PVCC

PVCC

AVCC

ACN

ACP

CMSRC

ACDRV

STAT

TS

TTC

PGND

PGND

BTST

REGN

BATDRV

OVPSET

ACSET

SRP

SRN

CELL/FB

1

24

AGND

2

3

4

5

6

7

8

9

10

11

23

22

21

20

19

18

17

16

15

14

12

13

bq24170

bq24172

SLUSAD2B

– NOVEMBER 2010 – REVISED APRIL 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.

RGY PACKAGE

DESCRIPTION (CONTINUED)

(TOP VIEW)

The bq24170/172 provides power path selector gate

driver ACDRV/CMSRC on input NMOS pair ACFET

(Q1) and RBFET (Q2), and BATDRV on a battery

PMOS device (Q3). When the qualified adapter is

present, the system is directly connected to the

adapter. Otherwise, the system is connected to the

battery. In addition, the power path prevents battery

from boosting back to the input.

The bq24170/172 charges a battery from a DC

source as high as 17V, including a car battery. The

input over-voltage limit is adjustable through the

OVPSET pin. The AVCC, ACP, and ACN pins have a

30V rating. When a high voltage DC source is

inserted, Q1/Q2 remain off to avoid high voltage

damage to the system.

For 1 cell applications, if the battery is not removable,

the system can be directly connected to the battery to

SPACER

simplify the power path design and lower the cost.

SPACER

With this configuration, the battery can automatically

supplement the system load if the adapter is

SPACER

overloaded.

SPACER

The bq24170/172 is available in a 24-pin, 3.5mm x

5.5mm thin QFN package.

PIN FUNCTIONS

PIN

TYPE

DESCRIPTION

NO.

NAME

1,24

SW

P

Switching node, charge current output inductor connection. Connect the 0.047-

µF bootstrap capacitor

from SW to BTST.

2,3

PVCC

P

Charger input voltage. Connect at least 10-

µF ceramic capacitor from PVCC to PGND and place it as

close as possible to IC.

4

AVCC

P

IC power positive supply. Place a 1-

µF ceramic capacitor from AVCC to AGND and place it as close as

possible to IC. Place a 10-

Ω resistor from input side to AVCC pin to filter the noise. For 5V input, a 5-Ω

resistor is recommended.

5

ACN

I

Adapter current sense resistor negative input. A 0.1-

µF ceramic capacitor is placed from ACN to ACP to

provide differential-mode filtering. An optional 0.1-

µF ceramic capacitor is placed from ACN pin to AGND

for common-mode filtering.

6

ACP

P/I

Adapter current sense resistor positive input. A 0.1-

µF ceramic capacitor is placed from ACN to ACP to

provide differential-mode filtering. A 0.1-

µF ceramic capacitor is placed from ACP pin to AGND for

common-mode filtering.

7

CMSRC

O

Connect to common source of N-channel ACFET and reverse blocking MOSFET (RBFET). Place 4-k

Ω

resistor from CMSRC pin to the common source of ACFET and RBFET to control the turn-on speed. The

resistance between ACDRV and CMSRC should be 500-k

Ω or bigger.

8

ACDRV

O

AC adapter to system switch driver output. Connect to 4-k

Ω resistor then to the gate of the ACFET

N-channel power MOSFET and the reverse conduction blocking N-channel power MOSFET. Connect

both FETs as common-source. The internal gate drive is asymmetrical, allowing a quick turn-off and

slower turn-on in addition to the internal break-before-make logic with respect to the BATDRV.

9

STAT

O

Open-drain charge status pin with 10-k

Ω pull up to power rail. The STAT pin can be used to drive LED or

communicate with the host processor. It indicates various charger operations: LOW when charge in

progress. HIGH when charge is complete or in SLEEP mode. Blinking at 0.5Hz when fault occurs,

including charge suspend, input over-voltage, timer fault and battery absent.

10

TS

I

Temperature qualification voltage input. Connect a negative temperature coefficient thermistor. Program

the hot and cold temperature window with a resistor divider from VREF to TS to AGND. The temperature

qualification window can be set to 5-40

°C or wider. The 103AT thermistor is recommended.

2

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© 2010–2011, Texas Instruments Incorporated