LM5037: Operating LM5037 in Open Loop Operation For Development Purpose?

Puneeth Kumar Srikanta Murthy67

Part Number: LM5037

Hi,

I am using LM5037 circuit for my circuit. I wanted to test it in open loop to see it operates properly. The TINA simulation works perfectly for my circuit in open loop. But the hardware doesn't seem to behave as expected for the same configuration. Currently I have moved away from my PCB and am testing the circuit on breadboard. The issue still persists. I am using the application circuit provided in the datasheet(300kHz oscillator frequency). I have shorted the RES and CS pins to ground. Any suggestions to run the circuit in open module would be helpful.

I have tried providing a smal voltage value at the COMP pin and also connecting a resistor. In every case the PWM output does not come out even if all the intended signals are what they are supposed to be according to the simulation model from TINA.

I look forward to suggestions.

Thanks,

Puneeth

over 8 years ago

0 Daniel Ruiz over 8 years ago

TI__Intellectual 2910 points

Puneeth,

Thank you for your interest in LM5037. I have contacted the applications engineering team for this device. They should be able to provide feedback within the next day or so. In the meantime, any further specifics about your application will be helpful for the experts to help you diagnose the behavior you are experiencing: schematic, TINA-TI files, oscilloscope captures on key pins, operating supply/bias voltages, etc.

- Daniel

0 Puneeth Kumar Srikanta Murthy67 over 8 years ago in reply to Daniel Ruiz

Prodigy 30 points

Hi Daniel,

Page 27 from the following link www.ti.com/.../lm5037.pdf .

Thanks,
Puneeth

0 Daniel Ruiz over 8 years ago in reply to Puneeth Kumar Srikanta Murthy67

TI__Intellectual 2910 points

Puneeth,

Have you tried to operate without grounding SS? Per datasheet section 7.3.5, connecting SS to ground forces the internal PWM control signal to
ground, reducing the output duty cycle quickly to zero. I would imagine this could be the root cause for the lack of output you observe.

0 Puneeth Kumar Srikanta Murthy67 over 8 years ago in reply to Daniel Ruiz

Prodigy 30 points

Hi Daniel,

The SS pin is not grounded. I have grounded RES pin. The SS pin is connected as per the schematic.

Puneeth

0 Daniel Ruiz over 8 years ago in reply to Puneeth Kumar Srikanta Murthy67

TI__Intellectual 2910 points

Apologies. I misread your original post. Please allow a little time for our experts on this part to provide feedback.

0 Wangxin Huang over 8 years ago in reply to Puneeth Kumar Srikanta Murthy67

TI__Intellectual 1550 points

Puneeth,

We've responded via email. You should receive updates from our FAE Kurt shortly.

Regards,

Wangxin

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LM5037: Operating LM5037 in Open Loop Operation For Development Purpose?