BQ24133 Datasheet, PDF (3/35 Pages) Texas Instruments – 1.6-MHz Synchronous Switch-Mode Li-Ion and Li-Polymer Stand-Alone Battery Charger with Integrated MOSFETs and Power Path Selector

bq24133
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PIN
NO.
NAME
8
ACDRV
9
STAT
10 TS
11 TTC
12 VREF
13 ISET
14 CELL
15 SRN
16 SRP
17 ACSET
18 OVPSET
19 BATDRV
20 REGN
21 BTST
22,23 PGND
Thermal AGND
Pad
SLUSAF7B – DECEMBER 2010 – REVISED MAY 2011
PIN FUNCTIONS (continued)
TYPE
DESCRIPTION
O AC adapter to system switch driver output. Connect to 4-kΩ 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.
O Open-drain charge status pin with 10-kΩ 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.
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.
I Safety Timer and termination control. Connect a capacitor from this node to AGND to set the fast charge
safety timer(5.6min/nF). Pre-charge timer is internally fixed to 30 minutes. Pull the TTC to LOW to disable
the charge termination and safety timer. Pull the TTC to HIGH to disable the safety timer but allow the
charge termination.
P 3.3V reference voltage output. Place a 1-μF ceramic capacitor from VREF to AGND pin close to the IC.
This voltage could be used for programming ISET and ACSET and TS pins. It may also serve as the
pull-up rail of STAT pin and CELL pin.
I Fast charge current set point. Use a voltage divider from VREF to ISET to AGND to set the fast charge
current:
I_CHG
=
V_ISET
20 ´ R_SR
The pre-charge and termination current is internally as one tenth of the charge current. The charger is
disabled when ISET pin voltage is below 40mV and enabled when ISET pin voltage is above 120mV.
I Cell selection pin. Set CELL pin LOW for 1-cell, Float for 2-cell (0.8V-1.8V), and HIGH for 3-cell with a
fixed 4.2V per cell.
I Charge current sense resistor negative input. A 0.1-μF ceramic capacitor is placed from SRN to SRP to
provide differential-mode filtering. A 0.1-μF ceramic capacitor is placed from SRN pin to AGND for
common-mode filtering.
I/P Charge current sense resistor, positive input. A 0.1-μF ceramic capacitor is placed from SRN to SRP to
provide differential-mode filtering. A 0.1-μF ceramic capacitor is placed from SRP pin to AGND for
common-mode filtering.
I Input current set point. Use a voltage divider from VREF to ACSET to AGND to set this value:
I_DPM
=
V_ACSET
20 ´ R_AC
I Valid input voltage set point. Use a voltage divider from input to OVPSET to AGND to set this voltage.
The voltage above internal 1.6V reference indicates input over-voltage, and the voltage below internal
0.5V reference indicates input under-voltage. In either condition, charge terminates, and input NMOS pair
ACFET/RBFET turn off. LED driven by STAT pin keeps blinking, reporting fault condition.
O Battery discharge MOSFET gate driver output. Connect to 1kohm resistor to the gate of the BATFET
P-channel power MOSFET. Connect the source of the BATFET to the system load voltage node. Connect
the drain of the BATFET to the battery pack positive node. The internal gate drive is asymmetrical to
allow a quick turn-off and slower turn-on, in addition to the internal break-before-make logic with respect
to ACDRV.
P PWM low side driver positive 6V supply output. Connect a 1-μF ceramic capacitor from REGN to PGND
pin, close to the IC. Generate high-side driver bootstrap voltage by integrated diode from REGN to BTST.
P PWM high side driver positive supply. Connect the 0.047-µF bootstrap capacitor from SW to BTST.
P Power ground. Ground connection for high-current power converter node. On PCB layout, connect
directly to ground connection of input and output capacitors of the charger. Only connect to AGND
through the Thermal Pad underneath the IC.
P Exposed pad beneath the IC. Always solder Thermal Pad to the board, and have vias on the Thermal
Pad plane star-connecting to AGND and ground plane for high-current power converter. It dissipates the
heat from the IC.
Copyright © 2010–2011, Texas Instruments Incorporated
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