HC5513 Intersil Corporation, HC5513 Datasheet - Page 13

• Manufacturer Part Number: HC5513
• Description: TR909 DLC/FLC SLIC with Low Power Standby
• Manufacturer: Intersil Corporation

The function of this circuit is to maintain the tip and ring
voltages symmetrically around V
longitudinal currents. The differential transconductance
amplifiers G
the required current to maintain V
When a longitudinal current is injected onto the tip and ring
inputs, the voltage at V
V
appears between the input terminals of the differential
transconductance amplifiers G
and G
turn feed the differential inputs of current sources I
respectively. I
ended and 500 differentially, thus leading to a change in I
and I
The circuit shown in Figure 20(B) illustrates the tip side of
the longitudinal network. The advantages of a differential
input current source are: improved noise since the noise due
to current source 2I
to differential current gain and minimized offset error at the
Operational Amplifier inputs via the two 5k resistors.
Digital Logic Inputs
Table 1 is the logic truth table for the TTL compatible logic
input pins. The HC5513 has two enable inputs pins (E0, E1)
and two control inputs pins (C1, C2).
The enable pin E0 is used to enable or disable the DET
output pin. The DET pin is enabled if E0 is at a logic level 0
and disabled if E0 is at a logic level 1.
The enable pin E1 gates the ground key detector to the DET
output with a logic level 0, and gates the loop or ring trip
detector to the DET output with a logic level 1.
A combination of the control pins C1 and C2 is used to
select 1 of the 4 possible operating states. A description of
each operating state and the control logic follow:
BAT
R
/2. When V
R
that is equal to 500(
are the differential currents I
T
T
and G
I
LONG
and I
C
changes by the amount V
O
R
R
is now correlated, power savings due
accomplish this by sourcing or sinking
I
have current gains of 250 single
C
LONG
moves from it’s equilibrium value
I
I
LONG
LONG
I
FIGURE 20A.
66
) and 500( I
T
V
V
R
T
+
and G
-
BAT
+
-
C
at V
TIP
RING
/2, in the presence of
R
R
HC5513
LARGE
LARGE
1
R
V
and I
FIGURE 20. LONGITUDINAL IMPEDANCE NETWORK
BAT
C
. The output of G
2
+
-
).
/2.
C
2
, this change
, which in
I
I
1
2
T
and I
I
I
R
T
T
T
R
G
G
I
I
1
2
V
T
R
HC5513
BAT
/2
Open Circuit State (C1 = 0, C2 = 0)
In this state the SLIC is effectively off. All detectors and both
the tip and ring line drive amplifiers are powered down,
presenting a high impedance to the line. Power dissipation is
at a minimum.
Active State (C1 = 0, C2 = 1)
The tip output is capable of sourcing loop current and for
open circuit conditions is about -4V from ground. The ring
output is capable of sinking loop current and for open circuit
conditions is about V
normal. The loop current and ground key detectors are both
active, E0 and E1 determine which detector is gated to the
DET output.
Ringing State (C1 = 1, C2 = 0)
The ring relay driver and the ring trip detector are activated.
Both the tip and ring line drive amplifiers are powered down.
Both tip and ring are disconnected from the line via the
external ring relay.
Standby State (C1 = 1, C2 = 1)
Both the tip and ring line drive amplifiers are powered down.
Internal resistors are connected between tip to ground and ring
to V
The loop current and ground key detectors are both active, E0
and E1 determine which detector is gated to the DET output.
AC Transmission Circuit Stability
To ensure stability of the AC transmission feedback loop two
compensation capacitors C
Figure 21 (Application Circuit) illustrates their use.
Recommended value is 2200pF.
BAT
to allow loop current detect in an off-hook condition.
RING
TIP
V
R
R
C
LARGE
LARGE
BAT
+ 4V. VF signal transmission is
TC
TRANSCONDUCTANCE
FIGURE 20B.
WITH DIFFERENTIAL INPUTS
TIP DIFFERENTIAL
and C
TIP CURRENT SOURCE
5k
AMPLIFIER
I
1
20
RC
5k
2I
are required.
0
I
1
V
+
BAT
-
G
T
/2