Sony SNC-WR632C Service Manual page 61

4-3. PS-858 Board
Power block
Voltages of 24 VDC and 5 VDC used in this unit are generated from 24 VAC input to CN2003 or the DC
voltage fed from a LAN connector.
During feeding of 24 VAC
24 VAC is input from CN2003 to a PS-858 board through an HC-51 board.
The input 24 VAC is generated as a direct current through a line filter (L2001) using a rectifier circuit.
IC2001 and Q2001 to Q2005 are rectifier circuits.
IC2001 controls Q2001 to Q2005 in the voltage state of AC input and makes them operate as a single-
phase bridge rectifier circuit.
Q2006 (rush prevention circuit) charges rectifier capacitors (C2020 to C2030) with a current through R2043
and R2044 in a state where it is off when the power is turned on. Q2006 is turned on after the power is on.
IC2002, Q2008, T2001, and Q2009 are insulation-type AC/DC converters.
The converters can be operated between a voltage of 30 VDC rectified in24 VAC and a voltage of 50 V at
the time of HPoE.
IC2002 incorporates a certification circuit of HPoE and a switching power control function of PWM.
During feeding of HPoE, the feeding voltage from a LAN connector is separated from a signal on an
SY-416 board and input to IC2002 through CN2002.
IC2002 has a resistance value, conforming to the standard of HPoE, between pins 5 and 6, and pin 13. A
voltage is applied here. A feeding hub detects the current flowing through the resistance value so as to
judge that equipment conforming to the standard of HPoE is connected.
FET between pins 5 and 6 and pins 26 and 27 of IC2002 is turned on in IC2002 when the feeding hub
applies a supply voltage. At that time, FET starts operating as an AC/DC converter.
IC2002 controls the ON time of Q2008 and generates 24 VDC on the secondary winding of T2001.
A pulse waveform proportional to an input voltage is generated on the primary control winding of T2001.
IC2002 detects the crest value of a pulse at pin 16 and controls so that the output of the AC/DC converter
is 24 VDC irrespective of fluctuations in the input voltage.
IC2002 also turns on Q2009 through T2002 with the OFF timing of Q2008 and controls so that C2034 is
charged with the secondary current of T2001.
The power mode information detected using IC2002 is transferred to the SY-416 board through PH2001
and PH2002.
During input of 24 VAC, Q2001 is turned on and the HPoE certification block of IC2002 is turned off.
Only the power block of IC2002 operates as a general power control circuit.
24 VDC power control block
A voltage of 24 VDC generated using an AC/DC converter block is output to CN1004 through a 24 VDC
power control block.
The 24 VDC power control block turns on and off the control of 24 VDC from a PS-858 board by the port
control of IC601 (SoC) on an SY-416 board.
A control signal is sent from IC601 on the SY-416 board to pin 8 of CN2501.
When a voltage at pin 8 of CN2501 is 3.3 V, Q2504 and Q2502 are turned on and an output voltage of 24
VDC from the PS-858 board is turned on.
When the power of this unit is turned on, in the initial state, a voltage of 24 VDC on the PS-858 board is
in an OFF state.
During start of this unit, 24 VDC is turned on and the power to a drive system and camera block is turned on.
4-5 (E)
SNC-WR632C/WR602C