LM5050-1-Q1: Power consumption when VS = 0 (or disconnected), and IN/OUT are powered?

Mohan Gurunathan

Part Number: LM5050-1-Q1
Other Parts Discussed in Thread: LM5050-1

Hello,

I am using LM5050-1 (part number: LM5050Q1MK-1/NOPB) in an application where I want to power the chip from an external VS supply, as shown in the graphic below.

However, the VS supply will be at +12V when the product is "on," and when the product is "off" VS will be at 0 Volts.

The IN pin is connected to a Lithium-Ion battery pack, and the IN/OUT is connected with a MOSFET as described in the datasheet.

I would like to know how the LM5050 behaves when there is power on the IN/OUT pins, but VS is not powered. Will the chip draw any leakage current on the IN or OUT pins? In other words, will it drain my Lithium-ion battery when the product is on the "OFF" state?

Please let me know if this question is clear. Thank you.

over 4 years ago

0 Lokesh Ghulyani over 4 years ago

TI__Expert 8630 points

Hello Mohan,

There are internal circuits in LM5050-1 which will draw current from IN & OUT pins when Vs is not powered ON. The magnitude of this current will be a function of voltage on IN and OUT pins,

OFF pin of LM5050-1 can be used to turn-off the internal circuits of LM5050-1 but Vs needs to be powered for this (>5V).

0 Mohan Gurunathan over 4 years ago in reply to Lokesh Ghulyani

Intellectual 500 points

Hi Lokesh,

Thank you for the reply and explanation. This answers my initial question.

I have another question about LM5050. The datasheet suggests to use an RC filter on the "VS" pin, with R=100 ohms. I am wondering if it is OK to use R=200 ohms, since I already have 200 ohms in my BOM (but not 100 ohms). Please let me know if 200 ohms would work as well. Thank you.

-Mohan

0 Praveen GD over 4 years ago in reply to Mohan Gurunathan

TI__Guru 57737 points

Hi Mohan,

The current flowing into the VS pin is only around 100 uA. So, There shouldn't be any issue in using 200 ohms resistor is between OUT and VS pins.

0 Mohan Gurunathan over 4 years ago in reply to Praveen GD

Intellectual 500 points

Thank you Praveen, this is helpful and resolved my questions.

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LM5050-1-Q1: Power consumption when VS = 0 (or disconnected), and IN/OUT are powered?