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LM74722-Q1: LM74722-Q1

Rudra prasad1
Prodigy 40 points
Part Number: LM74722-Q1
Other Parts Discussed in Thread: LM74910-Q1

Hello Team,

I need help for LM74722-Q1 short circuit protection, application is to drive the HSD outputs.

Am facing an issue when HSD output is in short circuit condition. Power for HSD is controlled from LM74722.

When the HSD output is in short circuit mode LM74722 is damaged, and it is failing to protect.

Please find the attached circuit below and help me.

Regards,

Rudraprasad V

  • 0
    TI__Guru 57737 points

    Hi Rudraprasad,

    LM74722-Q1 is not capable of detecting over-current and protecting the system from output short-circuit.

    For output short-circuit protection, you will have to consider using LM74910-Q1. The LM749x0-Q1 ideal diode controller drives and controls external back to back N-Channel MOSFETs to emulate an ideal diode rectifier with power path ON/OFF control with overcurrent and overvoltage protection. The wide input supply of 3 V to 65 V allows protection and control of 12-V and 24-V automotive battery powered ECUs. The device can withstand and protect the loads from negative supply voltages down to –65 V. An integrated ideal diode controller (DGATE) drives the first MOSFET to replace a Schottky diode for reverse input protection and output voltage holdup. With a second MOSFET in the power path the device allows load disconnect (ON/OFF control) in case of overcurrent and overvoltage events using HGATE control. The device has integrated current sense amplifier which provides accurate current monitoring with adjustable overcurrent and short circuit thresholds.

  • 0 in reply to Praveen GD
    Prodigy 40 points

    Thanks praveen,

    1.Is there any way to protect the LM74722 by short circuit, because the PCB is manufactured, and we are in critical situation. We observed the lm74722 is failed when the high side driver tries to protect the load from short circuit. We increased the output capacitor and it worked 3 to 4 times, but it failed after some times.

    2.If it not possible, please confirm the below application is possible by LM74910,

    My applications to drive inductive loads and the rated current is 25A@28V.

  • 0 in reply to Rudra prasad1
    TI__Guru 57737 points

    Hi Rudraprasad,

    Firstly we should understand the root cause of LM74722-Q1 failure.

    When the down-stream circuit HSD device turns OFF the power path after detecting a output short, there can be be transient over voltage seen at the input of HSD which is the output of LM74722-Q1. If this transient over voltage is higher than the LM74722-Q1 device Abs Max rating, then the device can get damaged.

    Can you share the waveform captures during output short-circuit with LM74722-Q1 Input and output signals captured?