Am79R79*/Le79R79
Ringing Subscriber Line Interface Circuit
DISTINCTIVE CHARACTERISTICS
I
Ideal for short-loop applications
I
Ideal for ISDN terminal adaptor and fixed radio
access applications
I
On-chip ringing with on-chip ring-trip detector
I
Low standby state power
I
Battery operation:
— V
BAT1
: –40.5 V to –75 V
— V
BAT2
: –19 V to V
BAT1
I
On-chip battery switching and feed selection
I
On-hook transmission
I
Two-wire impedance set by single external
impedance
I
Programmable constant-current feed
I
Programmable Open Circuit voltage
I
Programmable loop-detect threshold
I
Current gain = 1000
I
Ground-key detector
I
Tip Open state for ground-start lines
I
Polarity reversal option available
I
Internal V
EE
regulator (no external –5 V power
supply required)
I
Two on-chip relay drivers and snubber circuits
I
Space Saving Package Options (8x8 QFN)
BLOCK DIAGRAM
Relay
Driver
RTRIP1
RTRIP2
Relay
Driver
RYOUT2
RYE
RYOUT1
D1
D2
C1
C2
C3
E1
DET
RD
VTX
RSN
RINGIN
RDC
RDCR
A(TIP)
Ring-Trip
Detector
HPA
Two-Wire
Interface
HPB
Signal
Transmission
B(RING)
Power-Feed
Controller
Ground-Key
Detector
Off-Hook
Detector
Input Decoder
and Control
VBAT2
Switch
Driver
VBAT1
RSGL
RSGH
B2EN
VCC VNEG BGND AGND/DGND
*This product can be ordered using ordering part numbers Am79R79 or Le79R79. The Am79R79 ordering part number will be
discontinued after 6/30/02, at which time the product will only be available using the Le79R79 ordering part number.
Document ID#
080152
Date:
Rev:
I
Version:
Distribution:
Public Document
Mar 25, 2002
1
GENERAL DESCRIPTION
The Legerity family of subscriber line interface circuit
(SLIC) products provide the telephone interface func-
tions required throughout the worldwide market. Leger-
ity SLIC devices address all major telephony markets
including central office (CO), private branch exchange
(PBX), digital loop carrier (DLC), fiber-in-the-loop
(FITL), radio-in-the-loop (RITL), hybrid fiber coax
(HFC), and video telephony applications.
The Legerity SLIC devices offer support of BORSHT
(battery feed, overvoltage protection, ringing, supervi-
sion, hybrid, and test) functions with features including
current limiting, on-hook transmission, polarity reversal,
Tip Open, and loop-current detection. These features
allow reduction of linecard cost by minimizing compo-
nent count, conserving board space, and supporting
automated manufacturing.
The Legerity SLIC devices provide the two- to four-wire
hybrid function, DC-loop feed, and two-wire supervision.
Two-wire termination is programmed by a scaled imped-
ance network. Transhybrid balance can be achieved with
an external balance circuit or simply programmed using
a companion Legerity codec device, the Am79C02/03/
031 DSLAC™ device, the Am79Q02/021/03 Program-
mable Quad SLAC (QSLAC™) device, or the
Am79Q5457/4457 Nonprogrammable QSLAC device.
The Le79R79 Ringing SLIC device is a bipolar mono-
lithic SLIC that offers on-chip ringing. Now designers
can achieve significant cost reductions at the system
level for short-loop applications by integrating the ring-
ing function on chip. Examples of such applications
would be ISDN terminal adaptors, fiber-in-the-loop, ra-
dio-in-the-loop, hybrid fiber/coax and video telephony
(home-side) boxes. The Le79R79 Ringing SLIC can
provide sufficient voltage to meet the stringent LSSGR
five-ringer equivalent specification. Using a CMOS-
compatible input waveform and wave shaping R-C net-
work, the Le79R79 Ringing SLIC can provide trapezoi-
dal wave ringing to meet various design requirements.
