The ISL6237 dual step-down, switch-mode power-supply (SMPS) controller generates logic-supply voltages in battery-powered systems. The ISL6237 includes two pulse-width modulation (PWM) controllers, 5V/3.3V and 1.5V/1.05V. The output of SMPS1 can also be adjusted from 0.7V to 5.5V. The SMPS2 output can be adjusted from 0.5V to 2.5V by setting REFIN2 voltage. This device features a linear regulator providing 3.3V/5V, or adjustable from 0.7V to 4.5V output via LDOREFIN. The linear regulator provides up to 100mA output current with automatic linear-regulator bootstrapping to the BYP input. When in switchover, the LDO output can source up to 200mA. The ISL6237 includes on-board power-up sequencing, power-good (POK_) outputs, digital soft-start, and internal soft-stop output discharge that prevents negative voltages on shutdown. Constant on-time PWM control scheme operates without sense resistors and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic pulse-skipping mode maintains the switching frequency above 25kHz, which eliminates noise in audio applications. Other features include pulse skipping, which maximizes efficiency in light-load applications, and fixed-frequency PWM mode, which reduces RF interference in sensitive applications.