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 LTC4412 IC (Linear Technology)

I'm using 2 power sources as shown in below picture. The status pin is suggested to pull HIGH to VCC(which can be the adapter input). As mentioned that Status pin OUTPUT is LOW when Wall adapter present, but the actual voltage I'm getting is 6.8V and when only battery(7.4v) is present the voltage is 7.2V. So how can I detect source presence using LTC4412. Kindly help regarding this issue.

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  • \$\begingroup\$ Where precisely is the pull-up resistor supplied from? Also, are your given measurements the STATUS pin voltages for each case, or something else? \$\endgroup\$ – ThreePhaseEel Feb 25 '19 at 13:26
  • \$\begingroup\$ Yes, the measurements are of STAT pin. The resistor is pulled up with wall adapter input line(12V) \$\endgroup\$ – PCBLearner182 Feb 25 '19 at 13:29
  • \$\begingroup\$ Is there a reason you don't use the LTC4412 output for pulling up the STAT line instead? \$\endgroup\$ – ThreePhaseEel Feb 25 '19 at 13:31
  • \$\begingroup\$ If not pulling up the pin, voltage is 0V when both battery and 12V sources are present and 1.8v-2.2v when only battery is present. So a little confusion is there \$\endgroup\$ – PCBLearner182 Feb 25 '19 at 13:36
  • \$\begingroup\$ The stat pin is an open collector which does not pull HIGH. So, when a wall adapter is present, the pin is 0V. When no wall adapter is present, the output is open. But, because there is no wall adapter to pull up the voltage, the voltage is still 0V or some weird value. You should connect \$\endgroup\$ – Huisman Feb 25 '19 at 13:55

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