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U840B
Digital / Wipe-Wash Control for Rear or Front Wiper
Description
The circuits U840B (DIP8) and U840B-FP (SO8) are designed as interval wipe/ wash timer for automotive applications. The interval pause t3 can be set in a range from 0.8 s to 22 s by an external 30 kW potentiometer. All other time periods are determined by the basic frequency f0 of the oscillator. The wipe/ wash (WIWA) mode has priority over the interval mode. The program Pin PP controls, whether the wiper immediatly starts to wipe, or with a delay time t4 of 0.8 s. The inputs CP and INT are digital debounced, the turn-on as well as the turn-off. The integrated relay driver is protected against short circuits and is switched to conductive condition in the case of a load-dump. The circuit is protected with the recommended external circuitry against load-dump and RF interference, refer to ISO 7637-1/3 (DIN 40839).
Features
D Interval-switch A and B to GND D Wipe/ wash push button to VBatt D Output driver protected against short circuit digital
debounced: t6 = 10 ms
D Program Pin PP determines turn-on delay t4 during
wipe-wash mode PP to GND: t4 = 0.8 s PP to VS: t4 = 0 s Interval mode: t4 = 0 s
D D D D
All time periods digital determined by RC-oscillator Turn-on time of relay t2 = 375 ms Adjustable interval pause, t3 = 0.8 to 22 s Dry wiping time t5 = 3.7 s
D Inputs CP and INT digital debounced, t1 = 100 ms D All inputs with integrated RF protection D Load-dump protected and interference protection
according to ISO 7637-1/3 (DIN 40839)
Ordering Information
Extended Type Number U840B U840B-FP Package DIP8 SO8 Remarks
Pin Description
Pin 1 2 3 4 5 6 7 8 Symbol INT CO RO PP WASH VS GND OUT Function Interval input C oscillator R oscillator Program pin Wash signal Supply voltage Ground Output INT 1 8 OUT
CO RO
2
7
GND
U840B
3 6 Vs WASH
13299
PP
4
5
Figure 4. Pinning
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U840B
Block Diagram
VS GND
CP- comparator WASH + -
Stabilization POR Load-dump - detection OUT
Logic
PP + - PP- comparator Interval comparator +- Short-circuit comparator Shunt
Oscillator
INT 1.2 k
C 1 F
R 47 k
13285
Figure 1. Block Diagram
Circuit Description
Power Supply
For reasons of interference protection and surge immunity, all circuits must be provided with an RC-circuit for current limitation in the event of overvoltages and for buffering in the event of voltage dips at VS. Suggested dimensioning: R4 = l80 W C1 = 47 mF, refer to figure 2. Between VS and GND there is an integrated 14 V Z-diode. The operation voltage is between VBatt = 9 to 16 V. The capacitor can be dimensioned smaller, if is used in the supply for a diode quad for polarity independence. In this case, there is no discharging through R4 in the event of negative interference pulses, but only a discharging from the self current input of the circuit. Typical value: 10 mF.
Pin CO and GND. The basic frequency is adjusted to 320 Hz (3.125 ms) by R6 = 39 kW and C2 = l00 nF. The tolerances and the temperature coefficients of the external devices determine the precision of the oscillator frequency. A metallic-film resistor l% and a capacitance 5% with a TC of a MKT or MKS2 capacitance is suggested. The debouncing time t1, the turn-on time of the relay t2, the delay time t4, the dry wiping time t5 and the debouncing time t6 (short circuit detection) depend on the oscillator frequency f0 as follows: Debouncing time INT, CP Turn-on time relay Interval pause Delay time wipe/wash mode Dry wiping time Debouncing time SC t1 = 24 to 32 l/f0 t2 = 120 l/f0 t3 = 296 1/fint t4 = 256 l/f0 t5 = 1184 l/f0 t6 = 2 to 3 1/f0
Oscillator
In the circuit all timing sequences are derived from an RC oscillator which is charged by an internal current source and discharged by an integrated 500-W resistor. The basic frequency f0 is determined by the resistor RO between Pin RO and GND and by the capacitance CO between 2 (8)
SC (short circuit) = collector current of relay driver IC > 500 mA. The clock counts of the debouncing times are not fixed because the switching of the signals and the system clock are asynchronous. The cause of the clock count variation is shown by the example of the short circuit debouncing (figure 2). TELEFUNKEN Semiconductors Rev. A2, 03-Feb-97
U840B
The relay output is activated. The internal logic of the IC queries the short-circuit detection SC during the positive slope of the system clock CL. A 3-stage shift register is loaded by the positive slope of clock 1, 2 and 3 and the relay output is switched off. A short circuit signal which happened after the positive slope of clock 0 is just recognized by the positive slope of clock l. Therefore the debouncing of the short signal continues two to three clock periods.