In order to further enhance the suitability of this device
in short-loop, distributed switching applications, Leger-
ity has maximized power savings by incorporating bat-
tery switching on chip. The Le79R79 Ringing SLIC
device switches between two battery supplies such that
in the off-hook (active) state, a low battery is used to
save power. In order to meet the Open Circuit voltage
requirements of fax machines and maintenance termi-
nation units (MTU), the SLIC automatically switches to
a higher voltage in the on-hook (standby) state.
Like all of the Legerity SLIC devices, the Le79R79 Ring-
ing SLIC device supports on-hook transmission, ring-
trip detection, programmable loop-detect threshold, and
is available with on-chip polarity reversal. The Le79R79
Ringing SLIC device is a programmable constant-cur-
rent feed device with two on-chip relay drivers to operate
external relays. Several performance grades are avail-
able to meet both CCITT and LSSGR requirements,
including various longitudinal balance options. This
unique device is available in the proven Legerity 75 V
bipolar process.
2
Am/
Le
79R79 Data Sheet
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
Am79R79*
J
C
TEMPERATURE RANGE
C = Commercial (0°C to 70°C)
PACKAGE TYPE
J = 32-pin Plastic Leaded Chip Carrier
PERFORMANCE GRADE OPTION
–1 = 52 dB Longitudinal Balance, Polarity Reversal
–2 = 63 dB Longitudinal Balance, Polarity Reversal
–3 = 52 dB Longitudinal Balance, No Polarity Reversal
–4 = 63 dB Longitudinal Balance, No Polarity Reversal
WAFER FOUNDRY FACILITY
A = Optional character designating wafer foundry facility
DEVICE NUMBER/DESCRIPTION
Am79R79
Ringing Subscriber Line Interface Circuit
Le79R79
C
TEMPERATURE RANGE
C = Commercial (0°C to 70°C)
PACKAGE TYPE
J = 32-pin Plastic Leaded Chip Carrier
Q = 32-pin Quad Flat No Lead
PERFORMANCE GRADE OPTION
–1 = 52 dB Longitudinal Balance, Polarity Reversal
–2 = 63 dB Longitudinal Balance, Polarity Reversal
–3 = 52 dB Longitudinal Balance, No Polarity Reversal
–4 = 63 dB Longitudinal Balance, No Polarity Reversal
DEVICE NUMBER/DESCRIPTION
Le79R79
Ringing Subscriber Line Interface Circuit
Valid Combinations
–1
–2
–3
–4
Valid Combinations
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 military–grade
products.
Am79R79
Am79R79A
JC
Valid Combinations
–1
–2
–3
–4
Le79R79
JC
QC**
*This product can be ordered using ordering part numbers Am79R79 or Le79R79. The Am79R79 ordering part number will be
discontinued after 6/30/02, at which time the product will only be available using the Le79R79 ordering part number.
**Due to size constraints, QFN devices are marked by omitting the “Le” prefix and the performance grade dash character. For
example, Le79R79-2QC is marked 79R792QC.
Am/
Le
79R79 Data Sheet
3
CONNECTION DIAGRAMS
Top View
RYOUT2
B(RING)
32
VBAT2
BGND
A(TIP)
31
VCC
4
3
2
1
RYE
RYOUT1
B2EN
VBAT1
D1
E1
C3
C2
DET
RD
30
29
28
27
26
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
RTRIP1
RTRIP2
HPB
HPA
RINGIN
RDCR
VTX
VNEG
RSN
32-pin PLCC
25
24
23
22
21
C1
D2
NC
RSGH
RSGL
B(RING)
RDC
RYOUT2
AGND/DGND
26
BGND
VCC
A(TIP)
RYE
RYOUT1
B2EN
VBAT1
D1
E1
C3
C2
32
1
2
3
4
31
30
29
28
27
RTRIP1
25
24
23
22
21
VBAT2
RD
RTRIP2
HPB
HPA
RINGIN
RDCR
VTX
VNEG
RSN
32-pin QFN
5
6
7
8
9
10
11
Exposed Pad
20
19
18
17
16
12
13
14
15
DET
C1
D2
N/C
RDC
Notes:
