SLUSEM9A September 2022 – June 2024 UCC21755-Q1
PRODUCTION DATA
- 1
- 1 Features
- 2 Applications
- 3 Description
- 4 Pin Configuration and Functions
-
5 Specifications
- 5.1 Absolute Maximum Ratings
- 5.2 ESD Ratings
- 5.3 Recommended Operating Conditions
- 5.4 Thermal Information
- 5.5 Power Ratings
- 5.6 Insulation Specifications
- 5.7 Safety Limiting Values
- 5.8 Electrical Characteristics
- 5.9 Switching Characteristics
- 5.10 Insulation Characteristics Curves
- 5.11 Typical Characteristics
- 6 Parameter Measurement Information
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3
Feature Description
- 7.3.1 Power Supply
- 7.3.2 Driver Stage
- 7.3.3 VCC and VDD Undervoltage Lockout (UVLO)
- 7.3.4 Active Pulldown
- 7.3.5 Short Circuit Clamping
- 7.3.6 Internal Active Miller Clamp
- 7.3.7 Desaturation (DESAT) Protection
- 7.3.8 Soft Turn-Off
- 7.3.9 Fault (FLT), Reset and Enable (RST/EN)
- 7.3.10 Isolated Analog to PWM Signal Function
- 7.4 Device Functional Modes
-
8 Applications and Implementation
- 8.1 Application Information
- 8.2
Typical Application
- 8.2.1 Design Requirements
- 8.2.2
Detailed Design Procedure
- 8.2.2.1 Input Filters for IN+, IN-, and RST/EN
- 8.2.2.2 PWM Interlock of IN+ and IN-
- 8.2.2.3 FLT, RDY, and RST/EN Pin Circuitry
- 8.2.2.4 RST/EN Pin Control
- 8.2.2.5 Turn-On and Turn-Off Gate Resistors
- 8.2.2.6 Overcurrent and Short Circuit Protection
- 8.2.2.7 Isolated Analog Signal Sensing
- 8.2.2.8 Higher Output Current Using an External Current Buffer
- 8.2.3 Application Curves
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Revision History
- 13Mechanical, Packaging, and Orderable Information
8.2.2.4 RST/EN Pin Control
RST/EN pin has two functions. It is used to enable or shutdown the outputs of the driver and to reset the fault signaled on the FLT pin after DESAT is detected. RST/EN pin needs to be pulled up to enable the device; when the pin is pulled down, the device is in disabled status. By default the driver is disabled with the internal 50-kΩ pulldown resistor at this pin.
When the driver is latched after DESAT is detected, the FLT pin and output are latched low and need to be reset by the RST/EN pin. The microcontroller must send a signal to RST/EN pin after the fault to reset the driver. The driver will not respond until after the mute time tFLTMUTE. The reset signal must be held low for at least tRSTFIL after the mute time.
This pin can also be used to automatically reset the driver. The continuous input signal IN+ or IN- can be applied to RST/EN pin. There is no separate reset signal from the microcontroller when configuring the driver this way. If the PWM is applied to the noninverting input IN+, then IN+ can also be tied to RST/EN pin. If the PWM is applied to the inverting input IN-, then a NOT logic is needed between the PWM signal from the microcontroller and the RST/EN pin. Using either configuration results in the driver being reset in every switching cycle without an extra control signal from microcontroller tied to RST/EN pin. One must ensure the PWM off-time is greater than tRSTFIL in order to reset the driver in cause of a DESAT fault.
Figure 8-4 Automatic Reset Control