Electronic Design

Dual Step-Down Controller Offers Adjustable Switching Frequency

Operating from an input voltage range of 5.5 to 28 V or 5 V ±10%, the MAX15023 from Maxim Integrated Products is a dual, synchronous step-down controller that generates two independent output voltages. Each output is adjustable from 85% of the input voltage down to 0.6 V and supports loads of 12 A or higher. Input voltage ripple and total RMS input ripple current are reduced by interleaved 180° out-of-phase operation.

The MAX15023 offers the ability to adjust the switching frequency from 200 kHz to 1 MHz with an external resistor. Its adaptive synchronous rectification eliminates the need for external freewheeling Schottky diodes. The device also uses the external low-side MOSFET’s on-resistance as a current-sense element, eliminating the need for a current-sense resistor. This protects the dc-dc components from damage during output overloaded conditions or output short-circuit faults without requiring a current-sense resistor. Hiccup-mode current limit reduces power dissipation during short-circuit conditions. The MAX15023 includes two independent power-good outputs and two independent enable inputs with precise turn-on/turn-off thresholds, which can be used for supply monitoring and for power sequencing.

Additional protection features include cycle-by-cycle, low-side, sink peak current limit, and thermal shutdown. Cycle-by-cycle, low-side, sink peak current limit prevents reverse inductor current from reaching dangerous levels when the device is sinking current from the output. The MAX15023 also allows pre-biased startup without discharging the output and features adaptive internal digital soft-start. This new proprietary feature enables monotonic charging of externally large output capacitors at startup. It also achieves good control of the peak inductor current during hiccup-mode short-circuit protection.

The MAX15023 is available in a space-saving and thermally enhanced 4- by 4-mm, 24-pin TQFN-EP package. The device operates over the -40°C to 85°C extended temperature range.

Maxim Integrated Products

www.maxim-ic.com

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