BQ24232H_15 Datasheet, PDF (31/42 Pages) Texas Instruments – bq2423xx USB-Friendly Lithium-Ion Battery Charger and Power-Path Management IC

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11 Power Supply Recommendations
bq24230H, bq24232H
SLUSBI8A – JANUARY 2014 – REVISED DECEMBER 2014
11.1 Requirements for OUT Output
To provide an output voltage on SYS, the bq2423xH require either a power supply from 4.35 V to 6.0 V input for
bq24230H and from 4.35 V to 10 V for bq24232H to fully charge a battery.The supply must have at least 100 mA
current rating connected to IN; or, a single-cell Li-Ion battery with voltage > VBATUVLO connected to BAT. The
source current rating needs to be at least 1.5 A in order to provide maximum output current to SYS.
11.2 USB Sources and Standard AC Adapters
In order for charging to occur the source voltage measured at the IN terminals of the IC, factoring in cable/trace
losses from the source, must be greater than the VINDPM threshold (in USB mode), but less than the maximum
values shown above. The current rating of the source must be higher than the load requirements for OUT in the
application. For charging at a desired charge current of ICHRG, IIN > (ISYS+ ICHRG). The charger limits IIN to
the current limit setting of EN1/EN2.
11.3 Half-Wave Adapters
Some low-cost adapters implement a half rectifier topology, which causes the adapter output voltage to fall below
the battery voltage during part of the cycle. To enable operation with low-cost adapters under those conditions,
the bq2423xH family keeps the charger on for at least 20 ms (typical) after the input power puts the part in sleep
mode. This feature enables use of external low-cost adapters using 50-Hz networks.
12 Layout
12.1 Layout Guidelines
• To obtain optimal performance, the decoupling capacitor from IN to GND (thermal pad) and the output filter
capacitors from OUT to GND (thermal pad) must be placed as close as possible to the bq2423xH, with short
trace runs to both IN, OUT, and GND (thermal pad).
• All low-current GND connections must 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.
• The high current charge paths into the 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 bq2423xH 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 report entitled:
QFN/SON PCB Attachment (SLUA271).
Copyright © 2014, Texas Instruments Incorporated
Product Folder Links: bq24230H bq24232H
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