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Agere Systems |
Data Sheet
June 1998
L7590C Telephone Ringing Driver
Features
s Applies a battery-backed, single-ended, sinusoidal
ringing signal to the telephone loop
s Ringing capability:
— 40 Vrms into 5 North American REN
— 30 mApeak into 4 German REN
s Built-in current limiting
s Low power dissipation in idle and ringing modes
s Requires 5 V, a high-value negative dc supply, and
a digital input sequence
Description
The L7590C Telephone Ringing Driver produces a
low-frequency sinusoidal ringing signal for analog
telephone loops. This is accomplished by producing
an output pulse stream that is an amplified replica of
the digital input. The output is then filtered to produce
a sine wave. The peak-to-peak output level is deter-
mined by the magnitude of the negative high-voltage
dc applied to the device (up to –170 V).
The required input is a 100 kHz CMOS-compatible
pulse stream, pulse-width modulated (PWM) at the
desired ringing frequency. The output stage consists
of one upper and one lower drive transistor with an
internal control circuit.
The L7590C IC is optimized for low power dissipation
and is available in a 16-pin, surface-mount package.
GNDD VDD
GNDR CB1 CB2
EN
CLK
CLOCK
CONTROL
BIAS
CIRCUIT
VREF
VNEG
LEVEL
SHIFT
AND
OUTPUT
TIMING
CURRENT
LIMIT
30 Ω
VNEG
Figure 1. Block Diagram
OUT
L1
L2
12-3057a (f)
L7590C Telephone Ringing Driver
Data Sheet
June 1998
Pin Information
Pin Symbol Type
Name/Function
14 VDD — +5 V Power Supply.
3 GNDD — Digital Ground.
12 GNDR — Ringing Ground.
8
VNEG
— Negative Power Supply. Determines the swing of the ringing generator. Connect
a 1 µF capacitor from VNEG to VREF.
5
VREF
— Internal Reference Voltage. Connect a 1 µF capacitor from VREF to VNEG.
16 CLK I Clock. Modulated pulse stream. Low = 0 V. High = VDD.
7
OUT
O Ringing Generator Output. Connect to ringing relay contact through a filter.
1 CB1 — Bootstrap Capacitor. Connect a 0.1 µF capacitor between CB1 and CB2.
2 CB2 — Bootstrap Capacitor. Connect a 0.1 µF capacitor between CB1 and CB2.
9 L1 — Filter Inductor. Connect an inductor to pin L2.
10 L2 — Filter Inductor. Connect an inductor to pin L1.
15 EN — Not Enable. A logic low activates the internal circuitry. A logic high puts the device
in a low-power powerdown mode.
Absolute Maximum Ratings (TA = 25 °C)
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are abso-
lute stress ratings only. Functional operation of the device is not implied at these or any other conditions in excess
of those given in the operational sections of this data sheet. Exposure to absolute maximum ratings for extended
periods may adversely affect device reliability.
Parameter
Min Typ Max Unit
VDD
VNEG
Timing Input Voltage
Storage Temperature Range
Maximum Junction Temperature
Relative Humidity Range
—
—
–0.5
–40
—
5
7.0
–200
—
—
150
—
—
—
7.0
125
—
95
V
V
V
°C
°C
%
2 Lucent Technologies Inc.
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