Data Sheet
May 2001
L8576B Dual Ringing SLIC
Operating States (continued)
These states are selected using three logic inputs, B2, RNGNG, and NDISC. B2 sets normal operation, either with
forward or reverse battery. RNGNG overrides B2 and applies ringing with the polarity of tip and ring reversed on
edges of the B2 signal. The slope of the waveform is determined by a resistor from RRNG to AGND. Logic input
NDISC puts the device into a loop current denial state (disconnect). Tip and ring amplifiers are saturated against
ground with about a 100 µA current source. This creates a level in the loop current sensing circuitry that
approaches a loop closed state. Some conditions on the tip and ring could cause the circuit to indicate loop closed
even though the loop is open. This situation can be prevented by connecting a 300 kΩ resistor from VBAT to each of
the outputs of the tip and ring amplifiers (see Figure 2). This will pull the amplifier output to about 30 V above VBAT,
keeping the NSTAT output at a steady high (on-hook indication) level. If the disconnect state is not used or the
NSTAT output during the disconnect state is not recognized or used, then the resistors are not needed.
Table 2 below summarizes the operating input state coding.
Table 2. Input State Coding
NDISC RNGNG B2
State
1
1
1
0
0
1
1
0
Forward Battery, Normal Talk, and Feed State. Pin PT is positive with respect to PR.
Reverse Battery, Normal Talk, and Feed State. Pin PT is negative with respect to PR.
1 ↑ Ringing Is Applied to PT and PR. On the transition, PT starts towards a positive volt-
age (with respect to PR). The endpoint of this state is PT at BGND and PR at VBAT.
1
0
1
0 ↓ Ringing Is Applied to PT and PR. On the transition, PT starts towards a negative volt-
age (with respect to PR). The endpoint of this state is PT at VBAT and PR at BGND.
0/1
0/1 Disconnect State. The tip and ring amplifiers are turned off, and the SLIC goes into a
high-impedance state (>100 kΩ).
Absolute Maximum Ratings (at TA = 25 °C)
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are abso-
lute stress ratings only. Functional operation of the device is not implied at these or any other conditions in excess
of those given in the operational sections of the data sheet. Exposure to absolute maximum ratings for extended
periods can adversely affect device reliability.
Parameter
Symbol
Min
Typ
Max
Unit
5 V dc Supplies
VCC
VBAT
—
–0.5
–75
—
—
7.0
V
V
Office Battery Supply
0.5
Logic Input Voltage
–0.5
—
—
VCC + 0.5
V
Logic Input Clamp Diode Current, per Pin
Logic Output Voltage
—
±20
—
—
mA
V
—
–0.5
—
VCC + 0.5
Logic Output Current, per Pin
Analog Input Voltage
—
±35
—
—
7.0
—
mA
V
—
–7.0
—
Maximum Junction Temperature
Storage Temperature Range
Relative Humidity Range (noncondensing)
Ground Potential Difference (BGND to AGND)
PT or PR Fault Voltage (dc)
—
165
—
°C
°C
%
V
Tstg
—
–40
125
95
—
5
—
—
—
±3
—
—
VBAT – 5
VBAT – 15
3
V
PT or PR Fault Voltage (10 µs x 1000 µs)
—
—
15
V
Note: The IC can be damaged unless all ground connections are applied before, and removed after, all other connections. Furthermore, when
powering the device, the user must guarantee that no external potential creates a voltage on any pin of the device that exceeds its rat-
ings. For example, inductance in a supply lead could resonate with the supply filter capacitor to cause a destructive overvoltage.
Agere Systems Inc.
9
AGERE [ AGERE SYSTEMS ]
