ZHCSB85F November 2011 – October 2021 TPS62140 , TPS62140A , TPS62141 , TPS62142 , TPS62143
PRODUCTION DATA
- 1 特性
- 2 應用
- 3 說明
- 4 Revision History
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Detailed Description
- 9 Application and Implementation
- 10Power Supply Recommendations
- 11Layout
- 12Device and Documentation Support
- 13Mechanical, Packaging, and Orderable Information
8.4.3 100% Duty-Cycle Operation
The duty cycle of the buck converter is given by D = VOUT/VIN and increases as the input voltage comes close to the output voltage. In this case, the device starts 100% duty-cycle operation, turning on the high-side switch 100% of the time. The high-side switch stays turned on as long as the output voltage is below the internal setpoint. This allows the conversion of small input-to-output voltage differences, for example, for the longest operation time of battery-powered applications. In 100% duty-cycle mode, the low-side FET is switched off.
The minimum input voltage to maintain output voltage regulation, depending on the load current and the output voltage level, is calculated as:
where
- IOUT is the output current
- RDS(on) is the RDS(on) of the high-side FET
- RL is the DC resistance of the inductor used