AS1907-C16-T - Austriamicrosystems

AS1907, AS1908, AS1909

Low-Voltage Microprocessor Reset Circuits

www.austriamicrosystems.com/Supervisors/AS1907-09 Revision 1.07 1 - 11

Datasheet

1 General Description

The AS1907/AS1908/AS1909 microprocessor supervisory circuits

are ideal for monitoring the supply voltage of digital systems and

microprocessors.

The devices are designed to initiate a reset if the supply voltage goes

below a predefined threshold. The duration of the reset is either 1.5,

30, or 150ms (typ.) after the supply voltage has risen above the pre-

set threshold (see Ordering Information on page 10).

The devices are available as the standard products listed in Table 1.

The reset thresholds are factory-set between 1.6 and 2.5V in steps

of approximately 100mV (see Table 5 on page 7).

The devices exhibit excellent reliability, and can reduce system costs

by eliminating the need for external components. The extremely low

current consumption makes the devices ideal for use in portable

applications.

The integrated reset comparator was specifically designed to ignore

fast transients on VCC.

The devices are available in a 3-pin SOT23 package.

Figure 1. Application Diagrams

2 Key Features

 3 Output Types: Push/Pull RESET, Push Pull RESETN, and

Open Drain RESETN

 Reset Threshold Range: 1.6 to 2.5V (~100mV increments)

 RESET/RESETN:

- Valid to VCC = 0.7V (AS1907 and AS1908)

- Valid to VCC = 1.0V (AS1909)

 Reset Pulse Widths: 1, 20, and 100ms

 Supply Vo ltage Range: +0.7 to +3.6V

 Supply Current Range: 2.6 to 7.0µA

 Power Supply Transient Immunity

 Requires No External Components

 Operating Temperature Range: -40 to +125ºC

 3-pin SOT23 Package

3 Applications

The devices are ideal for use in cordless and mobile phones, MP3

players, CD and DVD players, PDAs, handheld computers, digital

cameras, hard drives, and any other application where power supply

supervisory control is required.

Table 1. Standard Products

Model Output Type Reset Type

AS1907 Push/Pull Active-Low

AS1908 Push/Pull Active-High

AS1909 Open-Drain Active-Low

RESET

AS1908

Micro-

processor

VCCVCC

GND 1

VCC 3 VCC 3

RESET I/O

RESETN

AS1907

GND 1

VCC 3

GND 1

Micro-

processor

VCC 3

RESET I/O

GND 1

RESETN

AS1909

Micro-

processor

VCC

GND 1

VCC 3 VCC 3

RESET I/O

GND 1

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AS1907/AS1908/AS1909

Datasheet - Pinout

4 Pinout

Pin Assignments

Figure 2. Pin Assignments (Top View)

Pin Descriptions

Table 2. Pin Descriptions

Pin Number Pin Name Description

1GND

Ground

RESET Active-High Reset Output (AS1908). This pin stays high whenever VCC is below the RESET

threshold VTH (see page 7), and for tTP (see page 4) after VCC rises above VTH.

RESETN Active-Low Reset Output (AS1907, AS1909). This pin remains low while VCC is below the

RESET threshold VTH (see page 7), and for tTP (see page 4) after VCC rises above VTH.

Note: This pin is open-drain on the AS1909.

3VCC Positive Supply Voltage. Connect to +0.7 to +3.6V supply.

AS1908/

AS1907/

AS1909

GND

RESET,

RESETN

3VCC

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AS1907/AS1908/AS1909

Datashee t - A b s o l u t e M a x i mu m R a t i n g s

5 Absolute Maximum Ratings

Stresses beyond those listed in Table 3 may cause permanent damage to the device. These are stress ratings only, and functional operation of

the device at these or any other conditions beyond those indicated in Section 6 Electrical Characteristics on page 4 is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

Table 3. Absolute Maximum Ratings

Parameter Min Max Units Comments

Electrical Parameters

VCC to GND -0.3 +5.0 V

Open-Drain RESETN -0.3 +6.0 V

Push/Pull RESET, RESETN -0.3 VCC +

0.3 V

Input Current (VCC)20mA

Output Current (RESET, RESETN) 20 mA

Continuous Power Dissipation

(TAMB = +70ºC) 320 mW 3-pin SOT23 derate 4mW/ºC above +70ºC

Temperature Ranges and Storage Conditions

Junction Temperature +150 ºC

Storage Temperature Range -55 +150 ºC

Package Body Temperature +260 ºC

The reflow peak soldering temperature (body temperature)

specified is in accordance with IPC/JEDEC J-STD-020

“Moisture/Reflow Sensitiv ity Cl ass ific ati on for Non-

Hermetic Solid State Surface Mount Devices”.

