TL7660: Problem with generating -5V using TL7660

Shamsul Arefeen Al Mahmud

Part Number: TL7660

Hello, I am trying to generate -5V using TL7660. I am using 2 capacitors (c1 and c2) 10uF tantalum type same as the datasheet suggested (C1 positive is with pin 2 and C2 positive is grounded). But when I am providing +5V or +3.3V in Vcc the out is always +0.25V. I can't figure out why its happening. Can someone suggest how the circuit should be for TL7660?

Thanks in advance.

Shamsul

over 3 years ago

0 Brigitte over 3 years ago

TI__Guru 61135 points

Hello Shamsul,

Please check out page 9, Figure 3 in the datasheet of TL7660 for the right circuit.

Please add an additional capacitor close to VIN to stabilize the input voltage.

You could as well use ceramic capacitors. 10uF on input, output and between pins 2 and 4.

Best regards,
Brigitte

0 Shamsul Arefeen Al Mahmud over 3 years ago in reply to Brigitte

Prodigy 120 points

Hello Brigitte,
Thanks for the reply. I am following exactly the Figure-3 in the datasheet of TL7660. I have added two parallel capacitors (2.2u and 100n) to the +5v supply of the TL7660. However, I didn't use any capacitor close to VIN pin. I will try to add that. I can try to use ceramic capacitors of 10uF in between pin 2 and 4, also from Vout pin to ground.

0 Brigitte over 3 years ago in reply to Shamsul Arefeen Al Mahmud

TI__Guru 61135 points

Hello Shamsul,

Ok, then I will wait until I get an update from you.

Best regards,
Brigitte

0 Shamsul Arefeen Al Mahmud over 3 years ago in reply to Brigitte

Prodigy 120 points

Hello Brigitte,

0 Shamsul Arefeen Al Mahmud over 3 years ago in reply to Brigitte

Prodigy 120 points

Hello Brigitte,

Thanks for your reply. I solved the problem. I changed the c1 and c2 to 10uF ceramic type capacitor and I kept open LV and OSC pins. Now its giving me -5V as output.

Thanks again.

Shamsul

0 Brigitte over 3 years ago in reply to Shamsul Arefeen Al Mahmud

TI__Guru 61135 points

Hello Shamsul,

Thank you very much for your feedback. I will close this thread now.

Best regards,
Brigitte

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TL7660: Problem with generating -5V using TL7660