IDT821611J IDT, Integrated Device Technology Inc, IDT821611J Datasheet - Page 9

• Manufacturer Part Number: IDT821611J
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT821611J

• Number Of Channels: 1
• On-hook Transmission: Yes
• Polarity Reversal: Yes
• On-chip Ring Relay Driver: Yes
• Operating Supply Voltage (typ): 3.3/5V
• Operating Temp Range: -40C to 85C
• Package Type: PLCC
• Operating Temperature Classification: Industrial
• Pin Count: 32
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Not Compliant

FUNCTIONAL DESCRIPTION
functions. It provides many user programmable features including 2-wire
impedance matching, loop-detect threshold and ring-trip threshold
setting, constant current feeding, 4-wire to 2-wire gain setting, etc. The
following sections describe these functions in detail.
SLIC STATES CONTROL
Standby or Reverse Active state. A combination of the control pins C3,
C2 and C1 select one of the possible five operating states. See
for details. The IDT821611 provides an off-hook detector and a ring-trip
detector on chip to support the necessary signaling functions. The
selection of the detectors is based on the SLIC operating state. The
output of the detectors is reported by the DET pin. Once a hook switch
event or ring-trip event occurs, the DET pin goes low.
Table 2 — SLIC Operating States
outputs are in high impedance condition. In this state, the off-hook
detector is inoperative and the power dissipation reduces to the lowest.
The Disconnect state is useful for out-of-service lines.
activated and the TIP and RING outputs are in high impedance
condition. The ringing source is connected by an external ring relay to
the line. In Ringing state, the status of the ring-trip detector is reported
by the DET pin.
convention applies. All signal transmission and loop supervision
functions are active. The status of the off-hook detector is gated to the
DET pin.
resulting in low power dissipation. The off-hook detection function
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IDT821611
Functional Description
State
The IDT821611 implements the basic telephone line interface
The IDT821611 can be operated in Disconnect, Ringing, Active,
When the SLIC is in Disconnect state, both the TIP and RING
When the SLIC is in Ringing state, the ring relay driver (RINGOUT) is
In Active state, the SLIC is fully functional. The standard battery
In Standby state, most of the internal circuitry is powered down,
Disconnect
Ringing
Active
Standby
0
1
2
3
4
5
C3
1
1
1
1
0
0
0
0
Control Pins
C2
0
0
1
1
1
0
0
1
C1
0
1
0
1
0
0
1
1
Disconnect
Two-Wire
Reserved
Standby
Reverse
Ringing
Status
Active
Active
Off-hook Detector
Off-hook Detector
Off-hook Detector
Ring-trip Detector
Ring-trip Detector
Ring-trip Detector
DET Output
Table 2
7
operates normally, but signal transmission is not enabled. This state
allows for monitoring off-hook transitions while maintaining lowest
possible power consumption.
Active state, except that the normal battery feed convention is reversed.
During Reverse Active state, the status of the off-hook detector is
reported by the DET pin.
OFF-HOOK DETECTOR
Active, Reverse Active or Standby state. The output of the DET pin goes
low when an off-hook event is detected.
which is connected between the RD and AGND pins.See
details.
following equations:
determines the on-hook to off-hook time constant. The value of C
typical on-hook to off-hook time constant of 0.5 ms is calculated by:
RING-TRIP DETECTOR
Ringing state, the on-chip ring relay driver (RINGOUT) is activated and
the ringing source is connected by the ring relay to the Tip and Ring
lines through the resistors R
DET pin. When the loop goes off-hook, the bridging resistors R
R
DB to go positive with respect to DA and the DET pin goes low.
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3
B(RING)
The Reverse Active state provides the same functionality as the
The off-hook detector monitors the hook switch of the loop during
The loop-detect threshold is programmed by an external resistor R
The loop current threshold I
The R-C network, formed by the capacitor C
Figure 2
The ring-trip detector monitors the loop status and reports it via the
and R
A(TIP)
Reverse Active
C
I
D
ON
4
, and the filter capacitors C
=
shows a general ringing circuit for the IDT821611. During
=
Two-wire
Interface
0.5ms
---------------- -
Figure 1 Loop-Detect Threshold Setting
R
510
--------- -
R
SLIC
D
D
Off-hook
Detector
1
and R
Interface
ON
Digital
2
.
RT1
and I
I
and C
OFF
OFF
=
RT2
C1
C2
C3
DET
AGND
RD
are calculated by the
415
--------- -
R
LONG HAUL SLIC
D
D
cause the voltage on
and the resistor R
October 8, 2003
R
D
Figure 1
B1
C
D
D
, R
for a
B2
for
D,
D,
,