BQ24250C_15 Datasheet, PDF (37/46 Pages) Texas Instruments – bq24250C 2A Single Input I2C, Standalone Switch-Mode Li-Ion Battery Charger with Power-Path Management

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bq24250C
SLUSBY7 – JULY 2014
10 Power Supply Recommendations
The devices are designed to operate from an input voltage range between 4.35V and 10.5V. This input supply
must be well regulated. If the input supply is located more than a few inches from the bq24250C charger,
additional bulk capacitance may be required in addition to the ceramic bypass capacitors.
11 Layout
11.1 Layout Guidelines
1. Place the BOOT, PMID, IN, BAT, and LDO capacitors as close as possible to the IC for optimal performance.
2. Connect the inductor as close as possible to the SW pin, and the SYS cap as close as possible to the
inductor minimizing noise in the path.
3. Place a 1-μF PMID capacitor as close as possible to the PMID and PGND pins, making the high frequency
current loop area as small as possible.
4. The local bypass capacitor from SYS to GND must be connected between the SYS pin and PGND of the IC.
This minimizes the current path loop area from the SW pin through the LC filter and back to the PGND pin.
5. Place all decoupling capacitors close to their respective IC pins and as close as possible to PGND (do not
place components such that routing interrupts power-stage currents). All small control signals must be routed
away from the high-current paths.
6. To reduce noise coupling, use a ground plane if possible, to isolate the noisy traces from spreading its noise
all over the board. Put vias inside the PGND pads for the IC.
7. The high-current charge paths into IN, Micro-USB, BAT, SYS, and from the SW pins must be sized
appropriately for the maximum charge current to avoid voltage drops in these traces.
8. For high-current applications, the balls for the power paths must be connected to as much copper in the
board as possible. This allows better thermal performance because the board conducts heat away from the
IC.
Copyright © 2014, Texas Instruments Incorporated
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