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the schematic of input section can be seen below.
the Output section is disconnected, it means that VBAT don't have any load.
the input voltage is 28V, it means that VBAT1_IN=28V.
the current we measured for this section is 3mA when input voltage is 28V.
according to specification the current should be around 0.6mA for 28V.
please advise how we can reduce the current consumption of LM5050-1?
the FET we are using is PSMN2R6-40YS.
As described here you would be correct to expect 600uA of current.
I have no idea why you would measure so much current (i.e.3 mA).
With 28.0V at Vin, 0V at Off, and Vout open, I have measured 449 uA of input current on the LM5050-1 eval board in the lab.
Thanks for your reply.
Can you please measure the currnet in GND(pin 2) as I dont have the EVM here.
Yes, but it will take awhile as I need to dismount the LM5050-1 from the circuit board. Attempting to simply de-solder and lift the pin from the PCB will typically break the pin off.
I would expect the pin 2 (Gnd) current to be the same as what I have already measured (i.e the sum of Iin, Iout and Ivs).
Can you please dismount R1 and replace it with R2, supply voltage to J1 and than to measure the current(Ivs and Iin)?
Is this in addition to, or instead of, your earlier request for ground pin current?
Confirmed that the LM5050-1 pin 2 (Gnd) current is the sum of Iin, Iout and Ivs.
" ... to measure the current (Ivs and Iin)? ... "
But do NOT include Iout which is biased though the MOSFET body diode?
OK, can do.
I measure Iin+Ivs at 459uA.
Dear Donald Jones,
Thank you very much for the support, it was very helpful.
If there will ne more issues I will contact you.
Did you find the cause of the additional ~2.5mA of current drain?
Not yet. We will wait for the EVM and compare it to our PCB.
Your test helped us a lot and proved that the IC can fit our requirments.
The costumer got the EVM and now the problem is more clear:
He measured the current and saw the same problem.
I will explain the problem:
when using the EVB as is, there isn't any problem because it's only one device.
the pins : Vin, Vout and Vs consume the power as in specification.
BUT when using two devices. the problem appear.
When there isn't power on pin Vin and there is power in pins Vout, Vs. then the power consumption of Vout,Vs is 3.3mA.
you can verify the problem by applying power to R1 while there isn't power in Vin on the EVB
Please advise how can I reduce the current on Vout, Vs where there isn't power on Vin.
I would recommend to change the connection of VS pins from Vout to Vin. If you read the datasheet on page 2 in Pin Descriptions, TI recommends to connect VS either Vout or Vin. In this case the turn off of the Vin1 will cause the turn off the whole chip and I think it will not more consume the power. If you compare the circuit by customer with one by Donald you see that Donald has connected VS to Vin and measured small current, but customer has connected VS to Vout and measured bgger current.
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