CL
The collector current is permanently measured by an integrated shunt and in the case of a short-circuit (IC > 500 mA) to VBatt, the relais output is stored disabled. The backspacing of the short-circuit buffer is possible if the switches interval and wipe/ wash are opened. A new attempt to switch on from INT or WASH cause again a switch off of the relay output, if the short-circuit still exists, otherwise the normal function is possible. The short-circuit detection is digital debounced about a period of l0 ms, so that shorter interference peaks at the power supply do not disable the output transistor because the interference peaks cause a higher current and pretend a short-circuit. During a load-dump impulse the output transistor is switched to conductive condition to prevent destruction. The short circuit detection is suppressed during the loaddump.
SC
t6
REL ON
Figure 2. The debouncing of the short circuit detection
These times can be adjusted (except t3) by variation of the external frequency determined devices. The oscillator frequency is calculated approximately with the following formula: f0
Interference Voltages and Load-Dump
The IC supply is protected by R4, C1 and an integrated Z-diode, the inputs are protected by a series resistor, integrated 14-V Z-diode and RF capacitor. The RC-configuration stabilizes the supply of the circuit during negative interference voltages so that the power-on reset (POR) does not arise and reset the function of the circuit. The relay output is protected against short interference peaks by an intergrated 28-V Z-diode, and during load-dump the relais output is switched to conductive condition for a battery voltage of greater than approximately 30 V. The output transistor is dimensioned so that it can absorb the current, produced by the load-dump pulse.
[ 1 (0.832
C2
(300
) R ))
6
The resistor between the interval switch and Pin INT determines the interval pause. During the interval pause the current source is switched, the frequency is determined by the interval resistor. After the end of the interval pause, the oscillator switches again to the basic frequency. This procedure allows interval pause times between 0.8 s to 22 s. The dependence of the interval pause t3 from the interval resistor and therefore from the position of the switch A and B is shown in table 1.
Table 1. Function table
WASH L X L L L H B 1 X 2 3 X X A 1 X 1 1 2 X INT OFF X R1+R2 R1 GND X C 1 2 1 1 1 1 OUT OFF ON INT1 INT2 INT3 WIWA Note +V OUT C 11 cycles/min 27 cycles/min 44 cycles/min
Power-on Reset
When the operating voltage is switched on, an internal power-on reset pulse (POR) is generated which sets the logic of the circuits to defined intinial condition. The relay output is disabled, the short circuit buffer is reset.
Functional Description
Interval Function
By closing the interval switch A and/or B to GND (refer to function table l) for a time longer than the debouncing time t1 = l00 ms the relay is activated for a time of t2 = 375 ms, whereafter the interval pause begins. The oscillator switches to a frequency which is determined by R1 to R3. At the end of the interval pause, t3, the relay is activated for a time t2. If, during the turn-on time of the relay, the switches A and B are opened (also the opening is debounced), then the 3 (8)
Relay Output
The relay output is an open-collector Darlington transistor with integrated 28-V Z-diode for limitation of the inductive cut-out pulse of the relais coil. The maximum static collector current must not exceed 300 mA and saturation voltage is typically 1.2 V for a current of 200 mA. TELEFUNKEN Semiconductors Rev. A2, 03-Feb-97
U840B
time t2 runs off, one turn of the wiper arm is finished. Afterwards it the interval mode can be immediatly activated. The resistor between the interval switch and Pin INT determines the interval pause. The circuit U840B is so dimensioned, that a linear resistor-time-characteristic is used. Therefore, a doubling of the resistor evokes a doubling ot the interval pause. With the help of the resistor R3 the characteristic can be shifted parallel to its axis. The resistors R1 and R2 keep their values. An increasing of R3 shifts the characteristic to longer interval pauses. With it the interval pause can be adjusted to the demanded values by the dimensioning of R3. The resistor R3 must not be smaller than l kW, otherwise the linearity of the resistor-time-characteristic cannot be guaranteed and too great a current flows from the input INT to GND. The input PP is connected to ground, the debouncing time of the WIWA mode is extended for 800 ms. The water is sprayed on the windscreen before the wiper begins its job. PP to GND: 0.8 s delay time PP to VS: 0.1 s delay time
Interval Wipe/Wash Mode
The interval function is interrupted when the wash button is operated. In this case, the 0.8 s delay time t4 is reduced to the 100 ms debouncing time. Interval function begins after the wipe/ wash function is over.
