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
8.4.4 Current Limit and Short Circuit Protection
The TPS6214x devices are protected against heavy load and short-circuit events. If a short circuit is detected (VOUT drops below 0.5 V), the current limit is reduced to 1.6 A, typically. If the output voltage rises above 0.5 V, the device runs in normal operation again. At heavy loads, the current limit determines the maximum output current. If the current limit is reached, the high-side FET is turned off. Avoiding shoot through current, then the low-side FET switches on to allow the inductor current to decrease. The low-side current limit is typically 2.4 A. The high-side FET turns on again only if the current in the low-side FET has decreased below the low-side current-limit threshold.
The output current of the device is limited by the current limit (see Section 7.5). Due to internal propagation delay, the actual current can exceed the static current limit during that time. The dynamic current limit is calculated as follows:
where
- ILIMF is the static current limit, specified in Section 7.5
- L is the inductor value
- VL is the voltage across the inductor (VIN – VOUT)
- tPD is the internal propagation delay
The current limit can exceed static values, especially if the input voltage is high and very small inductances are used. The dynamic high-side switch peak current is calculated as follows:
