SI3461 Silicon Laboratories, SI3461 Datasheet - Page 12

• Manufacturer Part Number: SI3461
• Description: SINGLE-PORT IEEE 802.3AT POE/POE PSE INTERFACE
• Manufacturer: Silicon Laboratories

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Si3461
4.1. Reset State
At power-up or if reset is held low, the Si3461 is in an inactive state with the pass FET Q4 off.
4.2. Operating Mode Configuration
At power-up, the Si3461 reads the voltage on the STATUS pin, which is set by a DIP switch and a resistor network.
The STATUS pin voltage level configures all of the Si3461's operating modes as summarized in Table 6.
12
Notes:
1. After power-up, the STATUS pin drives the base of an NPN transistor that controls an LED.
2. There is a trade-off in selecting the mode setting resistor values between voltage step accuracy and additional worst-
3. Each mode setting resistor should be connected either to GND or +3.3 V through the DIP switch. Care should be taken
4. A reset is required after a DIP switch position change for the new mode to take effect.
Pin Voltage (V)
case supply current. For high-value resistors, the base current will alter the voltage steps while low-value resistors may
place higher load on the STATUS pin while driving the LED. The suggested resulting parallel resistance used by the
Si3461-EVB is 2.0 k  .
not to short the +3.3 V supply to GND.
0.122 to 0.338
0.338 to 0.548
0.548 to 0.756
0.756 to 0.961
0.961 to 1.162
1.162 to 1.366
1.366 to 1.575
1.575 to 1.784
1.784 to 1.990
1.990 to 2.196
2.196 to 2.407
2.407 to 2.618
2.618 to 2.838
2.838 to 3.044
STATUS
< 0.122
> 3.044
PSE Type
1
1
1
2
1
1
1
2
1
1
1
2
1
1
1
2
Table 6. Operating Modes
Midspan/
Endpoint
Endpoint
Endpoint
Endpoint
Endpoint
Endpoint
Endpoint
Endpoint
Endpoint
Midspan
Midspan
Midspan
Midspan
Midspan
Midspan
Midspan
Midspan
Rev. 1.0
Operating Mode
Restart Action on Fault or
Overload Event Condition
Restart after disconnection
Restart after disconnection
Restart after disconnection
Restart after disconnection
Restart after disconnection
Restart after disconnection
Restart after disconnection
Restart after disconnection
1,2,3,4
Auto restart after 2 s
Auto restart after 2 s
Auto restart after 2 s
Auto restart after 2 s
Auto restart after 2 s
Auto restart after 2 s
Auto restart after 2 s
Auto restart after 2 s
Power (W)
Available
15.4
15.4
15.4
15.4
30
30
30
30
4
7
4
7
4
7
4
7
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