The lead finish for Pb-free leaded packages is matte tin

(100% Sn).

Humidity non-condensing 885%

Moisture Sensitive Level 1 Represents a max. floor life time of unlimited

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AS1907/AS1908/AS1909

Datasheet - Electrical Characteristics

6 Electrical Characteristics

VCC = Full Range, T AMB = -40 to +125ºC (unless otherwise specified). T yp values are at VCC = +3.0V, T AMB = +25ºC. All limits are guaranteed.

The parameters with min and max values are guaranteed with production tests or SQC (Statistical Quality Control) methods.

Table 4. Electrical Characteristics

Parameter Symbol Conditions Min Typ Max Unit

Supply Voltage Range VCC

TAMB = 0 to +85ºC AS1907, AS1908 0.7 3.6

AS1909 1.0 3.6

TAMB = -4 0 to +85ºC AS1907, AS1908 0.78 3.6

AS1909 1.2 3.6

TAMB = -40 to +125ºC 1.2 3.6

Supply Current1

1. Not valid if VCC = VTH.

ICC VCC = 1.8V, no load 2.4 6.0 µA

VCC = 2.5V, no load 2.6 7.0

TAMB = +25ºC VTH -

0.9% VTH VTH +

0.9% V

RESET Threshold Voltage VTH TAMB = 0ºC to +50°C;

AS1909C17, AS1909C168, AS1909C188 only VTH -

1.2% VTH VTH +

1.2% V

TAMB = -40 to +125ºC VTH -

3% VTH VTH +

3% V

VCC Falling Reset Delay tRD VCC falling at 10V/ms 33 µs

RESET Active

Time-Out Period tTP

AS190x-Azz-T 1 1.5 2 msAS190x-Bzz-T 20 30 40

AS190x-Czz-T 100 150 200

RESETN Output Low Voltage; RESET

asserted

(AS1907/AS1909) VOL ISINK = 50µA, VCC ≥ 1.0V 0.4 V

ISINK = 500µA, VCC ≥ 1.8V 0.3

RESETN Output High V oltage; RESET

Not Asserted (AS1907) VOH ISOURCE = 200µA, VCC ≥ 1.8V 0.8 x

VCC V

ISOURCE = 500µA, VCC ≥ 2.7V 0.8 x

VCC

RESET Output Voltage; RESET

Asserted (AS1908) VOH ISOURCE = 1µA, VCC ≥ 1.0V 0.8 x

VCC V

ISOURCE = 200µA, VCC ≥ 1.8V 0.8 x

VCC

RESET Output Voltage; RESET Not

Asserted (AS1908) VOL ISINK = 500µA, VCC ≥ 1.8V 0.3 V

ISINK = 1.2mA, VCC ≥ 2.7V 0.3

RESETN Output Leakage Current;

RESETN

Deasserted (AS1909) ILEAK VCC > VTH 0.5 µA

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AS1907/AS1908/AS1909

Datasheet - Typical Operating Characteristics

7 Typical Operating Characteristics

TAMB = +25ºC (unless otherwise specified).

Figure 3. Supply Current vs. Temperature Figure 4. Supply Current vs. Supply Voltage

Figure 5. Normalized Reset Timeout Period vs. Figure 6. Output Voltage Low vs. Temperature

Temperature, VTH = 2.3VReset Asserted

Figure 7. Max. Transient Duration vs. Figure 8. VCC falling Propagation Delay vs.

Reset Comparator OverdriveTemperature

1.4 1.8 2.2 2.6 3 3.4 3.8

Supply Volt age ( V)

Supply Cur r ent ( µA) .

2.2

2.4

2.6

2.8

3.2

-50 -25 0 25 50 75 100 125

Temperature (° C)

Supply Cur r ent ( µA) .

VCC = 2.5V

VCC = 1.8V

-50 -25 0 25 50 75 100 125

Temperature ( °C)

O utput V olt age Low ( m V ) .

VCC = 1.8V

ISINK = 500µA

VCC = 2.2V

ISINK = 500µA

VCC = 0.7V

ISINK = 50µA

VCC = 1.0V

ISINK = 50µA

0.9

1.1

1.2

1.3

-50 -25 0 25 50 75 100 125

Temperature (° C)

Norm. Reset Timeout Period .

100

120

140

-50 -25 0 25 50 75 100 125

Temperature (° C)

Pr opagation Delay ( µ s ) .

100

200

300

400

500

600

700

0.1 1 10 100 1000

Reset Comparator Overdr ive (mV)

M ax . T r ans ient Duration (µs) .

Reset Occurs

Reset does

not Occur

VCC falling at 1V/ms

VCC falling at 10V/ms

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AS1907/AS1908/AS1909

Datasheet - Typical Operating Characteristics

Figure 9. Output Voltage Low vs. VCC, ISINK = 50µA Figure 10.

Output Voltage Low

vs. VCC, ISINK = 100µA

Figure 11. Output Voltage Low vs. VCC, ISINK = 500µA

0.7 1 1.3 1.6 1.9 2.2

VCC (V)

O utput V olt age Low ( m V ) .

Temp = -40°C

Temp = +25°C

Temp = +85°C

Temp = +125°C

0.7 1 1.3 1.6 1.9 2.2

VCC (V)

O utput V olt age Low ( m V ) .

Temp = -40°C

Temp = +25°C

Temp = +85°C

Temp = +125°C

100

150

200

250

0.7 1 1.3 1.6 1.9 2.2

VCC (V)

O utput V olt age Low ( m V ) .

Temp = -40°C

Temp = +25°C

Temp = +85°C

Temp = +125°C

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AS1907/AS1908/AS1909

Datasheet - Application Information

8 Application Information

Negative Going VCC Transients

All devices are effectively immune to short-duration, negative-going VCC transients (glitches). The Maximum Transient Duration vs. Reset Com-

parator Overdrive graph (see page 5) shows the maximum pulse width that a negative-going VCC transient may typically have without issuing a

reset signal. As the amplitude of the transient increases, the maximum allowable pulse width decreases.

Valid Reset Output

If VCC falls below 1V and approaches the minimum operating voltage of 0.7V , push/pull-type reset sinking/sourcing capabilities greatly decrease.

High-impedance CMOS-logic inputs connected to RESET can drift to indeterminate voltages, although this is normally not a problem since most

microprocessors do not operate at VCC < 1V.

For the AS1908, where RESET must be valid to VCC = 0, a 100kΩ pull-up resistor between RESET and VCC (see Figure 1 on page 1) will hold

RESET high if VCC falls below 0.7V.

For the AS1907, where RESET must be valid down to 0V, add a pull-down resistor between RESET and GND (see Figure 1 on page 1) to elimi-

nate stray leakage currents and hold RESET low. A pull-down resistor of 100kΩ is large enough not to load RESET yet small enough to pull it

low.

Since the AS1909 has an open-drain, active-low output, it typically uses a pull-up resistor. With this device, RESET will most likely not maintain

an active condition, but will drift to a non-active level due to the pull-up resistor and the reduced sinking capability of the open drain device.

Therefore, this device is not recommended for applications where the RESET pin is required to be valid down to VCC = 0.

Bi-Directional Microprocessor Interface

The RESET output on the AS1909 is open-drain, thus this device can interface easily with microprocessors that have bi-directional reset pins,

such as the Motorola 68HC11.

Connect the RESET output of this device directly to the microprocessor’s RESET I/O pin with a single pull-up resistor to allow either device to

assert reset (see Figure 1 on page 1).

Layout Considerations

The devices require proper layout and design procedures for optimum performance.

 Short, wide traces should be used to reduce stray inductance and capacitance.

