19-4118; Rev 2; 2/09
KIT ATION EVALU E L B A AVAIL
Dual Quick-PWM Step-Down Controller with Low-Power LDO, RTC Regulat...
19-4118; Rev 2; 2/09
KIT ATION EVALU E L B A AVAIL
Dual Quick-PWM Step-Down Controller with Low-Power LDO, RTC
Regulator
General Description
The MAX17020 is a dual Quick-PWM™ step-down power-supply (SMPS) controller with synchronous rectification, intended for main 5V/3.3V or I/O 1.5V/1.05V power generation in battery-powered systems. Lowside MOSFET sensing provides a simple low-cost, highly efficient current sense for valley current-limit protection. Combined with the output overvoltage and undervoltage protection features, this current limit ensures robust output supplies. The 5V/3.3V or 1.5V/1.05V SMPS outputs can save power by operating in pulse-skipping mode or in ultrasonic mode to avoid audible noise. Ultrasonic mode forces the controller to maintain switching frequencies greater than 20kHz at light loads. An internal 100mA linear
regulator can be used to either generate the 5V bias needed for power-up or other lower power “always-on” suspend supplies. An independent bypass input allows automatic bypassing of the linear
regulator when the SMPS is active. This main controller also includes a secondary feedback input that triggers an ultrasonic pulse (DL1 turned on) if the SECFB voltage drops below its threshold voltage. This refreshes an external charge pump driven by DL1 without overcharging the output voltage. The device includes independent shutdown controls to simplify power-up and power-down sequencing. To prevent current surges at startup, the internal voltage t...