This question is specific for ACT2802X series 5V/2.5A Backup Battery Pack Manager IC.

On page 15, there is a schematic that provides a solution for auto plug-in detection. However, I cannot understand how this is achieved? What is the thing that comes out from the USB connector's shield in the schematic? I cannot also find a USB connector with "plugged" output.

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PB pin is described as:

Push button input, connect a push button from this pin to AGND, internally pulled up by a 3MΩresistor to battery. PB starts up boost converter if HZ pin is grounded and VIN is not present. For ACT2802B/ACT2802C, if this pin is pushed for 3s, flashlight is enabled.


For ACT2802QL-T/ ACT2802-T1026, When HZ=0, if PB is pulled low more than 100ms, boost converter is enabled; For ACT2802B/ACT2802C, when HZ=0, if PB is pulled low more than 30ms, boost converter is enabled.

PB High Input Voltage = 0.9V (typical)

PB Low Input Voltage = 0.75V (typical)

  • \$\begingroup\$ Do you happen to know what type of USB connector it is? Micro-USB connectors have 5 pins. The 5th being for determining host or slave connection mode. I'd agree that the schematic is poorly labeled, but have a look at this: electronics.stackexchange.com/questions/35462/… \$\endgroup\$ – krb686 Sep 3 '14 at 13:16
  • \$\begingroup\$ @krb686 No, unfortunately this is from a datasheet that I was looking at. Thank you for the link. \$\endgroup\$ – abdullah kahraman Sep 3 '14 at 14:34

Typically, the shield is connected "somewhere" to the ground connection. Either at this connector or at the other end of the cable. In either instance, plugging in the cables will short the case/shield to ground which is equivalent to closing the PB switch.

| improve this answer | |
  • \$\begingroup\$ Wow, that is a great thing that I didn't know of! Thank you very much :) \$\endgroup\$ – abdullah kahraman Sep 3 '14 at 15:20
  • \$\begingroup\$ @abdullahkahraman don't accept the answer so quickly, see what other answers you get. \$\endgroup\$ – placeholder Sep 3 '14 at 15:21

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