LDC0851EVM: Shut down current in LDC0851

Hello,

Can you share your schematic and clarify where you have connected the ammeter? The shutdown current in the datasheet does not include the additional current draw from the resistor divider on the ADJ pin.

Best Regards,

The ammeter is connected in between S2 and the VDD of the board( that is when the battery is connected). 
The ADJ pin is grounded and the current consumption is reduced to 7uA from 50uA in the shutdown mode, but still, we can not achieve the 140nA current consumption in shutdown mode.
The chip itself consumes 7uA current in its shutdown mode even when all itself decoupling capacitors and the sensing coils are removed.

Hello,

Thanks for sharing your schematic. Just to clarify, when you grounded the ADJ pin, you also removed R3, correct? 

I'm concerned about the LED connected to the OUT pin (D3). The absolute maximum current on the OUT pin is 5mA. When OUT goes low and the diode turns on, it looks like it will sink >10mA of current into the OUT pin (assuming Vdd = 3.3V). If Vdd = 1.8V, the current is still much too close to the absolute maximum. You may have damaged your device. If you have any devices that you have not tested yet, I suggest removing D3 and R2 and retesting the current consumption.

Best Regards,

Hi,

We've already removed D3 and and R2, yet the current consumption remains same as mentioned (9 uA at SD mode ). Schematic we provided is from TI(EVM0851). Is there any other solution to reach 140nA in shutdown mode(SD).

Thank you

Hello,

Thank you for your patience. Can you try removing the switches and shorting EN directly to GND? 

Best Regards,

Hi,

Sorry for replying late. We did as you told but current remains same.Is there anything else we could do?

Hello,

My apologies for the delayed reply. Have you tested more than one device? Do you see the same supply current for each device? The shutdown current is a typical spec in the datasheet, so variation from the nominal value is certainly possible. However, if none of your devices are measuring anywhere close to the typical spec, then it's more likely a problem with either the measurement setup or the configuration of the device that we can debug.

Best Regards,

Hello,

Apologies, Though we did not actually get a value near 140nA, We found a workaround. Instead of going to sleep mode,we turn off the sensor,Anyway thank you for your support.