TL391B: leakage current when VCC=0V but V+ =12V

Wiky Liao

Intellectual 2040 points

Part Number: TL391B
Other Parts Discussed in Thread: TINA-TI, LM339

Hi Team,

Our customer is using TL391B for power detection, V+ is connected to 12V battery pack anytime, VCC=15V comes from adapter, V- is resistance divider of VCC. If 15V adaper doesn't present, the TL391B would not get the power, so we wish TL391B not work in here. But we are wondering the leakage current at V+ pin.

We use TINA-TI to simulate the situration, V+ leakage current seems fine, but we note the VCC leakage will up to 550uA, that's un-acceptable in battery pack application. Could you help to confirm the leakage current 550uA is correct? thanks.

over 4 years ago

0 Paul Grohe over 4 years ago

TI__Guru 66486 points

Hello Wiky,

When the inputs are above the supply, the input devices B-E junctions are reverse biased, and the leakages are in the picoamps at room temperature (simple diode leakage). This is true even with VCC = 0V.

For more information, please see the LM339 family appnote, which explains the input stage and expected behaviors:

Application Design Guidelines for LM339, LM393, TL331 Family Comparators

The device starts drawing VCC supply current around 1.2V as it starts to operate. The VCC 550uA (should be around 200uA for the 391B - model needs to be tweaked) is the supply current that is expected for operation. The model uses a simple current source to create the supply current, so it will create current down to Vcc=0V.

Below 1.2V the supply currents will be unpredictable (and is not a valid operating range), but should be <1uA range (internal biasing not yet operational) before it starts up.

0 Wiky Liao over 4 years ago in reply to Paul Grohe

TI__Intellectual 2040 points

Hi Paul,

Thanks for your comments. I will request sample for double check the quiescent current.

0 Joe Vanacore over 4 years ago in reply to Wiky Liao

TI__Mastermind 19145 points

Hi Wiki,

I believe that Paul answered all of your questions. I will now close this thread. Upon receiving your samples, please create a new thread or respond to this one if you need further support.

Best Regards,

Joe

Applications Engineer

Linear Amplifiers Business Unit | Comparators Product Line (CMPS)

All information in this correspondence and in any related correspondence is provided “as is” and “with all faults”, and is subject to TI’s Important Notice (http://www.ti.com/corp/docs/legal/important-notice.shtml)

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TL391B: leakage current when VCC=0V but V+ =12V