Switch Contact Currents
The contact current of the interval switch is 0.6 to 3 mA. Of course the current depends on the position of the interval switches. The contact current of the wash button is fixed by the internal resistance of the water pump. A pull-down resistor is integrated at the input WASH. Therefore, the input is connected to ground in the case of an open wash push button and a pump which is not connected.
Wipe/ Wash Releasing and Program Pin PP
After operating the wash button, the relay is activated after the debouncing (Pin PP connects to VS). As long as the button is pushed, water is sprayed on the windscreen by the water pump. After releasing the wash button, after 100 ms reverse debouncing, the dry wiping time t5 begins to start. At the end of the dry wiping time the relay is disabled.
V Batt
Input Leakage Resistance
With a resistor more than 40 kW between INT to GND the interval function is not activated. The wipe/ wash function is not activated by a leakage resistance > 10 kW and recommended external circuitry.
R 4 180 R 5 10 k 8 7 6 5 C 1 47 F
U840B
Water pump M R 3 1.4 k R 1 1.3 k R 2 4.7 k 2 1 C 2 1 A 3 2 1 B
13286
1
2
3
4 R 6 39 k
C 2 100 n F
Wiper motor M Park switch
Figure 3. Application circuit with interval and WIWA operation
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U840B
Absolute Maximum Ratings
Parameters Supply voltage Ambient temperature range Storage temperature range max. junction temperature t = 60 s t=1h Symbol VS VS Tamb Tstg TJ Value 24 18 -40 to +100 -55 to +125 150 Unit V V C C C
Thermal Resistance
Parameters Junction ambient DIP8 SO8 Symbol RthJA RthJA Value 110 160 Unit K/W K/W
Electrical Characteristics
VBatt = 13.5 V, Tamb = 25C, reference point ground (Pin 7) circuit with recommended external circuitry Parameters Test Conditions / Pin Symbol Min. 9 Typ. Max. 16 3 4 180 47 14 14 25 1 40 14 13 0.5 * VS 120 14 25 0.5 10 20 1.0 1.2 60 VS 60 Unit V mA V
Supply Supply voltage range VS Supply current, all pushI6 buttons open Undervoltage threshold V6 POR Series resistance RV Filter capacitance CS Internal Z-diode V6 INT input (Pin 1) Protective diode V1 Internal capacitance C1 External resistance RINT Leakage resistance RL PP input (Pin 4) Protective diode V4 Internal capacitance C4 Threshold V4 Pull-down resistance R4 WASH-input (Pin 5) Protective diode V5 Internal capacitance C5 Threshold V5 Leakage resistance RL Pull-down resistance R5 Relay output with limitation of short circuit current (Pin 8) Saturation voltage 100 mA V8 Saturation voltage 200 mA V8 Relay coil resistance RREL TELEFUNKEN Semiconductors Rev. A2, 03-Feb-97
W mF
V V pF kW kW V pF V kW V pF V kW kW V V
W
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U840B
Parameters Test Conditions / Pin Output current Normal operation Output pulse current Load dump Internal Z-diode Short circuit threshold Oscillator input Oscillator capacitance, Pin 2 ( 5%, TC MKT, MKS2) Oscillator resistance, Pin 3 ( 1% TC) Oscillator frequency Upper switching point Lower switching point Internal discharge resistance Times External circuitry see oscillator input Debouncing time CP, INT Interval turn-on time Interval pause Turn-on delay Wipe/ wash mode, PP to GND Dry wiping time Debouncing time short circuit tD = debouncing time 1. Interval cycle time 2. Interval cycle time 1. Interval cycle time Symbol I8 I8 V8 I8 C2 28 500 100 Min. Typ. Max. 300 1.5 Unit mA A V mA nF
R6 f0 V2 V2 R2
39 320 3 1 500
kW Hz V V
W
t1 t2 t3 t4 + tD
67 300 0.8 800
110 450 22 1000
ms ms s ms
t5 + tD t6
3400 6
4200 11
ms ms
t2 + t3,1 t2 + t3,2 t2 + t3,3
1200 1980 4900
1500 2450 6100
ms ms ms
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U840B
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
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U840B
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
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