UCC2808-2: UCC3808

Saeed Valipour

Part Number: UCC2808-2
Other Parts Discussed in Thread: UCC2808A-2

Tool/software:

Hi Guys,

I want to use UCC2808A-2 as a half bridge controller in the secondary side. So using FB and a voltage divider instead of Optocoupler and COMP. Is there any reference design for that? i have no idea where to connect COMP pin? Float? Also, if I don't want any current protection, shall I just connect RC pin to GND?

Thanks a lot in advance

4 months ago

0 Adhvaidh Aravind 4 months ago

TI__Expert 3820 points

Hi Saeed,

UCC2808A-2 is a new device. So we do not have a reference design for it, yet.

COMP pin is the input for the IC's PWM comparator. It controls the duty cycle (please refer to the block diagram). If COMP pin is left to float, it could pick up noise, and saturate the amplifier.

Please refer to 7.2 Typical Application in the datasheet for an example.

No, RC pin is the oscillator programming pin. Shorting it to ground stops the oscillator from working. Did you mean CS pin?

0 Saeed Valipour 4 months ago in reply to Adhvaidh Aravind

Prodigy 20 points

Hi Adhvaidh,

Yes i made a mistake. i meant CS pin. i want to disable it with by connecting to the GND with a resistor. is it possible?

about the main question, in the block diagram COMP is the output of the ampifier. so if i connect FB why i need to connect COMP too?

also when im not allowed to make it float, then what is the solution? connecting to the ground through a resistor and a capacitor?

0 Adhvaidh Aravind 4 months ago in reply to Saeed Valipour

TI__Expert 3820 points

You can add maybe a type-2 compensation circuit.

For more information on compensation, please refer to this application note:

https://www.ti.com/lit/an/slva662/slva662.pdf?ts=1760139778204

Thanks,

Addy

Power management

Power management forum

UCC2808-2: UCC3808