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
8.4.2 Power Save Mode Operation
The TPS6214x enters its built-in power-save mode seamlessly if the load current decreases. This secures a high efficiency in light-load operation. The device remains in power-save mode as long as the inductor current is discontinuous.
In power-save mode, the switching frequency decreases linearly with the load current, maintaining high efficiency. The transition into and out of power-save mode happens within the entire regulation scheme and is seamless in both directions.
TPS6214x includes a fixed-on-time circuit. An estimate for this on-time, in steady-state operation with FSW = low, is:
For very small output voltages, an absolute minimum on-time of about 80 ns is kept to limit switching losses. The operating frequency is thereby reduced from its nominal value, which keeps efficiency high. Also the off-time can reach its minimum value at high duty cycles. The output voltage remains regulated in such case. Using tON, the typical peak inductor current in Power Save Mode can be approximated by:
When VIN decreases to typically 15% above VOUT, the TPS6214x does not enter power-save mode, regardless of the load current. The device maintains output regulation in PWM mode.