BL1240 BELLING | Alldatasheet

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Technical content

Features

/circle6 Low current consumption, in order to allow the parallel operation of 4 devices. /circle6 Integrated rectifier bridge with zener diodes to protect against overvoltages. /circle6 Little external circuitry. /circle6 Tone and switching frequencies adjustable by external components. /circle6 Integrated voltage and current hysteresis.

Description

BL1240 is a monolithic integrated circuit designed to repace mechanical bell in telephone sets in connection with an electro-acoustical converter. It can drive directly a piezoceramic converter (buzzer) or a dynamic loudspeaker. The output current capability of BL1240 is higher than standard ringer. For driving a dynamic loud-speaker BL1240 can simply use a decoup ling capacitor, thus eliminating the usual transformer. No current limitation is provided on the output stage of BL1240, so a minimum load DC of 50 ohm is adviced, in series with a proper capacitor. The two tone frequencies generated are switched by an internal oscillator in a fast sequence and made audible across an output amplifier in the loud-speaker, both tone frequencies and the switching frequency can be externally adjusted. The supply voltage is obtained from the AC ring signal and the circuit is designed so that noise on the line or variatins of the ringing signal cannot affect correct operation of the device.

http://www.belling.com.cn - 2 - 8/14/2006 Total 5 Pages Wrote by 2006 Pin connection Pin Pin Pin Pin Symble Symble Symble Symble Function Description Function Description Function Description Function Description 11 11 LINE LINE LINE LINE Telephone line Telephone line Telephone line Telephone line 22 22 GND GND GND GND Ground Ground Ground Ground 33 33 Csw Csw Csw Csw Sweep rate control capacitor Sweep rate control capacitor Sweep rate control capacitor Sweep rate control capacitor 44 44 R R RRAA AA Output frequency control resistor Output frequency control resistor Output frequency control resistor Output frequency control resistor 55 55 OUT OUT OUT OUT Output freq Output freq Output freq Output frequency uency uency uency 66 66 NC NC NC NC Not connected Not connected Not connected Not connected 77 77 C C CCrr rr Rectifier capacitor Rectifier capacitor Rectifier capacitor Rectifier capacitor 88 88 LINE LINE LINE LINE Telephone line Telephone line Telephone line Telephone line BL1240 1 2 3 4 5 6 7 8

http://www.belling.com.cn - 3 - 8/14/2006 Total 5 Pages Wrote by 2006 BLOCK DIAGRAM Figure 1 : Test Circuit RECTIFIER BRIDGE TONE FREQUENCY GENERATOR SWITCHING FREQUENCY GENERATOR OUTPUT STAGE THRESHOLD CIRCUIT WITH HYSTERESIS 8 7 6 5 4321 IN IN TELEPHONE LINE RECTIFIER CAPACITOR N.C. BUZZER TELEPHONE LINE GND SWEEP RATE CONTROL CAPACITOR OUTPUT FREQUENCY CONTROL RESISTOR 8 5 1 2 3 4

7 R L

2.2 k 1 uF 10 uF LINE VOUT VAB )1943 1ln 04 . 01 ()( 1 10 72 . 21 4 f 750 nF CfSWEEP =

http://www.belling.com.cn - 4 - 8/14/2006 Total 5 Pages Wrote by 2006 ABSOLUTE MAXIMUM RATING ( Ta = 25 °° °°C unless otherwise specified ) RECOMMENDED OPERATING CONDITION ( Ta = 25 °° °°C unless otherwise specified ) ELECTRICAL CHARACTERISTICS ( Ta = 25 °° °°C ) AC OPERATION Parameter Symbol Value Unit Calling Voltage (f = 50 Hz) Continuous V AB (ON) 120 Vrms Calling Voltage (f = 50 Hz) 5s ON/10s OFF V AB (ON/OFF) 200 Vrms DC Supply Current IDC 30 mA Operating Temperature Tamb -20 to +70 °C Storage and Junction Temperature Tstg -65 to +150 °C Parameter Symbol Min. Typ. Max. Unit Calling Voltage (f = 50 Hz) Continuous V AB (ON) 75 120 Vrms Parameter Symbol Test Conditions Min. Typ. Max. Unit DC Power Supply Voltage V DC 26 V Activation Voltage V ON 12.2 13.2 V Sustaining Voltage V OFF 8 9 V Output Voltage Swing V OUT VDC - 5 V 70 mA Short Circuit Current (pins 5-2) VDC = 20 V, R L = 250 ΩIOUT kΩ Differential Resistance in OFF Condition (pins 8-1) R D 6.4 1.5 1.8 mA Current Consumption without Load (pins 8-1) V DC = 9.3 to 2.5 V IDCO f1 / f2 1.33 1.43 7.5 Hz 1.22 1.6 kHz 1.74 2.14 kHz Sweep Frequency Output Frequency f2 Output Frequency f1 VDC = 26 V, R A = 14 k Ω, V3 = 0V VDC = 26 V, R A = 14 k Ω, V3 = 6V VDC = 26 V, R A = 14 k Ω, Csw = 0.1 uF f sw