L3030 STMicroelectronics, L3030 Datasheet - Page 8

• Manufacturer Part Number: L3030
• Description: SUBSCRIBER LINE INTERFACE KIT
• Manufacturer: STMicroelectronics

L3000S - L3030
The AC characteristic is just the resistance of the
two serial resistors RP.
In Stand-bymode the batterypolarity is just in direct
condition,that is the TIP wire more positive than the
RING one ; boost battery is not achievable. There
are two possible line conditions where the SLIC is
expected to be in stand-by mode :
1) ON-HOOK (I
2) OFF-HOOK (I
When the SLIC is in stand-by mode, the power dis-
sipation of L3000S does not exceed 120mW (from
-48V) eventually increased of a certain amount if
some current is flowing into the line.
The power dissipation of L3030 in the same condi-
tion, is typically 120mW.
The Stand-byMode is set when the byte sent to the
L3030 Serial Digital Interface has the first two bits
(BIT0R and BIT1R) equal to ”0”.
Settingto 0 all the 8 bits of the command sent to the
digital interface of L3030, the bias currents of both
L3000S and L3030 are reduced and only some
parts of the two circuits are active similarly to the
stand-by mode ; in this situation, named power-
down denial, the line sensors are disabled
(ON/OFF-HOOK line conditions cannot be recogni-
zed) and the current supplied to the line is limited at
0.25mA.
Conversation (CVS) or Active Mode
In conversationmodeit is possibleto selectbetween
two different DC Characteristics by the BIT5R of the
Figure 2 : DC Characteristic (n.b.) I
Note :
8/29
condition.
the SLIC is waiting for command to activate
conversation.
1. This value of voltage battery, named apparent battery, is fixed internally by the control unit and is independent of the actual battery
value. So, the voltage drop in the low impedance region is 15V. It is also possible to increase up to 25V this value setting BIT3R to 1.
line
line
< 5mA). Normal on-hook
> 7mA). Handset is unhooked,
LIM
= 25/30/45/70mA.
Serial Interface.
1) Normal Battery (NB)
2) Boost Battery (BB)
It is also possibleto select(BIT4R)the polarity of the
DC line voltage and (BIT6R-BIT7R) one of the four
values of limiting current (25mA or 30mA or 45mA
or 70mA).
Battery reverse can take place either before or du-
ring conversation.
As far as the DC characteristic in Normal Battery is
concerned, three different feeding conditions are
present :
a) current limiting region ; the DC impedance of the
b) standard
c) low impedance region ; the battery value is
Switching betweenthe three region is automaticwi-
thout discontinuity, and depends on the loop resi-
stance.Fig. 2 shows the DC characteristic in normal
battery condition.
Whenthe boostbatteryconditionisactivatedthe low
impedance region can never be reached by the sy-
SLIC is very high (> 20 Kohm) and therefore the
systemworkslike a currentgenerator,the current
value being set through the digital interface
(25/30/45/70mA).
characteristic is equal to a – 48V (– 60V) battery
(note 1), in series with two resistors, whose value
is set by external components (see external
component list of L3030).
reducedto 33V (45V) and the serial resistance is
reduced to the value specified in stand by mode,
that is :
2
3
x RFS
feeding
2RP
system
region
;
the