L3000S datasheet(7/29 Pages) STMICROELECTRONICS

7 / 29 page

Table 1.

Pin 28 of L3030 / Pin 12 of L3000S

(C2)

– 3

Pin 27 of L3030

11 of L3000S

+ 3

Stand-by

Conversation in Normal

Battery Direct Polarity

Conversation in Normal

Battery Reverse Polar

Not allowed.

Conversation in Boost

Battery Direct Polarity

Conversation in Boost

Battery Reverse Polar

– 3

Not allowed.

Ringing with Direct

Polarity

Not allowed.

states as listed in Table. 1.

Appropriate combinations of two pins define the

three modes of the ST SLIC, that are :

a) Stand-by (SBY)

b) Conversation (CVS), Normal and Reverse pola-

rity

c) Ringing (RING)

d) Boost Battery (BB), Normal and Reverse polarity

A fifth status, Power down (PD), can be set discon-

necting the bias resistor (RH) from pin 10 of L3000S

by means of an external transistor.

The main difference between Stand-by and Power

down is that in SBY the power consumption on the

voltage battery VB– (– 48V) is reduced but the

L3000S DC feeding and monitoring circuits are still

active. In PD the power consumption on VB- is re-

duced to zero, and the L3000S is completely swit-

ched off.

The SBYstatus shouldbe used when the telephone

is in On hook and PD status only in emergencycon-

dition when it is mandatory to cut any possible dis-

sipation but no operation are requested.

OPERATING MODES

Stand-by (SBY) Mode

In this mode, the bias currents of both L3000S and

L3030are reducedas only someparts of the two cir-

cuits are completely active, control interface and

current sensors among them. The current supplied

to the line is limited at 7mA, and the slope of the DC

characteristic corresponds to :

(RFS + 2RP)

The Line voltage in on Hook conditionis just the bat-

tery voltage minus the voltage drop (approx. 15V) of

the output stage amplifiers (see Fig. 1).

Figure 1 : DC Characteristics in Stand-byMode.

L3000S - L3030

7/29

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