FX375 查看數據表（PDF） - CML Microsystems Plc

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FX375

Private Squelch Circuit

CML Microsystems Plc 

Pin Number Function

FX375J FX375LG

FX375LH FX375LS

1

2

Xtal/Clock: The input to the clock oscillator inverter. An external 4MHz Xtal or clock

input is to be applied at this pin. See Figure 2.

2

3

Xtal: The 4MHz output of the clock oscillator inverter. See Figure 2.

3

4

Load/Latch: This input regulates the operation of the eight input latches : D0, D1, D2,

D3, D4, D5, Rx/Tx and Private Enable for both parallel and serial input load modes.

Rx/Tx and Private Enable inputs can be used independently in either mode by the use

of Load/Latch and Control inputs configured as shown in Table 3, the data format

(D0 – D5), remains as set. This input has an internal 1MΩ pullup resistor.

4

–

D – (Serial Enable 1) :

5

The Rx/Tx tone programming and function inputs.

5

5

D4 – (Serial Enable 2) :

Programmed as shown in Table 2 these inputs will select

the CTCSS tone frequency and parallel or serial loading

6

6

D3 – (Serial Data Input) :

function. Notone, when set in receive, enables the Rx

Audio Output and forces the Rx Tone Decode Output to a

7

7

D2 – (Serial Clock Input) :

logic '0,' in transmit the Tx Tone Output is held at VBIAS

(Notone). These inputs each have an internal 1MΩ pullup

8

–

D

1

9

–

D

0

resistor. If FX375LG or LS package styles are used Pin 5

(Serial Enable 2) should be externally connected to VSS.

10

8

Rx Tone Decode Output : The output of the decode comparator. In Rx a logic '0'

indicates 'CTCSS tone decoded' above the internal reference level, or Notone

programmed. This action internally enables the Rx audio path and Frequency Inversion

function (when applicable) as shown in Table 1. In Tx this output is a logic '1'.

11

9

Decode Comparator Input : A logic '1' at this pin, in Rx, is compared internally with a

fixed reference level, a more positive input value will produce a logic '0' at the Rx Tone

Decode Output. This input should be externally connected to the Rx Tone Detect

Output via external integrator components C7, R2, R3, D1 (see Figure 2).

12

10

Rx Tone Detect Output : This output, in Rx, goes to a logic '1' when a valid,

programmed CTCSS tone is received at the Rx Tone Input. This input should be

externally connected to the Decode Comparator Input via external integrator

components C , R , R , D (see Figure 2).

7231

13

–

Notone Output : Outputs a logic '0' when a " Notone" CTCSS code has been

programmed . It can be used to operate squelch circuitry under receive "Notone"

conditions.

14

11

V : Negative supply rail (GND).

SS

The FX375LG and LS package styles are configured as a serial-data loading device,

Parallel Programing Inputs D0, D1 and D5, and the NOTONE Output pin functions are not

available.

2

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