MC44BS374T1/374T1A Advance Information

Modes of Operation

For test purposes, it is possible to disable the 263ms delay using Test Mode1-State1.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 31.25KHz with a

4.0MHz 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:

NOTE:

Programming a division-ratio N=0 is not allowed.

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.

Figure 7. Typical Attenuator Application with Pin Diode

N

F

8

---

128

4

---------

×

=

N

2048

N11

×

1024

N10

×…… 4 N2

×

2

N1

×

N0

+

+

+++

=

LOP pin

Vcc

TV Out

Antenna

Input

Freescale Semiconductor, Inc.

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