[Example]
Trouble shooting-Additional Switch ICs solves the problem~
Checking circuit itself seemed to be OK, but a trouble is detected! As is often the case with such a trouble, an additional component is used. Here, the actual trouble shooting example is introduced. It might be useful to choose a device not only for trouble shooting but also just a simple component's selection.
This example is such kind of case.
Case 3:Additional Switch ICs solves the problem
Switch ICs can cut off the power path and consumption current of the application can be suppressed. Simple on and off can be realized by using a MOSFET, but if you choose a switch IC, soft-start function and protection function can be expected.
Background of the trouble
The power line of the application is 3.3V. This line was directly connected to the device A and the device B. But the device A should start up later than device B and the input of device B should reach more than 1.5V when the device A start-up.

Customer's issue and condition confirmation
To solve the problem, some critical points must be considered.
Check points | Customer's issue and condition confirmation (Check points) |
---|---|
|
Input voltage |
|
Mount area size |
|
Voltage drop considering by on resistance of the switch IC. |
Trouble shoooting Process
According to the information from the customer, part can be sorted out.
Which type switch IC is the best?
- So-called load switched are usually low voltage input is acceptable, in this case, it is not preferreble for considering the input voltage condition.
- USB switch is one of candidates, but generally, the component size is relatively big. (Nisshinbo Micro Devices R5524K 1.8mm x 2.0mm)

Conclusion
We have an Ovp switch which can be used for this purpose. Part # is R5528Z
- The R5528Z series have UVLO function. The released voltage is typically 2.05V.
- The pacakge is WLCSP, 1.27mm x 1.27mm (0.64mm thickness). Current capability is 3A.
- On resistance is 54mohm@5V.
- Enable pin is "L" active. ENB pin is used for On and Off. In this case, if ENB pin is tied to GND, external control is unnecessary. Further, the debounce time is included after power on, so mis-operation by VIN ramp up variation can be avoided.

R5528001A Block Diagram
Trouble shooting
- Additional Switch ICs solves the problem
- Additional Switch ICs solves the problem
Usually, in the power line, the usage of a load switch is common, but in some cases, other purpose switches such as OVP switch could be suitable.