SA541

sames

6/16

SA541

SA54L1

Designation

Description

10

10

V

DD

Positive Supply input

99

V

SS

Negative Supply input

4

4

OSC OUT

Connections for 560KHz ceramic resonator

5

5

OSC IN

12

14

MUTE

Active high output during keying, tone transmission and

MUTE key depression. (See Note 1)

3

3

MASK

Output to disable speech circuit during pulse dialling

and

recall. (See Note 2)

6

6

FILT IN

Unity gain amplifier input and output for DTMF tone

7

7

FILT OUT

filtering

11

13

MF OUT

DTMF output

1

1

IMP

'Loop disconnect' dialling output.

2

2

SELECT

LD/DTMF selection, IDP and B:M ratio programming

13

15

C1

Column output connections for 16 button single contact

14

16

C2

keypad

15

17

C

20

22

C4

16

18

R1

Row input connections for 16 button single contact

17

19

R2

keypad

18

20

R3

19

21

R4

8

8

HSW

Hookswitch input. A logic 1 (High) indicates an “off-

hook” condition

-

11

LOCK

Lock Input must be tied to V

(except TBR, LNR and MUTE). Normal operation is

enabled by connecting LOCK to V

DD.

-

12

N/C

No connection

Note 1: The MUTE output is provided to disable the microphone while maintaining the

loop condition during DTMF transmission.

Note 2: The MASK output may be used to disconnect the whole speech circuit in order

to mantain the break condition whilst on-hook, during a Timed Break Recall

(TBR) operation or LD dialling.

Table 1: Pin Description