SLVSA67F February 2010 – April 2020 TPS62400-Q1 , TPS62402-Q1 , TPS62404-Q1 , TPS62405-Q1
UNLESS OTHERWISE NOTED, this document contains PRODUCTION DATA.
- 1 Features
- 2 Applications
- 3 Description
- 4 Revision History
- 5 Device Comparison Table
- 6 Pin Configuration and Functions
- 7 Specifications
- 8 Parameter Measurement Information
- 9 Detailed Description
-
10Application and Implementation
- 10.1 Application Information
- 10.2
Typical Application
- 10.2.1 Design Requirements
- 10.2.2
Detailed Design Procedure
- 10.2.2.1
Output Voltage Setting
- 10.2.2.1.1 Converter 1 Adjustable Default Output-Voltage Setting: TPS62400-Q1
- 10.2.2.1.2 Converter 1 Fixed Default Output-Voltage Setting (TPS62402-Q1, TPS62404-Q1, and TPS62405-Q1)
- 10.2.2.1.3 Converter 2 Adjustable Default Output-Voltage Setting (TPS62400-Q1):
- 10.2.2.1.4 Converter 2 Fixed Default Output-Voltage Setting
- 10.2.2.2 Output Filter Design (Inductor and Output Capacitor)
- 10.2.2.1
Output Voltage Setting
- 10.2.3 Application Curves
- 10.3 System Examples
- 11Power Supply Recommendations
- 12Layout
- 13Device and Documentation Support
- 14Mechanical, Packaging, and Orderable Information
9.4.1.3 100% Duty-Cycle Low-Dropout Operation
The converters offer a low input-to-output voltage difference while still maintaining operation with the use of the 100% duty-cycle mode. In this mode, the P-channel switch is constantly on. This is particularly useful in battery-powered applications to achieve longest operation time by taking full advantage of the whole battery-voltage range. The minimum input voltage to maintain regulation depends on the load current and output voltage, which one can calculate as:
where
- IOUTxmax = maximum output current plus inductor ripple current
- rDS(on)max = maximum P-channel switch rDS(on)
- RL = dc resistance of the inductor
- VOUTxmax = nominal output voltage plus maximum output-voltage tolerance
With decreasing load current, the device automatically switches into pulse-skipping operation, in which the power stage operates intermittently based on load demand. Running cycles periodically minimizes the switching losses, and the device runs with a minimum quiescent current, maintaining high efficiency.