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High Efficiency, Main Power Supply Controller for Notebook Computer

RT8205L/RT8205M

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The RT8205L/M is a dual step-down, switch mode power supply controller generating logic-supply voltages in battery powered systems. It includes two Pulse-Width Modulation (PWM) controllers adjustable from 2V to 5.5V, and also features fixed 5V/3.3V linear regulators. Each linear regulator provides up to 100mA output current with automatic linear regulator bootstrapping to the PWM outputs. An optional external charge pump can be monitored through SECFB (RT8205M). The RT8205L/M includes on-board power up sequencing, a power good output, internal soft-start, and internal soft-discharge output that prevents negative voltage during shutdown.
The constant on-time PWM control scheme operates without sense resistors and provides 100ns response to load transient response while maintaining nearly constant switching frequency. To eliminate noise in audio applications, an ultrasonic mode is included, which maintains the switching frequency above 25kHz. Moreover, the diode-emulation mode maximizes efficiency for light load applications. The RT8205L/M is available in a WQFN-24L 4x4 package.

Applications

  • Notebook and Sub-Notebook Computers
  • 3-Cell and 4-Cell Li+ Battery-Powered Devices
  • Notebook
Key Spec.
RT8205L RT8205M
Status Active Active
Vs (typ) (V) 19 19
Vin (min) (V) 6 6
Vin (max) (V) 25 25
Vout (min) (V) 2 2
Vout (max) (V) 5.5 5.5
Preset Vout (V) 3.3;5 3.3;5
Output Adj. Method Fixed;Resistor Fixed;Resistor
Accuracy (+/- %) 1.5 1.5
Freq (typ) (kHz) 300;375 300;375
Freq (min) (kHz) 200 200
Freq (max) (kHz) 500 500
Iq (typ) (mA) 0.2 0.2
Features Adjustable Current Limit;Adjustable Frequency;Built-in Bootstrap Switch;COT Control;Cycle-by-Cycle Current Limit;Diode Emulation Mode;Enable Input;Fast Transient Response;OCP;OVP;Power Good;SCP;UVP;Ultrasonic Mode Control Adjustable Current Limit;Adjustable Frequency;Built-in Bootstrap Switch;COT Control;Cycle-by-Cycle Current Limit;Diode Emulation Mode;Enable Input;Fast Transient Response;OCP;OVP;Power Good;SCP;UVP;Ultrasonic Mode Control
Package Type WQFN4x4-24 WQFN4x4-24
Features
  • Constant On-time Control with 100ns Load Step Response
  • Wide Input Voltage Range : 6V to 25V
  • Dual Adjustable Outputs from 2V to 5.5V
  • Secondary Feedback Input Maintains Charge Pump Voltage (RT8205M)
  • Fixed 3.3V and 5V LDO Output : 100mA
  • 2V Reference Voltage
  • Frequency Selectable via TONSEL Setting
  • 4700ppm/°C RDS(ON) Current Sensing
  • 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
Datasheet
TitleLast UpdateShareDownload
High Efficiency, Main Power Supply Controller for Notebook Computer2010/06/18
Reliability
Title Last Update ShareDownload
High Efficiency, Main Power Supply Controller for Notebook Computer 2015/05/19
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