ZHCSMM1C April 2023 – February 2024 TPS274C65
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Device Comparison Table
- 5 Pin Configuration and Functions
- 6 Specifications
- 7 Parameter Measurement Information
-
8 Detailed Description
- 8.1 Overview
- 8.2 Functional Block Diagram
- 8.3
Feature Description
- 8.3.1 Pin Diagrams
- 8.3.2 SPI Mode Operation
- 8.3.3 Programmable Current Limit
- 8.3.4 DO_EN Feature
- 8.3.5
Protection Mechanisms
- 8.3.5.1 Overcurrent Protection
- 8.3.5.2 Short Circuit Protection
- 8.3.5.3 Inductive-Load Switching-Off Clamp
- 8.3.5.4 Inductive Load Demagnetization
- 8.3.5.5 Thermal Shutdown
- 8.3.5.6 Undervoltage protection on VS
- 8.3.5.7 Undervoltage Lockout on Low Voltage Supply (VDD_UVLO)
- 8.3.5.8 Power-Up and Power-Down Behavior
- 8.3.5.9 Reverse Current Blocking
- 8.3.6 Diagnostic Mechanisms
- 8.3.7 LED Driver
- 8.4 Device Functional Modes
- 8.5 TPS274C65BS Available Registers List
- 8.6 TPS274C65 Registers
- 9 Application and Implementation
- 10Device and Documentation Support
- 11Revision History
- 12Mechanical, Packaging, and Orderable Information
8.3.5.2 Short Circuit Protection
The TPS274C65xS provides output short-circuit protection to ensure that the device will prevent current flow in the event of a low impedance path to GND, removing the risk of damage or significant supply droop. The TPS274C65xS is guaranteed to protect against short-circuit events regardless of the state of the ILIM pins and with up to 36 V supply at 125°C.
Figure 8-21 shows the behavior of the TPS274C65xS when the device is enabled into a short-circuit.
Figure 8-21 Enable into Short-Circuit
BehaviorDue to the low impedance path, the output current will rapidly increase until it hits the current limit threshold. Due to series inductance and deglitch, the measured maximum current may temporarily exceed the ICL value defined as ICL_ENPS, however it will settle to the current limit.
In this state high power is dissipated in the FET, so eventually the internal thermal protection temperature for the FET is reached and the device safely shuts down. If the device is not configured in latch mode, the device will wait tRETRY amount of time and turn the channel back on.
Figure 8-22 shows the behavior of the TPS274C65xS when a short-circuit occurs when the device is in the on-state and already outputting current. When the internal pass FET is fully enabled, the current clamping settling time is slower so to ensure overshoot is limited, the device implements a fast trip level at a level IOVCR. When this fast trip threshold is hit, the device immediately shuts off for a short period of time before quickly re-enabling and clamping the current to ICL_Reg level after a brief transient overshoot to the ICL_ENPS level. The device will then keep the current clamped at the regulation current limit until the thermal shutdown temperature is hit and the device will safely shut-off.
Figure 8-22 On-State Short-Circuit
BehaviorSoft Short- Circuit Behavior illustrated in Soft Short-Circuit Behavior shows the behavior of the TPS274C65xS when there is a small change in impedance that sends the load current above the ICL threshold. The current rises to ICL_LINPK since the FET is still in the linear mode. Then the current limit kicks in and the current drops to the ICL value.
Figure 8-23 Soft Short-Circuit BehaviorIn all of these cases, the internal thermal shutdown is safe to hit repetitively. There is no device risk or lifetime reliability concerns from repeatedly hitting this thermal shutdown level.