 Bypass capacitors should be as close to the device as possible.

 Large ground planes should be used wherever possible.

Table 5. Reset Thresholds

Reset Thresholds

TAMB = +25ºC TAMB = -40 to +125ºC

Suffix Min Typ Max Min Max

25 2.478 2.50 2.523 2.43 2.58

24 2.378 2.40 2.422 2.33 2.47

23 2.279 2.30 2.321 2.23 2.37

22 2.180 2.20 2.220 2.13 2.27

21 2.081 2.10 2.119 2.04 2.18

20 1.982 2.00 2.018 1.94 2.06

19 1.883 1.90 1.917 1.84 1.96

18 1.784 1.80 1.816 1.75 1.85

17 1.685 1.70 1.715 1.65 1.75

16 1.586 1.60 1.614 1.55 1.65

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AS1907/AS1908/AS1909

Datasheet - Package Drawings and Markings

9 Package Drawings and Markings

Figure 12. 3-pi n SOT23 Marking

Top Marking Bottom Marking

xxxx- encoded Datacode

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AS1907/AS1908/AS1909

Datasheet - Package Drawings and Markings

Figure 13. 3-pi n SOT23 Package

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AS1907/AS1908/AS1909

Datasheet

10 Ordering Information

The devices are available as the standard products shown in Table 6.

Non-standard versions require a minimum order of 30,000 units. Contact austriamicrosystems, AG for availability of non-standard versions.

Note: All products are RoHS compliant.

Buy our products or get free samples online at ICdirect: http://www.austriamicrosystems.com/ICdirect

For further information and requests, please contact us mailto:sales@austriamicrosystems.com

or find your local distributor at http://www.austriamicrosystems.com/distributor

* These devices are available in factory-set VCC reset thresholds from 1.6V to 2.5V, in approximately 100mV increments. Choose the desired

reset threshold suffix from (see Table 5 on page 7) and insert it instead of “yy” in the part number.

Factory-programmed reset timeout periods are also available. Insert the code corresponding to the desired nominal reset timeout period (see

Table 7) instead of “x” in the part number. All devices available in tape-and-reel only.

Table 6. Ordering Information

Ordering Code Marking Reset Type Reset Threshold Minimum Reset

Timeout Delivery Form

AS1908C18-T ASHU Active High 1.8V 100ms Tape and Reel

AS1908C20-T ASHV Active High 2.0V 100ms Tape and Reel

AS1907C16-T ASHP A cti ve Low 1.6V 100ms Tape and Re el

AS1907C18-T ASHQ Active Low 1.8V 100ms Tape and Reel

AS1907C20-T ASHR Active Low 2.0V 100ms Tape and Reel

AS1907C22-T ASNB A cti ve Low 2.2V 100ms Tape and Re el

AS1907B23-T ASHX Active Low 2. 3V 20ms Tape and Re el

AS1909C16-T ASHY Open Drain 1.6V 100ms Tape and Reel

AS1909C168-T ASSB Open Drain 1.68V 100ms Tape and Reel

AS1909C17-T ASHZ Open Drain 1.7V 100ms Tape and Reel

AS1909C18-T ASND Open Drain 1.8V 100ms Tape and Reel

AS1909C188-T ASTE Open Drain 1.88V 100ms Tape and Reel

AS1909C20-T ASH1 Open Drain 2.0V 100ms Tape and Reel

AS1909C22-T ASNC Open Drain 2.2V 100ms Tape and Reel

AS1909C23-T ASH2 Open Drain 2.3V 100ms Tape and Reel

Table 7. Coding of Factory-Trimmed Reset Active T ime-Out Period

Device Suffix tTP in Milliseconds

Min Typ Max

AS1907xyy-T*

AS1908xyy-T*

AS1909xyy-T*

A11.52

B203040

C 100 150 200

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AS1907/AS1908/AS1909

Datasheet

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Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale.

austriamicrosystems AG makes no warranty, express, statutory , implied, or by description regarding the information set forth herein or regarding

the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at

any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for

current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range,

unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are

specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100

parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location.

The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not

be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use,

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Tel: +43 (0) 3136 500 0

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