SLG59M1641 Power Switch Reverse Current Blocking Issue

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Last seen: 2 years 3 months ago
Joined: 2014-05-07 01:26
SLG59M1641 Power Switch Reverse Current Blocking Issue


I run into an issue when using this switch in my design. I have sent this question to the local FAE but decided to ask this question here to see anyone know why. My design has two power sources: P1 and P2. P1 is connected to Pin 1 of SLG59M1641 and P2 is connected to the output pin 8. When the P2 is not present, the system is powered by P1 and ON pin is low by default. When P2 is present, ON pin will toggle to HIGH. My P2 is 4.3 V and P1 is 3.7v. My understanding is when the ON pin 2 is HIGH, the voltage applied to the OUT pin 8 should be blocked by the 1641.

Unfortunately my measurement shows when the P2 (4.3V) is applied to the OUT pin 8 and ON pin is HIGH, the pin 1 voltage is around 4.0V regardless P1 is present or not. It appears that there is a single body diode in this design. Please let me know if it is the normal behavior of this part.



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Last seen: 1 year 1 month ago
Joined: 2017-11-27 23:25
Hi Jimmy,

Hi Jimmy,

For the benefit of others, we wanted to share the suggestions (sent seperately to you) from our team:

1.  Please check the connections on the '1641 package.  It could be a soldering issue.  Because if chip is ON and when one applies 4.3V to VOUT, it will indeed pass to VIN but once ON =1V or so, it will block reverse voltage.

2.  It is possible the '1641 device has been damaged.  Please try replacing the device on your board with a new '1641.

3.  Check to see if VIN and VOUT might be shorted on your board.  If this is the case, it does not matter if ON is HIGH or LOW.

4.  It is possible you are seeing the affects of the body diode of the FET.  I.E. while ON is LOW, 4.3V is being applied to VOUT and may pass to VIN.  Check to see if you see a voltage drop to 3.5V on the other side to confirm.

5.  Please check the device marking and confirm you have a '1641 soldered down.  Our devices are very small and its easy to make a mistake during assembly.