I have LT1019ACN8-5 IC output is 5V. I am using this IC to get Vref 3.3 for the ADS8320. is it ok if i use a voltage divider to the output pin to regulate 5v to 3.3v. Is it acceptable ?
\$\begingroup\$
\$\endgroup\$
4
-
1\$\begingroup\$ Is your load absolutely constant? \$\endgroup\$– PlasmaHHCommented May 16, 2017 at 14:56
-
\$\begingroup\$ @PlasmaHH Load --> I am using output to feed Vref of the ADS8320 [ti.com/lit/ds/symlink/ads8320.pdf] IC \$\endgroup\$– vassidefukCommented May 16, 2017 at 14:58
-
1\$\begingroup\$ Kind of a waste of a nice reference. The errors you get from the divider resistors will swamp the accuracy of the reference. \$\endgroup\$– John DCommented May 16, 2017 at 15:08
-
\$\begingroup\$ also i need to know difference between shunt and series type of these voltage reference ICs \$\endgroup\$– vassidefukCommented May 16, 2017 at 17:02
Add a comment
|
1 Answer
\$\begingroup\$
\$\endgroup\$
2
The reference input of the ADS8320 draws varying current depending on the sample rate, like many ADC converters without reference buffers.
At, say, 25uA, a source resistance of only 2 ohms will result in 1 lsb of change in reading due to the reference current. It's usually best to use a buffer that has low noise output. Sometimes this is surprisingly expensive to do right, although fortunately it's only 16 bits.
answered May 16, 2017 at 15:38
-
\$\begingroup\$ then LT1790-3.3V 60uA [cds.linear.com/docs/en/datasheet/6656fc.pdf] will be suit for this. or LT6656-3.3V High Output Drive Current: 5mA Min [cds.linear.com/docs/en/datasheet/1790fc.pdf] right? \$\endgroup\$ Commented May 16, 2017 at 16:41
-
\$\begingroup\$ Both those are pretty good. The 2nd one has about 1/3 the noise (+/- 0.3 LSB vs. +/1 LSB). Keep in mind the dropout voltage spec. \$\endgroup\$ Commented May 16, 2017 at 18:00