TIDA-01505: a few questions about the design

Bart

Expert 6370 points

Part Number: TIDA-01505
Other Parts Discussed in Thread: UCC28C43-Q1

Hello,

a few questions about TIDA-01505 and designing backup power supply based on it:

Is it possible to connect transformers secondary winding in series (in the application note they are in parallel) to get 30V instead of 15V?
Why was UCC28C43-Q1 chosen in this design (any particular reason, there are many flyback controllers)?
One big downside of this design is using optocoupler (not enough clearance and creepage and low CMTI<50kV/s) and without optocoupler, the output power is reduced. Can we propose any workarounds?

Thank you.

over 4 years ago

0 Xun over 4 years ago

TI__Mastermind 18120 points

Hi Bart,

1.It would work. The parallel winding structure increase the current rating, in series would generate 30V but would downgrade the converter Iout to half at least.

2. Firstly it supports large duty cycle range which is important for such wide Vin. Secondly, It is a controller with fixed switching frequency so that at light load there would be sufficient energy to charge the input cap. With valley switching controller at light load the switching frequency goes all the way down to ~1kHz. There is no recharge between the recharges. If the start-up circuit is turn-off, between this duration there is no source to recharge the VDD cap. During this 1ms, if the VDD cap is not big enough, it means device shut down.

3. There are two versions of this design: one with opto, the other one without opto. Please refer to the schematic.