TIDT195 September   2020  – MONTH 

 

  1.   Description
  2. 1Test Prerequisites
    1. 1.1 Voltage and Current Requirements
    2. 1.2 Required Equipment
  3. 2Testing and Results
    1. 2.1 Thermal Images
    2. 2.2 Efficiency and Power Dissipation Graphs
    3. 2.3 Efficiency and Power Dissipation Data
    4. 2.4 Voltage Regulation
  4. 3Waveforms
    1. 3.1 Start-up
    2. 3.2 Switch Node
    3. 3.3 Output Voltage Ripple
    4. 3.4 Load Transients
    5. 3.5 Short-Circuit Recovery Response

3.2 Switch Node

The following image shows the FET switch node voltage (RED) at TP3 and the input voltage (BLUE). The input voltage is 50 V and the 12-V output is loaded to 400 mA.

GUID-20200813-CA0I-J6L6-F2SN-VH9MJFQBKRHP-low.jpgFigure 3-5 FET Switch Node Voltage (Vsnode: 10 V/div, VIN: 10 V/div, 10 μs/div)

The following image (scope persistence on) shows the FET switch node voltage (RED) at TP3 and the input voltage (BLUE). The input voltage is 50 V and the 12-V output is loaded to 400 mA. This shows the effects of frequency dithering and valley switching on the switch node waveform.

GUID-20200813-CA0I-WSZJ-3Z53-WZL8RR1Q5VVW-low.jpgFigure 3-6 FET Switch Node Voltage (Vsnode: 10 V/div, VIN: 10 V/div, 10 μs/div)

The following image shows the FET switch node voltage (RED) at TP3 and the input voltage (BLUE). The input voltage is 50 V and the 12-V output is loaded to 10 mA.

GUID-20200813-CA0I-RZQZ-DWSR-TCNRFXJND3QS-low.jpgFigure 3-7 FET Switch Node Voltage (Vsnode: 10 V/div, VIN: 10 V/div, 50 μs/div) .
The following image shows the FET switch node voltage (RED) at TP3 and the input voltage (BLUE). The input voltage is 150 V and the 12-V output is loaded to 400 mA.
GUID-20200813-CA0I-SKKJ-L4FZ-M2LFJXJZG8W3-low.jpgFigure 3-8 FET Switch Node Voltage (Vsnode: 50 V/div, VIN: 50 V/div, 10 μs/div) .
The following image (scope persistence on) shows the FET switch node voltage (RED) at TP3 and the input voltage (BLUE). The input voltage is 150 V and the 12-V output is loaded to 400 mA. This shows the effects of frequency dithering and valley switching on the switch node waveform.
GUID-20200813-CA0I-QKT7-CT10-6Z6CLJ7TWRX2-low.jpgFigure 3-9 FET Switch Node Voltage (Vsnode: 50 V/div, VIN: 50 V/div, 10 μs/div) .
The following image shows the FET switch node voltage (RED) at TP3 and the input voltage (BLUE). The input voltage is 150 V and the 12-V output is loaded to 10 mA.
GUID-20200813-CA0I-RWGN-8S8W-MMHMQDWR5KHL-low.jpgFigure 3-10 FET Switch Node Voltage (Vsnode: 50 V/div, VIN: 50 V/div, 50 μs/div) .
The following image shows the switching voltages on each side of C1. The waveforms show the switch node voltage at TP3 (RED) and D1 cathode voltage (BLUE). The input voltage is 50 V and the 12-V output is loaded to 400 mA.
GUID-20200813-CA0I-M7S3-Q4B7-ZJM9BP4BSL4V-low.jpgFigure 3-11 FET Switch Node Voltage (Vsnode: 10 V/div, D1-Cathode: 10 V/div, 10 μs/div) .
The following image shows the switching voltages on each side of resistor divider R1/R2. The waveforms show the switch node voltage at TP3 (RED) and the voltage at R1 (side connected to D2) (BLUE). The input voltage is 50 V and the 12-V output is loaded to 400 mA.
GUID-20200813-CA0I-FVQW-J4VR-PVTH7B2WJXVR-low.jpgFigure 3-12 Switching Voltages (Vsnode: 10 V/div, D2-Cathode: 10 V/div, 10 μs/div) .

The following image shows the switching voltages on each side of resistor divider R1/R2. The waveforms show the switch node voltage at TP3 (RED) and the voltage at R1 (side connected to D2) (BLUE). The input voltage is 150 V and the 12-V output is loaded to 400 mA.

GUID-20200813-CA0I-Q5RZ-6MSR-SQFQ7MQXKKXK-low.jpgFigure 3-13 Switching Voltages (Vsnode: 50 V/div, D2-Cathode: 10 V/div, 5 μs/div) .