LE57D122BTC Zarlink, LE57D122BTC Datasheet - Page 3

• Manufacturer Part Number: LE57D122BTC
• Description: SLIC 2-CH 67dB 120mA 5V 44-Pin LQFP EP Tray
• Manufacturer: Zarlink

Specifications of LE57D122BTC

• Package: 44LQFP EP
• Number Of Channels Per Chip: 2
• Polarity Reversal: Yes
• Longitudinal Balanced: 67 dB
• Loop Current: 120 mA
• Minimum Operating Supply Voltage: 4.75 V
• Typical Operating Supply Voltage: 5 V
• Typical Supply Current: 9.3 mA

PRODUCT DESCRIPTION
The Le5712 device is designed for long loop high-density POTS applications requiring a low power, small footprint SLIC device.
The Le5712 device increases line card density by integrating two SLIC devices into a single 44-pin package. This reduction in
board space permits a higher density line card, which allows for amortizing common hardware across more channels. The
Le5712 device gives line card designers a simple control interface that supports seven states: Active, Active Metering, Reverse
Polarity, Reverse Polarity Metering, Standby, Tip Open and Disconnect (Ringing). The low cost and high performance Le5712
device provides the key features for POTS markets requiring loop start, loop start and metering, or ground start. The device
includes a thermal management feature for minimizing power dissipation on the SLIC. Alternatively, the device can be operated
in a dual battery configuration to reduce overall power consumption.
BLOCK DESCRIPTIONS
Two-Wire Interface
The two-wire interface provides DC current and sends voice and signalling information to a customer premise equipment. The
two-wire interface also receives the returning signals from the customer premise equipment.
This block implements the thermal management feature, which allows power that would otherwise be dissipated within the
package to be off loaded into an external resistor when the line is Off Hook. R
limits power within the SLIC device (Note: "i" denotes channel number).
The minimum value of R
where I
should be taken into account when selecting a value that meets this requirement. For example, if BAT
mA and R
the power in R
The power dissipated in the TMG resistor is given by:
where I
The maximum power on R
And the power dissipated per channel in the SLIC device while in the Active states is given by:
The maximum power dissipated per channel in the SLIC device while in the Active states is given by:
Refer to the Thermal Management for the Le5711 and Le7512 Dual SLIC Devices Application Note for further analysis and for
dual battery condition.
The AC signal swing supported by the two-wire interface is controlled by the SLIC state. For standard voice transmission, the
Active and Reverse Polarity states are used. To support voice plus meter pulses, the Active Metering and Reverse Polarity
Metering states are provided which have increased overhead to support 2.0 Vrms metering.
LIMITMIN
L
is the loop current, and R
LMIN
TMG
P
= 200 Ω then R
is the minimum programmed loop current limit and R
SLICi
below 1.0 W, and the total worst case SLIC power dissipation with both channels active below 1.6 W.
=
P
TMGi
0.003 BAT
SLICmaxi
TMG
is given by:
TMG
is given by:
P
R
L
=
RTMGmax
= 1.5 kΩ is the minimum recommended value. A value of 1.8 kΩ with 5% accuracy will keep
TMG
is the loop resistance.
+
0.003 BAT
(
BAT
≥
P
RTMG
--------------------------------------------------------------------------------------------------------------------------------- -
BAT
=
–
3
(
---------------------------------------------------------------------------------------------------------------------------
MAX
max
BAT
–
=
I
(
------------------------------------------------------------------------------------------ -
L
Zarlink Semiconductor Inc.
+
6 – I
(
BAT
R


max
1
L
–
+
+
LIMITMIN
–
I
2R
I
------------------------ - R
–
LIMITMIN
LIMITmax
5
5
F
–
–
3
2
+
I
I
LIMITmin
L
40
R
• R
R
⋅
)
TMG
LMIN
TMGmin
) I
(
(
–


2 R
3 mA
TMGmax
L
L
•
+
is the minimum loop resistance. The tolerance of R
–
(
R
2R
F
-------------- - BAT
R
Lmin
TMG
+
I
F
TMGi
 I

R
+
LMIN


(
+
40
------------------------ -
LIMITmax
2R
is connected from TMG
)
)
+
2
2
F
40Ω
+
–
40
5
)
+
)
–
)
I
2
----------------------- -
R
L
TMGmax
(
R
1
L
+
MAX
2R


F
= -56 V, I
+
i
to the VBAT pin and
40
)
)


LOOPMIN
= 30
TMG