Si3462-EVB

Rev. 1.2

11

6.6. Current Limit Control

power granting process and the actual output voltage. If the output current exceeds the threshold, a timer counts

up towards a timeout of 60 ms. If the current drops below the set threshold, the timer counts down towards zero at

1/16th the rate. If the timer reaches the set timeout, an overcurrent fault is declared, and the channel is shut down

by turning off the pass FET. Additionally, for Class 4 devices, if the output current reaches the ILIM level, the output

is shut down after 15 ms to protect the pass FET. After an overcurrent fault event, the LED will flash rapidly. As set

by the initial voltage on the STATUS pin at powerup, the Si3462 then automatically resumes the detection process

for “automatic restart configuration” unless the Si3462 is configured in a “restart after a disconnect condition” mode.

For the automatic restart configuration, the LED will flash rapidly after an overcurrent event for 2.2 seconds, and a

new detection cycle will be initiated. The LED will then flash at a 1.5 Hz rate to show that the detection is in

progress.

In the restart on disconnect configuration, the LED will flash rapidly until an open-circuit condition is detected

before a new detection cycle will start. Normally, an open-circuit condition can be created by removing the Ethernet

cable from the Si3462-EVB's RJ-45 jack labelled “PoE”. Power will not be provided until an open-circuit condition is

detected. Once the Si3462-EVB detects an open-circuit condition, the detection process begins. The status LED

blinks at a rate of 1.5 Hz, and the Si3462 is then allowed to go into classification and powerup mode if a valid PD

signature resistance is detected.

6.7. UVLO/OVLO

The Si3462-EVB reference design is optimized for 50 V nominal input voltages (44 V minimum to 57 V maximum).

If the input voltage drops below 42 V, a UVLO condition is declared, or, if it exceeds 60 V, an over-voltage condition

is declared, and the output is shut down in both cases. An undervoltage or an overvoltage event is a fault condition

reported through the status LED as a rapid blinking of 10 flashes per second. The UVLO and OVLO conditions are

continuously monitored in all operating states.

6.8. Status LED Function

During the normal detection sequence, the STATUS LED flashes approximately 1.5 times per second as the

detection process continues. After successful powerup, the LED glows continuously. If there is an error condition

(i.e., class level is beyond the programmed value or a fault or overcurrent condition has been detected), the LED

flashes rapidly at 10 times per second. This occurs for two seconds for normal error delay, and the detection

process automatically starts again after 2.2 s unless a “restart after disconnect condition” was set during the initial

configuration. Power will not be provided until an open-circuit condition is detected. Once the Si3462-EVB detects

an open-circuit condition, the LED blinks at 1.5 times per second.

If the PD is disconnected so that a disconnect event occurs, the LED starts flashing at 1.5 times per second once

the detect process resumes.