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L8576B

Dual Ringing SLIC

Agere -> LSI Corporation 

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 k Ω 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

0

1 Forward Battery, Normal Talk, and Feed State. Pin PT is positive with respect to PR.

1

0

0 Reverse Battery, Normal Talk, and Feed State. Pin PT is negative with respect to PR.

1

1 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

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

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

–0.5

—

7.0

V

Office Battery Supply

VBAT

–75

—

0.5

V

Logic Input Voltage

—

–0.5

—

VCC + 0.5

V

Logic Input Clamp Diode Current, per Pin

—

—

±20

—

mA

Logic Output Voltage

—

–0.5

—

VCC + 0.5

V

Logic Output Current, per Pin

—

—

±35

—

mA

Analog Input Voltage

—

–7.0

—

7.0

V

Maximum Junction Temperature

—

—

165

—

°C

Storage Temperature Range

Tstg

–40

—

125

°C

Relative Humidity Range (noncondensing)

—

5

—

95

%

Ground Potential Difference (BGND to AGND)

—

—

±3

—

V

PT or PR Fault Voltage (dc)

—

VBAT – 5

—

3

V

PT or PR Fault Voltage (10 µs x 1000 µs)

—

VBAT – 15

—

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.

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