BQ2406X Datasheet, PDF (27/31 Pages) Texas Instruments – 1A SINGLE-CHIP Li-Ion/Li-Pol CHARGE MANAGEMENT IC WITH THERMAL REGULATION

bq2406x
www.ti.com
SLUS689 – JUNE 2006
APPLICATION INFORMATION (continued)
Note that the PG pin is not deglitched, and it indicates input power loss immediately after the input voltage falls
below the output voltage. If the input source frequently drops below the output voltage and recovers, a small
capacitor can be used from PG to VSS to prevent /PG flashing events.
PCB LAYOUT CONSIDERATIONS
It is important to pay special attention to the PCB layout. The following provides some 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) should be placed as close as possible to the bq2406x, with short
trace runs to both IN, OUT and GND (thermal pad).
• 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.
• 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 bq2406x family are 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 (SLUA271).
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