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| U2642B Intermittent- and Wipe/ Wash Control for Wiper Systems Description With the U264xB, Atmel Wireless & Microcontrollers developed a family of intermittent- and wipe/wash control circuits for windshield or backlite wiper systems with identical basic functions. The circuit design provides the possibility to generate "x" versions using different metallization masks. Thus, it is easy to verify a broad range of time sequences which can be set independently of each other. Features D Relay activation can be controlled by a limit switch of the wiper motor or by a fixed activation period for systems without limit switch D Debounced input stages D Enable/disable of pre-wash delay by program pin D Polarity of WIWA: VBatt D Polarity of INT: VBatt D Relay output is protected with a clamping diode D Relay activation: D Interval pause: D After wiping: D Pre-wash delay: 0.64 s 10 s 5.8 s 0.91 s D Wipe/wash mode with priority D Protected in accordance to ISO/TR 7637-1 D EMC with intergrated filters Block Diagram VS OSC Voltage stabilization and POR Oscillator INT 21 V WIWA 21 V LS 21 V PP 21 V Input comparator Logic Loaddump detection and output control Open-collector relay driver REL 21 V GND 13944 Figure 1. Block diagram Ordering Information Extended Type Number U2642B U2642B-FP Package DIP8 SO8 Remarks Rev. A4, 05-Apr-01 1 (10) U2642B Pin Description Pin 1 2 3 4 5 6 7 8 Symbol INT WIWA LS PP GND REL VS OSC Function Intermittent input Wipe/wash (WIWA) input Limit switch (wiper motor) input Program pin Ground Relay output Supply voltage RC oscillator input Figure 2. Pinning INT WIWA LS PP 1 2 3 4 8 7 6 5 OSC VS REL GND 13365 Functional Description All times specified below refer to an oscillator frequency of 200 Hz. Figures 2 to 9 show the dependencies of the times upon battery voltage and temperature. The temperature dependence of the oscillator frequency is essentially determined by the temperature coefficient of the oscillator capacitor. The temperature dependence of the oscillator frequency can be reduced to minimum with a slightly negative temperature coefficient (N100). The capacitor used in figures 10 and 11 has a slightly positive temperatur coefficient. All times are permanently set and can be changed only jointly within certain limits by adjusting the oscillator frequency. See table 1. Interval Pause The interval pause tINT = 10 s follows tON. Opening of switch INT causes a debounce time, tD, and reclosing results in the relay on-time, tON, after tD. Wipe/Wash Function without Pre-Wash Delay (PP connected to GND) The water pump is switched on when the switch WIWA is pressed and, after the debounce time, tD, the relay is energized. After-wiping time tAW = 5.8 s starts as soon as switch WIWA is opened and the debounce time, tD, has expired. If the limit switch is connected, the relay remains energized until the wiper arm returns to park position, i.e., the motor current flows via the relay contact only. Intermittent Function The relay is energized for the time tON after the switch INT is switched on with respect to VBatt and after expiration of time tD (debounce). The debounce time ranges between 60 ms and 80 ms. A time period of 5 ms to 40 ms for internal sequence control must be added (asynchronism between operating instant and internal clock) e.g., the response time may range from 65 ms up to 120 ms. If the limit switch of the windscreen wiper motor is connected to Pin LS, the relay is energized as long as the switch is at high potential, regardless of the relay on-time, tON, i.e., the motor current in interval mode flows via the relay contact only. In park position, the motor winding at both ends is connected to ground via the limit switch and the motor is decelerated immediately. The limit switch input is debounced with tDL = 17 ms. The relay on-time, tON, always elapsed - even if the interval switch was opened beforehand. Wipe/Wash Function with Pre-Wash Delay (PP connected to VS) In wipe/wash mode, the relay is energized after a delay time. The water pump can spray water onto the windscreen during the delay time, tDEL. The on-delay time of the U2641B is: tDEL = tD + 0.84 s = 0.91 s If switch WIWA is closed longer than tD but shorter than tDEL, the after-wiping time, tAW, starts after expiration of tDEL. The wipe/wash function with or without on-delay tDEL can be selected by programming PP. PP connected to GND: PP connected to VS: without pre-wash delay with pre-wash delay The after-wiping time, tAW, is re-triggerable in both cases. 