CM9112 Datasheet, PDF (17/18 Pages) California Micro Devices Corp – Dual Inputs Dual Outputs High Accurate Fast Charger

Application Information (cont’d)
occur when LDO1 is disabled and the battery must
supply full system load.
P_Q2 = I_sys2 ⋅ R_DS
The Q2 and PCB heatsink must be rated for this power.
Layout Considerations
Because the internal thermal foldback circuit will limit
the current when the IC reaches 105°C it is important
to keep a good thermal interface between the IC and
the PC board. It is critical that the exposed metal on
the backside of the CM9112 be soldered to the PCB
ground. The Cu pad should is large and thick enough
to provided good thermal spreading. Thermal vias to
other Cu layers provide improved thermal perfor­
mance.
VIN, VSYS and VOUT are high current paths and the
traces should be sized appropriately for the maximum
current to avoid voltage drops. BSEN is the battery
feedback voltage and should be connected with its
trace as close to the battery as possible.
PRELIMINARY
CM9112
© 2006 California Micro Devices Corp. All rights reserved.
07/06/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 lTel: [phone] lFax: [phone] lwww.cmd.com
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