U3750BM TELEFUNKEN Semiconductors 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 interface 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 sending gain control (not used in DTMF) with the possibility of fixed gain (PABX) D D D D D Four ringing tones adjustable without external components D Internal speed up circuit permits a faster charge of VCC and VRAM capacitors Adjustable dynamic impedance D Logic bounce elimination Stabilized power supply for peripherals D Pulse dialling 66/33 or 60/40 or DTMF dialling select- Confidence level during pulse and DTMF dialling Receiving amplifier for dynamic or piezo-electric ear pieces D High-impedance microphone inputs (80 kW in symmetrical and 40 kW in asymmetrical) suitable for dynamic, magnetic, piezo-electric or electret microphone D Dynamic limiting in sending (anticlipping) prevents distortion of line signal and sidetone D Ringing balanced output in HVMOS for higher power capability 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 Benefits D Low number of external components D High quality through one chip solution Rev. A1: 16.07.1996 1 (20) U3750BM TELEFUNKEN Semiconductors Block Diagram 2 (20) Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Pin Description Pin 1 2 3 4 Symbol C4 C3 FLASH DC/FV 5 6 7 8 9 10 11 12 13 14 OL RESET TEEIN SHEN NC VRAM VCC VL OSCAB EC 15 16 17 18 19 20 21 TESTR GND NC AGA IREF SELF RGAB 22 MIC1 Rev. A1: 16.07.1996 Function Keyboard input Keyboard input Flashing selection Dialling selection (33/66 pulse, 40/60 pulse or DTMF) Open line output Output reset Test pins Test pins Not connected RAM and internal logic supply Power supply for peripherals Line voltage Test pin Extra current for peripherals or can be used to dissipate power for high line current applications. Test pin Ground Not connected Line length AGC adjustment Bias adjustment Electronic self input DC characteristic slope adjustment Microphone input Pin 23 24 25 26 27 Symbol MIC2 ZAC EM/FILT MOD EM/MF 28 ACL 29 30 31 32 33 34 35 36 37 38 E2 E1 NC REC ZAL OUT1 OUT2 VIR CK PAIR 39 BEAT 40 41 42 43 44 MF C1 C2 C6 C5 Function Microphone input Dynamic impedance adjustment First sending stage output Modulator output Second sending stage input and DTMF input Anticlipping time constant adjustment Receiver output Receiver output Not connected Receiver input Sidetone network Buzzer output Buzzer output Ringing supply Ceramic input (455 KHz) Adjustment between two pairs of ringing frequencies Beat adjustment of each pair of ringing frequencies DTMF output Keyboard inputs Keyboard inputs Keyboard inputs Keyboard inputs 3 (20) U3750BM TELEFUNKEN Semiconductors Application Circuit Absolute Maximum Ratings See application circuit Parameters DC line voltage Pin 36 DC line current Pin 36 Conversation line voltage Pin 12 Pulse duration, t = 20 ms Conversation line current Pin 12 Power dissipation, Tamb = 55°C Junction temperature Ambient temperature range Storage temperature range 4 (20) Symbol VIR IR VL VL IL Ptot Tj Tamb Tstg Value 35 30 15 17 150 1 125 –25 to +55 –55 to +155 Unit V mA V V mA W °C °C °C Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Thermal Resistance Parameters Junction ambient Symbol RthJA Value 70 Unit K/W Electrical Characteristics f = 1 kHz, fclock = 455 kHz, RE = 20 kW, Tamb = 25°C, unless otherwise specified, Q (Resonance factor) = 3100, L1 = 6.1 mH, C1 = 21 pF, CO = 268.5 pF, R1 = 5.5 W. All resistances are specified at 1%, all capacitance at 2%. Parameters Line voltage normal Line voltage operation Stabilized voltage Test Conditions / Pins IL = 8 mA IL = 15 mA IL = 28 mA IL = 60 mA figure 3 IL = 8 mA, ICC = 0.6 mA IL 28 mA, ICC = 2.1 mA figure 3 w Symbol VL VCC Min. 2.9 4.1 6.4 12.3 Typ. 2.0 3.3 2.5 3.5 3.7 47 39.5 –6 48 41 –7 49 42.5 –8 dB –73 –68 dBmp 4.5 Max. 3.6 4.9 7.3 13.7 Unit V V Transmission Sending gain VMI = 2 mVRMS (note 1) IL = 28 mA (GS max) IL = 60 mA (GS min) AGC IL = 28 to 60 mA figure 3 Psophometric sending noise VMI = 0, IL = 28 mA figure 3 Attenuation gain during VMI = 2 mVRMS, dialing IL = 28 mA figure 3 Microphone input figure 3 impedance (Pins 22–23) Common mode rejection IL = 28 mA ratio figure 3 From transmission to IL = 28 to 60 mA dialing mode figure 3, Pin 25 Dynamic limiter CACL = 470 nF, (anticlipping) RACL = 6.8 MW IL = 20 mA Output voltage swing IL 28 mA, (peak-to-peak value) VMI = 8 mVRMS figure 3 Overdrive dynamic range IL 28 mA figure 3 Line distortion (on 600 W) IL 28 mA VMI = 4.6 mVRMS VMI = 8 mVRMS VMI = 80 mVRMS figure 3 w w w Rev. A1: 16.07.1996 GS DGS AS 63 70 CMRR Step dB 120 kW 80 dB –100 3.0 +100 2.5 3.6 mV Vpp 4.2 5 dB 3 5 5 % 5 (20) U3750BM Parameters Available current Reception Receiving gain GR = VR/VL AGC Psophometric receiving noise Receiving distortion Receiver output impedance Receiver output offset Sidestone (VR/VM) Z line matching impedance Ringer Turn on voltage Turn off voltage Current consumption without load Output voltage swing Output tone frequencies TELEFUNKEN Semiconductors Test Conditions / Pins Close switch S4 IL = 28 mA IL = 60 mA figure 3 Pin 14 VL = 0.3 VRMS IL = 28 mA (GR max) IL = 60 mA (GR min) IL = 28 to 60 mA figure 4 VL = 0V, IL = 28 mA figure 4 Pin 29–30 IL = 15 mA, VR = 2.8 Vpp IL = 28 mA, VR = 5.5 Vpp IL = 60 mA, VR = 5.0 Vpp figure 4 VR = 50 mVRMS, IL = 28 mA figure 4 Pin 29–30 IL = 28 mA figure 4 Pin 29–30 IL = 28 mA figure 3 VL = 0.3 VRMS IL = 28 and 60 mA figure 4 Measured at pin VIR figure 5 figure 5 VIR = 18 V Load = 10 kW figure 5 Pin 38 grounded Pin 38 open Sweep frequencies Leakage current 6 (20) Pin 39 grounded Pin 39 open VIR = 30 V IIL at VIL = 0 V Pins 38 and 39 figure 5 Symbol GR DGR Min. Typ. 7.0 35 8 40 10 2.5 –6 11 4 –7 45 VON VOFF VOUT 9.5 Unit mA 12 5.5 –8 dB –65 dBmp 3 3 3 % 85 W +650 mV 36 40 dB 660 750 W 16 18.0 V 1.5 V mA 65 –650 580 Max. 10.5 1.2 VIR–2 Vp 1458 1166 547 438 4.0 9.1 Hz Hz 5 mA Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Parameters Test Conditions / Pins DTMF generation Pin 4 grounded Tone frequency accuracy VRAM = 3.5 V (confidence tone included) Low group tone level (Note 2) (depends on external Measured on 600 W components) IL = 28 mA figure 3 High group tone level (Note 2) (depends on external Measured on 600 W components) IL = 28 mA figure 3 Preemphasis (depends on (Note 2) external components) Measured on 600 W IL = 28 mA figure 3 DTMF distortion (depends (Note 2 and note 3) on external components) Measured on 600 W IL = 28 mA, 300 < f < 3400 Hz figure 3 DTMF transmission time DTMF interdigit time Transmission mute tmMF Confidence tone Only by serial bus FCT frequency Tone level (depends on Measured on 600 W external components) IL = 25 mA figure 3 Symbol Min. Typ. –0.4 tMF tIMF Max. Unit +0.25 % –10 –8 –6 dBm –8 –6 –4 dBm 1 2 3 dB 3.5 % 82.4 89.2 171.6 ms ms ms 80.2 89.2 169.4 440.9 –9 Hz dBm Note 1: sending gain: GS = VL/VMI with the values of RAG1 and RAG2 (figure 3) so the maximum gain is at 28 mA and the minimum gain is at 60 mA. Note 2: For DTMF measurements, close switches S1 and S3 and select each group of frequencies on the keyboard. Note 3: The level of each harmonic on line is under the limited curve given below with the filter components value chosen for the test. Figure 1 Rev. A1: 16.07.1996 7 (20) U3750BM TELEFUNKEN Semiconductors dBm ( 600W ) –30 –40 –50 –60 0.1 1 10 100 1000 f ( kHz ) 93 7831 e Figure 2 DTMF distortion Figure 3 Test circuit 8 (20) Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Figure 4 Test circuit Figure 5 Test circuit S5 (Pin 38) S6 (Pin 39) Pair of Frequencies (Hz) ON ON OFF OFF ON OFF ON OFF 1458/1166 1458/1166 547/438 547/438 Rev. A1: 16.07.1996 Sweep Frequency (Hz) 4 9.1 4 9.1 9 (20) U3750BM TELEFUNKEN Semiconductors Electrical Characteristics of Logical Part fclock = 455 kHz (other specifications as under electrical characteristics) Parameters VRAM Speed-up off threshold Speed-up on threshold Logic operating voltage in normal mode IRAM Oscillator on Leakage Inputs: C1, C2, C3, C4, C5, C6, DC/FV, FLASH Keyboard pins: C1, C2, C3, C4, C5, C6 Internal pull down Output current FLASH, DC/FV Internal pull-up current IPV Leakage current Timing and frequency Reset time tr (see figure 6 and 7) Clock start-up time