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U643B
Flasher, 30-mW Shunt
Description
The bipolar integrated circuit U643B is used in relaycontrolled automotive flashers where a high-level EMC is required. Lamp outage is indicated by frequency doubling during hazard warning as well as direction mode.
Features
D Temperature and supply voltage compensated flashing frequency D Frequency doubling indicates lamp outage D Relay driver output with high current carrying capacity and low saturation voltage D Minimum lamp load for flasher operation: 1 W D Very low susceptibility to EMI D Protection according to ISO/TR 7637/1 level 4
Block Diagram
+ VS + 49 6 C1 4 Measuring comparator K 1 V6-81 mV 20 kW K1 2 R3 Shunt 5 kW 7 30 mW
K2 R1 Pulse generator 3 49 a-Comparator K2 20 kW 49 a-Comparator K3 K3 23 V 20 kW 5 kW IC Ground 1
95 9756
Relay 8 R2 49 a 1.5...2.2 kW
5
R4 470 W 5 W 21 W 21 W 21 W 21 W 5 W Indicator lamps GND - 31
Figure 1. Application circuit as a car flasher, Resistor R1 and R2: 1/4 Watt R4 for protection against continuous reversed polarity: 0.5 Watt
Ordering Information
Extended Type Number U643B U643B-FP Package DIP8 SO8 Remarks
Rev. A3, 10-Apr-01
1 (5)
U643B
Pin Description
Pin 1 2 3 4 5 6 7 8 Symbol GND VS REL OSC OSC VS LD SI IC ground Supply voltage VS Relay driver C1 Oscillator R1 Oscillator Supply voltage VS Lamp failure detection Start input (49a)
Figure 2. Pinning OSC REL 3 4 VS 2 7 LD
Function
GND 1 8 SI
U643B
6 Vs
5
OSC
94 9290
Functional Description
Pin 1, GND The integrated circuit is protected against damage via resistor R4 to ground (-31) in the case of battery reversal. An integrated protection circuit together with external resistances R2 and R4 limits the current pulses in the IC. Pin 2, Supply voltage, VS - Power The arrangement of the supply connections to Pin 2 must be so as to ensure that, on the connection printed circuit board (PCB), the resistance of VS to Pin 6 is lower than that to Pin 2. Pin 3, Relay control output (driver) The relay control output is a high-side driver with a low saturation voltage and capable to drive a typical automotive relay with a minimum coil resistance of 60 W. Pin 4 and 5 Oscillator Flashing frequency, f1, is determined by the R1C1 components as follows (see figure 1): f1 [ where 1 C1 Hz mized layer resistance from point VS / shunt to Pin 6 is recommended. Pin 7, Lamp outage detection The lamp current is monitored via an external shunt resistor R3 and an internal comparator K1 with its reference voltage of typ. 81 mV (VS = 12 V). The outage of one lamp out of two lamps is detected according to the following calculation: Nominal current of 1 lamp: 21 W / (VS = 12 V): Ilamp = 1.75 A Nominal current of 2 lamps: 2 x 21 W / (VS = 12 V): Ilamp = 3.5 A. The detection threshold is recommended to be set in the middle of the current range: Ioutage [ 2.7 A Thus the shunt resistor is calculated as: R3 = VT (K1) / Ioutage R3 = 81 mV/2.7 A = 30 mW. Comparator K1`s reference voltage is matched to the characteristics of filament lamps (see "control signal threshold" in the data part). The combination of shunt resistor and resistance of wire harness prevents Pin 7 from a too high voltage in the case of shorted lamps. Pin 8, Start input Start condition for flashing: the voltage at Pin 8 has to be below K3 threshold (flasher switch closed). Humidity and dirt may decrease the resistance between 49 a and GND. If this leakage resistance is u 5 kW the IC is still kept in its off-condition. In this case the voltage at Pin 8 is between the thresholds of comparators K2 and K3. During the bright phase the voltage at Pin 8 is above the K2 threshold, during the dark phase it is below the K3 threshold. For proper start conditions a minimum lamp wattage of 1 W is required.
R1
1.5
C1 47 mF R1 + 6.8 kW to 510 kW
In the case of a lamp outage (see Pin 7) the oscillator frequency is switched to the lamp outage frequency f2 with f2 [ 2.2 f1. Duty cycle in normal flashing mode: 50% Duty cycle in lamp outage mode: 40% (bright phase) Pin 6, Supply voltage, Sense For accurate monitoring via the shunt resistor, a mini-
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Rev. A3, 10-Apr-01
U643B
Absolute Maximum Ratings
Reference point Pin 1 Parameters Supply voltage Surge forward current tP = 0.1 ms Pin 2 and 6 tP = 300 ms Pin 2 and 6 tP = 300 ms Pin 8 Output current Pin 3 Power dissipation Tamb = 95C Tamb = 60C Junction temperature Ambient temperature range Storage temperature range DIP 8 SO 8 DIP 8 SO 8 Ptot Ptot Ptot Ptot TJ Tamb Tstg 420 340 690 560 150 -40 ... + 95 -55 ... + 150 mW mW mW mW C C C IFSM IFSM IFSM IO 1.5 1.0 50 0.3 A A mA A Pin 2 and 6 Symbol VS Value 16.5 Unit V
Thermal Resistance
Parameters Junction ambient DIP8 SO8 Symbol RthJA RthJA Value 110 160 Unit K/W K/W
Electrical Characteristics
Typical values under normal operation in application circuit (see figure 1), VS (+49, Pin 2 and 6) = 12 V. Reference point ground (-31), Tamb = 25C, unless otherwise specified Parameters Supply voltage range Supply current: Dark phase Bright phase Relay output: saturation voltage reverse current Start delay Frequency tolerance Bright period Frequency increase Control signal threshold Basic frequency f1 Control frequency f2 Lamp outage VS = 15 V VS = 9 V VS = 12 V 49a to GND Pin 7 Pin 7 Pin 7 First bright phase Pin 3 IO = 150 mA, VS= 9 V with resistance = 60 W Test Conditions / Pins Pin 2 and 6 Pin 2 and 6 IS IS 4.5 45 7.0 8 11 mA mA Symbol VS (+49) Min. Typ. 9 to 15 Max. Unit V
VO IO ton df1 f1 f2 f2 VR3 VR3 VR3 RP PL 1 -5 47 37 2.15 f1 85 66 76 91 71 81 4
1.0 0.1 10 +5 53 45 2.3 f1 97 76 87 5
V mA ms % % % Hz mV mV mV kW W
Leakage resistance Lamp load
Rev. A3, 10-Apr-01
3 (5)
U643B
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
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Rev. A3, 10-Apr-01
U643B
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
Rev. A3, 10-Apr-01
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