UBA2051(A;C)

Speech/transmission part
` Low DC line voltage; operates down to 1.45 V (excluding voltage drop over external polarity guard)
` Line voltage regulator with adjustable DC voltage
` Regulated 3.3 V supply (VDD) for the dialler part and peripherals compatible with:
    Speech mode
    Ringer mode
    Trickle mode.
` Unregulated supply (VCC) for the transmission part and peripherals
` Transmit stage with:
    Microphone amplifier with symmetrical high-impedance inputs
    DTMF input with confidence tone on receive output.
` Receive stage with:
    Receive amplifier with asymmetrical output
    Earpiece amplifier with adjustable gain (and gain boost facility) for all types of earpieces.
` AGC: line loss compensation for microphone and receive amplifiers.
Dialler part
` Last Number Redial (LNR) (32 digits)
` Pulse dialling:
    10 PPS and 20 PPS (resistor option)
    M/B 2 : 3 and 1 : 2 (resistor option).
` DTMF timing:
    Manual dialling with minimum duration for bursts and pauses (85/85 ms)
    Calibrated timing during redialling (85/85 ms).
` Pulse or tone mode select at start-up (resistor option)
` Flash function (600, 300, 98 and 80 ms) (resistor options)
` Access pause time 2.0 and 3.6 s (resistor option);access pauses in series are possible
` [*/T] key (for mixed mode dialling) or separate [P ® T] key
` Repertory memory integrity check
` Keytone generation (only UBA2050, UBA2050A and UBA2051C)
` Dial Mode Output (DMO) function during pulse dialling and flash function (only UBA2050 and UBA2051)
` LED output for DTMF dialling indication (only UBA2050A and UBA2051A)
` Function keys:
    [LNR/P], [R] and [P ® T]
    [STORE], [MEM], [M1], [M2] and [M3] (only UBA2051, UBA2051A and UBA2051C).
` Resistor options:
    [*/T] key definition (MMS)
    Pulse or Tone mode Selection (PTS)
    Flash Time Selection (FTSA and FTSB)
    Make/Break ratio Selection (MBS)
    Pulses Per Second (PPS)
    Access Pause Time (APT).
` 13 repertory numbers (only UBA2051, UBA2051A and UBA2051C):
    3 direct memories (21 digits)
    10 indirect memories (21 digits).
` Supply and temperature independent tone output
` On-chip DTMF filtering for low output distortion ("CEPT CS 203" compatible)
` On-chip oscillator suitable for low-cost 3.579545 MHz quartz crystal or ceramic resonator
` Uses standard single-contact keyboard
` Keyboard entries fully debounced.
Ringer part
` Ringer input frequency discrimination
` 3-tone ringer with 4 programmable melodies (selectable via keyboard by keys [1] to [4])
` 4-level volume control (selectable via keyboard by keys [5] to [8]).

The ICs UBA2050, UBA2050A, UBA2051, UBA2051A and UBA2051C contain all the functions needed to build a fully electronic telephone set.

In many places in the text, figures and tables, the description of UBA2050, UBA2050A, UBA2051, UBA2051A and UBA2051C is not applicable for all the five types, but only for one or two or for a combination. These combinations will be referred to by means of short denotations as given in Table 1.
Table 1 Denotations of types

The devices UBA2050, UBA2050A, UBA2051, UBA2051A and UBA2051C incorporate a speech/transmission part, a dialler part and a ringer part. By offering a wide range of possible adaptations for each part, the UBA205xx applications can be easily adapted to meet different requirements.

Speech/transmission part
The speech/transmission part performs all transmission and line interface functions required in fully electronic telephone sets. It performs electronic switching between transmission and dialling. The IC operates at a DC voltage down to 1.45 V (with reduced performance) to facilitate the use of telephone sets connected in parallel.When the line current is high enough, a fixed amount of current is derived from pin LN in order to create a supply point at pin VDD. The voltage at pin V_DD is regulated at 3.3 V to supply the dialler and ringer parts and peripheral circuits.

Dialler part
The dialler and ringer parts of the IC UBA2050, UBA2050A, UBA2051, UBA2051A and UBA2051C are responsible for the system control, system settings and the generation and detection of various signals.The dialler offers a 32-digit last number redial function.

The UBA2051x offers in addition 13 memories (3 direct + 10 indirect) of 21 digits.During pulse dialling the DMO output of the UBA205x can be used to decrease the line voltage. During tone dialling the LED output of the UBA205xA is used to indicate DTMF dialling. A keytone is available if a valid key is pressed for the types UBA2050x and UBA2051C.

Ringer part
The ringer part offers a discriminator input which enables the MDY/TONE output as soon as a valid ring frequency is detected. It offers a choice of 4 different 3-tone melodies and a 4-level volume control, both programmable via the keyboard. An external very low cost ringer output stage for a buzzer is needed. Stabilized supply (V_DD) during ringer mode for dialler and ringer part is included.