2 (10) Rev. A4, 05-Apr-01 U2642B Intermittent and Wipe/Wash Mode The wipe/wash function has priority over the interval function. If switch WIWA is closed during the interval function, wipe/wash mode is activated immediately after the debounce time, tD, even if an on-delay is programmed (tDEL = 0 s). Expiry of tAW is directly followed by the next relay on-time, tON, of intermittent mode. Power Supply For reasons related to protection against interference and destruction, the Pin VS must be provided with an RC network for limiting the current in the event of overvoltage and for buffering in the event of voltage drops. Proposed ratings: RV = 510 W, CV = 47 mF. An integrated 14-V Zener diode is connected between VS and GND. Oscillator All timing sequences are derived from an RC-oscillator whose charging time, t1, is determined by an external resistor ROSC and whose discharging time, t2, is determinated by an integrated 2-kW resistor. Since tolerance and temperature response of the integrated resistor are far higher than those of the external resistor, t1/t2 must be selected to be greater than 20 for stability reasons. The minimum value of ROSC should not be less than 68 kW. Calculating cycle duration and frequency: t = t1 + t2 = COSC fOSC = 1/t ( 0.74 ROSC + 2260 W) Interference Voltages and Load-Dump In the case of transients, the integrated Zener diode limits the voltage of the relay output to approximately 28 V. In the case of load-dump, a current (dependent upon RV and CV) flows through the integrated 14-V Zener diode, and the relay output is switched on at VBatt > 30 V in order to avoid destruction of the output. The output transistor is rated such that it can withstand the current generated during the load-dump through the relay coil. In practice, the windscreen wiper motor is switched on via the relay and thus the amplitude of the load-dump pulse is limited. The supply voltage of the circuit is limited to 14 V by the integrated Zener diode, and the inputs are protected by external protective resistors and integrated Zener diodes. RF suppression is implemented with a low-pass filter at the inputs, consisting of a protective resistor and the integrated capacitor. and Calculating the capacitor for a given resistor: COSC = t / ( 0.74 ROSC + 2260 W) Calculating the oscillator resistance for a given capacitor: ROSC = 1.34 ( t / COSC - 2260 W) Recommended frequency: fOSC = 200 Hz (for ROSC = 200 kW, COSC = 33 nF) All times can be varied jointly within specific limits by varying the oscillator frequency (see table 1). The oscillator is operable up to 50 Hz. Table 1 Change in times by varying the oscillator frquency fosc (Hz) 100 120 140 160 180 200 220 240 260 280 300 400 tD [ms] 140 116 100 87 77 70 64 58 54 50 46 35 tDL [ms] 35 29 25 22 19 17 16 14 13 12 11 9 Power-on Reset (POR) When the supply voltage is applied, a power-on reset pulse is generated which sets the circuit's logic to a defined initial state. The POR threshold is approximately VS = 4.3 V. tON [ms] 1280 1066 915 800 710 640 581 533 493 457 426 320 tINT [s] 20.0 17.0 14.0 12.5 11.0 10.0 9.0 8.2 7.6 7.0 6.5 5.0 tAW [s] 11.6 9.6 8.3 7.2 6.4 5.8 5.3 4.8 4.5 4.1 3.9 2.9 tDEL [s] 1680 1400 1200 1050 933 840 763 700 645 600 560 420 Rev. A4, 05-Apr-01 3 (10) U2642B Absolute Maximum Ratings With recommended external circuitry Parameter Supply voltage (static) Supply current pulse Supply current pulse Relay output current (static) Relay output current pulse Ambient temperature range Storage temperature range Power dissipation Power dissipation DIP8 SO8 300 ms Test Conditions 5 min 2 ms 300 ms Symbol VBatt IS IS IREL IREL Tamb Tstg Ptot Ptot Value 24 1.5 150 300 1.5 -40 to +95 -55 to +125 0.45 0.34 Unit V A mA mA A C C W W Thermal Resistance Parameters Junction ambient Junction ambient DIP8 SO8 Symbol RthJA RthJA Value 120 160 Unit K/W K/W Electrical Characteristics Reference point Ground GND, Tamb = 25_C, VBatt = 13.5 V, unless otherwise specified (see figures 11 and 12) Parameters Voltage supply Supply voltage Supply current Undervoltage threshold (POR) Internal Z-diode Internal capacitor Series resistance Filter capacitor Oscillator input OSC Internal discharge resistor Lower switching-point voltage Upper switching-point voltage Input current Oscillator frequency Test Conditions / Pin Pin 7 Symbol VBatt IS VS VZ CS RV CV Pin 8 RDIS VOSC VOSC VOSC = 0 V -IOSC fOSC 1.3 2.0 3.2 0.16 VS 0.20 VS 0.24 VS 0.55 VS 0.60 VS 0.65 VS kW V V mA Hz Min 6.0 0.5 3.0 13.5 Typ Max 16.0 3.0 5.1 16.2 Unit V mA V V pF W mF 2.0 14.0 