RT8223B

RT8223A/B High Efficiency, Main Power Supply Controller for Notebook Computers General Description The RT8223A/B dual step-down, switch-mode powersupply controller generates logic-supply voltages in battery-powered systems. The RT8223A/B includes two pulse-width modulation (PWM) controllers fixed at 5V/ 3.3V or adjustable from 2V to 5.5V. This device also features 2 linear regulators providing fixed 5V and 3.3V outputs. The linear regulator each provides up to 70mA output current with automatic linear-regulator bootstrapping to the PWM outputs. The RT8223A/B includes on-board power-up sequencing, the power good output, internal softstart, and internal soft-discharge output that prevents negative voltages on shutdown. A constant on-time PWM control scheme operates without sense resistor and provides 100ns response to load transients while maintaining a relatively constant switching frequency. The unique ultrasonic mode maintains the switching frequency above 25kHz, which eliminates noise in audio applications. Other features include diodeemulation mode (DEM), which maximizes efficiency in light-load applications, and fixed-frequency PWM mode, which reduces RF interference in sensitive application Features z z z z z z z z z z z z z Wide Input Voltage Range 6V to 25V Dual Fixed 5V/3.3V Outputs or Adjustable from 2V to 5.5V, 1.5% Accuracy Fixed 3.3V and 5V LDO Output : 70mA 2V Reference Voltage ±1% : 50μA Constant ON-Time Control with 100ns Load Step Response Frequency Selec...