I want to knwo what is the Iout of VN7140, and what is the meanning of the "Iout - Internally limited", why the chip will shut down when the load is about 4A?

[HJian.11]

..

[Peter BENSCH]

Suppose you are talking about the VN7140AS or VN7140AJ then its datasheet says:

Current limitation

The device is equipped with an output current limiter in order to protect the silicon as well as the other components of the system (e.g. bonding wires, wiring harness, connectors, loads, etc.) from excessive current flow. Consequently, in case of short circuit, overload or during load power-up, the output current is clamped to a safety level, IlimH, by operating the output power MOSFET in the active region.

The datasheet also mentiones IlimL with a typical value of 4A.

Please note: The limit values are also influenced by the chip temperature. Therefore, knowing your setup can be helpful in fully answering your question.

Regards

/Peter

[HJian.11]

hi, Peter,

thank you for your quick response.

now I use 24VDC to drive a Rload=8Ohm, is it overcurrent or overheating?

thanks

Hai

[Peter BENSCH]

Hi, Hai,

If the 8 ohm load is a resistive load, 24 V will only result in 3 amps of current, which is below the limit. Section 3.2 of the data sheet applies to the case of overtemperature:

Thermal shutdown In case the junction temperature of the device exceeds the maximum allowed threshold (typically 175°C), it automatically switches off and the diagnostic indication is triggered. According to the voltage level on the /FaultRST pin, the device switches on again as soon as its junction temperature drops to TR (/FaultRST = Low) or remains off (/FaultRST = High).

Regards

/Peter

[Cristiana SCARAMEL]

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