The MAX17570 is a high-efficiency, high-voltage, synchronous step-down DC-DC converter with integrated MOSFETs operates over a wide 4.5V to 60V input voltage range. The converter delivers output current up to 300mA at 3.3V (MAX17570A, MAX17570D), 5V (MAX17570B, MAX17570E), and adjustable output voltages (MAX17570C, MAX17570F). When EN/UVLO and V<sub>CC</sub> UVLO are satisfied, an internal power-up sequence soft-starts the error-amplifier reference, resulting in a clean monotonic output-voltage soft-start independent of the load current. The V<sub>OUT</sub>/FB pin monitors the output voltage through a resistor-divider. RESET pin transitions to a high-impedance state 1024 cycles after the output voltage reaches 95% of regulation. By pulling the EN/UVLO pin to low, the device enters the shutdown mode and consumes only 2.2μA (typ) of standby current.
The MAX17570A/B/C operate in pulse-width modulation (PWM) mode at all loads and the MAX17570D/E/F operate in PFM mode at light loads. In PWM mode, the inductor current is allowed to go negative. PWM operation is useful in frequency sensitive applications and provides fixed switching frequency at all loads. In PFM mode, converter disables negative inductor current and additionally skips pulses at light loads for high efficiency. In PFM mode, the inductor current is forced to a fixed peak of 150mA every clock cycle until the output rises to 102.3% of the nominal voltage. Once the output reaches 102.3% of the nominal voltage, both high-side and low-side FETs are turned off and the part enters hibernate operation until the load discharges the output to 101.1% of the nominal voltage. Most of the internal blocks are turned off in hibernate operation to save quiescent current. After the output falls below 101.1% of the nominal voltage, the device comes out of hibernate operation, turns on all internal blocks, and again commences the process of delivering pulses of energy to the output until it reaches 102.3% of the nominal output voltage. The advantage of the PFM mode is higher efficiency at light loads because of lower quiescent current drawn from supply.
APPLICATIONS
- Factory Automation
- Aftermarket Automotive
- General Point of Load
