Dear supplier ,
For the high side switch TPS272C45D, it may cause 0.24W power dissipation when it enters into standby mode. We measure the voltage of the GDN pin ,there is 0.735V voltage . It is a little strange. We want to reduce the power dissipation of the IC when into standby mode . Please review the schematic whether there is a error and please help to analyze the reason of the high power dissipation! Thank you very much !
Dear Elizabeth ,
Thank you for reply !
Change the R815 to 0R and do the test again, the voltage of R815 is 0.644V and the power consumption has not changed. We calculate the power dissipation is to read current change of the power supply. When we remove the R836 R833, it can cause 5mA current change when the power supply is 48V. We also use the highside switch TPS27S100B in our design .The voltage of PIN 1 of BAS21 is almost zero when it enter into standby mode . There is no power dissipation problem of the TPS27S100B. Hope it can help!
Looking forward to your reply , thank you !
Dear Elizabeth ,
In our project, the 48V input voltage is steped down to 12V by LM5145 first ,and then supplies power to TPS272C45D. The picture below shows the current chagne of power supply , please check it .
The TPS272C45D is still work after seeing this behavior.
We test the current consumption of TPS272C45D by multimeter when it enter into standby mode. The current is about 1mA . It is really strange, I don't know where the rest of the power goes!
When add the R836 R833, we remove all around components of TPS272C45D one by one , only remove R814 R815 and D803, the current of power supply come back to 9mA.
It seems that the stange phenomenon is appear when TPS272C45D connect to GND. Please help to analyze this problem ,thank you very much !
Dear Tim,
Thank you for your reply.
I am a little confused . The current consumption is 0.5 uA in the datasheet, please check it again? if you have any suggestions for LM5145 to redcue the standby power consumption ? thank you very much !
Dear Tim and Elizabeth,
Thank you for your reply.
We measure a about 1mA current when the device setup is OFF. please see the picture below .Thank you all !
Hi Fu,
I do not see any issues with your schematic. What is the granularity of the ammeter being used? Can it detect uA?
If the VS is being shared with any other devices, that would increase the current draw.
The TPS272C45 device will only draw up to 3uA under the following condition when the device is off.
Please provide waveforms probing VS, EN, VOUT, IOUT for the relevant channel to confirm this behavior.
Best Regards,
Elizabeth
Dear Elizabeth,
Please see the attachment. Due to the insufficient number of oscilloscope channels, I tested them separately. We did not add load, so I did not test the Iout. I really want to know what is the voltage of IC_GND when EN and DIAG is 0V on the EVM board ? thank you very much !
Hello,
We would expect the IC_GND to have a voltage offset from module ground equal to the forward voltage drop of the diode used, which would be up to 1.25V in the case of BAS21 (shown below).
Do note, in your final design, the BAS21 diode specifically is not needed (another diode could be used), and in some cases we advice the BAS21 not be used.
To elaborate, with regard to ground network recommendations:
On the reverse side, the diode needs to handle all the reverse standoff voltage you can see. The reason BAS21 was chosen on the EVM was to test ISO standards for the automotive version of the part. If less reverse standoff handling capability is needed, a different diode can be chosen, and another Schottky diode can be used
The main recommendation is you don't want to see greater than 0.6V on the IC ground pin to ensure you don't unintentionally trigger the loss of ground
Best Regards,
Elizabeth
Dear Elizabeth,
Thank you for your reply .
According to the SPEC, the max current of IOUT(OFF) is only 3uA, but in our design ,the current is 1mA. What might be the cause of this phenomenon? thank you very much!
