TM
Document ID# 080146
Date:
Oct 14, 2004
Rev:
J
Version: 1
Distribution:
Public Document
Le7920
Subscriber Line Interface Circuit
VE580 Series
The Le7920 Subscriber Line Interface Circuit implements the
basic telephone line interface functions, and enables the
design of low cost, high performance, POTS line interface
cards.
DISTINCTIVE CHARACTERISTICS
Control states: Active, Ringing, Standby,
and Disconnect
Low standby power (35 mW)
19 V to 58 V battery operation
On-hook transmission
Two-wire impedance set by single external
impedance
Programmable constant-current feed
Programmable loop-detect threshold
Programmable ring-trip detect threshold
No 5 V supply required
Current Gain = 500
On-chip Thermal Management (TMG) feature
Four on-chip relay drivers and relay snubbers, 1
ringing and 3 general purpose (32 PLCC)
BLOCK DIAGRAM
Controller
C2
C1
RSN
Two-Wire
Interface
HPA
HPB
Signal
Transmission
Input Decoder
and Control
Off-Hook
Detector
Ring-Trip
Detector
Power-Feed
DA
DB
BGND
VCC
VBREF
RDC
AGND/DGND
VTX
VBAT
A(TIP)
B(RING)
RINGOUT
DET
CAS
RYOUT1
RD
TMG
D1
Relay
Driver
Ring Relay
Driver
Relay
Driver
Relay
Driver
D2
D3
RYOUT2
RYOUT3
2
Le7920 VE580 Series Data Sheet
TABLE OF CONTENTS
Connection Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Top View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3
Pin Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Operating Ranges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Electrical Characteristics (continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Electrical Characteristics (continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Relay Driver Schematics. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
DC Feed Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Test Circuits. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Test Circuits (continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Test Circuits (continued) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
Physical Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
32-Pin PLCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Revision Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision C to Revision D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision D to Revision E . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision E to Revision F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision F to Revision G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision G to Revision H. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision H to Revision I. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Revision I1 to Revision J1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
Le7920 VE580 Series Data Sheet
3
ORDERING INFORMATION
Standard Products
Legerity standard products are available in several packages and operating ranges. The order number (Valid Combination) is
formed by a combination of the elements below.
Valid Combinations list configurations planned to
be supported in volume for this device. Consult
the local Legerity sales office to confirm availabil-
ity of specific valid combinations, to check on
newly released combinations, and to obtain addi-
tional data on Legerity's standard militarygrade
products.
Valid Combinations
*Legerity reserves the right to fulfill all orders for this device with parts marked with the "Am" part number prefix, until such time
as all inventory bearing this mark has been depleted. It should be noted that parts marked with either the "Am" or the "Le" part
number prefix are equivalent devices in terms of form, fit, and function. The only difference between the two is in the part number
prefix appearing on the topside mark.
Valid Combinations
Le7920*
1
2
JC
DJC
Note: Green package meets RoHS Directive 2002/95/EC of the European
Council to minimize the environmental impact of electrical equipment.
Le7920
J
PERFORMANCE GRADE
Blank = Standard specification
1 = 53 dB Longitudinal Balance
2 = 63 dB Longitudinal Balance
C = Commercial (0
C to 70C)*
Subscriber Line Interface Circuit
C
DEVICE NUMBER/DESCRIPTION
Le7920
D= Green package (see note)
PACKAGING MATERIAL
Blank= Standard package
PLCC package
4
Le7920 VE580 Series Data Sheet
CONNECTION DIAGRAM
Top View
DA
RYOUT2
RYOUT3
TMG
VBAT
D2
D1
NC
NC
DET
RD
HPB
HPA
VTX
VBREF
RSN
AGND
NC
RYOUT1
BGND
VCC
B(
R
I
NG
)
A(
T
I
P)
DB
RINGOUT
C2
NC
RD
C
5
6
7
8
9
10
11
12
13
29
28
27
26
25
24
23
22
21
14 15
16 17 18
19 20
4
3
2
1
32
31 30
CAS
D3
NC
C1
Notes:
1. Pin 1 is marked for orientation.
2. NC = No Connect
32-Pin
PLCC
Le7920 VE580 Series Data Sheet
5
PIN DESCRIPTIONS
Pin Name
Type
Description
AGND/DGND
Ground
Analog and Digital ground.
A(TIP)
Output
Output of A(TIP) power amplifier.
BGND
Ground
Battery (power) ground.
B(RING)
Output
Output of B(RING) power amplifier.
C2C1
Inputs
Decoder. TTL compatible. C2 is MSB and C1 is LSB.
CAS
Capacitor
Anti-Saturation pin for capacitor to filter reference voltage when operating in anti-
saturation region.
D3D1
Input
Relay Driver Control. D3D1 control the relay drivers RYOUT1, RYOUT2, and RYOUT3.
Logic Low on D1 activates the RYOUT1 relay driver. Logic Low on D2 activates the
RYOUT2 relay driver. Logic Low on D3 activates the RYOUT3 relay driver. TTL
compatible.
DA
Input
Ring-trip negative. Negative input to ring-trip comparator.
DB
Input
Ring-trip positive. Positive input to ring-trip comparator.
DET
Output
Switchhook detector. Logic Low indicates that selected detector is tripped. Logic inputs
C2C1, E1, and E0 select the detector. Open-collector with a built-in 15 k
pull-up
resistor.
HPA
Capacitor
High-Pass Filter Capacitor. A(TIP) side of high-pass filter capacitor.
HPB
Capacitor
High-Pass Filter Capacitor. B(RING) side of high-pass filter capacitor.
NC
--
No Connect. Pin not internally connected.
RD
Resistor
Detect resistor. Detector threshold set and filter pin.
RDC
Resistor
DC feed resistor. Connection point for the DC feed current programming network. The
other end of the network connects to the receiver summing node (RSN).
RINGOUT
Output
Ring Relay Driver. Open-collector driver with emitter internally connected to BGND.
RSN
Input
Receive Summing Node. The metallic current (both AC and DC) between A(TIP) and
B(RING) is equal to 500 times the current into this pin. The networks that program
receive gain, two-wire impedance, and feed resistance all connect to this node.
RYOUT1
Output
Relay/Switch Driver. Open-collector driver with emitter internally connected to BGND.
RYOUT2
Output
Relay/Switch Driver. Open-collector driver with emitter internally connected to BGND
(PLCC only).
RYOUT3
Output
Relay/Switch Driver. Open-collector driver with emitter internally connected to BGND
(PLCC only).
TMG
--
Thermal Management. External resistor connects between this pin and VBAT to offload
power from SLIC.
VBAT
Battery
Battery supply and connection to substrate.
VBREF
--
This is an Legerity reserved pin and must always be connected to the VBAT pin.
VCC
Power
+5 V power supply.
VTX
Output
Transmit Audio. This output is a 0.50 gain version of the A(TIP) and B(RING) metallic
voltage. VTX also sources the two-wire input impedance programming network.
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