Datasheet

MCP1630 LOW-COST NIMH BATTERY
CHARGER REFERENCE DESIGN
© 2007 Microchip Technology Inc. DS51648A-page 7
Chapter 2. Installation and Operation
2.1 INTRODUCTION
The MCP1630 Low-Cost NiMH Battery Charger Reference Design demonstrates
Microchip’s high-speed Pulse Width Modulator (PWM) (the MCP1630) used in a
battery charger application. When used in conjunction with a microcontroller, the
MCP1630 will control the power system duty cycle to provide output voltage or current
regulation. The PIC12F683 microcontroller can be used to regulate output voltage or
current, switching frequency and maximum duty cycle. The MCP1630 generates duty
cycle and provides fast overcurrent protection based off various external inputs.
External signals include the input oscillator, the reference voltage, the feedback voltage
and the current sense. The output signal is a square-wave pulse. The power train used
for the MCP1630 Low-Cost NiMH Battery Charger Reference Design is a Single-Ended
Primary Inductive Converter (SEPIC).The PIC12F683 microcontroller is programma-
ble, allowing the user to modify or develop their own firmware routines to further
evaluate the MCP1630 Low-Cost NiMH Battery Charger Reference Design in this
application.
2.2 FEATURES
The MCP1630 Low-Cost NiMH Battery Charger has the following features:
• Programmed parameters - modified in firmware
• Factory Settings:
- Preconditioning Charge Current =170 mA
- Preconditioning Threshold = 3V
- Constant Current Fast Charge = 1.35A
- Charge Termination based on delta - V
BATT
/ delta time
- Charge Termination based on delta + T
BATT
/ delta time, with external
thermistor installed
• Top Off Charge Current = 130 mA for 1 Hour
• Overvoltage protection (battery removed)
• Overcharge protection to prevent damaging the battery
• Overcurrent protection in the event of a shorted battery
• Battery reversal protection
• Input short circuit protection
• Overtemperature protection to prevent the battery from reaching too high a tem-
perature during charge
• Soft-start capability by holding the reference voltage low during power-up
• The MCP1630 Low-Cost NiMH Battery Charger has the flexibility to optimize the
charging algorithm for new battery technology, different battery chemistries or
different battery pack configurations
• Proprietary features can be added by modifying the firmware contained in the
PIC12F683
• The factory-programmed source code is available
• Ability to adapt to environmental effects, such as ambient temperature