L9216B/H
Preliminary Data Sheet
September 2001
High-Voltage Ringing SLIC with Ground Start
The device offers a ground start mode. In this mode,
the tip drive amplifier is turned off. The device presents
a high impedance (>100 kΩ) to PT and a current-lim-
ited battery (VBAT1) to PR. VBAT1 is clamped to less than
56.5 V in this mode as PR. A ring current detector for
ring ground detection is included for ground start appli-
cations. The threshold is user programmable via exter-
nal resistors. See the Applications section of this data
sheet for more information on supervision functions.
Output pin RGDET indicates current flowing in the ring
lead.
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
6.0 V, allowing for an undistorted signal of 3.14 dBm
into 900 W. This overhead is fixed. The ring trip detec-
tor is turned off during active modes to conserve power.
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 47 mA for a –85 V VBAT1.
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
battery 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.
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.
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.
Longitudinal balance is consistent with North American
GR-909 requirements. Specifications are given in Table
12.
Data control is via a parallel unlatched control scheme.
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.
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%.
A forward disconnect mode is provided, where all cir-
cuits are turned off and power is denied to the loop.
Circuitry is added to the L9216 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 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 (ac-cou-
pled) is 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.
Overhead in the active modes (VBAT2 applied) is fixed
to approximately 6.0 V is achieved. This is adequate
for a 3.14 dBm overload into 900 Ω.
Transmit and receive gains have been chosen to mini-
mize the number of external components required in
the SLIC-codec ac interface, regardless of the choice
of codec.
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.
Agere Systems Inc.
5
ZARLINK [ ZARLINK SEMICONDUCTOR INC ]
