ZHCSKG7B June 2019 – February 2024 UCC5390-Q1
PRODUCTION DATA
- 1
- 1 特性
- 2 应用
- 3 说明
- 4 Pin Configuration and Function
-
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 for DWV Package
- 5.7 Safety-Related Certifications For DWV Package
- 5.8 Safety Limiting Values
- 5.9 Electrical Characteristics
- 5.10 Switching Characteristics
- 5.11 Insulation Characteristics Curves
- 5.12 Typical Characteristics
- 6 Parameter Measurement Information
- 7 Detailed Description
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11Device and Documentation Support
- 12Revision History
- 13Mechanical, Packaging, and Orderable Information
8.2.2.2 Gate-Driver Output Resistor
The external gate-driver resistors, RG(ON) and RG(OFF) are used to:
- Limit ringing caused by parasitic inductances and capacitances
- Limit ringing caused by high voltage or high current switching dv/dt, di/dt, and body-diode reverse recovery
- Fine-tune gate drive strength, specifically peak sink and source current to optimize the switching loss
- Reduce electromagnetic interference (EMI)
The output stage has a pull-up structure consisting of a P-channel MOSFET and an N-channel MOSFET in parallel. The combined peak source current is 17 A for UCC5390-Q1 . Use Equation 1 to estimate the peak source current.
where
- RON is the external turn-on resistance, which is 2.2 Ω in this example.
- RGFET_Int is the power transistor internal gate resistance, found in the power transistor data sheet. We will assume 1.8Ω for our example.
- IOH is the peak source current which is the minimum value between 17 A, the gate-driver peak source current, and the calculated value based on the gate-drive loop resistance.
In this example, the peak source current is approximately 4.45 A as calculated in Equation 2.
Similarly, use Equation 3 to calculate the peak sink current.
where
- ROFF is the external turn-off resistance, which is 2.2 Ω in this example.
- IOL is the peak sink current which is the minimum value between 17 A, the gate-driver peak sink current, and the calculated value based on the gate-drive loop resistance.
In this example, the peak sink current is the minimum value between Equation 4 and 17 A.
The estimated peak current is also influenced by PCB layout and load capacitance. Parasitic inductance in the gate-driver loop can slow down the peak gate-drive current and introduce overshoot and undershoot. Therefore, TI strongly recommends that the gate-driver loop should be minimized. Conversely, the peak source and sink current is dominated by loop parasitics when the load capacitance (CISS) of the power transistor is very small (typically less than 1 nF) because the rising and falling time is too small and close to the parasitic ringing period.