ton Time line break generating a reset: tlb Debounce time, te RESET output (with 390 W series) Output low current Output high current OL output Output low current Output high current MF output High impedance CK Input Low input leakage High input leakage 10 (20) Test Conditions / Pins IL = 8 mA IL = 15 to 70 mA Symbol VSOFF VSON Min. 2.4 1.9 Typ. 2.75 2.2 2.5 3.5 VRAM = 3.5 V Input voltage low, VIL Input voltage high, VIH Max. 2.9 2.3 800 300 0.2 VRAM 0.8 VRAM Unit V V V V mA mA V V VIL = 3.5 V VIH = 0 V 15 0.8 50 2.5 mA mA VIL = 0 V VIH = 3.5 V 0.5 5 1 mA mA In mode 60/40 In mode 66/33 and DTMF mode 30 33 5 290 319 14 15.4 In mode 60/40 In mode 66/33 and DTMF mode In mode 60/40 In mode 66/33 and DTMF mode 24 26.4 ms ms ms 300 330 34 37.4 ms ms ms ms VOL = 2.5 V VOL = 0.5 V IOL IOH 0.25 0.25 1.2 1.2 mA mA VOL = 0.5 V IOL IOH 2 1 20 4 mA mA 150 200 200 150 0.5 350 550 550 350 mA mA mA mA mA 1 1 mA mA VOHI = 1.4 V FL = L, FH = H, VOH = 3.5 V FB = L, FH = H, VOH = 0 V FB = H, FH = L, VOH = 3.5 V FB = H, FH = L, VOH = 0 V VIL = 0.5 V VIL = 3.0 V Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Parameters Serial bus (see figure 12) Pulse width clock Pulse width enable signal Set-up time data to clock Hold time data from clock Enable time Time between two transmissions Pulse dialing (OL) Dialing pulse frequency Test Conditions / Pins Symbol Min. twl, twh tel, teh tset up 2 2 0 100 0 900 te tRRN In mode 60/40 (Pin 4 tied to RESET) In mode 66/33 (Pin 4 not connected) TOL Dialing pulse period Break time tb Make time tm tIDOL Interdigit time Transmission mute: tmol = (tm + tb) @ n + tm1 n pulses dialling Flash pulse Flash pulse duration Transmission mute Pause time Rev. A1: 16.07.1996 Pin 3 to GND Pin 4 to RESET Pin 3 to GND Pin 4 to NC Pin 3 to GND Pin 4 to GND Pin 3 to NC Pin 4 to RESET Pin 3 to NC Pin 4 to NC Pin 3 to NC Pin 4 to GND Pin 3 to RESET Pin 4 to RESET Pin 3 to RESET Pin 4 to NC Pin 3 to RESET Pin 4 to GND In mode 60/40 In mode 66/33 In mode DTMF In mode 60/40 In mode 66/33 In DTMF mode tfl tmfl Tp Typ. Max. Unit ms ms ms ms ms ms 10 Hz 10.11 Hz 100 98.9 60 66 40 33 ms ms ms ms ms ms ms ms ms 830 813 [n@100 + 30] [[email protected] + 22] 833 816.5 (n@100) + 32 ([email protected]) + 24.2 89.5 98.5 102.5 239.5 263.5 274.0 109.5 120.5 125.0 830 813 846 92 101 105 242 266 277 112 123 128 832 815.5 848.5 3116 3075 3012 3118 3077 3110 ms ms ms 11 (20) U3750BM TELEFUNKEN Semiconductors Power-on Reset and Pin RESET Pin RESET To avoid undefined states of the device when it is powered on, an internal reset clears the control logic. When the power supply rises above the internal reference level, the pin RESET goes to high during trt. After a line break longer than tlb, a reset is generated. A short line break (< tlb) does not affect the reset. Power on reset timings (t > tlb). It is the power on reset output. 1) VRAM > VSON at t = 0 . . . . . . . . . a) Trt = Tr + T on . . . . . . . . . . . . . . . . . . . . . . b) In test mode, it permits to force the IC U 3750 BM in permanent DTMF dialing by applying a negative voltage (test schematic figure 3). Data Acquisition Input data is derived from any standard matrix keyboard (15 keys) or from a remote microcontroller. Keyboard The keyboard is connected to the IC by six pins, (see figure 8). Its matrix is triangular. a) b) Figure 6 2) VRAM < VSON at t = 0 . . . . . . . . . a) Trt = T (VRAM to VS off) + Tr + T on . . . . b) Figure 8 Keyboard inputs to the U 3750 BM Internal pull down resistors (typical value: 120 kW) are connected to the inputs Ci. A push button is made by a short-circuit of two pins among the six. Entries are scanned every 12 ms or 13.2 ms and go to the logical state 1 during this scanning. a) The scanning is inhibited as soon as a calibrated linebreak is produced at the OL output. The scanning-cycle has eight phases: six of them are reserved for the scanning of the six pins, the two others are kept for the reset of the logic keyboard (T0) and the acquisition (T7). A push button is valid, if it is unique and if it’s pressed long enough (see table of pressed and released push buttons). b) Figure 7 12 (20) Every acquisition time, T7, the input code is decoded into 5 bits (with or without a pressed push button). The microprocessor can read it as soon as the logic keyboard has set a flag, tested about every 800 ms and which indicates that a pushbutton has been correctly detected. Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Table 2 The scanning principle Keyboard clock Ti except T0, T1, T7 T1 T0 or T7 Scanning cycle 2 ms 2 ms 1.956 ms 22 ms 12 ms 2.2 ms 2.2 ms 2.156 ms 22 ms 13.2 ms T0: reset of the logic keyboard T7: acquisition of the code present at the keyboard Scanning Push button Figure 9 The scanning principle Rev. A1: 16.07.1996 13 (20) U3750BM TELEFUNKEN Semiconductors Timing of a Push Button The information from a pressed push button or released push button is taken into account if it is still present during at least two sampling times, T7. Table 3 Timing of a push button Clock Keyboard 2 ms, 2.2 ms Minimum time – push button on Minimum time – push button off Min. 14 15.4 24 26.4 Typ. 24 26.4 24 26.4 Max. 34 37.4 34 37.4 Unit ms ms ms ms The entries are debounced on both the leading and trailing edges for 34 ms or 37.4 ms according to the value of the keyboard clock, and so the time remains less than 40 ms. At this time the information can be processed. If the information is still present after more than 40 ms, it is only taken one time. Serial Bus The remote microcontroller is connected to the IC by 4 pins: C2, C3, C4, C5 (see figure 10). Figure 10 Connection of the microcontroller to the U3750BM C2 transmits the data, C3 the clock, C4 the enable signal, and C5 indicates the state of the dialer: C5 = 0, dialer is busy C5 = 1, dialer is free Data is serially shifted in a 5-bit register during the positive going transition of the clock pulse. The positive going transition of the enable signal validates the transmission. 14 (20) Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors Figure 11 Timing of the serial bus Code Entries Table 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 Rev. A1: 16.07.1996 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 0 1 0 1 * 1 2 3 4 5 6 7 8 9 0 A B C D # 16 R flash Redial Confidence tone Micro inhibition Pause 23 15 (20) U3750BM TELEFUNKEN Semiconductors Dialer The IC includes a dialing circuit for either pulse dialing or dual tone multifrequency dialing. The dialer transmits the codes decoded by the logic keyboard on the outputs OL and MF. Mode Selection The choice of dialing is made by the tri-state-level on the DC/FV Pin FV DC = Z FV DC tied to pin RESET FV DC = 0 on the dialing. The code A is filtered and corresponds to eleven pulses. Dialing As soon as the code is detected by the logic keyboard and written in RAM, it can only be loaded in the dialer if the dialer is not occupied and a pause is not generated. pulse dialing in 66/33 ms Pulse Dialing pulse dialing in 60/40 ms DTMF dialing calibrated The output which provides control signals for proper timing in pulse dialing is pin, OL. The dialling starts with a make time (see figure 12). When the circuit is in pulse mode, it is possible to change over to DTMF dialing with the “ * ” key. The code “ * ” is sent in line. The circuit returns in pulse mode after a reset condition or after a flash pulse (see figure 14). Dialing Codes The dialing codes are the numeric keys 0 to 9, and the non numeric keys A, B, C, D, *, #. All are stored in RAM. The codes A, B, C and D can be only transmitted by the serial bus. In pulse dialing, the code #, B, C and D have no effect Dual tone Multifrequency Dialing The output pin, MF, provides the multifrequency signal to transmit in line. This signal results from the sum of two frequency pulses modulated and requires a filter to compose a dual sine wave. The frequencies are chosen in a low group and a high group. Table 3 shows the frequency tolerance of the output tones for DTMF signalling. In manual dialing or in redial, output tone is timed with a fixed duration. Table 4 Frequency tolerance of the output tones for DTMF signaling Standard Frequency Hz Low Group 697 770 852 941 High Group 1209 1336 1477 1633 Tone Output Frequency Hz Frequency Deviation % Hz 697.8 768.6 848.9 940.1 +0.12 –0.18 –0.37 –0.10 +0.85 –1.42 –3.12 –0.92 1210.1 1338.2 1477.3 1636.7 +0.09 +0.17 +0.02 +0.22 +1.11 +2.23 +0.27 +3.69 Tone output frequency when using a 455 kHz ceramic. 