BQ24740_07 Datasheet, PDF (22/32 Pages) Texas Instruments – Host-controlled Multi-chemistry Battery Charger with Low Input Power Detect

bq24740
SLUS736 – DECEMBER 2006
www.ti.com
THERMAL SHUTDOWN PROTECTION
The QFN package has low thermal impedance, which provides good thermal conduction from the silicon to the
ambient, to keep junctions temperatures low. As added level of protection, the charger converter turns off and
self-protects whenever the junction temperature exceeds the TSHUT threshold of 145°C. The charger stays off
until the junction temperature falls below 130°C.
Status Outputs (EXTPWR, LPMD, DPMDET pin)
Four status outputs are available, and they all, except for LPMD, require external pull up resistors to pull the pins
to system digital rail for a high level.
EXTPWR open-drain output goes low under either of the two conditions:
1. ACDET is above 2.4 V
2. Adapter current is above 1.25 A using a 10-mΩ sense resistor (IADAPT voltage above 250 mV). Internally,
the AC current detect comparator looks between IADAPT and an internal 250-mV threshold. It indicates a
good adapter is connected because of valid voltage or current.
STAT open-drain output goes low when charging. A high level on STAT indicates the charger is not charging;
therefore, either, CHGEN pin is not low, or the charger is not able to charge because input voltage is still
powering up and the 700-ms delay has not finished, or because of a fault condition such as overcurrent, input
over voltage, or TSHUT over temperature.
LPMD push-pull output goes low when the input current is higher than the programmed threshold via LPREF
pin. Hysteresis can be programmed by putting a resistor from LPREF pin to LPMD pin.
DPMDET open-drain output goes low when the DPM loop is active to reduce the battery charge current (after a
10-ms delay).
Table 2. Component List for Typical System Circuit of Figure 1
PART DESIGNATOR
Q1, Q2, Q3
Q4, Q2
D1
R_AC, R_SR
L1
C1, C6, C7, C11, C12
C4, C8, C10
C2, C3, C9, C13, C14, C15
R3, R4, R5
R1
R2
R6
R7
R8
R9
QTY
3
2
1
2
1
5
3
6
4
1
1
1
1
1
1
DESCRIPTION
P-channel MOSFET, –30V,-6A, SO-8, Vishay-Siliconix, Si4435
N-channel MOSFET, 30V, 12.5A, SO-8, Fairchild, FDS6680A
Diode, Dual Schottky, 30V, 200mA, SOT23, Fairchild, BAT54C
Sense Resistor, 10 mΩ, 1%, 1W, 2010, Vishay-Dale, WSL2010R0100F
Inductor, 10µH, 7A, 31mΩ, Vishay-Dale, IHLP5050FD-01
Capacitor, Ceramic, 10µF, 35V, 20%, X5R, 1206, Panasonic, ECJ-3YB1E106M
Capacitor, Ceramic, 1µF, 25V, 10%, X7R, 2012, TDK, C2012X7R1E105K
Capacitor, Ceramic, 0.1µF, 50V, 10%, X7R, 0805, Kemet, C0805C104K5RACTU
Resistor, Chip, 10 kΩ, 1/16W, 5%, 0402
Resistor, Chip, 432 kΩ, 1/16W, 1%, 0402
Resistor, Chip, 66.5 kΩ, 1/16W, 1%, 0402
Resistor, Chip, 33 kΩ, 1/16W, 1%, 0402
Resistor, Chip, 200 kΩ, 1/16W, 1%, 0402
Resistor, Chip, 24.9 kΩ, 1/16W, 1%, 0402
Resistor, Chip, 1.8 MΩ, 1/16W, 1%, 0402
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