U6433B-FP 데이터 시트보기 (PDF) - Temic Semiconductors

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U6433B-FP

Flasher, 18-m
Shunt, Frequency Doubling Disabling

Temic Semiconductors 

U6433B

Pin Description

Pin Symbol

Function

1

GND IC ground

2

VS Supply voltage

3

REL Relay driver

4

OSC Oscillator

5

OSC Oscillator

6

VS Supply voltage

7

LD Lamp failure detection

8

SI Start input (49a)

GND 1

8 SI

VS 2

REL 3

7 LD

U6433B

6 Vs

OSC 4

5 OSC

13298

Figure 2. Pinning

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):

where

[f1

R1

1

C1

1.5 Hz

 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-

mized layer resistance from point VS / shunt to Pin 6 is

recommended.

Pin 7, Lamp outage detection

Control Signal Threshold 1 ( 49-mV Comparator K1)

The detection point for lamp failure can be calculated

from the control signal threshold, typically 49 mV with

VS = 12 V. With a measuring resistance of R3 = 18 mW,

the frequency change-over is reached at a lamp load of

21 W + 11.4 W. The variation of the control signal

threshold supply voltage takes into account the PTC char-

acteristic of filament lamps.

Control Signal Threshold 2 ( 8-mV Comparator K4)

A voltage drop at R3 between 49 mV and 8 mV shunt

resistor lets the flasher work in frequency doubling mode.

If the voltage drop decreases to a value below

VR3MAX = 8 mV, frequency doubling is disabled. This

can be achieved either with a switch which by-passes the

shunt resistor ( e.g., a special hazard warning switch ) or

with a small lamp load.

The arrangement of the supply connections to Pins 2 and

6 must ensure that, on the connection, PCB, the layer

resistance from VS to Pin 6 is lower than the one to Pin 2.

y Flasher operation starts with a lamp load of PL 1 W.

Pin 8, Start input

Start condition for flashing: the voltage at Pin 8 has to be

below K3 threshold (flasher switch closed).

u Humidity and dirt may decrease the resistance between

49 a and GND. If this leakage resistance is 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.

2 (5)

Rev. A3, 07-Jun-99

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