le79231 Zarlink Semiconductor, le79231 Datasheet - Page 17

• Manufacturer Part Number: le79231
• Description: Intelligent Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

Driver Descriptions
Control bits RD1, RD2, and RD3 do not affect the operating mode of the Le79231 ISLIC device. These signals usually perform
the following functions.
Thermal-Management Equations
Applies to all modes except Standby, which has no thermal management..
TIMING SPECIFICATIONS
Note:
1.
2.
3.
The P1
After a power-on reset or hardware reset, the relay outputs from the Le79231 ISLIC device turn all relays off. An unassuming state is to
place the relay control pins, which are level triggered, to a reset state for all relays. Any noise encountered only raises the levels toward the
register lock state.
When writing to the Le79231 ISLIC device registers, the sequence is:
a) Set LD pin to mid-state
b) Place appropriate data on the P1
c) Assert the LD pin to High or Low to write the proper data
d) Return LD pin to mid-state
I
P
PT
I
RMGPi = RMGLi = R
PT
R
P
PT
trSLD
tfSLD
tSLDPW
tSDXSU
tSDXHD
tSDXD
L
L
–
SLIC
SLIC
TMG
< 5 mA
> 5 mA
3 pins are updated continuously during operation by the LD signal.
RTMG
RTMG
RTMG
Symbol
= (S
= (S
= I
Driver
R1
R2
R3
: total power dissipation of RMGPi and RMGLi
= 0
L
= (I
(S
BAT
BAT
BAT
L
– 5 mA)
– I
– I
– I
L
L
(R
(R
L
(R
LD
LD
LD
P1,P2,P3
P1,P2,P3
P1,P2,P3
L
L
TMG
2
+ 2R
L
A logic 1 on RD1 turns the R1 driver on and operates a relay connected between the R1 pin and VCCD. R1
drives the ring relay when external ringing is selected.
A logic 1 on the RD2 signal turns the R2 driver on and routes current from the R2 pin to the RYE pin. In the
option where the RYE pin is connected to ground, the R2 pin can sink current from a relay connected to
VCCD.
Another option is to connect the RYE pin to the BD (Ring) lead and connect a test load between R2 and the
AD (Tip) lead. This technique avoids the use of a relay to connect a test load. However, it does not isolate the
subscriber line from the line card. The test load must be connected to the Le79231 ISLIC device side of the
protection resistor to avoid damage to the R2 driver.
A logic 1 on the RD3 signal turns the R3 driver on and routes current from the R3 pin to the RYE pin. In the
option where the RYE pin is connected to ground, the R3 pin can sink current from a relay connected to
VCCD.
Another option is to connect the RYE pin to the B (Ring) lead and connect a test load between R3 and the A
(Tip) lead. This technique avoids the use of a relay to connect a test load. However, it does not isolate the
subscriber line from the line card. The test load must be connected to the Le79231 ISLIC device side of the
protection resistor to avoid damage to the R3 driver.
+ 2R
(2R
+ 2R
Signal
TMG
FUSE
FUSE
FUSE
Equation
)
–
)) • I
)) / (2(I
3 pins
)) + 0.3 W – PT
L
+ 0.3 W
L
Rise time Le79231 ISLIC device LD
pin
Fall time Le79231 ISLIC device LD pin
LD minimum pulse width
P1–3 data Setup time
P1–3 data hold time
Max P1–3 data delay
– 5 mA))
Zarlink Semiconductor Inc.
RTMG
Parameter
17
Description
TMG resistor-current is limited to be 5 mA < I
no current flows in the TMG resistor and it all flows in the
Le79231 ISLIC device.
These equations are valid when
R
because the longitudinal voltage is one-half the battery
voltage and the TMG switches require approximately 2 V.
To choose a power rating for R
P
RATING
TMG
• (I
> PT
L
– 5 mA) < (S
Min
4.5
4.5
3
RTMG
/ 2
Description
BAT
Typ
– (R
TMG
L
+ R
:
F
)I
Max
L
2
2
5
) / 2 – 2
L
. If I
L
< 5 mA,
Unit
µs