Other Parts Discussed in Thread: TEST2
Hi,
My customer had come across a problem of short circuit test when using MC33063A for buck function.
Schematic sames as below except for two items:
- Cin=200uF(electrolytic capacitor) parallel with 0.1uF(ceramic capacitor)
- Add a magnetic bead between the diode and GND.
Test condition:
- VIN=24VDC, Vout=5V(typical500mA)
Test1 :
- Vout 5V short test, IC burn(pin 1)
Test2:
- Change the Rsc resistor from 0.33ohm to 1ohm; Vout 5V short test for 5mins, no problem.
Test3:
- Remove the magnetic bead, keep the Rsc=0.33ohm; Vout 5V short test for 5mins, no problem.
Question:
- Why the current limit doesn't on the Test1?
- Customer will keep the magnetic bead, which is their standard circuit. How to pass the S/C test under this condion? What could we do to achieve that?
If you need any more information, please let me know. Looking forward to your reply. Thanks.