MP3924 datasheet(29/56 Pages) MPS

29 / 56 page

MP3924

– QUAD-PORT IEEE 802.3AF/AT PSE CONTROLLER

MP3924 Rev. 1.0

MonolithicPower.com

7/16/2021

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

Watchdog

The MP3924 implements a watchdog to monitor

the SCL line for I2C activity. If there is no

transition on the SCL line for about 2.5s during

I2C communication, then the I2C port and all

power output ports shut down. The WDS bit is

set to 1 to indicate the error condition. WDS

must be reset before any port can be re-

enabled. After watchdog protection is triggered,

the port shuts down until the host re-enables

the ENx bits.

By default, the watchdog is off after start-up. To

enable the watchdog function, set the WDEN bit

to 1.

Over-Temperature Protection (OTP)

Over-temperature

protection

(OTP)

implemented to prevent the chip from thermal

runaway.

When

the

junction

temperature

exceeds its upper threshold, the MP3924 shuts

down all ports (the I2C and registers still work).

Once the temperature drops below its recovery

threshold, the ports are enabled again with a

new detection cycle. The OTP bit is set to 1

after OTP recovery.

MP3924 Datasheet(PDF) 29 Page - Monolithic Power Systems