Mitsubishi V19-V21, Tehnical Manual

Page: 27 / 71

5-5
When P-ON2 goes High, it turns Q9A21 Off:
• Allowing Q9A20 to conduct, generating the
SW 12V supply.
• The SW 12V supply enables IC9A22, which
outputs the SW 5V supply.
At a pre-programmed recording time, using the TV
as the Signal source, only the P-ON2 line goes High.
This activates only the signal processing circuits in
the TV.
DM Power Supply
Figure 5-4 illustrates the DM Power Supply, which
is located on a separate PCB in the DM Module.
STBY 28V and STBY 12V from the Main Standby
circuitry are input to the DM Power Supply. Both
voltages are routed to the digital circuitry in the mod-
ule. The STBY 12V also provides power for the Regu-
lator circuitry in the DM Power Supply.
The DM Regulation circuitry generates two supplies
DM 5V and DM 3.3V. The Regulator consists of
four ICs, IC9B00, Q9B00, Q9B01 and Q9B02.
IC9B00 is a Pulse Width Modulator (PWM), and
Q9B00, Q9B01 and Q9B02 are comprised of
MOSFET transistors. Multiple Drain and Source
connections are used to increase current handling ca-
pability.
Q9B00 and Q9B01 are connected in a push-pull con-
figuration. Gate drive is generated in IC9B00.
UGATE drives Q9B00, and LGATE drives Q9B01.
The output of the push-pull circuit is at the junction
Q9B00 Source and Q9B01 Drain. The output is fil-
tered to generated the DM 3.3V supply.