Features

• Fast Charge Nickel-Cadmium, Nickel-Metal-Hydride, Lithium Ion or Lead-Acid Batteries under µP Control
• Flexible Current Regulation:
  - Programmable 111kHz PWM Current Regulator with Built-In PFET Driver
  - PFET Current Gating
• Discharge Mode
• Measures Battery Voltage, Battery Temperature and Ambient Temperature with Internal 10-Bit ADC
• Battery Voltage, Temperature and Charge Time Fault Protection
• Built-In Voltage Regulator and Programmable Battery Attenuator
• Easy-to-Use 3- or 4-Wire Serial µP Interface
• Accurate Gas Gauge Function
• Wide Supply Range: VDD = 4.5V to 16V
• Can Charge Batteries with Voltages Greater Than VDD
• Can Charge Batteries from Charging Supplies Greater Than VDD
• Digital Input Pins Are High Impedance in Shutdown Mode

Typical Application

Description

The LTC1325 provides the core of a flexible, cost-effective solution for an integrated battery management system. The monolithic CMOS chip controls the fast charging of nickel-cadmium, nickel-metal-hydride, lead-acid or lithium batteries under microprocessor control. The device features a programmable 111kHz PWM constant current source controller with built-in FET driver, 10-bit ADC, internal voltage regulator, discharge-before-charge controller, programmable battery voltage attenuator and an easy-to-use serial interface.

The chip may operate in one of five modes: power shut-down, idle, discharge, charge or gas gauge. In power shutdown the supply current drops to 30µA and in the idle mode,an ADC reading maybe made withou tany switching noise affecting the accuracy of the measurement. In the discharge mode, the battery is discharged by an external transistor while the battery is being monitored by the LTC1325 for fault conditions. The charge mode is terminated by the µP while monitoring any combination of battery voltage and temperature, ambient temperature and charge time. The LTC1325 also monitors the battery for fault conditions before and during charging. In the gas gauge mode the LTC1325 allows the total charge leaving the battery to be calculated.