UCC28950: hardware & system design tools forum

Nithin c

Prodigy 180 points

Part Number: UCC28950

Tool/software:

Hi,

How to configure ucc28950 ic work in open loop condtion for test purpose

we have to generate output pulse without any feed back loop

7 months ago

0 Hemanth Sreeperumbudur 7 months ago

TI__Intellectual 2480 points

Hi Nithin,

To run UCC28950 in open loop, connect EA- and COMP pins together. The error amplifier output now tracks the voltage at EA+ in voltage follower configuration. Apply a voltage at EA+ starting with 0V, and slowly increasing should help provide open loop operation.

If you have any related question, click on 'Ask related question'. If you have a new question, use 'Ask a new question' option.

Regards
Hemanth

0 Nithin c 7 months ago in reply to Hemanth Sreeperumbudur

Prodigy 180 points

i have connected 100nf at SS pin to ground

DELAB, DELCD, DELEF connected to ground throuh a 10k resistance

RT 60K to ground

SYNC pin open

RSUM connected to VREF

Is it correct?

0 Nithin c 7 months ago in reply to Nithin c

Prodigy 180 points

i want to check the out pulse of ic with out any external connection

0 Hemanth Sreeperumbudur 7 months ago in reply to Nithin c

TI__Intellectual 2480 points

Nithin,

Please connect the control circuit components per the requirements and following datasheet including the frequency setting, you need.

Recommend to use 15kohm for DELAB, DELCD, DELEF and ADELEF to GND. RSUM connecting to VREF makes the controller work in voltage mode control

Please refer UCC2895x-Q1 Automotive Phase-Shifted Full-Bridge Controller for Wide-Input Voltage Range Applications datasheet (Rev. C) for more details.

Regards
Hemanth

0 Nithin c 7 months ago in reply to Hemanth Sreeperumbudur

Prodigy 180 points

This is the wave form of SS pin

Waveform at EA- pin

There is no output pulses

Please help me to resolve this problem

0 Hemanth Sreeperumbudur 7 months ago in reply to Nithin c

TI__Intellectual 2480 points

Nithin,

Did you go through each pin functionality in the datasheet?

Can you measure all the pin voltages, that should help you debugging the circuit having understood each pin functionality and expected voltage.

Please use all 4 or 8 channels to see them in sync.

Regards
Hemanth

0 Nithin c 7 months ago in reply to Hemanth Sreeperumbudur

Prodigy 180 points

Voltage level at each pin given here

RT : 2.5V

TMIN : 1V

DELEF :2.5V

DELCD : 0.2V

DELAB : 0.2V

All are square pulses with on time 20ms and off time 130ms

EA pin and COM i have given below

EA+ : 3.3V

0 Hemanth Sreeperumbudur 7 months ago in reply to Nithin c

TI__Intellectual 2480 points

Hi Nithin,

I will get back to you by tomorrow.

Regards
Hemanth

0 Hemanth Sreeperumbudur 7 months ago in reply to Hemanth Sreeperumbudur

TI__Intellectual 2480 points

Nithin,

"EA pin and COM i have given below"

Are you applying any voltage at COMP pin directly?

Regards
Hemanth

0 Hemanth Sreeperumbudur 6 months ago in reply to Hemanth Sreeperumbudur

TI__Intellectual 2480 points

Nithin,

Just to re-iterate and for future reference on this thread, voltage shall not be applied at COMP pin directly. As mentioned before the EA should operate in voltage follower mode.

Hope the issue got resolved as I don't see further discussion for about two weeks. Closing the thread.
If you have a related question click on 'Ask a related question' and click on 'Ask a new question' otherwise.

Regards
Hemanth

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