Microchip Technology MCP7386X, User Manual

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MCP7386X Evaluation Board User’s Guide
DS51475C-page 8
©
2006 Microchip Technology Inc.
FIGURE 2-1: Setup Configuration Diagram.
2.3 DETAILED DESCRIPTION
The MCP7386X Battery Charger Evaluation Board is set up to evaluate simple,
stand-alone, linear charging of single/dual-cell Lithium-Ion/Lithium-Polymer battery
packs. The reference design provides constant current charging, followed by constant
voltage charging with automatic charge termination. As provided, the MCP7386X
Battery Charger Evaluation Board is set for a fast charge, constant current level of
1.2A, typical for single-cell applications. The MCP73861 is provided in a 4 x 4, 16-lead
QFN package and is equipped with shutdown control, status indicator, fault indicator,
safety timer and a continuous cell temperature monitor. For dual-cell applications, the
MCP73862 or MCP73864 can be substituted for the MCP73861. Refer to the
MCP73861/2/3/4 data sheet (DS21893) for details on the individual device features.
2.3.1 Input Source
The MCP7386X Battery Charger Evaluation Board is designed to provide a fast charge
current of 1.2A, typical. The input source should provide a voltage in the range of 5V to
12V. The input source should be capable of providing a minimum of 7.5W.
Lower peak currents can be obtained by adjusting the value of the charge programming
resistors (R
2
). A corresponding lower-power input source may then be utilized. Refer
to the MCP73861/2/3/4 data sheet (DS21893) for details on determining the
appropriate programming resistor.
2.3.2 Safety Timer Periods
The MCP7386X Battery Charger Evaluation Board can be used with a variety of battery
packs. As provided, the MCP7386X Battery Charger Evaluation Board is set up to
perform well with single-cell, 1000 mAh battery packs. Battery packs with alternative
capacities and various charge currents can be implemented. The safety timer periods
may need to be adjusted in order to ensure a full charge. The safety timer periods can
be adjusted by changing the capacitance of C
3
. Refer to the MCP73861/2/3/4 data
sheet (DS21893) for details on determining the appropriate timer capacitance.
2.3.3 Disable Control
The MCP7386X Battery Charger Evaluation Board is designed to provide stand-alone
operation. The installed MCP73861 device is enabled whenever the input source is
present. To disable charging, a jumper can be placed between J1, EN and J3 (V
IN
–).
+
-
Single
Lithium-Ion
Cell
Unregulated
Wall Cube