# LS1240A Linear Integrated Circuit

## Electronic Tone Ringer

Description
· Monolithic integrated circuit designed as a telephone ringer.
· Drives piezo-ceramic converters (buzzers) directly.
· Higher output current capacity than standard ringers.
· Can drive dynamic loudspeakers with a decoupling capacitor.

Features
· Low current consumption
· Integrated rectifier bridge with overvoltage protection (zener diodes).
· Minimal external circuitry required.
· Adjustable tone and switching frequencies via external components.
· Integrated voltage and current hysteresis.

Pin Configuration
· 1: LINE (B-wire)
· 2: GND (Ground)
· 3: Csw (Sweep rate control capacitor)
· 4: Ra (Output frequency control resistor)
· 5: OUT (Buzzer)
· 6: NULL (Not connected)
· 7: Cr (Rectifier capacitor)
· 8: LINE (A-wire)

Ordering Information
· Packages: DIP-8, SOP-8
· Packing: Tube, Tape Reel

Absolute Maximum Ratings
· Calling Voltage (Continuous): 120 V RMS
· Calling Voltage (5s ON/10s OFF): 200 V RMS
· Supply Current: 30 mA
· Operating Temperature: -40 to +70 °C
· Storage Temperature: -65 to +150 °C

Electrical Characteristics (TA = 25°C)
· Supply Voltage: 26V
· Current Consumption (no load): 1.5 - 1.8 mA
· Activation Voltage: 12-13.5V
· Sustaining Voltage: 7.8-9.3V
· Output Voltage Swing: VS-5V
· Short Circuit Current: 70mA (VS=20V, RL=250Ω)
· Output Frequencies: 1.55-2.53 kHz
· Sweep Frequency: 5.25-9.75 Hz (C1=100nF, R1=14kΩ)
· Programming Resistor Range: 8-56 kΩ

Application Notes
· Minimum load impedance of 50 ohms is advised.
· Tone frequencies and switching frequency are adjustable.
· Designed to be immune to line noise.