MAX17625 and MAX17626 are high-frequency synchronous step-down DC-DC converters with integrated MOSFETs and compensation components that operate over a 2.7V to 5.5V input-voltage range. MAX17625 and MAX17626 support up to 700mA load current and allow the use of small, low-cost input and output capacitors. The output voltage can be adjusted from 0.8V to 3.3V.
When the EN pin is asserted, an internal power-up sequence ramps up the error-amplifier reference, resulting in output-voltage soft-start. The FB pin monitors the output voltage through a resistor-divider. The devices select either PFM or forced-PWM mode depending on the state of the MODE pin at power-up. By pulling the EN pin to low, the devices enter shutdown mode and consume only 0.1µA (typ) of standby current.
The devices use an internally compensated, fixed-frequency, peak-current mode control scheme. On the falling edge of an internal clock, the high-side pMOSFET turns on and continues to be on during normal operation until at least the rising edge of the clock (for 40ns). An internal error amplifier compares the feedback voltage to a fixed internal reference voltage and generates an error voltage. The error voltage is compared to the sum of the current-sense voltage and the slope-compensation voltage by the PWM comparator to set the on-time. During the on-time of the pMOSFET, the inductor current ramps up. For the remainder of the switching period (off-time), the pMOSFET is kept off and the low-side nMOSFET turns on. During the off-time, the inductor releases the stored energy as the inductor current ramps down, providing current to the output. Under overload conditions, the cycle-by-cycle current-limit feature limits the inductor peak current by turning off the high-side pMOSFET and turning on the low-side nMOSFET.
Applications
- Factory Automation
- Personal Electronics
- Point-of-Load Power Supply
