V1P8ANA output current

Hello Lhagva 

You can find info about the typ values on the ADXL354 DS page 4/5 :




Regarding to the resistor divider approach, it is not an option supplyin the sensor using the Vsupply pin and thus the internal LDO regulators to feed V1p8ana.

If you do not want to use the internal LDO, I would suggest using an LDO to externally supply V1p8ana.

Hope this helps,

Mario SM

Hi Mario,

Thank you for your reply.

I think the parameter you mentioned specifies current required for V1P8ANA pin, when LDO regulator is disabled and external reference voltage is used to supply power to the ADXL354.

I would like to know how much current does LDO of ADXL354 can supply to V1P8ANA pin, when LDO is enabled.

Best regards.

Lhagva

Hello again Lhagva 

Could you share some more details about your desired implementation? I am not sure about how you want to configure the supply.

If I am not wrong, from the DS supply current needs data the 1M ohm voltage divider would prevent the sensor to work on measurement mode if you feed the part on the V1P8ANA pin. (Vdd/R =~ 3u A < 138 uA)

Regarding to the max current delivery while the LDO is working; should be around 50 uA, not much higher.

Wish you a wonderful weekend,

Mario SM

Hello MarioSM 

Thank you for your reply. I am sorry for non complete information. Please see below my circuit implementation.

I need 0.9V offset voltage for amplifier, to get this I am going to use internal LDO V1P8ANA output, R19, R20 voltage divider need to draw 1.8V/(500kOhm+500kOhm)=1.8uA current from V1P8ANA.

Also U4 will supply 2.5V reference voltage to my ADC, V1P8ANA will supply voltage to non-inverting input of U4, but I think current is very small.

I think my question is clear now, is V1P8ANA able to supply current for it.

Best regards,

Lhagva 

Hello MarioSM 

Thank you for your reply. I am sorry for non complete information. Please see below my circuit implementation.

I need 0.9V offset voltage for amplifier, to get this I am going to use internal LDO V1P8ANA output, R19, R20 voltage divider need to draw 1.8V/(500kOhm+500kOhm)=1.8uA current from V1P8ANA.

Also U4 will supply 2.5V reference voltage to my ADC, V1P8ANA will supply voltage to non-inverting input of U4, but I think current is very small.

I think my question is clear now, is V1P8ANA able to supply current for it.

Best regards,

Lhagva 

Hello Lhagva 

Looks good, I was not completely following your approach, much clearer now.

Let us know if you have any other question.

best regards,

Mario SM

Hello MarioSM 

Since we have three axis, we need 1.8uA x 3 = 5.4uA

Do you think V1P8ANA can supply this current?

Best regards,

Lhagva 

Hi Lhagva 

In our experience there should be no problem if you do not sink much more than 50 uA, but this is not guaranteed by the design.

hope it helps,

Mario SM