SLUSFU6A September   2025  – November 2025 UCC27834-Q1 , UCC27884-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Dynamic Electrical Characteristics
    7. 5.7 Timing Diagrams
    8. 5.8 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Input Stages and Interlock
      2. 6.3.2 Undervoltage Lockout (UVLO)
      3. 6.3.3 Level Shifter
      4. 6.3.4 Output Stage
      5. 6.3.5 Low Propagation Delays and Tightly Matched Outputs
      6. 6.3.6 HS Node dV/dt
      7. 6.3.7 Operation Under Negative HS Voltage Condition
    4. 6.4 Device Functional Modes
      1. 6.4.1 Input and Output Logic Table
      2. 6.4.2 Operation Under 100% Duty Cycle Condition
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 Design Requirements
      2. 7.2.2 Detailed Design Procedure
        1. 7.2.2.1 Selecting HI and LI Low Pass Filter Components (RHI, RLI, CHI, CLI)
        2. 7.2.2.2 Selecting Bootstrap Capacitor (CBOOT)
        3. 7.2.2.3 Selecting VDD Bypass Capacitor (CVDD)
        4. 7.2.2.4 Selecting Bootstrap Resistor (RBOOT)
        5. 7.2.2.5 Selecting Gate Resistor RON/ROFF
        6. 7.2.2.6 Selecting Bootstrap Diode
        7. 7.2.2.7 Estimate the UCC278X4-Q1 Power Losses
      3. 7.2.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Device Support
      1. 8.1.1 Third-Party Products Disclaimer
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Support Resources
    5. 8.5 Trademarks
    6. 8.6 Electrostatic Discharge Caution
    7. 8.7 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.7 Operation Under Negative HS Voltage Condition

A typical half-bridge configuration with the UCC278X4-Q1 is shown in Figure 6-5. There are parasitic inductances in the power circuit from die bonding and pinning in QT/QB and PCB tracks of power circuit, the parasitic inductances are labeled LK1,2,3,4.

During switching of HS, the current path of power circuit is changed to current path 2 from current path 1. This is known as current commutation. The current across LK3, LK4 and body diode of QB pulls HS lower than VSS, like shown in the waveform in Figure 6-5. However, the UCC278X4-Q1 offers robust operation under these conditions of negative voltage on HS.

UCC27834-Q1 UCC27884-Q1 HS Negative Voltage In Half-Bridge Configuration Figure 6-5 HS Negative Voltage In Half-Bridge Configuration

The level shifter circuit is referenced to VSS (refer to Figure 6-1), the voltage from HB to VSS is the supply voltage of the level shifter. When HS is a negative voltage with respect to VSS, the voltage of HB–VSS is decreased, as shown in Figure 6-6. There is a minimum operational supply voltage of the level shifter, if the supply voltage of level shifter is too low, the level shifter cannot pass the HI signal to HO. The minimum supply voltage of the level shifter of the UCC278X4-Q1 is 3V, so the recommended HS specification is dependent on HB-HS. The specification of minimum recommended HS is –9V at HB – HS = 12V.

In general, HS can operate until -9V when HB – HS = 12V. If HB–HS voltage is different, the minimum HS voltage changes accordingly.

UCC27834-Q1 UCC27884-Q1 Level Shifter Supply Voltage with Negative HS Figure 6-6 Level Shifter Supply Voltage with Negative HS
Note:

HO logic operational for HS within –9V to 200V while HB – HS = 12V

The capability of a typical UCC278X4-Q1 device to operate under a negative voltage condition on the HS pin is reported in Figure 6-8. The test method is shown in Figure 6-7.

UCC27834-Q1 UCC27884-Q1 Negative Voltage Test Method Figure 6-7 Negative Voltage Test Method
UCC27834-Q1 UCC27884-Q1 NTSOA (Negative Transient Safe Operating Area) Maximum Negative HS Voltage vs Pulse Width Figure 6-8 NTSOA (Negative Transient Safe Operating Area) Maximum Negative HS Voltage vs Pulse Width

The above curve is a typical curve based on limited units tested at 25°C and at VHB –VHS= 15 V. The curve gives a general guideline as to what negative transients the device can survive, but it is still recommended to limit the negative transients to within the device recommended specifications through layout and design.