A problem met in the design of switching power supply

[Martilda]

Hi, I'm using a switching power supply chip LM2575 to drive the load by turning DC voltage 24V to 1.5V. It works well except a problem...

Everytime when the power’s off, the capacitor C2 (maybe?) will still supply power to the load for a short period. Due to this, I cannot turn off the load immediately.
If the problem is not caused by C2, then what’s the cause?

I wonder if there are any solutions to this problem?

Sorry for my poor English, but I really need your suggestions! Thanks in advance!


(R3 is the load)

[David]

Try reducing the value of C2. Also, if you need the voltage on R3 to drop very quickly, try a double-pole switch - one pole to switch the input to the chip, the other to switch the supply to R3.