Synchronous buck regulator ICs for USB charging: automotive qualified

August 12, 2015 // By Graham Prophet
With wide input-voltage range and remote load regulation, A8652 and A8653 from Allegro MicroSystems are automotive regulator ICs targeted specifically at USB power applications.

The devices are high output current synchronous buck regulator ICs that provide tight load regulation over a wiring harness without the need for remote sense lines. This remote load regulation is achieved with an integrated open-loop correction scheme that, given a known wiring harness resistance, adjusts the output voltage based on the measured load current and a user programmable gain, achieving ±2% accuracy at 500 mV of correction.

The remote load regulation control includes a 115% regulated voltage clamp in conjunction with a dynamic overvoltage protection circuit using threshold changing with the correction voltage.

A8652 and 8653 each include a user-configurable load-side current limit to fold back the output voltage during an output overcurrent condition. The devices regulate nominal input voltages from 4.0 V to 36 V and remain operational even when the input voltage drops as low as 2.6 V. When the input voltage approaches the output voltage, the duty cycle is maximised to maintain the output voltage.

Key features include externally set soft-start time, an external compensation network for power-train optimisation, an “enable” input to enable the output voltage, a “SYNC/FSET” input to synchronise or set the PWM switching frequency, and a “power OK” output to indicate when the output voltage is within regulation.

Protection features include input undervoltage lockout, cycle-by-cycle current limit, “hiccup” mode short-circuit protection, dynamic overvoltage protection, and thermal shutdown. Both devices provide open-circuited, adjacent pin short-circuit, and short-to-ground protection at every pin for automotive and non-automotive applications.

The A8652/53 devices are available in a 16-pin eTSSOP package with exposed pad for enhanced thermal dissipation. Maximum junction temperature is +150ºC. Data sheet here.

Allegro MicroSystems; www.allegromicro.com