Si3461
12 Rev. 1.0
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.
Table 6. Operating Modes
1,2,3,4
STATUS
Pin Voltage (V)
Operating Mode
PSE Type Midspan/
Endpoint
Restart Action on Fault or
Overload Event Condition
Available
Power (W)
< 0.122 1 Midspan Restart after disconnection 4
0.122 to 0.338 1 Midspan Restart after disconnection 7
0.338 to 0.548 1 Midspan Restart after disconnection 15.4
0.548 to 0.756 2 Midspan Restart after disconnection 30
0.756 to 0.961 1 Midspan Auto restart after 2 s 4
0.961 to 1.162 1 Midspan Auto restart after 2 s 7
1.162 to 1.366 1 Midspan Auto restart after 2 s 15.4
1.366 to 1.575 2 Midspan Auto restart after 2 s 30
1.575 to 1.784 1 Endpoint Restart after disconnection 4
1.784 to 1.990 1 Endpoint Restart after disconnection 7
1.990 to 2.196 1 Endpoint Restart after disconnection 15.4
2.196 to 2.407 2 Endpoint Restart after disconnection 30
2.407 to 2.618 1 Endpoint Auto restart after 2 s 4
2.618 to 2.838 1 Endpoint Auto restart after 2 s 7
2.838 to 3.044 1 Endpoint Auto restart after 2 s 15.4
> 3.044 2 Endpoint Auto restart after 2 s 30
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-
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
.
3. Each mode setting resistor should be connected either to GND or +3.3 V through the DIP switch. Care should be taken
not to short the +3.3 V supply to GND.
4. A reset is required after a DIP switch position change for the new mode to take effect.
