BQ24075T Datasheet, PDF (25/29 Pages) Texas Instruments – 1.5A USB-Friendly Li-Ion Battery Charger and Power-Path Management IC

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bq24075T
bq24079T
SLUS937 – DECEMBER 2009
When the input is between V_UVLO and V_IN(DT), the device enters sleep mode. After entering sleep mode for 20ms
the internal FET connection between the IN and OUT pin is disabled and pulling the input to ground will not
discharge the battery, other than the leakage on the BAT pin. If one has a full 1000mAHr battery and the leakage
is 10μA, then it would take 1000mAHr/10μA = 100000 hours (11.4 years) to discharge the battery. The battery ‘s
self discharge is typically 5 times higher than this
Layout Tips
1. To obtain optimal performance, the decoupling capacitor from IN to GND (thermal pad) and the output filter
capacitors from OUT to GND (thermal pad) should be placed as close as possible to the bq2407xT, with
short trace runs to both IN, OUT and GND (thermal pad).
2. All low-current GND connections should be kept separate from the high-current charge or discharge paths
from the battery. Use a single-point ground technique incorporating both the small signal ground path and the
power ground path.
3. The high current charge paths into IN pin and from the OUT pin must be sized appropriately for the
maximum charge current in order to avoid voltage drops in these traces
The bq2407xT family is packaged in a thermally enhanced MLP package. The package includes a thermal pad to
provide an effective thermal contact between the IC and the printed circuit board (PCB); this thermal pad is also
the main ground connection for the device. Connect the thermal pad to the PCB ground connection. Full PCB
design guidelines for this package are provided in the application note entitled: QFN/SON PCB Attachment
Application Note.
Copyright © 2009, Texas Instruments Incorporated
Product Folder Link(s): bq24075T bq24079T
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