Can you connect a voltage source to the output of a transconductance amplifier?

[cupoftea]

Hi,
Can you connect a volt source (eg output of an opamp buffer) directly to the output of a transconductance error amplifier?
(eg to the VAO transconductance amp in UCC28070A)?

UCC280780A

https://www.ti.com/lit/ds/symlink/ucc28070a.pdf?ts=1658228370989&ref_url=https%253A%252F%252Fwww.google.com%252F

(Sorry i lost my other overly long-winded post about this, which wasn't ensconced with +ve responses)

 

[BradtheRad]

Some outputs source current. Some sink current. Some do both.

In other words:
a) provide a path to ground,
b) or a path to VSupply,
c) or both.

 

[dick_freebird]

An OTA will control output current according to input difference, in closed loop. What happens when, say, the output is railed by input being hard steered, is a detail question. Like if the low side output device is fully "on", due to an error condition that won't close or closes way slow, will you violate pin current or pdiss? Or is self protection (given an unusually stiff load) designed in?

 

[cupoftea]

What happens when, say, the output is railed by input being hard steered, is a detail question. Like if the low side output device is fully "on", due to an error condition that won't close or closes way slow, will you violate pin current

Thanks, this is a great point, i think i will use a 1k resistor to connect the voltage to its output, just in case.....the 1k should be small enough to overcome the "normal" output resistance of the xconductance amp.......so i can get something between say 1.5 to 4v at the xconductance output....and fool the UCC28070A that their is a load connected and stop the VAO xconductnace amp from railing high and causing UCC28070A shutown.

This is all so i can see the gate drive pulsing before i connect it to the fet.

 

[FvM]

Not clear what you want to achieve. Overriding VAO means you break the voltage feedback loop and set a fixed output power. This makes only sense if the PFC output power is consumed by a suitable sink, e.g. a battery. Otherwise you'll drive the converter into OVP shutdown (provided Vsense is still monitoring the output voltage).

 

[cupoftea]

Thanks, sorry i should have said, there wont be any power throughput, this is just to check the gate drive is pulsing and not stuck high......the gate drive wont actually be connected to the fet...its also to check the max duty cycle setting isnt violated due to "wrong component" etc.