(1) Pullup rail could be either VREF or other system rail.

0.010

0.010

Q1 (ACFET)

SI4835BDY

P

P

CSSN

CSSP

ACIN

VREF

CE

SDA

SCL

SMBus

VICM

HOST

(EC)

UGATE

PHASE

BOOT

VDDP

LGATE

PGND

CSOP

CSON

PACK+

PACK-

CHRG_IN

ADAPTER +

ADAPTER -

GND

bq24745

309k

1%

49.9k

1%

R1

R2

1uF

C4

C2

0.1u

C3

0.1u

100pF

C5

C6

1u

Q3

FDS6680A

Q4

FDS6680A

0.1uF

C7

L1

5.6uH

D1

BAT54

C8

1u

C9

0.1uF

C10

0.1uF

C13

2x10u

C15

10uF

VFB

ICOUT

ICREF

Q2 (RBFET)

SI4835BDY

Controlled by

HOST

C14

10uF

C17

0.1uF

R10

10k

R11

10k

EAI

FBO

NC

NC

EAO

27

28

2

12

3

26

7

9

10

8

14

16

4

5

6

1

15

17

18

19

20

25

21

23

24

DCIN

VDDSMB

11

ACOK

10k

R3

13

DISCRETE

LOGIC

RC6

10

Dig I/O

+3.3V_ALWAYS

OR

+5V_ALWAYS

R12

10k

22

100

R22

C1

2.2u

RC1

2.2

DISCRETE

LOGIC

R20

20k

R21

200k

R19

7.5k

C21

2000pF

C22

130pF

C23

51pF

bq24745

SLUS761D

– DECEMBER 2007 – REVISED OCTOBER 2011

www.ti.com

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

DESCRIPTION (CONTINUED)

The bq24745 features dynamic power management (DPM) and input power limiting. These features reduce

battery-charge current when the input power limit is reached to avoid overloading the ac adaptor when supplying

the load and the battery charger simultaneously. A highly accurate current-sense amplifier enables precise

measurement of input current from the ac adapter, allowing monitoring the overall system power. If the adapter

current is above the programmed low-power threshold, a signal is sent to host so that the system optimizes its

performance to the power available from the adapter. An integrated comparator monitors the input current

through the current-sense amplifier, and indicates when the input current exceeds a programmable threshold

limit.

TYPICAL APPLICATIONS

Figure 1. Typical System Schematic Using External Input-Current Comparator (Discrete Logic) Instead of

Internal Comparator

2

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© 2007–2011, Texas Instruments Incorporated

Product Folder Link(s) :bq24745