BQ24080-Q1 Datasheet, PDF (18/28 Pages) Texas Instruments – Li-Ion and Li-Pol Automotive Charger

bq24080-Q1, bq24081-Q1
SLUSCB6 – MAY 2015
11 Layout
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11.1 Layout Guidelines
It is important to pay special attention to the PCB layout. The following provides some guidelines:
• To obtain optimal performance, the decoupling capacitor from V_CC to V_(IN) and the output filter capacitors from
OUT to V_SS should be placed as close as possible to the device, with short trace runs to both signal and V_SS
pins. The V_SS pin should have short trace runs to the GND pin.
• All low-current V_SS 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.
• The high-current charge paths into IN and from the OUT pins must be sized appropriately for the maximum
charge current in order to avoid voltage drops in these traces.
• The device is packaged in a thermally enhanced MLP package. The package includes a thermal pad to
provide an effective thermal contact between the device and the printed circuit board (PCB). Full PCB design
guidelines for this package are provided in the application report entitled, QFN/SON PCB Attachment
(TI Literature Number SLUA271).
11.2 Layout Example
Low resistance path for
current flow
Device U1 GND Pad
For thermal improvement
Place VIA to GND plane if the plane is on a different layer
Low resistance path for
current flow
Device U1 bq24080-Q1, bq24081-Q1
Input Capacitor C1
Close to U1 pin IN
Output Capacitor C2
Resistor R3 to set ISET
Figure 13. Board Layout
18
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