Hey guys,
I have a 3-wire temperature sensor (DS18B20) wired up to a headphone jack. I have the corresponding receptacle on the PCB. If the device is powered off before insertion of the plug, everything is fine.
However, inserting the jack while the device is running causes the device to reset. This is because during the insertion of a headphone jack, there are temporary shorts that occur:
* Sleeve gets shorted to the ring
* Sleeve gets shorted to the tip
* Ring gets shorted to the tip
Once its fully inserted nothing is shorting with one another.
The device is resetting because when a power rail gets shorted to ground, it pulls too much current and the voltage regulators that are upstream shut-down until the high current is removed.
You might be wondering, why not use the version of receptacle/jack that has the built in switches? The switches indicate when the plug is inserted in all the way, at which point I could activate the power and problem solved right? I cannot do this because the user has the option of using an audio extension cable... so plugging/unplugging at the other end of the cable would cause the temporary shorts and the problem would remain.
Another note: I cannot switch to a different style of plug, it has to be a 3 wire stereo audio jack.
I had an idea of using an LDO voltage regulator (such as the "TC1014" which is a 50mA regulator) using this as a current limiter. I was thinking I could use one of these on the 2 red dots I indicated in my schematic. My idea is that when this gets shorted to ground, this will cause an over current situation so the TC1014 will just shutdown and no current will flow.
Would this work? Is there a better solution? I am pretty stuck on this so any help is greatly appreciated, thanks!
Here is a schematic for reference:
In this schematic going from right to left, the rectangular box is the "sleeve", the middle connector is the "ring", and the last connector is the "tip" (in this case, this is the data line that is being pulled high to 3.3V).
And here is the datasheet to the audio jack/receptacle (I am using the "SJ1-3523N" version):
http://www.mouser.com/ds/2/670/sj1-352xn-series-535548.pdf
I have a 3-wire temperature sensor (DS18B20) wired up to a headphone jack. I have the corresponding receptacle on the PCB. If the device is powered off before insertion of the plug, everything is fine.
However, inserting the jack while the device is running causes the device to reset. This is because during the insertion of a headphone jack, there are temporary shorts that occur:
* Sleeve gets shorted to the ring
* Sleeve gets shorted to the tip
* Ring gets shorted to the tip
Once its fully inserted nothing is shorting with one another.
The device is resetting because when a power rail gets shorted to ground, it pulls too much current and the voltage regulators that are upstream shut-down until the high current is removed.
You might be wondering, why not use the version of receptacle/jack that has the built in switches? The switches indicate when the plug is inserted in all the way, at which point I could activate the power and problem solved right? I cannot do this because the user has the option of using an audio extension cable... so plugging/unplugging at the other end of the cable would cause the temporary shorts and the problem would remain.
Another note: I cannot switch to a different style of plug, it has to be a 3 wire stereo audio jack.
I had an idea of using an LDO voltage regulator (such as the "TC1014" which is a 50mA regulator) using this as a current limiter. I was thinking I could use one of these on the 2 red dots I indicated in my schematic. My idea is that when this gets shorted to ground, this will cause an over current situation so the TC1014 will just shutdown and no current will flow.
Would this work? Is there a better solution? I am pretty stuck on this so any help is greatly appreciated, thanks!
Here is a schematic for reference:
In this schematic going from right to left, the rectangular box is the "sleeve", the middle connector is the "ring", and the last connector is the "tip" (in this case, this is the data line that is being pulled high to 3.3V).
And here is the datasheet to the audio jack/receptacle (I am using the "SJ1-3523N" version):
http://www.mouser.com/ds/2/670/sj1-352xn-series-535548.pdf
