Mitsubishi V19-V21, Tehnical Manual

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6-4
Note that the SDA-MN and SCL-MN signals to the
2HDW circuitry are routed through IC7A04 and
IC7A03, respectively. Both of the ICs are level shift
ICs, reducing the signal amplitude from the 5 volt
range to 3.3 volts. This is necessary since the con-
trolled circuitry on 2HDW uses a 3.3 volt DC supply
and the TV µPC uses a 5 volt supply.
Additional control of the 2HDW circuitry is provided
by conventional, one direction, D-OUT, D-IN and
SCLK lines.
Single direction asynchronous data lines are used for
communication between the TV µPC and the DM
µPC.
• TV DM TXD … transfers data from the TV
µPC to the DM µPC.
• TV DM RXD … transfers data from the DM
to the TV µPC.
• TV DM RTS … Request to Transmit
• TV DM CTS … Clear to Transmit
If there is no communication between the TV µPC
and the DM µPC, the TV will not switch On.
DC Supplies
Figure 6-3 shows the DC supplies for the TV µPC cir-
cuitry. The TV µPC requires a 5 volt DC supply. The
STBY 12V supply is the source for the Control cir-
cuitry 5 volt supplies. IC9C00 regulates the 12 volts
down to 5 volts, the 5VHU DC supply.
The 5VHU supplies power directly to IC5H00, the
Flash Protect IC, and is the source for all the other
Control circuitry 5 Volt supplies. Each of the sup-
plies is isolated by Low Pass LC Filters.
• 5VHU-1 … Supplies IC7A00 5V STBY and
Reset IC, IC7A02
• 5VHU-2 … Supplies IC7A00 AVCC
• 5VHU-3 … Supplies the Remote Preamps
• 5VHU-4 … IC7A00 5V STBY2 and
E2PROM IC, IC7A01
• 5VHU-5 … Supplies Buffer IC, IC2B00
Reset Circuitry
Microprocessors must be reset to their nominal state
when power is first applied, otherwise lockup oc-
curs.
Figure 6-4 shows the Reset circuitry in the
V19. The TV µPC’s Reset Input is at pin 12. Reset