UM95089 UMC | Alldatasheet
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Technical content
Features
® Wide operating voltage range: 2.5 to 10.0 Voits ®™ Specifically designed for electronic telephone applica- ® Optimized for constant operating supply voltage, tions typically 3.5V. " = Tone amplitude stability is within 21.548 of the oper- ‘Serves as an interface directly to @ standerd telephone ating temperature range push-button keyboard with common terminal = Low power CMOS circuitry allows device power to be = Low total harmonic distortion Corived directly from the telephone lines or from small = Dual tone as well as single tone ility @ Uses TV crystal standard (3.58MHz) to derive ali Direct replacement for AMI S25080 end Mostek frequencies thus providing high accuracy and stability MK5089 tone generators. General Description The UM95089 DTMF Generator is specifically designed TV crystal standard which provides high accuracy and to implement a dual tone telephone dialing system in stability. The required sinusoidal waveform for the applications requiring fixed supply operation and high individual tones is digitally synthesized on the chip. The stability tone output level, making it well suited for waveform so generated has low total harmonic distortion. electronic telephone applications. The device can serve A voltage reference is generated on the chip which is ‘as an interface directly to a standard push-button telephone stable over the operating temperature range and regulates keyboard with common terminal connected to Veg and ‘the signal levels of the dual tones to meet recommended ‘operates directly from the telephone lines. All necessary telephone industry specifications. dual-tone frequencies are derived from the widely used Pin Configuration Block Diagram Yoo (]' 6 [J ey | eT] ra] B= ce[]2 is] sm = 1 as [ai rem 1 : = ioe [| iS ats [re sa] _ ‘uM95089 oe el eS Vss [6 nD]ra aoe o| feel ca AKD 1 | og BS | 62] epee osco []s ofa v= or 3-17
®ume um95089 EE Absolute Maximum Ratings* *Comments DC Supply Voltage (Vp —Vss) ----+++2,-+ *10.5V Stresses above those listed under “Absolute Maximum Operating Temperature « «== +--+: ee C0 470°C Ratings” may cause permanent damage tothe device. This Storage Temperature... se ee ve 0 ‘i 4 , ' i
Electrical Characteristics
(Specifications apply over the operating temperature range of —25°C to 70°C unless otherwise noted. Absolute values of measured parameters are specified.) OPERATING VOLTAGE F [tow outs Yop 28 00 [vata Reyrremea | $Nortore Surwage | Vo [18 | [100 |v | orp rr win er Pre i OPERATING CURRENT pe [> [= [= aaa ne a touts Standby Mode t Vip = 10.0¥ No Key Selected, Pico | [| me | | Yenaricninctrie | Vpp = 3.0¥ One Key Selected, [ico | [oe [oe [me | vaasemiceectnie | Operating Mode Vop = 10.0V One Key Selected, Ton and ARD Outputs Unloaded PORE OUR ae ao aero —] Tove Ot [or =100_[ | =70 [tm | Von =35¥ A= t00K em | | RaiootcounmeRowTore | ca | 24 [27 [38 | o8 | Vop=25=105v [emonion | wos ||| 10 | opm asm toov | Fore GuisnoreyBome [wee [|e fem fT AKD OUTPUT [owsutnSik rene [toy [08 [18 [| mA | Yoo=30v vouroey | [ovina costo Coren ——[ ton [| 1 | [oA | Mops 190v OSCILLATOR _INPUT/OUTPUT Ome Key Saeco Out ———(|_lon | Oz [082 [ [mA] Vopr a0vve-o8v | sth Grr [Torres [2 | [ma | Yop 100 Vou =oev | | sacesesom [oe TR oe a | soir bor a [orstmarsenie tine [eran | [2 | § | ns _| vop=a0=ioov un cae input ita [eyo | | 2 fT we | oF | Yoo oo [eyo [| fe [oF | vop=toov ROW, COLUMN AND CHIP ENABLE INPUTS a 8 (Voo" | Psvemenefom PR] owe f Input Current (Pul-up) [iw [30 [eo Tso [wk | Vo =30V viwsoov [rig [00 [so e60 na [Vp = 1007 viyeoov | 3-18
@umc uM95089 Crystal Specification Tone Output (TONE) A standard TV color burst crystal is specified to have UM95089 uses the Johnson counters and resistor ladder much tighter tolerance than necessary for tone genera- network (see block diagram) to synthesize the two desired tion application. By relaxing the tolerance specification, frequencies in sinewaves (see Fig. 4) and then uses the the cost of the crystal can be reduced. The recommended ladder network to mix the two. It then drives bipolar crystal specification is as follows: NPN transistor, connected as emitter follower, to allow proper impedance transformation and at the same time Frequency: 3.58 MHz £0.02% Preserve signal level. Rg < 1000hm, Ly = 96MH, Cy = 0.02pF, Cy = SPF, Cy = 12pF Inhibiting Single Tones (STI) | The STI input is used to inhibit generation other than | Reference Voltage dual tones, It has an internal pull-down to Vgg- When this input is left unconnected or connected to Vsg, Single The structure of the reference voltage employed in the Tone Mode is disabled. When this input is connected.to UM95089 is shown in Fig. 1, It has the following charac: Vp), Single Tone Mode as well as Dual Tone Mode may teristics: be generated as follows: a) V is proportional to the supply voltage. Output tone Dual Tone Mode: When one row and one column is amplitude, which is a function of (Vpp — Vper) selected, dual tone output consisting of an appropriate | increases with supply voltage (Fig. 2). tow group and high group tone is generated. If two-digit b) The temperature coefficient of Vpee is low due to keys that are not in the same row or in the same column 2 single Vag drop. Use of a resistive divider also are pressed, the dual tone mode is disabled and no output j provides an accuracy of better than 10%, Asa result, is provided. tone amplitude variations over temperature and unit | to unit differences are held to less than +1.0dB over Single Tone Mode: Single tones either in the low or high | normal. ‘group can be generated as follows —— A low group tone | c) Resistor values in the divider network are so chosen can be generated by pressing two-digit keys in the ap- that Vage is above the Vge drop of the tone output propriate row. A high group tone can be generated by | transistor even at the low end of the supply voltage pressing two-digit keys in the appropriate column, i.e., | range. The tone output clipping at low supply voltage _selecting the appropriate column input and tworow inputs is thus eliminated, which improves distortion per- _in that column. formance. Chip Enable Input (CE) \\ Pin Description The Chip Enable input has an internal pull-up to Vop- Onciliator (SCI, OSCO) When this pin is left unconnected or conected to Vo, this chip operates normally. When connected to Vg, | UM95089 contains an oscillator circuit with the necessary ‘tone generation is inhibited. All other chip functions parasitic capacitances and feedback resistor on chip s0 operate normally. | that it is only necessary to connect a standard 3.58MHz | TV crystal across the OSC! and OSCO terminals to implement the oscillator function. The oscillator functions any Key Down (Muta) Output (AKD) | whenever a row input is activated. ‘The AKD output consists of an open drain N channel device (see Fig. 5). When no keys are pressed, the AKD | Keyboard (FF... Fa,01,05,05,00) output is open. When a key is pressed, the AKD output UM95089 hes internal pull-up resistors present on the Vss- | row and column inputs (20Kohm-10Kohm). Low Yevels on a row and a column input corresponds to a key closure. iMas009 san serve as an. interface. with the standard Power (Vo. Vas) telephone push-button keyboard (See Fig. 3). The These are the power supply inputs. UMO5089 is designed common of the keyboard must be connected to Vgg. to operate from 2.5 to 10.0 Volts. a 3-19