mc44bs374t1a Freescale Semiconductor, Inc, mc44bs374t1a Datasheet - Page 22

• Manufacturer Part Number: mc44bs374t1a
• Description: Pll Tuned Uhf And Vhf Audio/video High Integration Modulator
• Manufacturer: Freescale Semiconductor, Inc

Modes of Operation
For test purposes, it is possible to disable the 263ms delay using Test Mode 1-State 1.h (this is called speed
up mode).
16.5 UHF Oscillator-VHF range
The UHF oscillator is fully integrated and does not require any external components.
For low frequency testing or VHF range operation ( test mode 1, states 1.b to 1.e ), the UHF oscillator can
be internally divided by: 2, 4, 8, or 16.
16.6 UHF PLL Section
The reference divider is a fixed divide-by-128, resulting in a reference frequency of 31.25 KHz with a
4.0 MHz crystal.
The prescaler is a fixed divide-by-8 and is permanently engaged.
The programmable divider division-ratio is controlled by the state of control bits N0 to N11.
The divider-ratio N for a desired frequency F (in MHz) is given by:
with:
16.7 Logic Output Port (LOP)
The LOP pin controls any logic function. The primary applications for the LOP are to control an external
attenuator or an external switch, between the antenna input and TV output. A typical attenuator application
with PIN diode is shown in Figure 7. The LOP pin switches the PIN attenuator depending on the signal
strength of the Antenna Input. This reduces the risks of intermodulation in certain areas. The LOP can also
be used as an OFF position bypass switch or for other logic functions in the application.
Programming a division-ratio N=0 is not allowed.
Figure 7. Typical Attenuator Application with Pin Diode
N
Freescale Semiconductor, Inc.
=
MC44BS374T1/374T1A Advance Information
For More Information On This Product,
Antenna
2048 N11
Input
Go to: www.freescale.com
+
1024
LOP pin
Vcc
N
N10
NOTE:
=
F
-- -
8
+
128
-------- -
4
+
4 N2
+
2
TV Out
N1
+
N0