LM49450: constant component at the HP outputs

Vladimir Priyatelev

Part Number: LM49450

Hi.

I have constant positive voltage at the outputs HPL and HPR. ChargePump frequency 323375 Hz (measured on C1N), CPVdd and HPVdd - 2.5V, IOVdd, DVdd, Vdd, LSVdd - 3.3V. On HPVss i have +0.4V. What voltages should be at such power voltages at BYPASS, REF and HPVss pins?

over 4 years ago

0 Luis Fernando Rodriguez S. over 4 years ago

TI__Guru* 84915 points

Hi, Vladimir,

Could you provide a circuit schematic for more details on this, please?

Thank you.

Best regards,
Luis Fernando Rodríguez S.

0 Vladimir Priyatelev over 4 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 40 points

Circuit schematic same as "Typical Application" in "lm49450.pdf".

0 Vladimir Priyatelev over 4 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 40 points

Hi.

The problem was a poor-quality board.

The second question about the maximum input voltage on HPS pin.

However, the voltage values on the pins BYPASS, REF and HPVss remain unresolved.

0 Luis Fernando Rodriguez S. over 4 years ago in reply to Vladimir Priyatelev

TI__Guru* 84915 points

Hi, Vladimir,

Regarding your question about the HPS pin, its maximum voltage level VDD + 0.3V. Please don't expose this pin constantly to these limits since it may result in a risk to damage the device.

The voltage value on the BYPASS and REF pins is generated internally. It is a mid-rail voltage determined by VDD / 2.

HPVSS is a negative supply created from the positive supply voltage (CPVDD). You should get a negative value on this pin with a similar voltage level of CPVDD.

Best regards,
Luis Fernando Rodríguez S.

0 Vladimir Priyatelev over 4 years ago in reply to Luis Fernando Rodriguez S.

Prodigy 40 points

Thank you very much.

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LM49450: constant component at the HP outputs