LM2601MTC - National Semiconductor

LM2601

LM2601 Adapter Interface Circuit

Literature Number: SNVS079B

LM2601

OBSOLETE

August 25, 2011

Adapter Interface Circuit

General Description

The Adapter Interface Circuit (AIC) is used to sense the pres-

ence of an external power source for a portable computer. It

notifies the computer if a source is present and indicates if the

source is appropriate for charging battery packs inside the

computer. The AIC also senses an adapter current and its

direction. AIC isolates the adapter and signals the computer

when peak current threshold is exceeded.

LM2601 drives P-channel FETs. No high current rated Schot-

tky diode is required to implement an adapter switchover

circuit. This significantly decreases additional heat dissipation

during simultaneous fast battery charging while running a

computer, particularly in Maximum Performance mode of op-

eration

Features

■Detects an AC-DC adapter suitable for battery charging or

an airplane or car power line adapter that should not be

used for battery charging

■Allows the implementation of intelligent switchover circuits

for portable systems

■LM2601 shuts down automatically when adapter is

removed

■Low leakage current from battery when not powered

■Drives P-channel FETs, no Schottky diodes are required

■No reverse inrush current from battery into the adapter

output capacitance

■Allows for battery capacity gas-gauge calibration under

system software/firmware control

■Adapter over current threshold programmable with

external resistors

■Wide input range: 5V - 24V

■Available in TSSOP-14 package

Applications

■Portable Computers

■Portable IAs (Internet Appliances, Information Appliances)

■Other Battery Powered Devices

Block Diagram

10130901

101309 Version 3 Revision 4 Print Date/Time: 2011/08/25 16:34:51

LM2601 Adapter Interface Circuit

Pin Configuration

TSSOP-14

10130902

Ordering Information

Order Number Package Number Package Type Supplied As*

LM2601MTC MTC14 TSSOP-14 Rail (94 Units/Rail)

LM2601MTCX MTC14 TSSOP-14 Tape and Reel (2500 Units/Reel)

* Partial Rails are available, there is no minimum order quantity. Tape and Reel is supplied as full reels only.

Pin Description

Pin No. Name Function

1 MPS DELAY A capacitor between this pin and ground sets the delay of the MPS risetime. See MPS DELAY

description in Typical Application section.

2 MASTER POWER

SOURCE

Bi-directional logic pin. If driven high by an external source, indicates that a battery is powering the

power bus. If driven high by the AIC, indicates the adapter is powering the bus. AIC cannot drive

MPS low. If there is no valid adapter voltage present, the pin is not an output but a high impedance

logic input. The input is pulled-down via an internal 40k resistor.

3 ADAPTER ENABLE Logic input pin. Active high. Grants permission to the adapter to drive both the power bus and the

MPS signal.

4 ADAPTER

PRESENT

Logic output pin. High when 12 volts < VADAPTER < 17 volts. The output typically has 40k pull-down

resistor. The source current is not internally limited and the part can be damaged if the output is

shorted to ground when driven HIGH.

5 CHARGER

PRESENT

Logic output pin. High when VADAPTER > 17 volts. The output typically has 40k pull-down resistor.

The source current is not internally limited and the part can be damaged if the output is shorted to

ground when driven HIGH.

9 GND IC ground pin.

10 DISCONNECT Drives the gate of the disconnect P-ch FET.

11 BACKFEED Drives the gate of the backfeed P-ch FET.

12 DIRECTION SENSE Connection for current sense resistor to control BACKFEED.

13 PEAK SENSE Connection for current sense resistor to control DISCONNECT.

14 VADAPTER Power input pin. Output of AC adapter, auto adapter or airline adapter.

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101309 Version 3 Revision 4 Print Date/Time: 2011/08/25 16:34:51

LM2601

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,

please contact the National Semiconductor Sales Office/

Distributors for availability and specifications.

