Microchip Technology MCP1630RD-DDBK3 Manual De Usuario

© 2006 Microchip Technology Inc.

DS51641A-page 9

A four cell battery pack (with internal protection) is connected to the J1 connector 
before applying input power and pressing SW1 to start the charge cycle. Once the 
battery pack is connected, SW1 can be pressed to start the synchronous buck 
converter (assuming there is no 7.0V input applied to J2). With the battery pack 
connected, the source for J2 can be “hot” plugged in and out, a voltage will always be 
present on J2 until SW1 is pressed shutting off the converter.

As an alternative to the four cell Li-Ion battery pack, a battery pack simulation circuit 
can be used, (

). This simulation circuit consists of an adjustable metal wound 

power load resistor (10

Ω, 100W), Aluminum Electrolytic Capacitor (3,300 µF 25V) and 

Schottky Diode (10V, 30V). For evaluating the bidirectional converter design, the bat-
tery simulator circuit is recommended. When using the battery pack simulator, the 
operating point for charging and discharging can be easily be adjusted using the V

BATT

 

power supply and load resistor value.

Two LED’s are connected to the I/O of the PIC16F88 to provide status of the charger. 
LED D3 provides indication that the converter is running while LED D5 flashing 
provides indication that the converter is charging. With a 6.5V to 7.0V source applied 
to J2 while the converter is running, a charge cycle is initiated. Once the charge cycle 
is complete, the charger will continue to operate providing 0 mA of current to the 
battery. If the source is removed from J2, the converter will regulate the V

BULK

 voltage 

to 6.0V with a load up to 6A.

The best way to evaluate the MCP1630V Bidirectional 4 Cell Li-Ion Charger Reference 
Design is to operate the bidirectional power system over a wide range using the battery 
pack simulator. The simulator consists of a 10

Ω

 power resistor, diode and variable 

voltage source. When configured as shown in 

, the circuit will simulate a 

battery. The load

 

resistor is used to sink current from the charger while a large capacitor 

is used to simulate the battery voltage (V

SIM

). By adjusting the V

SIM

 voltage, different 

operating points in the charge cycle can be evaluated.
Once evaluated using the battery pack simulator, the bi-directional reference design 
can be used to run charge and discharge cycles using a four cell Li-ion battery pack. If 
using an actual Li-ion battery pack, it must have the proper protection features 
including, (overvoltage, overcurrent, overtemperature, etc.).