P R E L I M I N A R Y
14
Le79R251 ISLIC Data Sheet
4.
When the Le79R251 device and ISLAC device is in the anti-sat operating region, this parameter is degraded. The exact degradation
depends on system design.
5.
–55 dBm gain tracking level not tested in production. This parameter is guaranteed by characterization and correlation to other tests.
6.
This spec is valid from 0 V to VBL or –50 V, whichever is lower in magnitude.
7.
Other ringing-voltage characteristics are set by the ISLAC device.
OPERATING MODES
The Le79R251 device receives multiplexed control data on the P1, P2 and P3 pins. The LD pin controls the loading of P1, P2,
and P3 values into the proper bits in the Le79R251 device control register. The device control register is a register in within the
Le79R251 that latches the multiplexed relay and state data. This is organized as two sets of three bits: RD1-RD3 for the relay
data and C1-C3 for the state control. When the LD pin is less than 0.6 V, P1–P3 will contain data for relay control bits RD1, RD2
and RD3. These are latched into the first three bits in the Le79R251 device control register. When the LD pin is more than
CREF - 1, P1–P3 will contain ISLIC control data C1, C2, and C3, which are latched into the last three bits of the Le79R251 device
control register. Setting the voltage on the LD pin to VREF
±
0.3 V locks the contents of the Le79R251 device control register.
The operating mode of the Le79R251 device is determined by the C1, C2, and C3 bits in the control register of the Le79R251
device. The table below defines the Le79R251 device operating modes set by these signals.
Under normal operating conditions, the ISLIC device does not have active relays. The Le79R251 device to ISLAC device
interface is designed to allow continuous real-time control of the relay drivers to avoid incorrect data loads to the relay bit latches
of the Le79R251 devices.
To perform external ringing, the ISLAC device from the Intelligent Access voice family is set to external ringing mode
(RMODE = 1), enables the ring relay, and puts the Le79R251 device in the Standby mode.
Table 1.
Operating Mode Descriptions
Note:
1.
In these modes, the ring lead (B-lead) output has a –50 V internal clamp to battery ground (BGND).
C3
C2
C1
Operating Mode
Battery Voltage
Selection
Operating Mode
Connection
to RMGPi &
RMGLi
Resistors
Notes
0
0
0
Standby
High Battery (BATH)
and BGND
(High ohmic feed): Loop
supervision active, A and B
amplifiers shut down
Open
1
0
0
1
Tip Open
High Battery (BATH)
and BGND
Tip Open: AD at High-
Impedance, Channel A power
amplifier shut down
Open
1
0
1
0
On-Hook
Transmission,
Fixed Longitudinal
Voltage
High Battery (BATH)
and BGND
Fixed longitudinal voltage of
–29 V
A and B
Amplifier
Output
0
1
1
Disconnect
Low Battery selection
at VBL
AD and BD at High-Impedance,
Channel A and B power
amplifiers shut down
1
0
0
Active Boosted
Battery
High Battery (BATH)
and Positive Battery
(BATP)
Active feed, normal or reverse
polarity
1
0
1
Active High Battery
High Battery (BATH)
and BGND
1
1
0
Active Low Battery
Low Battery (BATL)
and BGND
1
1
1
Active Internal
Ringing
High Battery (BATH)
and Positive Battery
(BATP)
Active internal ringing