Automotive-qualified synchronous buck regulator ICs for USB charging

11-08-2015 | Allegro | Power

The new A8652 and A8653 from Allegro MicroSystems Europe extends the company’s portfolio of automotive regulator ICs by adding two devices targeted specifically at USB power applications. The new 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 500mV 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. The 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 4V to 36V and remain operational even when the input voltage drops as low as 2.6V. 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 under-voltage 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 to satisfy the most demanding automotive and non-automotive applications. The A8652/53 devices are available in a 16-pin eTSSOP package with exposed pad for enhanced thermal dissipation. The package is lead (Pb) free, with 100% matt tin lead frame plating. The maximum junction temperature is +150C, says the company.

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