SA545 Ver la hoja de datos (PDF) - South African Micro Electronic Systems

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componentes Descripción

Fabricante

SA545

PULSE/DTMF SWITCHABLE DIALLERS WITH 10 REPERTORY MEMORIES

South African Micro Electronic Systems 

SA545

F. PIN 12 (SA545)/PIN 14 (SA54L5)

a) MUTE

b) MUTE

G. LNR Protocol

a) Numbers entered after * or # are never retained in the LNR store. (Attractive

for banking applications since PIN is not retained).

b) Numbers entered after * or # are retained in the LNR store if initial mode is

set to DTMF.

TYPICAL APPLICATIONS

The circuit in Figure 7 uses a constant current supply to draw current from the

telephone line which is used to power the SA54X5. The 2,5V reference diode

produces a stabilised supply voltage which determines the DTMF tone level of the

SA545.

In Figure 8, a stabilising voltage from the speech circuit is used to supply the SA545

during DTMF dialling to give accurate tone levels.

The SA545 is powered via the 150KΩ resistor during TBR operations and LD dialling

breaks, and via T1 during dialling makes. This configuration minimises the

component count, at the expense of allowing a leakage current of about 450µA

during dialling breaks. The 47µF reservoir capacitor maintains and smoothes the

supply to the chip.

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