ZHCSBM9C SEPTEMBER 2013 – June 2018 TPS53513
PRODUCTION DATA.
- 1 特性
- 2 应用
- 3 说明
- 4 修订历史记录
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 5-V LDO and VREG Start-Up
- 7.3.2 Enable, Soft Start, and Mode Selection
- 7.3.3 Frequency Selection
- 7.3.4 D-CAP3 Control and Mode Selection
- 7.3.5 Power-Good
- 7.3.6 Current Sense and Overcurrent Protection
- 7.3.7 Overvoltage and Undervoltage Protection
- 7.3.8 Out-Of-Bounds Operation
- 7.3.9 UVLO Protection
- 7.3.10 Thermal Shutdown
- 7.4 Device Functional Modes
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文档支持
- 12机械、封装和可订购信息
7.4.1 Auto-Skip Eco-mode Light Load Operation
While the MODE pin is pulled to GND directly or through 150-kΩ resistor, the TPS53513 device automatically reduces the switching frequency at light-load conditions to maintain high efficiency. This section describes the operation in detail.
As the output current decreases from heavy load condition, the inductor current also decreases until the rippled valley of the inductor current touches zero level. Zero level is the boundary between the continuous-conduction and discontinuous-conduction modes. The synchronous MOSFET turns off when this zero inductor current is detected. As the load current decreases further, the converter runs into discontinuous-conduction mode (DCM). The on-time is maintained to a level approximately the same as during continuous-conduction mode operation so that discharging the output capacitor with a smaller load current to the level of the reference voltage requires more time. The transition point to the light-load operation IO(LL) (for example: the threshold between continuous- and discontinuous-conduction mode) is calculated as shown in Equation 6.
where
- fSW is the PWM switching frequency
Using only ceramic capacitors is recommended for Auto-skip mode.