LE57D122BTC Zarlink, LE57D122BTC Datasheet - Page 5

• 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

Input Decoder and Control
The input decoder and control block provides a means for a microprocessor or SLAC device IC to control such system states as
Active, Active Metering, Reverse Polarity, Reverse Polarity Metering, Standby, Tip Open and Disconnect (Ringing). The input
decoder and control block has TTL-compatible inputs, permitting interfacing to 5 or 3.3 V VCC controllers which set the operating
states of the SLIC device. It also provides the loop supervision signal sent back to the controller.
From power up, the device is in disconnect state unless over-written by external control inputs.
Device State Decoding
(For channel i = 1 or 2)
Off-Hook Detector (OHD)
The On-to-Off-hook and Off-to-On-hook detections are based on loop current and are defined as |I
hook (OHD) and Off-to-On-hook (OND) thresholds are programmed with the R
and Standby states.
Upon the loss of battery the DET pin will be HIGH.
Off-hook detection or DET state should be ignored during on-hook metering.
Ground Start Detector (GSD)
This detector is active in the Tip Open state. The threshold, I
For ground start lines, the device is in the Tip Open state between calls. When a ring ground condition is detected, the device
should be switched to the Active state. During this period, the DET pin will be active if the ring to ground current is greater than
twice the I
that a firmware time-out period is applied in case the call attempt is abandoned and DET never goes low. The time-out is reset
once an active DET is seen in the Active state.
Ring-Trip Detector
In the Disconnect state, the ring-trip detector is active. While the DB
High to indicate on hook. When an off hook condition occurs, the DB
pin will go Low to indicate off hook during ringing (ring-trip) has been detected. The system implements the Ringing state using
external control of a ring relay in combination with the Disconnect SLIC device state, which enables the ring-trip detector.
The
are selected for a typical battery-backed ringing applications such as for the US (TR-57) and China (GF002).
The
components are selected for a typical earth-backed ringing applications such as in India (G/LLT and G/MLT).
Fault Detector
The DSLIC device provides a fault detection function in the Active states on each channel. Under a fault condition the detector
senses longitudinal voltage at tip and ring and flags a fault by pulling the FLT
outputs, and may be monitored to clearly identify a fault condition from a loop condition.
In case of low level longitudinal AC induction the FLT
Upon the loss of battery the FLT pin will be LOW.
POTS Application Circuit (POTS with no metering),
Pulse Metering Application Circuit (Pots with metering),
OHD
threshold. The DET pin will go active once the ring ground is removed and a loop is applied. It is recommended
State
0
1
2
3
4
5
6
7
C3
0
0
0
0
1
1
1
1
i
C2
0
0
1
1
0
0
1
1
i
C1
0
1
0
1
0
1
0
1
I
Zarlink Semiconductor Inc.
I
OHD
OHD
i
i
may pulse at twice the frequency of the induction signal.
=
=
I
935V
------------ -
GSD
OND
Reverse Polarity Metering
R
on page 18
5
D
, is defined by the same equation used for the OHD.
Reverse Polarity
Two-Wire state
+
Active Metering
Hysteresis
Disconnect
i
i
Reserved
Tip Open
pin is more negative than the DAC pin, the DET pin will be
pin becomes more positive than the DAC pin, and the DET
Standby
Active
on page 20
shows a ring trip bridge configured and components
i
pin Low. The FLT
D
resistor and the threshold applies to all Active
shows a ring trip bridge configured and
DET
i
pins are compatible with logic
OHD
GSD
OHD
OHD
OHD
OHD
RTD
i
N/A
AD
output
- I
BD
| / 2. The On-to-Off-