TLV7031: Iq is too high

Hello Allen,

The total current will be TLV7031 IQ, plus current through R13 and R1, output current not shown in partial schematic and other things on VBAT bus (not on this schematic).

High current due to:

1) output current not shown

2) TLV7031 damage

3) Other VBAT current 

Does this happen on one or few samples or does it happen on all samples?

1) TLV7031 output to MCU input, it almost no current comsumption.
2) its function is OK. it can output H/L refer to input.
3) I have removed TLV7031. the current of other circuit is only 4uA.
4) >20 samples , I don't test all of devices

Allen,

Try removing C14; that interferes with the comparator hysteresis function.

Removed it. But the same current consumption.

Allen,

In that case, all >20 were damaged or maybe wrong pinout. What is the full part number used? I can order that and measure supply current in my lab.

Allen Huang said:

But current comsumption is about 300uA @output=low; 500uA@output=high

Are these value consistent on the samples tested? Is this a new circuit board; meaning did this work correctly in the past?

TLV7031DBVR,SOT-23, pin out shown as the schematic.

Allen

Sorry to hear about your measurements and thanks for your post.

What is the value of VBAT?  How are you isolating the current for the tlv7031 so you are not including current in rest of the circuit?

Chuck

VBAT=3V
When I remove TLV7031, the current of rest circuit is about 4uA.

TLV7031 output pin only connect to MCU input. So almost no current consumption.

Allen

I can only think of a few things to try.  First, you mentioned having 20 samples or so.  How many have shown this behavior?  Have you seen the problem of high IQ on multiple boards or only on one.  If only tested on one, I suggest trying a second board to see if you the same high IQ is observed.

I can imagine your frustration as you stated this is a known good circuit but is there any way you can lift pin 5 or temporarily disconnect from VBAT and power from a different power supply?  Or would it be possible to look at the part on its own off the board?  While anything is of course possible, it is highly unlikely that all the parts sent to you were bad as this device has been in production for many years with little to no quality issues.  

Before doing anything, I would like to see waveforms of both inputs, the output and VCC all on one oscilloscope screenshot to make to confirm there is no oscillation going on.

Sorry again for the problem and hopefully we can help determine the root cause.  Responses after today will be delayed until Monday as most of us are off today and tomorrow.  Just wanted to give you heads up.

Chuck

Allen,

I'll order samples today, but I doubt I'll see high current.

The circuit is very simple so the result you see is very odd. On the other hand is the circuit too simple? Do you have a bypass capacitor near TLV7031? Is this circuit on a printed circuit board or a breadboard?

1) no bypass cap near TLV7031. 
2) on PCB

Thanks for your post.  We are on holiday break and will review when we return on Monday.

Chuck

Allen,

Sample have been shipped to me. I should get them and test them by end of this week.

TLV1851 is another option to try as this issue is hard to solve because it doesn't yet make sense. 

Hi Ron

Sorry, it's Mouser's IC issue.

My supplier buy this IC from Mouser. 

I replaced it by TI's sample. And it's OK now.

Allen,

I am glad you have found a solution.