LUCL9500AGF-DT datasheet(5/32 Pages) AGERE

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Preliminary Data Sheet

September 2001

High-Voltage Ringing SLIC for VoIP Applications

L9500A

Agere Systems Inc.

Description (continued)

Forward and reverse battery active modes are used for

off-hook conditions. Since this device is designed for

short-loop applications, the lower-voltage VBAT2 is

applied during the forward and reverse active states.

Battery reversal is quiet, without breaking the ac path.

Rate of battery reversal may be ramped to control

switching time.

The magnitude of the overhead voltage in the forward

and reverse active modes has a typical default value of

7.0 V, allowing for an on-hook transmission of an undis-

torted signal of 3.14 dBm into 900

Ω. Additionally, this

allows sufficient overhead for 500 mV of meter pulse if

desired. This overhead is fixed. The ring trip detector is

turned off during active modes to conserve power.

Because on-hook transmission is not allowed in the

scan mode, an on-hook transmission mode is defined.

This mode is functionally similar to the active mode,

except the tip ring voltage is derived from the higher

VBAT1 rather than VBAT2.

In the on-hook transmission modes with a primary bat-

tery whose magnitude is greater than a nominal

51 V, the magnitude of the tip-to-ground and ring-to-

ground voltage is clamped at less than 56.5 V.

To minimize on-hook power, a low-power scan mode is

available. In this mode, all functions except off-hook

supervision are turned off to conserve power. On-hook

transmission is not allowed in the scan mode.

In the scan mode with a primary battery whose magni-

tude is greater than a nominal 51 V, the magnitude of

the tip-to-ground and ring-to-ground voltage is clamped

at less than 56.5 V.

A forward disconnect mode is provided, where all cir-

cuits are turned off and power is denied to the loop.

The device offers a ring mode, in which a power ring

signal is provided to the tip/ring pair. During the ring

mode, a user-supplied, low-voltage ring signal is differ-

entially input to the device’s RINGIN input. This signal is

amplified to produce the power ring signal. This signal

may be a sine wave or filtered square wave to produce

a sine wave on trapezoidal output. Ring trip detector

and common-mode current detector are active during

the ring mode.

With maximum VBAT1 and a sine wave input, the L9500

has sufficient power to ring a 5 REN (1386

Ω + 40 µF)

ringing load into 500

Ω of physical resistance.

This feature eliminates the need for a separate external

ring relay, associated external circuitry, and a bulk ring-

ing generator. See the Applications section of this data

sheet for more information.

Both the ring trip and loop closure supervision func-

tions are included. The loop closure has a fixed typical

10.5 mA on- to off-hook threshold in the active mode

and a fixed 11.5 mA on- to off-hook threshold from the

scan mode. In either case, there is a 2 mA hysteresis.

The ring trip detector requires only a single-pole filter at

the input, minimizing external components. The ring

trip threshold at a given battery voltage is fixed. Typical

ring trip threshold is 42.5 mA for a –70 V VBAT1.

The device offers a ground start mode. In this mode the

tip drive amplifier is turned off. The device presents a

high impedance (>100 k

Ω) to PT and a current limited

battery (VBAT1) to PR. VBAT1 is clamped to less than

56.5 V in this mode at PR. The NSTAT loop current

detctor is used for ring ground detection. In the ground

start mode, since the loop current is common mode,

the loop closure threshold is reduced in half, thus main-

taining loop supervision at specified levels.

Upon reaching the thermal shutdown temperature, the

device will enter an all off mode. Upon cooling, the

device will re-enter the state it was in prior to thermal

shutdown. Hysteresis is built in to prevent oscillation.

Data control is via a parallel unlatched control scheme.

The dc current limit is fixed to either 25 mA or 40 mA

depending if ground or open is applied to the VPROG

current limit programming pin. Programming accuracy

is ±8%.

Circuitry is added to the L9500 to minimize the inrush

of current from the VCC supply and to the battery supply

during an on- to off-hook transition, thus saving in

power supply design cost. See the Applications section

of this data sheet for more information.

The L9500 uses a voltage feed-current sense architec-

ture; thus the transmit gain is a transconductance. The

L9500 transconductance is set via a single external

resistor, and this device is designed for optimal perfor-

mance with a transconductance set at 300 V/A. This

interface is single ended. The L9500 offers a differen-

tial receive interface with a gain of 8.

The L9500 is internally referenced to 1.5 V. This refer-

ence voltage is output at the VREF output of the device.

The SLIC output VITR is also referenced to 1.5 V. The

SLIC inputs RCVP/RCVN are floating inputs.

The L9500 is packaged in a 28-pin PLCC or a 48-pin

MLCC package.

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