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I am using this Buck Converter

Input Voltage Range - 8-16V

Output Voltage - 5V

Load Current - 550mA

This 5V is the power supply (Vcc) to the mentioned IC loads :
Microcontroller , LED Driver , 2x CAN Transceivers & 5V to 3.3V LDO

My questions :

  1. I want to check what would happen if I short the Output of the 5V Buck Regulator for a fraction of second. (a) How to perform and check what would happen if I short circuit the output of the regulator while it is still connected to the Vcc of the above mentioned IC Loads? Won't those ICs get damaged if I short the Output of the 5V?

Objective of the Short Circuit test : Just want to understand what would happen if the buck regulator is shorted for some reason in my board. Is there a recommended time duration for how long the output can be shorted?

  1. Is it recommended to perform the short circuiting of the Buck Regulator output when it is connected to the above IC Loads?

  2. Usually do the buck converters have short circuit protection? By this, do they mean that if the regulator output is shorted, the IC does not provide a lot of output current (so a to protect the underlying loads and the PCB)? Is my understanding correct?

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1 Answer 1

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  1. Shorting the buck regulator output to GND probably will not damage any of the downstream components. BUT ...

  2. It NEVER is "recommended" to apply a dead short to the output of a switching regulator. Some linear regulators, such as in lab or bench supplies, use this technique to set the output current limit, but your circuit is not that.

  3. This part has an internal switch transistor rating of 2.5 A. It has internal overcurrent monitoring and protection. The threshold value is very loosely specified, but the minimum value is 3.1 A.

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  • \$\begingroup\$ thank you for the answer. 1. Just curious to understand, how does the shorting of the regulator output does not affect any downstream components? In the PCB, when we short the 5V, the 5V Vcc and the ground of the downstream components are also shorted right. Since current takes a path of least resistance, a huge current might flow through the Vcc and the ground planes on the PCB which might heat up the downstream ICs and may cause it to get damaged, right? Please explain. I am confused on how the downstream components might not affected? \$\endgroup\$
    – user220456
    Jul 10, 2020 at 3:22
  • \$\begingroup\$ 2. When you say , "Some linear regulators, such as in lab or bench supplies' - do you mean, Linear regulator ICs or bench power supplies like, for eg, say, GPC-3030D? \$\endgroup\$
    – user220456
    Jul 10, 2020 at 3:23
  • \$\begingroup\$ 3. I tried searching, the internal switch transistor which you mentioned in the Buck regulator datasheet. I was not able to find it. Could you please tell me where you figured it out and how it might help with the short circuit protection? \$\endgroup\$
    – user220456
    Jul 10, 2020 at 3:27
  • \$\begingroup\$ when you short VCC to GROUND the current flows though the conductors that form the short circuit, the ICs down stream do not form part of the short circuit, so they will not see this current. if the ICs are driving capacitive loads they may see capacitor discharge currents through the protection diodes on the outputs that are connected to the capacitive loads. (eg your LDO is probablty driving a capacitive load) \$\endgroup\$ Jul 10, 2020 at 5:35
  • \$\begingroup\$ Can someone help me with the answers for these comments? \$\endgroup\$
    – user220456
    Jul 10, 2020 at 11:11

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