VADAPTER −0.3V to 28V

VPEAK SENSE, VDIRECTION SENSE,

VBACKFEED, VDISCONNECT −0.3V to VADAPTER

VADAPTER ENABLE,

VMASTER POWER SOURCE −0.3V to 5.5V

VMPS DELAY −0.3V to 2V

Storage Temperature −40°C to 125°C

ESD Ratings

Human Body Model (Note 2)

Machine Model (Note 3)

2kV

200V

Operating Ratings (Note 1)

Supply Voltage (VADAPTER)5V to 24V

Ambient Temp. Range −20°C to 70°C

Junction Temp. Range −20°C to 85°C

Electrical Characteristics

Limits with standard typeface apply for TJ = 25°C, and limits in boldface type apply over the full temperature range (Note 4)

Symbol Parameter Conditions Min Typ Max Units

VAE Adapter Enable -

3V- or 5V-CMOS or TTL Logic Input

High

Low

2.0

0.8 V

VAP, CP Logic Output Voltage

Adapter present, Charger present

High

Low, ISINK = 5µA

2.9 3.1

0.25 0.6 V

VMPSIMaster Power Source

5V-CMOS Logic Input

High

Low

4.0

0.8 V

VMPSOLogic Output Voltage

Master Power Source

VADAPTER > 5.8V

High

Low

4.5 4.75

0.05 0.5

VADAPTER Adapter Voltage for VAP Low-to-High

Transition

11.7 12.0 12.3

Hysteresis 1.8 2.0 2.2

VCHARGER Adapter Voltage for VCP

Low-to-High Transition 16.5 17.0 17.4

Hysteresis 0.08 0.10 0.12

ΔVBACKFEED Current Sense Differential Voltage

Threshold for Driving Backfeed FET

Vadapter − Direction sense,

VADAPTER = 5V

9 17

ΔVDISCONNECT Current Sense Differential Voltage

Threshold for Driving Disconnect FET

Vadapter − Peak sense,

VADAPTER = 24V

127

125

135 143

145

VBACKFEED, FET Control Voltage VADAPTER > 11V

High

VADAPTER -

0.5V

VDISCONNECT VADAPTER > 11V

Low

VADAPTER -

10V or GND

+0.5V,

whichever is

greater

tDRIVE Rise/Fall Time of FET Drive

(Note 5)

VADAPTER = 10V

CLoad = 3000pF

3 6µS

IQQuiescent Current VADAPTER = 24V 210 mA

IL,B,

IL,D

Leakage Current into Backfeed or

Disconnect

VADAPTER = 0V

VBACKFEED, VDISCONNECT = 18V

1 15 µA

IL,AE Input Current into Adapter Enable Input VAE = 3.3V,

Backfeed/Disconnect = 18V

50 µA

IL, MPS Input Current into MPS Input VMPS = 5.5V 175 µA

TCDELAY Delay Time Temperature Coefficient 4000 ppm/°C

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: The human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.

Note 3: The machine model is a 200pF capacitor discharged directly into each pin. All pins are rated for 200V except pins 4 and 5 which are rated for 100V.

Note 4: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

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LM2601

Note 5: Adapter Enable input is used to change the state of Disconnect, Direction Sense input is used to change the state of Backfeed.

a. Fall time is measured as the time it takes Backfeed or Disconnect voltage to go from a high level (approx. VADAPTER − 0.5V) to (VADAPTER − 4V) after the signal

is initiated at Adapter Enable or Direction Sense.

b. Rise time is measured as the time it takes Backfeed or Disconnect voltage to go from a low level (approx. 0.5V) to (VADAPTER − 2V) after the signal is initiated

at Adapter Enable or Direction Sense.

Typical Application

10130903

Notes

1. RSENSE value should be selected to guarantee that a

programmed over current will cause a voltage drop

across RSENSE of approx. 135mV. If a higher value of

RSENSE has to be selected then R1/R3 resistor divider

should be used to scale the voltage drop down.

2. Internal and external circuits associated with Direction

Sense and Backfeed FET pins allow to emulate a

Schottky diode functionality with much lower forward

voltage drop and, therefore, with much lower power

dissipation. R2/R4 resistor divider programs the

backfeed current protection threshold. The backfeed

FET Q1 turns off when the backfeed current pulse level

causes more than 9 mV (typical value) voltage drop

between Vadapter pin and Direction Sense pin.