16 (20) Rev. A1: 16.07.1996 TELEFUNKEN Semiconductors U3750BM Figure 12 Timing diagram for pulse dialing Figure 13 Timing diagram for DTMF dialing Figure 14 Timing diagram for mixed mode dialing Rev. A1: 16.07.1996 17 (20) U3750BM TELEFUNKEN Semiconductors Flash Control Microphone Inhibition Detecting a “R” code produces either a short timed line break (< 200 ms ) or long timed line break (>200 ms) at the OL output. Like the confidence tone, it is a flip flop function activated through the serial bus by the code 21 (in decimal). For the duration of the flash, it is not possible to take information from the keyboard. Organization Flash signifies that the circuit executes a particular work as a dialing, a redial, or a pause function, and the code “R” is lost and not used. The flash pulse resets the read address counter and does not erase the data storage, so later redial is possible. The flash duration is programmed by the FLASH pin (Pin 3) and depends on the selection of the tri-state-level pin (Pin 4). Mutes (transmission mute and dialing mute) become active high from the beginning of the line break. Timings explains this. According to these timings and what has previously been said, a second pulse flash could only follow the first one 810 ms or 850 ms later. Consequently the “R” entry remains inhibited during a time less than 1 second. Pause Function A pause separates the dial sequence. It is used for waiting for a dial tone. A pause code takes one position in the RAM like a digit. However, if the circuit executes a pause and if another pause code is entered, the storage of the second one does not occur. Furthermore, the pause running is aborted. Duration of the pause is given in electrical characteristics for the following configuration: digit, pause, digit, and consequently takes into account the interdigit. Particular Functions After the reset, the particular functions are cleared. The state of the circuit is no confidence tone, no microphone inhibition. Confidence Tone Output When the data entries are derived from the serial bus, a pulse frequency modulation corresponding to a 440 Hz sine wave can be generated on the output MF by transmitting the confidence tone code which is 20 (in decimal). The function confidence tone is a flip-flop function. 18 (20) RAM The RAM is 32 words of 5 bits and is organized in two parts: one for the data storage and the other for the working RAM. Safeguard The safeguard is guaranteed by an external capacitor. If VRAM decreases under the data retention supply voltage, the redial function is forbidden. After the reset of the circuit, a test is executed on VRAM in order to ensure the redial validity. Data storage Storage, overflow and erasing are realized through three address counters. The written address counter (P1) points out the location where the code will be stored. At each storage, P1 is incremented by one. As each code is recalled from the RAM for line dialing, the read address counter (M1) is incremented by one to select the RAM location of the next code to be recalled. Consequently, the difference between the contents of P1 and of M1 represents the number of codes that have been written into the RAM but not yet converted into line dialing. The third counter (P2) gives the real capacity of the redial register. Redial features Capacity If more than 23 codes are entered into the RAM memory, overflow results and the excess codes replace the data in the lower numbered RAM locations. In this event, automatic redial is no longer possible. Storage Storage pertains to the dialing codes 0 to 9, *, #, pause, A, B, C and D. It is independent of the dialing mode (pulse dialing or DTMF dialing).The storage generally contains the last digits transmitted. Use of redial The use of redial is