The MAX17554 and MAX17555 are ultra-small, high-efficiency, high voltage, synchronous step-down DC-DC converters with integrated MOSFETs that operate over a wide input voltage range and deliver up to 50mA of load current.
The MAX17554 operates over a wide input voltage range from 10V to 60V and the MAX17555 operates over a wide input voltage range from 4V to 60V. The MAX17554 offers a converter solution with only three active pins, whereas the MAX17555 offers a flexible converter design in terms of EN/UV and HYST thresholds and active-low RESET features.
The MAX17554A/MAX17555A and the MAX17554B/MAX17555B are fixed 3.3V and 5V output voltage devices, respectively. The MAX17554C/MAX17555C are adjustable output (0.8V to 0.9 x VIN) devices. The feedback voltage regulation accuracy of the converters over the -40°C to +125°C temperature range is ±1.5% for the MAX17554A/MAX17555A and the MAX17554B/MAX17555B, and ±1.25% for the MAX17554C/MAX17555C.
The devices feature a peak-current mode control architecture. During normal operation, at each rising edge of the clock, the high-side p-MOSFET turns on and remains on until either the appropriate or maximum duty cycle is reached or the peak current limit is detected. During the high-side p-MOSFET on-time, the inductor current ramps up. During the rest of the switching cycle or until the inductor current reaches zero, the high-side p-MOSFET remains off, the low-side n-MOSFET remains on, and the inductor current ramps down. The device features the Discontinuous Conduction Mode (DCM), in which the negative inductor current is inhibited to enable higher light load efficiency. In DCM, the device operates at a fixed switching frequency until the minimum on-time is reached. If the load demand is less than the energy corresponding to the minimum on-time pulse, the converter skips pulses to maintain output voltage regulation.
A fixed soft-start time of 0.8ms (typ) allows users to reduce input inrush current. The MAX17555 features an enable/undervoltage lockout (EN/UV) and a hysteresis (HYST) pins to allow the users to turn the device on or off at the desired input-voltage level. The MAX17555 also features an open-drain active-low RESET pin to provide a power-good signal to the system upon achieving successful regulation of the output voltage.
Applications
- Factory Automation
- Aftermarket Market Automotive
- General Point of Load
