L3037FNTR STMicroelectronics, L3037FNTR Datasheet - Page 6

• Manufacturer Part Number: L3037FNTR
• Manufacturer: STMicroelectronics

Specifications of L3037FNTR

• Number Of Channels: 1
• On-hook Transmission: Yes
• Polarity Reversal: Yes
• On-chip Ring Relay Driver: Yes
• Longitudinal Balanced: 70
• Operating Temp Range: -40C to 85C
• Package Type: PLCC
• Operating Temperature Classification: Industrial
• Pin Count: 44
• Mounting: Surface Mount
• Lead Free Status / RoHS Status: Supplier Unconfirmed

L3037
the ext. transistor to a proper value higher than
the real negative battery in order to reduce the
power dissipated by the L3037 itself.
b) Resistive feed region: the characteristic is
equal to a battery voltage (Vbat) in series with a
resistor (typ 400ohm or 800ohm) whose value is
set by one ext. resistor (see ext. components list).
c) Constant voltage region: the characteristic is
equal to the battery voltage - 12V in series with
the ext. protection resistors (typ 80ohm).
This voltage drop between battery and line termi-
nals for Il=0 allows on-hook transmission.
Fig. 1 shows the DC characteristic in active
mode. Fig. 2 shows the line current versus loop
resistance
Figure 1: DC Characteristic in active mode
Figure 2: Current vs. Loop Resistance.
In active mode the AC impedance at the line ter-
minals is sinthetized by the external components
ZAC and Rp according to the following formula:
Depending on the characteristic of the ZAC net-
work Zs can be either a pure resistance or a com-
plex impedance. This allows L3037 to meet diffe-
rent standard as far as return loss is concerned.
The capacitor CCOMP guarantees stability to the
system.
The two to four wire conversion is achieved by
means of a circuit that can be represented as a
Wheastone bridge, the branches of which are:
6/22
Rfeed = 2 x 200ohm,
Lim. currents: 25, 43, 55mA
Zs = ZAC/50 + 2*Rp
When L3037 is used with a second generation
combo (eg TS5070FN) which is able to perform the
two to four wire conversion, the two impedances
ZA and ZB can be removed and the ZB pin con-
nected to GND. The -6dB TX gain of the L3037 al-
lows the echo signal to remain always within the
COMBOII Hybrid balance filter dynamic range.
The injection of high frequency metering pulses is
carried out through the SLIC. An unbalanced 12 or
16KHz sinusoidal signal with shaping is, when ne-
cessary, applied at the TTXIN input of the SLIC.
A fixed transfer gain is provided for the metering si-
gnal. To avoid saturation in the 4-wire side a can-
cellation is provided in the 4-wire transmission path.
Cancellation is obtained via an external RC net-
work without the need for trimmed components.
When the TTX function is not used TTXIN input
should be connected to GND. Since this pin is di-
rectly connected to a summing node inside the
SLIC any signal applied to the TTXIN is transfer-
red to the line with a fixed transfer gain.
In special applications, this pin can be used to
modify the voltage drop (constant voltage region
of DC characteristic) simply by applying a proper
DC level on the TTXIN pin, allowing optimization
of the battery voltage versus the maximum nee-
ded AC signal swing.
In active mode, with a -48V battery voltage, the
L3037 dissipate 150mW for its own operation (in-
cluding the power dissipation from +5/-5 supply),
the dissipation related to the current supplied to
the line should be added in order to get the total
dissipation.
STAND-BY MODE (SBY)
In this mode the bias current of the L3037 is redu-
ced and only some part of the circuit are completely
active. The transversal current supplied to the line
is limited at 14mA. Common mode current rejection
is performed and the total current capability of the
output stages (TIP and RING) is limited to 30mA.
The open circuit voltage is |Vbat|-7V.
Both Off/Hook and Ground key detectors are acti-
ve. Signal transmission is not operating.
In stand-by mode, with a -48V battery voltage, the
L3037dissipates90mW typ. (including the power dis-
sipationfrom a +5/-5V supply).
Stand-by mode is usually selected when the telepho-
ne is in on-hook condition. It allows a proper off-hook
detection, even in the presence of high common
mode currents, or with telephone sets sinking a few
milliamperes of line currentin on-hook condition.
1) The line impedance (Zline)
2) The SLIC impedance at line terminals (Zs)
3) The balancing network ZA+RA connected
4) The network ZB between pin ZB and GND
between pin ZAC and ZB of L3037.
that shall copy the line
impedance.