always possible except if the content of the RAM is empty (P2 = 0). This happens when the RAM supply is not high enough , when an overflow occurred, or when previously an erroneous use of the redial occurred (start of manual dialing not equal to the content of the RAM). Rev. A1: 16.07.1996 U3750BM TELEFUNKEN Semiconductors If the redial is ordered after a manual dialing the redial is executed according to the digits already transmitted in line. The redial is effective if the comparison digit-by-digit of all digits is correct. It is not produced if the comparison is incorrect or if the number of digits exceeded the last capacity of the redial. During redial, entry codes are accepted. Procedure with * Storage does not pertain to the “*” code and the codes entered after it when the manual dialing starts with a numeric code or A, B, C, D, #, or pause codes. If the dialing starts with the “*” code, all codes can be stored. Note: the “#” code is treated for storage like a number. Procedure with flash The flash pulse does not reset the content of the RAM. Example: 1 2 3 R Redial µ å 1 2 3 R 1 2 3 Redial µ å 1 2 3 Erasing redial The erasing is possible through the serial bus with the decimal codes 16 and 23. There is not much difference between these two codes: code 16 always erases the redial, code 23 inhibits a later redial if it is transmitted after or before dialing codes. The following examples illustrates this. Transmitted Codes 123 16 Redial µ 123 Redial µ 123 Redial µ 123 Redial µ 123 Redial µ 123 Redial µ On Line 123 –nothing 23 16 4µ 23 4µ R 16 µ R 23 µ 123 – 1234 4 1234 – 123R – 123R 123 Special Case When the overflow flag is set and when the written address counter becomes equal to the read address counter, the codes are not stored. Dimensions in mm Package: PLCC 44 Rev. A1: 16.07.1996 19 (20) U3750BM TELEFUNKEN Semiconductors Ozone Depleting Substances Policy Statement It is the policy of TEMIC TELEFUNKEN microelectronic GmbH to 1. Meet all present and future national and international statutory requirements. 2. Regularly and continuously improve the performance of our products, processes, distribution and operating systems with respect to their impact on the health and safety of our employees and the public, as well as their impact on the environment. It is particular concern to control or eliminate releases of those substances into the atmosphere which are known as ozone depleting substances ( ODSs). The Montreal Protocol ( 1987) and its London Amendments ( 1990) intend to severely restrict the use of ODSs and forbid their use within the next ten years. Various national and international initiatives are pressing for an earlier ban on these substances. TEMIC TELEFUNKEN microelectronic GmbH semiconductor division has been able to use its policy of continuous improvements to eliminate the use of ODSs listed in the following documents. 1. Annex A, B and list of transitional substances of the Montreal Protocol and the London Amendments respectively 2 . Class I and II ozone depleting substances in the Clean Air Act Amendments of 1990 by the Environmental Protection Agency ( EPA) in the USA 3. Council Decision 88/540/EEC and 91/690/EEC Annex A, B and C ( transitional substances ) respectively. TEMIC can certify that our semiconductors are not manufactured with ozone depleting substances and do not contain such substances. We reserve the right to make changes to improve technical design and may do so without further notice. Parameters can vary in different applications. All operating parameters must be validated for each customer application by the customer. Should the buyer use TEMIC products for any unintended or unauthorized application, the buyer shall indemnify TEMIC against all claims, costs, damages, and expenses, arising out of, directly or indirectly, any claim of personal damage, injury or death associated with such unintended or unauthorized use. TEMIC TELEFUNKEN microelectronic GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 ( 0 ) 7131 67 2831, Fax number: 49 ( 0 ) 7131 67 2423 20 (20) Rev. A1: 16.07.1996