EVALSTSR30-60W STMicroelectronics, EVALSTSR30-60W Datasheet - Page 15

• Manufacturer Part Number: EVALSTSR30-60W
• Description: BOARD EVAL USING L6668 & STSR30
• Manufacturer: STMicroelectronics
• Type: AC/DC Switching Convertersr

Specifications of EVALSTSR30-60W

• Mfg Application Notes: EVALSTSR30-60W AppNote
• Main Purpose: AC/DC, Primary and Secondary Side
• Outputs And Type: 1, Isolated
• Power - Output: 60W
• Voltage - Output: 12V
• Current - Output: 5A
• Voltage - Input: 88 ~ 264VAC
• Regulator Topology: Flyback
• Frequency - Switching: 68kHz
• Board Type: Fully Populated
• Utilized Ic / Part: L6668, STSR30
• Input Voltage: 88 V to 264 V
• Output Voltage: 12 V
• Dimensions: 120 mm x 75 mm
• Product: Power Management Modules
• Silicon Manufacturer: ST Micro
• Silicon Core Number: L6668 And STSR30
• Kit Application Type: Power Management - Voltage Regulator
• Application Sub Type: SMPS
• Kit Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: L6668, STSR30
• Other names: 497-6389; EVALSTSR30-60W

Functional check
3.4
3.5
15/27
Figure 17. Short circuit at 88V
CH1: Q3 drain voltage
CH2: Self supply voltage
CH4: Short circuit current
Short-circuit tests
The demo board has been tested with a short circuit directly on the output connector. During
this fault condition, the circuit works in Hiccup mode thanks to the lack of self supply. Once
the short-circuit is removed, the converter restarts working normally. The high voltage start-
up generator of the L6668 ensures having constant on-off periods. The average output
current during the short-circuit is well below the nominal value (approx. 0.8A).
Overvoltage protection
The DIS pin of the L6668 is dedicated to a latched protection of the circuit. In this
application, it is used to provide overvoltage protection using components D11, R19, R28
and C13 connected to the auxiliary winding of the transformer. This network provides a
mean rectified value cycle by cycle of the auxiliary voltage that tracks the output voltage. In
the following figures, a feedback failure is simulated (open loop) and the most interesting
waveforms are shown. As explained, this protection is latched and it is necessary to recycle
the input power to restart the circuit.
Figure 19
operating at full load. In the whole input range during fault condition, V
V
CC
reaches 20V.
and
Figure 20
AC
- 60Hz
show the OVP protection intervention while the converter is
Figure 18. Short circuit at 264V
CH1: Q3 drain voltage
CH2: Self supply voltage
CH3: Short circuit current
OUT
reaches 14V and
AC
- 50Hz
AN2432