TPS60211: Abnormal Current

Please show the schematic of your circuit.

Hi Ray,
1. do you see same issue in every board? we need to avoid assembling issue or damaged IC.
2. could you also share the layout.

Hi Jasper

                 Thanks for your reply .This issue occours in release production ,not every board appears ,but quite a number .The possibility of  assemble issue is ruled out .So far we are not sure if the IC was demaged.

                  Here is the latset schematic and layout .

Hi Ray,
could you help to swap the ICs of the bad unit and the good unit? we can find if the issue goes with the IC.
what is the part number of the output capacitor? the datasheet suggests low ESR capacitor. so could you change to ceramic cap?

Hi Jasper
We have done that before ,and we wonder that there is something wrong with the IC. The IC works in a unstable state. This situation happens again when changed capactiors , less than before.While our procuction works in low power mode，the IC draws about 20mA from battery.

The layout can be much improved; the capacitors must be near the chip, connected with short traces. (See the layout example in the datasheet.)

It's also possible that that current has some other cause, e.g., leakage through the Zener, or improperly cleaned flux.

Hi Jasper
Can you do some experiments to see whether my problem will apprear again .The problems as you say have been ruled out under removing the tube .Of course i will improvr the layout.

Hi Ray,
I'm not fully understand your meaning.
you had done swap experiments and find the issue is caused by the IC, correct?
you had changed the output capacitor to ceramic capacitor? what is the result?
what is the capacitor used currently?

Hi Jasper
Yes,i had done the swapping IC experiments,Result is the IC may have some problems.
I had swapped the Tantalum Capacitor into Ceramic Capacitor,the problem was still there .When powered on for many times,the board still gets the percent of the abnormal current every now and then.

Hi
did you try to change the two 2.2uF capacitor to 1uF capacitor?
could you also try to place the IC in the EVM to check if the IC can operate normally?
please also measure the switching waveform in C1+- and C2+- pin.

Hi Jasper

     I have done the experiments as you adviced .changing 2.2uF cap to 1.0uF，measuring the waves. The abnormal cuurent remained.the following is my test result pictures.( The same device worked in normal and abmpraml current ).I get no EVM board to check...

Hi Jasper

     I have done the experiments as you adviced .changing 2.2uF cap to 1.0uF，measuring the waves. The abnormal current remained.the following is my test result pictures.( The same device worked in normal and abnormal current ).I get no EVM board to check...

Hi
the waveform seem to be the same in both normal and abnormal condition. is it a mass-production project? if yes, what is the fail rate?

Hi Jasper
Yes ,it is a mass-production project.About 20% of the total devices did not work , because of the lack of energy.

Hi
Could you send me several of your failure samples? it would be better that you can also send me one system board.

Hi Jasper
I will send you a PCB included the chip, once you write me the available address information.

Hi
I had sent a message with my address.