LP5810: Behavior when VCC and VLD are different

Conor

Part Number: LP5810

Tool/software:

Hi,

I am considering the following circuit configuration.
・VMCU=VCC=3.3V
・VLED=5V

Q1. Will it break if VCC=OFF, VLED=5V temporarily? In the above case, the LED lights up, and it seems that about 3V is applied from VCC via VLED→LED→OUT.

Q2. Can it be used with VCC=3.3V, VLED=5V? Can it be used even if the voltage of VCC and VLED are not the same? As far as I can see from the data sheet, VCC and VLED are defined separately.

Thanks,

Conor

2 months ago

0 Jared Zhou 2 months ago

TI__Genius 15295 points

Hi Conor,

Please refer my comments below:

1. Do you mean that when you only power on VLED, the LED will be lighted up?

2. Yes, they can be used separately.

BR, Jared

0 Conor 2 months ago in reply to Jared Zhou

Mastermind 9310 points

Hi Jared,

Jared Zhou said:
1. Do you mean that when you only power on VLED, the LED will be lighted up?

Yes, that is correct.
Due to the application specifications, there are moments when VCC = OFF and VLED = 5V temporarily.
I am concerned that under the above conditions, the LP5810 may be damaged.

Thanks,

Conor

+1 Jared Zhou 2 months ago in reply to Conor

TI__Genius 15295 points

Hi Conor,

Actually, it will not damage LP5810, the reason why LED is on when VCC=OFF and VLED=5V is because the internal IC circuit. The behavior is correct.

Can you please tell me why you need to separate the VCC and VLED?

BR, Jared

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LP5810: Behavior when VCC and VLD are different