Leakage current on TPS27082 device

jerome bolduc

Other Parts Discussed in Thread: TPS27082L

Hello,

We are using this switch on our deisgn and we have some problems with the OFF state. When the system is powered up and the switch is OFF, everything is fine. When we turn ON the switch, everything is fine too. But when we are turning OFF this switch, a strange behavior occurs. First of all, we have about 1V on the switch output, it should be zero, right? By putting a 60 ohms load on its output, I am able to pull the voltage down to zero. My most important concern is the leakage current on this state. The switch consumes about 2mA when it is in this configuration. We are using this switch on a USB3.0 design and the current consumption is very important. Our whole system when it is in the OFF state consumes 1mA, and with this switch the consumption is about 3-4mA. This 2mA is too high for us. In the datasheet, there is about 100nA of leakage current. Do you have any ideas how to reduce this leaking current?

In attachment is the schematics of the switch in our design.

Thanks,1682.TPS27082.pdf

Jérôme

over 12 years ago

0 Ron Michallick over 12 years ago

TI__Guru**** 167506 points

Jerome,

With "ON/OFF" pin at 0V, current consumption should be 40nA typical and 12uA max across temperature. This is IFIN spec at 5V.

How close to zero is ON/OFF when turned off? In 'OFF' mode the NMOS turns off and the PMOS turns off when "C1" (C30 in application) stops changing voltage (finishes charging). There is no VOUT discharge circuitry so VOUT may not go to zero.

When off, the voltage at R1C1 pin should be same as VIN.

I need voltage at VIN, VOUT, R1C1, and ON/OFF pins to troubleshoot why VIN current is 2mA.

0 jerome bolduc over 12 years ago in reply to Ron Michallick

Prodigy 60 points

6840.ENABLE_R1C1.TIF

4846.ENABLE_VIN.TIF

8780.ENABLE_VOUT.TIF

Here are the snapshots taken on one of our boards.

There is a discharge circuitry on its output, we have a 60 ohms load + a FPGA + HDMI receiver.

Our board is powered by the USB connector and when we unplug the USB cable and plug it again, everything is alright, there is no more 2mA consumption by the switch.

Thanks,

Jerome

0 Ron Michallick over 12 years ago in reply to jerome bolduc

TI__Guru**** 167506 points

Jerome,

Are you saying the problem has gone away or it only fails on first power up only?

0 jerome bolduc over 12 years ago in reply to Ron Michallick

Prodigy 60 points

The problem is only present when we put the ENABLE pin to OFF while VIN is still at 3.3V. If we unplug VIN from the switch and put it again to 3.3V while the ENABLE pin is still OFF, there is no problem.

0 Ron Michallick over 12 years ago in reply to jerome bolduc

TI__Guru**** 167506 points

Jorome,

I will test this in the lab to see if I get the same results.

0 Ron Michallick over 12 years ago in reply to Ron Michallick

TI__Guru**** 167506 points

Jorome,

I could not get a 2mA current (or any current to flow) when ON/OFF was low, regardless of sequencing.
Does this occur on more than one sample of TPS27082L?
Can you determine through which pins this current flows.

Power management

Power management forum

Leakage current on TPS27082 device