ATMEL U643B-FP, U643B Datasheet

Flasher, 30-m Shunt

Description

The bipolar integrated circuit U643B is used in relay­controlled automotive flashers where a high-level EMC
is required.

Features

 Temperature and supply voltage compensated

flashing frequency

 Frequency doubling indicates lamp outage
 Relay driver output with high current

carrying capacity and low saturation voltage

Block Diagram

6

C

1

4

Measuring comparator K

V6–81 mV

K

1

1

20 k 5 k

U643B

Lamp outage is indicated by frequency doubling during
hazard warning as well as direction mode.

 Minimum lamp load for flasher operation: ≥ 1 W
 Very low susceptibility to EMI
 Protection according to ISO/TR 7637/1 level 4

2

R

3

Shunt

7

30 m

+ V

+ 49

S

K

2

1

3

8

1.5...2.2 k

Relay

R

2

R

4

470 

GND

– 31

5

95 9756

Pulse

generator

49 a–Comparator K

49 a–Comparator K

K

3

2

20 k

3

23 V

20 k 5 k

IC Ground

R

1

Figure 1. Application circuit as a car flasher , Resistor R1 and R2: 1/4 W att

for protection against continuous reversed polarity: 0.5 Watt

R

4

Ordering Information

Extended Type Number Package Remarks

U643B DIP8

U643B-FP SO8

49 a

21 W 21 W 5 W21 W21 W5 W

Indicator lamps

Rev. A3, 10-Apr-01 1 (5)

U643B

Pin Description

Pin Symbol Function

1 GND IC ground
2 V
3 REL Relay driver
4 OSC C1 Oscillator
5 OSC R1 Oscillator
6 V
7 LD Lamp failure detection
8 SI Start input (49a)

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 R

Pin 2, Supply voltage, V
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 .

Pin 4 and 5 Oscillator
Flashing frequency, f1, is determined by the R1C1 compo­nents as follows (see figure 1):

f

Supply voltage V

S

Supply voltage V

S

limits the current pulses in the IC.

4

- Power

S



1

1

R1 C1 1.5

S

S

Hz

1

GND

V

2

S

SI

8

7

LD

U643B

3

REL

4

OSC

Figure 2. Pinning

mized layer resistance from point V
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 (V
of one lamp out of two lamps is detected according to the
following calculation:
Nominal current of 1 lamp: 21 W / (V
I

= 1.75 A

lamp

Nominal current of 2 lamps: 2 x 21 W / (V
I

= 3.5 A.

lamp

The detection threshold is recommended to be set in the
middle of the current range: I

outage

Thus the shunt resistor is calculated as:
R

= V

(K1) / I

3

T

R

= 81 mV/2.7 A = 30 m.

3

outage

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.

6

Vs

OSC

5

94 9290

/ shunt to Pin 6 is

S

= 12 V). The outage

S

= 12 V):

S

= 12 V):

S

 2.7 A

where C1  47 F

R1  6.8 k to 510 k

In the case of a lamp outage (see Pin 7) the oscillator
frequency is switched to the lamp outage frequency f
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-

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  5 k the IC

2

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.

Rev. A3, 10-Apr-012 (5)

Absolute Maximum Ratings

t

P

ms Pin 2 and 6

I

FSM

1.5

A

t

P

300 ms Pin 2 and 6

I

FSM

1.0

A

SO 8

P

tot

340

mW

saturation voltage

I

O

150 mA, V

S

V

Reference point Pin 1

Parameters Symbol Value Unit
Supply voltage Pin 2 and 6 V
Surge forward current

t

= 0.1 ms Pin 2 and 6 I

= 0.1

tP = 300 ms Pin 2 and 6

=

t

= 300 ms Pin 8

P

Output current Pin 3 I
Power dissipation

T

= 95°C DIP 8

amb

SO 8

T

= 60°C DIP 8

amb

SO 8
Junction temperature T
Ambient temperature range T
Storage temperature range T

Thermal Resistance

I

FSM

I

FSM

P
P
P
P

S

O

tot
tot
tot
tot

J

amb

stg

U643B

16.5 V

1.5 A

1.0
50

0.3 A

420
340
690
560

150 °C

–40 ... + 95 °C

–55 ... + 150 °C

A

mA

mW
mW
mW
mW

Parameters Symbol Value Unit

Junction ambient DIP8

SO8

R
R

thJA
thJA

Electrical Characteristics

Typical values under normal operation in application circuit (see figure 1), V
Reference point ground (–31), T

Parameters Test Conditions / Pins Symbol Min. Typ. Max. Unit
Supply voltage range Pin 2 and 6 V
Supply current: Pin 2 and 6

Relay output:

saturation voltage

reverse current
Start delay First bright phase t
Frequency tolerance f

Bright period Basic frequency f

Frequency increase Lamp outage f
Control signal threshold VS = 15 V Pin 7

Leakage resistance 49a to GND R
Lamp load P

= 25°C, unless otherwise specified

amb

S

Dark phase
Bright phase

Pin 3

I

= 150 mA, V

O

= 9 V

9

S

with resistance = 60  V

Control frequency f

1

2

V

V

= 9 V Pin 7

S

V

= 12 V Pin 7

S

V
V

(+49) 9 to 15 V

I

S

I

S

O

I

O

on

1

∆f

1

∆f

2

2

R3
R3
R3

P
L

2.15 f

110
160

(+49, Pin 2 and 6) = 12 V.

S

4.5

7.0

8

11

K/W
K/W

mA
mA

1.0

0.1

mA

10 ms
–5 +5 %
47

37

85
66
76

1

91
71
81

53

45

2.3 f
97

76
87

1

Hz

mV
mV
mV

4 5 k

1 W

V

%
%

Rev. A3, 10-Apr-01 3 (5)

U643B

Package Information

Package DIP8

Dimensions in mm

9.8

9.5

1.64

1.44

4.8 max

0.5 min

0.58

0.48

85

14

2.54

7.62

3.3

technical drawings
according to DIN
specifications

7.77

7.47

6.4 max

0.36 max

9.8

8.2

13021

Package SO8

Dimensions in mm

5.00

4.85

1.4

0.4

1.27

3.81

85

14

0.25

0.10

5.2

4.8

3.7

3.8

6.15

5.85

technical drawings
according to DIN
specifications

0.2

13034

Rev. A3, 10-Apr-014 (5)

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: [phone], Fax number: 49 (0)7131 67 2423

Rev. A3, 10-Apr-01 5 (5)