le9531cmqc Zarlink Semiconductor, le9531cmqc Datasheet - Page 25

• Manufacturer Part Number: le9531cmqc
• Description: Ringing Subscriber Line Interface Circuit
• Manufacturer: Zarlink Semiconductor

Applications
DC Loop Current Limit
In the Active Modes the DC current limit is determined by the operation state. The Low DC current limit is 25 mA.
The High DC current limit is 40 mA. Note that there is in the order of 10 k slope to the I/V characteristic in the
current-limit region; thus, once in current limit, the actual loop current will increase slightly, as loop length
decreases.
Upon off-hook in the Active or standby modes there will be a transient response of the current-limit circuit upon an
on- to off-hook transition.
Overhead Voltage
Scan State
If the magnitude of the primary battery is greater than 51 V (but no more than 100 V), the magnitude of the open
loop tip-to-ring open loop voltage is clamped typically between 44 V and 51 V. If the magnitude of the primary
battery is less than a nominal 51 V, the overhead voltage will track the magnitude of the battery voltage, i.e., the
magnitude of the open circuit tip-to-ring voltage will be about 4 V less than battery.
Active
If the magnitude of the primary battery is greater than 51 V (but no more than 100 V), the magnitude of the open
loop tip-to-ring open loop voltage is clamped typically between 41 and 49 V. If the magnitude of the primary battery
is less than a nominal 51 V, the overhead voltage will track the magnitude of the battery voltage, i.e., the magnitude
of the open circuit tip-to-ring voltage will be 6 to 8 V less than battery. Overhead is adequate for an on-hook
transmission of 3.14 dBm into 900  with additional head room for a 500-mV PPM signal under any specified loop
or any specified battery.
Ringing State
In the Ringing state, to maximize ringing loop length, the overhead is decreased to the saturation of the tip ring
drive amplifiers, a nominal 2.4 V.
During the Ringing state the ringing input is coming from RINGP/N path with a gain of 150. During the Ringing
state, to conserve power, the AAC amplifier in the transmit direction at VITR is deactivated. However, the AX
amplifier at VTX is active during the ring state; differential ring current may be sensed at VTX during the ring state.
Table 8 - Typical Active or Standby state On-Hook to Off-Hook Tip/Ring Current-Limit Transient
DC Loop Current:
DC Loop Current:
DC Loop Current:
R
R
R
LOOP
LOOP
LOOP
Transmission States
= 100 , On- to Off-hook Transition time < 5 ms
= 100  On- to Off-hook Transition time < 50 ms
= 100  On- to Off-hook Transition time < 300 ms
Parameter
Zarlink Semiconductor Inc.
Response
Le9531
25
ILIM + 60
ILIM + 20
Value
ILIM
Unit
mA
mA
mA
Data Sheet