Precision Integrated Analog Front End, Controller, and PWM for Battery Test and Formation Systems

The AD8452 combines a precision analog front-end controller and switch mode power supply (SMPS), pulse-width modulator (PWM) driver into a single silicon platform for high volume battery testing and formation manufacturing. A precision instrumentation amplifier (in-amp) measures the battery charge/discharge current, while an equally accurate difference amplifier measures the battery voltage. Internal laser trimmed resistor networks establish the in-amp and difference amplifier gains (66 V/V and 0.4 V/V, respectively), and stabilize the AD8452 performance across the rated operating temperature range.

Desired battery cycling current and voltage levels are established by applying precise control voltages to the ISET and VSET inputs. Actual charge and discharge current levels are sensed (usually by a high power, highly accurate shunt resistor) whose value is carefully selected according to system parameters. Switching between constant current (CC) and constant voltage (CV) loop integration is instantaneous, automatic, and completely transparent to the observer. A logic high at the MODE input selects the charge or discharge mode (high for charge, low for discharge).

The AD8452 simplifies designs by providing excellent performance, functionality, and overall reliability in a space saving 48-lead, 7 mm × 7 mm × 1.4 mm LQFP package rated for operation at temperatures from −40°C to +85°C.

Applications

* Battery formation and testing

* High efficiency battery test systems with recycle capability

* Battery conditioning (charging and discharging) systems

* CC and CV battery test and formation modes with transparent and automatic switchover, for systems of 20 Ah or less

* Precise measurement of voltage and current

* Independent feedback control blocks

* Highly accurate, factory trimmed instrumentation and differential amplifiers

* In-amp for current sense gain: 66 V/V

* Difference amplifier for voltage sense gain: 0.4V/V

* Stable over temperature: offset voltage drift <0.6 µV/°C (maximum)