15 510 47 1 200 2 50 k Note: All internally generated time sequences are derived from the oscillator frquency. The tolerances refer to a frequency adjusted to fOSC = 200 Hz. 4 (10) Rev. A4, 05-Apr-01 U2642B Electrical Characteristics (continued) Reference point Ground GND, Tamb = 25_C, VBatt = 13.5 V, unless otherwise specified (see figures 11 and 12) Parameters Test Conditions / Pin Symbol Input limit switch LS Pin 3 Internal protection-diode ILS = 10 mA VLS voltage Internal capacitor CLS Switching threshold VLS voltage Input current VLS = VS ILS Internal pull-up resistor RLS External protection resistor RS Inputs INT, WIWA and PP Pins 1, 2 and 4 Internal protection-diode IE = 10 mA VE voltage Internal capacitor CE Switching threshold VE voltage Input current VE = 0 V -IE Internal pull-down resistor RE External protection resistor RS Relay Output Pins 6 Saturation voltage I = 100 mA VREL Saturation voltage I = 200 mA VREL Z-diode clamp voltage I = 10 mA VREL Leakage current V = 14 V IREL Relay coil resistance RREL Load-dump protection VBatt threshold Internal pulse times Debouncing period inputs INT/WIWA 12 - 16 clocks tD Debouncing period inputs LS 3 - 4 clocks tDL Relay activation time 96 clocks tON Intermittent pause tINT After wiping period 1024 " 68 clocks tWIWA Pre-wash delay reaction 88 - 96 clocks tDEL time for switch-on delay = tDEL + tD Min 19.5 Typ 21.0 25 0.375 VS 0.5 VS 0.675 VS Max 25.5 Unit V pF V mA kW kW V pF V mA kW kW V V V mA W V 13 10 19.5 20 1 27 21.0 25 25.5 0.375 VS 0.5 VS 0.675 VS 13 10 20 1 27 19.5 60 28 21.0 1.1 1.5 25.5 12 42 33 60 15 70 17.5 480 5.92 80 20 4.78 440 5.46 480 ms ms ms s s ms Note: All internally generated time sequences are derived from the oscillator frquency. The tolerances refer to a frequency adjusted to fOSC = 200 Hz. Rev. A4, 05-Apr-01 5 (10) U2642B 1.0 0.9 0.8 0.7 t ON ( s ) 0.6 0.5 0.4 0.3 0.2 0.1 0.0 6 8 10 12 VBatt (V) 14 16 18 t AW ( s ) 10 9 8 7 6 5 4 3 2 1 0 6 8 10 12 VBatt (V) 14 16 18 min max Figure 3. Relay activation = f (VBatt) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 6 8 10 12 VBatt (V) 14 16 18 1.4 1.2 1.0 t DEL( s ) 0.8 0.6 0.4 0.2 0.0 6 Figure 5. After-wipe time = f (VBatt) max min t INT ( s ) 8 10 12 VBatt (V) 14 16 18 Figure 4. Interval pause = f (VBatt) Figure 6. Pre-wash delay = f (VBatt) 6 (10) Rev. A4, 05-Apr-01 U2642B 0.8 0.7 0.6 t ON ( s ) 0.5 0.4 0.3 0.2 -40 t AW ( s ) 8 7 max 6 5 4 3 2 1 0 -40 min -20 0 20 40 60 Temperature (C ) 80 100 -20 0 20 40 60 80 100 Temperature (C ) Figure 7. Relay activation = f (Temperature) 1.2 1.0 t DEL( s ) 0.8 0.6 0.4 0.2 -40 max min Figure 9. After-wipe time = f (Temperature) 12 10 8 t INT ( s ) 6 4 2 0 -40 -20 0 20 40 60 80 100 -20 0 Temperature (C ) 20 40 60 Temperature (C ) 80 100 Figure 8. Pre-wash delay = f (Temperature) Figure 10. Interval pause = f (Temperature) Note: The temperature characteristic is caused by the temperature coefficient TC of the external capacitor Rev. A4, 05-Apr-01 7 (10) U2642B Application Examples Kl 15 Rv 510 Rosc 200 k CV 47 F Cosc 33 nF 8 7 6 5 U2642B 1 INT Rs 10 k 2 3 Rs 10 k 4 WIWA Water- M pump M Wiper- motor 13907 Figure 11. Application without limit switch Kl 15 Rv 510 Rosc 200 k CV 47 F Cosc 33 nF 8 7 6 5 U2642B 1 INT Rs 10 k Rs 10 k WIWA Water- M pump Wiper- M motor Limit- switch 13908 2 3 4 Rs 10 k Figure 12. Application with limit switch 8 (10) Rev. A4, 05-Apr-01 U2642B Package Information Package DIP8 Dimensions in mm 9.8 9.5 1.64 1.44 7.77 7.47 4.8 max 6.4 max 0.5 min 0.58 0.48 7.62 8 5 2.54 3.3 0.36 max 9.8 8.2 technical drawings according to DIN specifications 13021 1 4 Package SO8 Dimensions in mm 5.00 4.85 1.4 0.4 1.27 3.81 8 5 0.25 0.10 0.2 3.8 6.15 5.85 5.2 4.8 3.7 technical drawings according to DIN specifications 13034 1 4 Rev. A4, 05-Apr-01 9 (10) U2642B Ozone Depleting Substances Policy Statement It is the policy of Atmel Germany 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. Atmel Germany GmbH 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. Atmel Germany GmbH 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 Atmel Wireless & Microcontrollers products for any unintended or unauthorized application, the buyer shall indemnify Atmel Wireless & Microcontrollers 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. Data sheets can also be retrieved from the Internet: http://www.atmel-wm.com Atmel Germany GmbH, P.O.B. 3535, D-74025 Heilbronn, Germany Telephone: 49 (0)7131 67 2594, Fax number: 49 (0)7131 67 2423 10 (10) Rev. A4, 05-Apr-01 |
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