1. Pin 1 is marked for orientation.
2. NC = No connect
3. The thermally enhanced QFN package features an exposed pad on the underside which must be electrically tied to VBAT1.
4
Am/
Le
79R79 Data Sheet
AGND/
DGND
RSGH
RSGL
PIN DESCRIPTIONS
Pin Names
AGND/DGND
A(TIP)
B2EN
BGND
B(RING)
C3–C1
D1
D2
DET
E1
HPA
HPB
RD
RDC
Type
Gnd
Output
Input
Gnd
Output
Input
Input
Input
Output
Input
Capacitor
Capacitor
Resistor
Resistor
Analog and Digital ground
Output of A(TIP) power amplifier
V
BAT2
Enable. Logic Low enables operation from V
BAT2
. Logic High enables operation from
V
BAT1
. TTL compatible.
Battery (power) ground
Output of B(RING) power amplifier
Decoder. TTL compatible. C3 is MSB and C1 is LSB.
Relay1 Control. TTL compatible. Logic Low activates the Relay1 relay driver.
(Option) Relay2 Control. TTL compatible. Logic Low activates the Relay2 relay driver.
Switchhook Detector. Logic Low indicates that the selected detector is tripped. Logic inputs
C3–C1 and E1 select the detector. Open-collector with a built-in 15 kΩ pull-up resistor.
(Option) Ground-Key Enable. A logic High selects the off-hook detector. A logic Low selects
the ground-key detector. TTL compatible.
High-pass filter capacitor. A(TIP) side of high-pass filter capacitor.
High-pass filter capacitor. B(RING) side of high-pass filter capacitor.
Detector resistor. Detector threshold set and filter pin.
DC feed resistor. Connection point for the DC feed current programming network, which
also connects to the receiver summing node (RSN). V
RDC
is negative for normal polarity
and positive for reverse polarity.
Connection point for feedback during ringing.
Ring Signal Input. Pin for ring signal input. Square-wave shaped by external RC filter.
Requires 50% duty cycle. CMOS-compatible input.
Saturation Guard High. Pin for resistor to adjust Open Circuit voltage when operating from
V
BAT1
.
Saturation Guard Low. Pin for resistor to adjust the anti-saturation cut-in voltage when
operating from both V
BAT1 and
V
BAT2
.
Receive Summing Node. The metallic current (AC and DC) between A(TIP) and B(RING)
is equal to 1000 x the current into this pin. The networks that program receive gain, two-wire
impedance, and feed resistance all connect to this node.
Ring-trip detector. Ring-trip detector threshold set and filter pin.
Ring-trip detector. Ring-trip detector threshold offset (switch to V
BAT1
). For power
conservation in any nonringing state, this switch is open.
Common Emitter of RYOUT1/RYOUT2. Emitter output of RYOUT1 and RYOUT2. Normally
connected to relay ground.
Relay/switch driver. Open-collector driver with emitter internally connected to RYE.
(Option) Relay/switch driver. Open-collector driver emitter internally connected to RYE.
Battery supply and connection to substrate.
Power supply to output amplifiers. Connect to off-hook battery through a diode.
Positive analog power supply.
Negative analog power supply. This pin is the return for the intern VEE regulator.
Transmit Audio. This output is 0.5066 gain version of the A(TIP) and B(RING) metallic
voltage. VTX also sources the two-wire input impedance programming network.
This must be electrically tied to VBAT1.
Description
RDCR
RINGIN
RSGH
RSGL
RSN
—
Input
Input
Input
Input
RTRIP1
RTRIP2
RYE
RYOUT1
RYOUT2
VBAT1
VBAT2
VCC
VNEG
VTX
Exposed Pad
Input
Input
Output
Output
Output
Battery
Battery
Power
Power
Output
Battery
Am/
Le
79R79 Data Sheet
5
