TELEFUNKEN Semiconductors
U3750BM
One Chip Telephone Circuit
Description
TELEFUNKEN microelectronic’s one chip telephone
circuit, U 3750 BM, is BICMOS integrated circuit that
performs all the speech and line interface functions
required in an electronic telephone set, the tone ringer, the
pulse and DTMF dialling with redial, a keyboard inter-
face with the possibility to interface with an external
microcontroller using the internal serial bus, and a power
supply for peripherals.
Features
D
Adjustable dc slope characteristic
D
Adjustable automatic line length receiving and send-
ing gain control (not used in DTMF) with the
possibility of fixed gain (PABX)
D
Four ringing tones adjustable without external
components
D
Internal speed up circuit permits a faster charge of
V
CC
and V
RAM
capacitors
D
D
D
D
Adjustable dynamic impedance
Stabilized power supply for peripherals
Confidence level during pulse and DTMF dialling
Receiving amplifier for dynamic or piezo-electric ear
pieces
D
Logic bounce elimination
D
Pulse dialling 66/33 or 60/40 or DTMF dialling select-
able by programming pin
D
Adjustable flashing duration
D
Pause function
D
Confidence tone (440 Hz)
D
Last number redial up to 23 digits
D
Standard low-cost ceramic 455 kHz
D
Binary data input in serial mode
D
Test-mode capability
D
High-impedance microphone inputs (80 k
W
in
symmetrical and 40 k
W
in asymmetrical) suitable for
dynamic, magnetic, piezo-electric or electret micro-
phone
distortion of line signal and sidetone
D
Dynamic limiting in sending (anticlipping) prevents
D
Ringing balanced output in HVMOS for higher power
capability
Benefits
D
Low number of external components
D
High quality through one chip solution
Rev. A1: 16.07.1996
1 (20)
TEMIC [ TEMIC SEMICONDUCTORS ]