3. Voltage difference (VDIRECTION SENSE - VADAPTER) must be

higher than 20mV to reliably isolate the adapter in case

of leakage.

4. R5 and R6 prevent the FETs from turning on unless

driven by LM2601.

5. CDELAY value can be calculated from the following

formula:

CDELAY(nF) = TDELAY(µs)/90 at 25°C

6. TDELAY temperature coefficient equals 4000ppm/°C. See

also the Typical Delay Time vs. Temperature graph.

7. Pin Master Power Source (MPS) should be connected to

System Management Controller's (SMC) and battery

packs' GPIOs. When SMC detects a powered AC

adapter via active signals at Charger Present or Adapter

Present outputs, it asserts Adapter Enable signal and

isolates the battery pack(s). Adapter Enable signal turns

the Disconnect FET on. When the AC adapter is

unplugged or powered off, SMC enables one of the

system battery packs. The battery packs' embedded

controller starts driving the logic MPS signal high that

turns the Disconnect FET off.

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LM2601

Typical Delay Time vs. Temperature

10130905

Application Information

The adapter interface circuit (AIC) IC provides the control

functions necessary for use in mating a constant voltage out-

put AC-DC adapter or airline adapter to a notebook computer

system or a portable device. It allows optimal battery charging

during computer operation, and allows battery discharge for

battery gas gauge calibration. It receives control signals from

the notebook computer, monitors input current from the

adapter, provides adapter voltage status to the notebook sys-

tem management microcontroller (or "embedded controller"),

and appropriately drives MOSFET switches to electrically

connect the adapter to the computer.

AIC will allow a system designer to solve various power man-

agement tasks typical for an adapter powered systems con-

taining a rechargeable battery.

When a notebook computer is being powered from a battery

and the adapter is plugged in, the computer should start

drawing power from the adapter, not from the battery. The

most time efficient charging scenario is when a computer

draws the full rated current from a constant voltage adapter.

The computer uses what it needs to run, and passes all re-

maining power on to the battery for charging. The computer

should be able to automatically refuse to charge a battery

when powered from an airplane power line. It may be neces-

sary sometimes to have a computer fully discharging the

battery and then fully recharging it (for battery gas gauge cal-

ibration purposes) while being powered by an AC adapter.

AIC will also allow a computer to prevent backfeeding current

into an adapter if the adapter is not powered while being

plugged into the computer (some of existing adapters can

draw current from the computer under this conditions for

charging the AC adapter output bulk capacitance from the

computer battery).

While the lowest usable adapter voltage is about 9.5V, that is

VADAPTER = 11.7V minus 2.2V hysteresis, AIC is operational

down to VADAPTER = 5V. This means that AIC will not generate

false readings down to VADAPTER = 5V. Such false readings

would be MPS = HIGH, ADAPTER PRESENT = HIGH,

CHARGER PRESENT = HIGH.

AIC determines usable voltage ranges by comparing

VADAPTER with an internal 2.5V voltage reference (see also

Electrical Characteristics). AIC detects operating current limit

and leakage current limit into the adapter jack by differential

sensing across current sense resistor RSENSE either directly

or scaled down by resistor dividers R1/R3 and R2/R4.

When designing the LM2601 into a system it may be neces-

sary to consider ESD protection requirements for the adapter

jack according to your system design spec.

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LM2601

Physical Dimensions inches (millimeters) unless otherwise noted

TSSOP-14 Package

14-Lead Thin Shrink Small-Outline Package

For Ordering, Refer to Ordering Information Table

NS Package Number MTC14

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101309 Version 3 Revision 4 Print Date/Time: 2011/08/25 16:34:51

LM2601

Notes

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101309 Version 3 Revision 4 Print Date/Time: 2011/08/25 16:34:51

LM2601

Notes

LM2601 Adapter Interface Circuit

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