IDT821621J IDT, Integrated Device Technology Inc, IDT821621J Datasheet - Page 10

• Manufacturer Part Number: IDT821621J
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT821621J

• Number Of Channels: 1
• On-hook Transmission: Yes
• Polarity Reversal: No
• 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

RELAY DRIVERS CONTROL
control the external ring relay. This ring relay driver is active only in
Ringing state. It is an internal transistor with the emitter internally
connected to BGND and the collector as the driver output (see
During ringing, the ring relay driver is activated and the ringing source is
connected by an external ring relay to the Tip and Ring lines through
ring feed resistors.
(RYOUT1, RYOUT2 and RYOUT3) on the chip. All of them are open-
collector drivers with emitters internally connected to BGND. They allow
for direct operation of external test relays. The digital pins D1 to D3 are
used to control the relay drivers RYOUT1, RYOUT2 and RYOUT3
respectively. Logic low on D1 to D3 activates their respective relay
drivers.
IDT821621
Functional Description
Ringing
Source
The IDT821621 provides an on-chip ring relay driver (RINGOUT) to
The IDT821621 also provides three additional relay drivers
Tip Line
Ring Line
BGND
+
-
R
2
Figure 3 Relay Drivers Schematic
K
R
R
1
Figure 2 Ring-trip Detection
Ring Relay
K
K
R
R
RINGOUT
R
R
R
R
R
R
B1
B2
3
4
F
F
BGND
C
C
RT2
RT1
RINGOUT
DA
DB
A(TIP)
B(RING)
SLIC
RYOUT1
RYOUT2
RYOUT3
Figure
3).
8
DC FEEDING
Figure
and a capacitor C
See
noise that may originate from the battery source and prevent the output
amplifiers from saturating. The value of this anti-saturation capacitor is
The IDT821621 provides constant-current feeding as shown in
Notes:
1.
2.
3.
The feed current is programmable. Two resistors R
The feed current I
An external capacitor C
(volts)
Figure 5.
VAB
R
L
4.
V
V
I
V
a
b
60
FEED
AB
AB
AB
0
=
=
=
=
0.857 V
I
0.857 V
Figure 5 DC Feed Programming Circuit
I
L
L
Figure 4 DC Feeding Characteristics
R
------------------------------------
R
Note 3
DC
L
DC1
′
=
(
(
Feed current is programmed by R
1250
form the network for programming the feed current.
FEED
+
------------------------------------R
R
BAT
BAT
A(TIP)
B(RING)
DC1
R
DC2
1250
is calculated by the following equation:
CAS
+
+
+
SLIC
1.2
3.3
R
connected to the CAS pin is used to filter
DC2
) I
) I
–
–
RDC
RSN
I
L
L
L
L
(mA)
R
------------------------------------
′
R
------------------------------------
,
where
DC1
DC1
Note 2
300
300
+
+
R
R
R
DC2
DC2
L
DC1
′
LONG HAUL SLIC
=
and R
R
R
October 8, 2003
R
DC1
DC2
L
DC2.
+
2R
DC1
Note 1
F
and R
C
30
DC
DC2
,