MP3924GU datasheet(26/56 Pages) MPS

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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.

repeats the detection cycle until a valid PD is

connected.

If the MP3924 runs in automatic mode after

start-up or reset, the DETENx and CLSENx bits

are set high based on the AUTO pin. If a port is

set to automatic mode via the I2C, the DETENx

and CLSENx bits do not change.

Semi-Automatic Mode

semi-automatic

mode,

the

MP3924

automatically

detects

and

classifies

the

connected PD. However, the port does not start

up until an I2C command is issued. Set the

MODEx bits to 10 to force the MP3924 to

operate in semi-automatic mode.

When the port is set to semi-automatic mode,

the DETENx and CLSENx bits to not change. If

the DETENx and CLSENx bits are high in semi-

automatic mode, the port repeats the detection

(and classification if the PD detection result is

valid) continuously. However, the port does not

start up until an I2C command is issued. If the

detection and classification are valid, the port

power can be turned on by a PONx bit. If the

port is powered off in semiautomatic mode, the

DETENx and CLSENx bits are reset to 0.

If the detection is valid and the port does not

turn on within 400ms in automatic or semi-

automatic mode, then the port initiates a new

detection sequence. If the final detection and

classification sequences are determined to be

invalid before the start-up command is received,

the device fails to turn on. At the same time, the

STFx bit is set and the MP3924 resets the

command. If the detection and classification

sequences are valid but a start-up command is

not issued after 400ms, then the STFx bit is set.

Manual Mode

In manual mode, all functions are controlled via

the

I2C

interface.

Manual

mode

recommended for system diagnostics. Set the

MODEx bits to 01 to force the ports to operate

in manual mode.

In manual mode, the DETENx and CLSENx bits

are set to 0. Set these bits to 1 to enable one-

time detection or classification. These bits reset

to 0 automatically.

The PONx bits power the port in manual mode.

The port turns on any time the PONx bit is set.

If the DETENx, CLSENx, and PONx bits are set

simultaneously, then the MP3924 executes a

detection cycle first. If

the DETENx and

CLSENx bits are set after the port starts up, the

MPM3924 ignores the DETENx and CLSENx

commands. The RDETx and RCLSx bits follow

the same logic.

If a PONx command is received while the

device recovers from a protection, then the

MP3924 does not turn on and the failure is

reported to the STFx bit.

Shutdown Mode

In shutdown mode, all detection, classification,

and port power output functions are off. To

force the MP3924 to operate in shutdown mode,

pull the AUTO pin to DGND before the device

starts up or resets. Set the MODEx bits to 00 to

set a port to shutdown mode.

Once a port is in shutdown mode, the power is

turned

off

and

the

corresponding

port

event/status registers are cleared, except for

the PECx and PGCx bits. The I2C interface still

operates in shutdown mode, but the ports do

not respond to any detection, classification, or

port start-up commands.

In certain AUTO pin configurations, the MODE

bits are set to 00 or 11 after start-up (or after a

reset). After start-up, all ports can switch

between the four modes. The registers and port

states are not changed by these bits unless

shutdown mode is selected.

9-Bit ADC

The MP3924 integrates a 9-bit analog-to-digital

converter (ADC) to continuously measure the

input voltage, output voltage, load current, and

junction temperature. The ADC also measures

PMAX once following start-up, or if the device is

reset. When any ADC information is required,

the host controller can read the corresponding

data registers. ADC conversion only works

when the port is enabled and if there is no data

update for the corresponding port when the port

is shut down. The register cannot be updated

while it is read, even if ADC conversion is

complete for that segment of data.

I2C Interface

The MP3924 features an I2C interface. The 7-bit

device address is defined as 010 xxxx, where

MP3924GU Datasheet(PDF) 26 Page - Monolithic Power Systems

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