SLUAAH3 October   2021 UCC28056

 

  1.   Trademarks
  2. 1How to Select the Correct Devices Version of UCC28056 Families?
  3. 2How to Complete the Schematic Review of the UCC28056?
    1. 2.1 VOSNS Pin
    2. 2.2 ZCD/CS Pin
    3. 2.3 DRV Pin
    4. 2.4 GND Pin
    5. 2.5 VCC Pin
    6. 2.6 COMP Pin
  4. 3How to Test and Confirm the UCC28056 Working Mode?
    1. 3.1 How to Capture the ZCD/CS Waveform?
    2. 3.2 How to Evaluate UCC28056 Normal Operation Mode Waveform?
  5. 4Protections and how to Identify Them?
    1. 4.1 OVP1
    2. 4.2 OVP2
    3. 4.3 OCP1
    4. 4.4 OCP2
  6. 5Application Debug Frequently Asked Questions (FAQs).
    1. 5.1  How is the UCC28056 GND Pin Connected?
    2. 5.2  There is CCM Inductor Current During Start-Up, is This a Normal Phenomenon?
    3. 5.3  How to Fine-Tune the RC Parameter on the ZCD/CS Pin?
    4. 5.4  Is it Possible to Increase the High Voltage Cap Value on the ZCD Cap Divider?
    5. 5.5  How to Separate the TONMAX Limit or OCP Protection When the PFC Output Voltage Cannot Follow the Regulated Voltage?
    6. 5.6  Does UCC28056 Support DC Input Application?
    7. 5.7  How Does RDG Change the Delay Time for Valley Switching Detection of the MOSFET?
    8. 5.8  Can UCC28056 Meet Harmonic Performance?
    9. 5.9  Does UCC28056 Have Soft Start?
    10. 5.10 Does the UCC28056 Support Auxiliary-Winding PFC Inductor Input on the ZCD Pin?
  7. 6References

1 How to Select the Correct Devices Version of UCC28056 Families?

Table 1-1 Device Comparison Table
DeviceUCC28056AUCC28056BUCC28056C
Where UsedPFC Output > 400 VApplication With Minimal Audible NoiseGeneral Purpose
Overvoltage Protection Threshold108% VOUT110% VOUT110% VOUT
Second Tier Overvoltage Protection Enabled✓✓
Burst Mode Threshold< 15% Load< 15% Load< 10% Load

The UCC28056 families integrate the Zero Current Detection (ZCD) and the Current Sense (CS) feature together at the ZCD/CS pin, to reduce the package size. This makes the devices cost-competitive in of the smallest packages available. The device layout is designed for both precise detection of drain-to-source voltage and OCP signal sampling. The UCC28056A, UCC28056B, and UCC28056C have improved the noise immunity on the ZCD pin making the controller more robust and less sensitive to noise from downstream.

Table 1-1 shows the key differences of each version. The UCC28056A removes the OVP2 feature. Use this device in applications with wider input voltage range and high output voltage. TI also recommends using the device in applications that are not allowed any restart event during surge or lighting test.

The UCC28056C has a lower burst mode threshold compared with the UCC28056A and UCC28056B. Use the UCC28056C in applications that need lower burst mode power.

The minimum frequency for UCC28056C is around 18 kHz to 20 kHz, and UCC28056A, UCC28056B minimum frequency can be higher than 20 kHz. For some applications that detect the audible noise through audible noise test equipment and scan the frequency from 20 Hz to 20 kHz, select the UCC28056A or UCC28056B version.

For more information about the differences of each version, see the UCC28056 Selection Guide application brief.