L7590C Datasheet, PDF (1/10 Pages) Agere Systems – Telephone Ringing Driver

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
CLOCK
CONTROL
CLK
BIAS
CIRCUIT
VREF
VNEG
LEVEL
SHIFT
AND
OUTPUT
TIMING
CURRENT
LIMIT
30 Ω
VNEG
Figure 1. Block Diagram
OUT
L1
L2
12-3057a (f)