mc44bc374t1 Freescale Semiconductor, Inc, mc44bc374t1 Datasheet - Page 16

• Manufacturer Part Number: mc44bc374t1
• Description: Pll Tuned Pal/ntsc Uhf And Vhf Audio/ Video High Integration Modulator Ic
• Manufacturer: Freescale Semiconductor, Inc

Modulator Operation
13 Modulator Operation
13.1 Power ON Settings
At power-ON, the MC44BC374T1 configuration is as follows:
13.2 Power Supply
The three device Vccs (pins 10, 13, 15) must be applied at the same time to ensure all internal blocks are
correctly biased. All other pins must not be biased before Vcc is applied to device (except STBY pin
during hardware standby mode).
13.3 Standby modes
During standby mode, the modulator is switched to low power consumption: the sound oscillator, UHF
oscillator, video and sound modulator sections bias are internally turned OFF.
The IIC bus section remains active.
Modulator can be switched in standby mode in 2 cases:
Hardware / Software standby modes
There is an internal logical “OR” function between the hardware and software standby modes:
16
C1—High Order Bits
C0—Low Order Bits
FM—High Order Bits
FL—Low Order Bits
Note:
Note:
Note:
Note:
•
•
N0 to N11 are set to have UHF oscillator on channel 71 (871.25MHz).
Peak White Clip is ON.
Sound frequency is 5.5MHz.
Picture to sound ratio is 12dB.
Software standby mode: combination of 3 bits of IIC message:OSC=0, SO=1 and ATT=1
Hardware standby mode: STBY pin is set to LO state
Hardware standby mode
Software standby mode
Modulator Mode
WRITE MODE
This power-ON configuration is not available when modulator is switched
ON from STBY pin.
When switching from STBY=LO to STBY=HI, the modulator
configuration is not guaranteed. An IIC message has to be sent to program
the modulator.
Bit 7
N5
1
0
0
MC44BC374T1 Technical Data
Normal
Normal
Normal
Bit 6
N4
0
1
0
NOTE:
NOTE:
Bit 5
N11
N3
Normal
Standby
Standby
0
0
Bit 4
N10
N2
0
0
Standby
Normal
Standby
Bit 3
N9
N1
0
1
Bit 2
N8
N0
0
0
Standby
Standby
Standby
Bit 1
N7
0
0
0
Bit 0
N6
MOTOROLA
0
0
0
ACK
ACK
ACK
ACK
ACK