TPS63020 Shutdown current

Please read the ground rules post at the top of this forum and edit your post title to include the guidelines there.  Your post title is meaningless without a part number.

Please make sure that you did not damage the device with all of the soldering.  Also, look at the input voltage with a scope and make sure it is DC, as it should be.  Also, check the output voltage and make sure there is no signal there.  Finally, look at the EN pin with a scope to make sure it is low.  Sometimes the jumpers don't make contact very well.

Lastly, make sure your meter is reading accurately and can read such low currents.  What does it read when it is not connected to anything?

When you are checking all signals that Chris mentioned above be sure to also, check the switch node to verify that the device is off and not switching. 

Sorry by post title, it's the first time that I post.

The EVM with changes has a good behavior with Ven=Vin=4,2V (DC voltage). In this case, It has a Vout=3,58V with and without load.

With Ven=0V, Vin =4,2V; the Vout is 0V with load and without load Vout is lower than 1V and it tends to 0V. I think that it happens because capacitors had been loaded to Vout before activating shutdown mode.

I did the measurement with a DC power analizer with a resolution of uA and with the device in shutdown mode, with Ven =0V, the current exceeds 200uA (my maximum scale range)

Even though there might be a temporary 1V on the output as the output ramps down, there should be no current flowing from the input to the output during shutdown for the load is disconnected from the input. 

You can test to see if your DC power analyzer is accurate by using a multimeter to measure current to the board. 

You mention changes to the EVM, verify that there is no additional loading on the power supply, (parallel with the converter). 

If possible post your schematic. 

It's my schematic

5040.TPS63020_test.pdf

I don't see anything that would cause the shutdown current to be high. Have you checked the current that you are drawing with another meter yet? Another thing to check would be your solder job and the removed components pads for shorts. Looks like you removed the bulk cap so, check there. 

I have tested the power analizer testing another circuits with correct results.

I have also checked  the bulk cap  solders and they don't have any solder problem.

I have ordered some samples of TPS63020 to change it in EVM and I´m going to check the circuit again. Next  week, I will give you an update with the results.

Thanks you,

Hi,

I changed the TPS63020 with equal results. The TPS63020EVM-487 has a good behavior in active mode but when the IC is turned off, the current rate is higher than 200uA.

Could you do the same measurement in this evaluation module and email me with the result?

I measure 8.45uA for your test circuit on our EVM except that PWR save is tied to Vin which should not change the shutdown current that dramatically, (200uA). With the extra bulk input cap it takes a little longer time to get to 8.5uA but, the input current is not 200uA either.  If you have no other resistors or caps on the input, your board is clean/having no shorts, and your power meter is accurate then I don't not see anything that can cause 200uA current. 

Sometimes when the meter is measuring so low, the meter can display some funny things, maybe even the limit. Try putting the current limit even lower on the meter then, measure again. 

Hi Michael,

I changed again the test circuit to be equal to the EVM. Now my EVM only has a difference with your EVM, the inductor that in my circuit is 1uH and in your EVM is 1,5uH. I supplied this circuit with 3.6V and configured it with Power Save, Power Good and Enable OFF. In this condictions, i made two captures of the power analizer measurement to a maximum current range of 100mA and 200uA to email you. In 200uA maximum measurement current range, our analizer has a resolution of 2uA.

In pictures values of 100mA maximum current range you can see that the current isn't fixed and has too much fluctuation. And in 200uA maximum current value, a lot of values are out of range and have a incorrect measurement because exceed current range.

5861.Measurement_TPS63020-EVM.xls

There is no units on this data but, it seems to me that the 100mA data suggests  a dc current close to 0A while the 200uA is not operating as expected. 

The units in second column are amps in both excel pages and the units in first column are steps of time ( Sample number x Sample interval (20.48 microseconds)). Yes, the 100mA data are around 0A but in my aplication this current value in shutdown mode (50uA aprox.) is much too high. In datasheet, shutdown current  value is lower than 1uA. I would need much lower power in shutdown mode for my aplication.

Hi Mr Green,

I've bought a new TPS63020EVM-487 and I've tried again. I made new measurements with 2uA sensibility power analizer. To make the precision measurement with 2uA precision, I used a maximum current range of 200uA. I haven't changed anything in the EVM only a jumper of  Enable state from ON to OFF and I have added female header to conect supply input and voltage output with  100ohms load. Then I have applied a supply voltage to 4,2V and the results are the same than in my circuit, no voltage output (0V) and overload current (more than 200uA).

Last week I made the same measurement with other similar circuit and the result was a current consumption of less than 1uA, imposible to measure it with our analizer.

The datasheet data isn't correct and Texas Instruments should review an change to don't waste the engineer time.

Best Regards,

Hi Mr. Caamano,

I am sorry for the delay and sorry that you are still experiencing issues. 

As I read through your post I just want to clarify some possible misunderstandings:

1. Texas Instruments completed a very rigorous testing and rating procedure to generate the rated numbers listed in the datasheet for the TPS63020 as we do with all of our products. 
2. The shutdown current for the TPS63020EVM-487 is not above 200uA. I have tested the Ishutdown with 4.2V in my lab and see a shutdown current between 3uA and 9uA pending on whether or not Power Save Mode is enable or not. 
3. When you say "added female header to conect supply input and voltage output with  100ohms load" I assume you mean that you replaced the header to Vin and added a 100ohm resistor load from Vout to GND. You are not saying that you have a resistor from Vin to Vout, correct? - If you have the resistor across the Vin to Vout then there is the current you are seeing. 
4. I am still concerned about your power analyzer. I would verify that it measures accurately by placing a 1M ohm resistor on your 4.2V supply and measure the current through the resistor. Also measure the Vin voltage and the voltage of the node between the resistor and the meter; make sure that the voltages are ~4.2V and ~0V respectfully. 
5. Can you tell me the model number of the analyzer? I might have the analyzer in my lab and can measure the Ishutdown with it. 
6. Also make sure that you are waiting a several seconds after Vin power up to measure the Ishutdown so, that the input caps are charged and not pulling large currents. 

Hello Mr Green,

Our power analizer is a N6762A with a MY4307304 Module (2uA precision to 200uA maximum measurement range) by Agilent  Tech. I've tested it with other board and measurements are accurate.

The 100 ohms resistor was placed between Vout an GND, and I also tested board without load.

I'm sure you are correctly measuring your board there, but we've triple checked everything here and tried with a second board "out of box" and we measure too much supply currect in shutdown mode for our aplication.

We have had a bad experience recently with one of your devices, the TAS5615 and we can't spend more time with this design sadly we are going to have to choose another up-down switching supply.

Thanks for your support, we couldn't solve our problem but I really appreciated it.

Best regards.