Panasonic Viera TC-P54Z1, Technical Manual

Page: 49 / 93

Slide #49
Panel Drive Start-up Circuit
After the confirmation of the voltages generated as the result of the 3.2V “TV-SUB-ON” command from
pin 52, the System MPU IC21100 outputs the “PANEL-STB-ON” command.
The 3.2V “PANEL-STB-ON” command from pin 30 of IC21100 is applied to the control pin (27) of
IC29004. This turns on the regulator section of this IC to output STB-D3.3V on pin 8.
Note: STB3.3V and STB-D3.3V are different voltages. STB3.3V is generated by IC25480 and STB-
D3.3V is generated by IC29004
The STB-D3.3V is used as VCC for the panel MPU (IC29003) and is also used to switch the clock
signal in IC25480.
The panel MPU (IC29003) starts its program execution when it receives the STB_D3.3V and the
crystal clock signal (Pin 42). When this happens, the 3.2V “PANEL-MAIN-ON” command is output on
pin 75.
The 3.2V “PANEL-MAIN-ON” command is applied to a switching circuit in the power supply. This forces
pin 38 of IC701 low to turn on the circuits that generate Vsus, Vda, P15V, and P5V.
When pin 38 goes low, pins 13, 21, and 22 also go low while pins 6 and 23 go high.
The power factor control circuit and the Vda/P15V generating circuit had already been turned on
previously when the “TV-SUB-ON” command was provided to the power supply.
The low command from pin 22 of IC701 is connected to an “Over-temperature-protector” inside MC302
before it is connected to a switching circuit to generate the Vda.
The high from pin 23 turns on a switching circuit to generate the P15V.
The high from pin 6 turns on a switching circuit to generate the P5V. This voltage is derived from the
15V.
The power factor control circuit and the Vsus generating circuit in the P-Vsus section of the power
supply are turned on when pins 13 and 21 go low. This allow for Vsus to be generated.