise noted.

No. Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Type*

*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter

Notes: 1. In this column, pin group names are given. Please refer to Section 2. “Pin Configuration” on page 2 in this document for

more details.

2. Operation of coils with higher impedance than the given value is possible but functional limitations might occur (inability to

reach to configured coil current). Coils with lower impedance should not be used as they might be detected as faulty.

9125L–RKE–03/11

Atmel ATA5279

6.7 Short circuit detection

AxP or AxN to Vbatt

HRL

LRL tOLdet 100 µs B

7 Zero Crossing Detector

7.1 Pos. slope detection

threshold 5V

ZC –10 +10 mV A

7.2 Polarity detection delay

Voltage jump from

VVSHS – 20mV to

VVSHS + 20mV

ZCdel 150 290 ns A

8 Sample and Hold Stage

8.1 Sampled differential

voltage

Sampling state

Current step 20

selected

VVSHS = 200 mVpp

VVSHS = 1 Vpp

Vsmpl,1

Vsmpl,2

830

440

970

560

9 Integrator Stage

9.1 Input offset voltage 5 Vofs,Integ –2.5 +2.5 mV B

9.2 Positive output linearity

VVSHS = 1.1Vpp

Current step 20

selected

INT,POS –20 –8 µA A

9.3 Negative output

linearity

VVSHS = 0.9Vpp

Current step 20

selected

INT,NEG 820µAA

9.6 Upper output voltage

limit

ICINT = 30µA

VSHS = 100mVp

Current step 20

selected

CINT,max 3.15 3.45 V A

10 References

10.1 Current step 1 level - VREF,S1 49.5 54.5 mV A

10.2 Current step 2 level - VREF,S2 97 105 mV A

10.3 Current step 3 level - VREF,S3 145 157 mV A

10.4 Current step 4 level - VREF,S4 192 208 mV A

10.5 Current step 5 level - VREF,S5 245 255 mV A

10.6 Current step 6 level - VREF,S6 294 306 mV A

10.7 Current step 7 level - VREF,S7 343 357 mV A

10.8 Current step 8 level - VREF,S8 392 408 mV A

10.9 Current step 9 level - VREF,S9 441 459 mV A

10.10 Current step 10 level - VREF,S10 490 510 mV A

10.11 Current step 11 level - VREF,S11 539 561 mV A

10.12 Current step 12 level - VREF,S12 588 612 mV A

10.13 Current step 13 level - VREF,S13 637 663 mV A

10.14 Current step 14 level - VREF,S14 686 714 mV A

8. Functional Parameters (Continued)

All parameters valid for 7.0V ≤VS ≤16.5V and –40°C ≤Ta ≤105°C unless otherwise noted.

No. Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Type*

*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter

Notes: 1. In this column, pin group names are given. Please refer to Section 2. “Pin Configuration” on page 2 in this document for

more details.

2. Operation of coils with higher impedance than the given value is possible but functional limitations might occur (inability to

reach to configured coil current). Coils with lower impedance should not be used as they might be detected as faulty.

9125L–RKE–03/11

Atmel ATA5279

10.15 Current step 15 level - VREF,S15 735 765 mV A

10.16 Current step 16 level - VREF,S16 784 816 mV A

10.17 Current step 17 level - VREF,S17 833 867 mV A

10.18 Current step 18 level - VREF,S18 882 918 mV A

10.19 Current step 19 level - VREF,S19 931 969 mV A

10.20 Current step 20 level - VREF,S20 980 1020 mV A

11 Digital Interface (SPI, Control Logic)

11.1 Supply current in

operation mode VVIF ≤5.5V 6 IsupVIF 0.6 1.9 3 mA A

11.2 Supply current in

power-down mode VVIF = 5.0V 6 2 30 µA A

11.3 SPI clock period Chip in operation 39 TSPI 4 × 1/fOSCI sD

11.4 SPI clock low-phase

timing Chip in operation 39 tLo,min 2 ×

1/fOSCI sD

11.5 SPI clock high-phase

timing Chip in operation 39 thi,min 2 ×

1/fOSCI sD

11.6 SPI output enabling

time Chip in operation tMISOon,max 100 ns D

11.7 SPI output disabling

time Chip in operation tMISOoff,max 100 ns D

11.8 Minimum SPI disable

time Chip in operation tSPIoff,min 4 ×

1/fOSCI sD

11.9 Minimum chip select

setup time Chip in operation tCSset,min 2 ×

1/fOSCI sD

11.10 Minimum chip select

hold time Chip in operation tCShold,min 2 ×

1/fOSCI sD

11.11 Minimum data input

setup time Chip in operation tsetup,min 100 ns D

11.12 Minimum data input

hold time Chip in operation thold,min 100 ns D

11.13 Output source

capability

VVIF = 5V

ISource = –1mA DO Vdig,H 4.75 V A

11.14 Output sink capability VVIF = 5 V

Isink = 1mA DO Vdig,L 0.25 V A

11.15 Input current

Vin = 0V

VVIF = 5.5V

Vin = 5.5V

VVIF = 5.5V

Iin,L

Iin,H

–0.2

–60

–20

0.2

µA A

8. Functional Parameters (Continued)

All parameters valid for 7.0V ≤VS ≤16.5V and –40°C ≤Ta ≤105°C unless otherwise noted.

No. Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Type*

*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter

Notes: 1. In this column, pin group names are given. Please refer to Section 2. “Pin Configuration” on page 2 in this document for

more details.

2. Operation of coils with higher impedance than the given value is possible but functional limitations might occur (inability to

reach to configured coil current). Coils with lower impedance should not be used as they might be detected as faulty.

9125L–RKE–03/11

Atmel ATA5279

11.16 Input high level

threshold VVIF = 3.1V DI VLH 0.48 0.64 VVIF A

11.17 Input low level threshold VVIF = 3.1V DI VHL 0.32 0.48 VVIF A

11.18 External reset input

timing tNRES,min 100 ns D

11.19 Tristate output leakage

current VMISO = 2.5V IL,max 500 nA A

8. Functional Parameters (Continued)

All parameters valid for 7.0V ≤VS ≤16.5V and –40°C ≤Ta ≤105°C unless otherwise noted.

No. Parameters Test Conditions Pin Symbol Min. Typ. Max. Unit Type*

*) Type means: A = 100% tested, B = 100% correlation tested, C = Characterized on samples, D = Design parameter

Notes: 1. In this column, pin group names are given. Please refer to Section 2. “Pin Configuration” on page 2 in this document for

more details.

2. Operation of coils with higher impedance than the given value is possible but functional limitations might occur (inability to

reach to configured coil current). Coils with lower impedance should not be used as they might be detected as faulty.

9125L–RKE–03/11

Atmel ATA5279

10. Package Information

9. Ordering Information

Extended Type Number Package Remarks

ATA5279P-PLQW VQFN48, 7mm × 7mm Taped and reeled, MOQ 4000

ATA5279P-PLPW VQFN48, 7mm × 7mm Taped and reeled, MOQ 1000

ATA5279C-PLQW VQFN48, 7mm × 7mm Taped and reeled, MOQ 4000

ATA5279C-PLPW VQFN48, 7mm × 7mm Taped and reeled, MOQ 1000

specifications

according to DIN

technical drawings

Issue: 1; 19.10.06

Drawing-No.: 6.543-5137.01-4

0.5 nom.

5.5

24 13

37 48

4.5±0.15

Bottom

Pin 1 identification

Top

Package: VQFN_7 x 7_48L

Exposed pad 4.5 x 4.5

Dimensions in mm

Not indicated tolerances ±0.05

0.2

0.9±0.1

0.4±0.1

Z 10:1

0.23±0.07

9125L–RKE–03/11

Atmel ATA5279

11. Revision History

Please note that the following page numbers referred to in this section refer to the specific revision

mentioned, not to this document.

Revision No. History

9125L-RKE-03/11 • ATA5279C on page 1 added

9125K-RKE-11/10 • Section 9 “Ordering Information” on page 38 changed

9125J-RKE-11/10 • Section 8 “Functional Parameters” numbers 4.9, 5.9, 6.6 and 6.7 on pages

33 to 35 changed

9125I-RKE-09/10

• Figure 1-1 “Block Diagram” on page 1 changed

• Table 2-1 “Pin Description” on page 3 changed

• Order of Figures 3-6 to 3-9 on pages 14 to 15 changed

• Figure 4-1 “Application Schematic for ATA5279” on page 27 changed

• Table 4-1 “Bill of Materials (BOM) for Typical Application Circuit” on page 28

changed

• Section 7 “Operating Range” on page 31 changed

• Section 8 “Functional Parameters” numbers 1.11 and 1.12 on page 32 added

• Section 8 “Functional Parameters” numbers 11.1 to 11.12 on page 36 changed

9125H-RKE-05/10

• Datasheet ATA5279P renamed in datasheet ATA5279

• Ordering number for small taped & reeled unit introduced as following:

ATA5279P-PLPW

9125G-RKE-01/10

• Features item 3 “On-off-keyed Data Modulation ... “ on page 1 changed

• Table 3-1 “States of Driver Outputs within Operation Modes” on page 6 added

• Table 3-4 “States of Control I/Os” on page 16 added

• Note 2 “For applications with 6 antennas ... “ on page 27 added

• Note “Application Note - LF Antenna Driver ATA5279P ... “ on page 30 added

• Section 5 “Absolute Maximum Ratings” part “Count of peaks over lifetime ... “

on page 31 changed

• Section 7 “Operating Range” Note 2 “Triggering the overtemperature ... “ and

Note 3 “For more details in terms ... “ on page 31 changed

• Data rate from 4.0kbit/s to 3.9kbit/s on pages 18, 19 and 23 changed

9125F-RKE-09/09

• Features changed

• Table 2-1 (page 2) changed

• Page 23: last paragraph changed

• Text under heading 3.4 “Boost Converter” changed

• Text under heading 3.6 “Diagnosis” changed

• New section “4.1 Application Hints” added

• Table Abs. Max. Ratings changed

• Table Th. Resistance added

• Table El. Characteristics changed

9125E-RKE-04/09 • Table “Functional Parameters” item 1.10 added and item 1.3 changed

9125D-RKE-02/09

• Section 3.9.2 “General Command Description” on pages 20 to 21 changed

• Section 3.9.3 “Driver-related Command Description” on pages 21 to 22

changed

9125C-RKE-01/09 • ATA5279 renamed in ATA5279N

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