High Efficiency, Main Power Supply Controllers for Notebook Computers

General Description
The RT8205A/B/C dual step-down, switch-mode power supply controller generates logic-supply voltages in battery-powered systems. The RT8205A/B/C includes two pulse-width modulation (PWM) controllers fixed at 5V/3.3V or adjustable from 2V to 5.5V. An alternative LGATE1
output LG1_CP can be used for external charge pump (RT8205B). And an optional external charge pump can be monitored through SECFB (RT8205C). 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 RT8205A/B/C includes on-board power-up sequencing, the power-good output, internal soft start, and internal soft-discharge output that prevents negative voltages on shutdown.

FEATUREs
Wide Input Voltage Range 6V to 25V
Dual Fixed 5V/3.3V Outputs or Adjustable from 2V to 5.5V, 1.5% Accuracy.
Alternative LGATE1 Output (LG1_CP) acts as Clock for Charge Pump (RT8205B)
Secondary Feedback Input Maintains Charge Pump Voltage (RT8205C)
Fixed 3.3V and 5V LDO Output : 70mA
2V Reference Voltage ±1% : 50μA
Constant ON-Time Control with 100ns Load Step Response
Frequency Selectable via TONSEL Setting
RDS(ON)Current Sensing and Programmable Current Limit combined with Enable Control
Selectable PWM, DEM, or Ultrasonic Mode
Internal Soft-Start and Soft-Discharge
High Efficiency up to 97%
5mW Quiescent Power Dissipation
Thermal Shutdown
RoHS Compliant and Halogen Free

APPLICATIONs
Notebook and Sub-Notebook Computers
3-Cell and 4-Cell Li+ Battery-Powered Devices