UAA1041BD 查看數據表（PDF） - Motorola => Freescale

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UAA1041BD

Automotive Direction Indicator

Motorola => Freescale 

UAA1041B

CIRCUIT DESCRIPTION

The circuit is designed to drive the direction indicator

flasher relay. Figure 2 shows the typical system configuration

with the external components. It consists of a network (R1,

C1) to determine the oscillator frequency, shunt resistor (RS)

to detect defective bulbs and short circuits in the system, and

two current limiting resistors (R2/R3) to protect the IC against

load dump transients. The circuit can be used either with or

without short circuit detection, and features overvoltage,

defective lamp and short circuit detection.

The lightbulbs L2, L3, L4, L5 are the turn signal indicators

with the dashboard–light L6. When switch S1 is closed, after

a time delay of t1 (in our example t1 = 75 ms), the relay will be

actuated. The corresponding lightbulbs (L2, L3 or L4, L5) will

flash at the oscillator frequency, independent of the battery

voltage of 8.0 V to 18 V. The flashing cycle stops and the

circuit is reset to the initial position when switch S1 is open.

Overvoltage Detection

Senses the battery voltage. When this voltage exceeds

20.2 V (this is the case when two batteries are connected in

series), the relay will be turned off to protect the lightbulbs.

Lightbulb Defect Detector

Senses the current through the shunt resistor RS. When one

of the lightbulbs is defective, the failure is indicated by

doubling the flashing frequency.

Pin 6 has to be connected to Pin 2, and the use of capacitor

C2 is not necessary. The circuit can also be used for other

warning flashers. In this example, when the handbrake is

engaged, it is signaled by the light (L1).

Figure 2. Typical System Configuration

C2

–VCC

1

JU–1

+V

8

RS

2

7

UAA1041B

–V

3

C1 +

6

4

5

R2

R1

R3

Relay

S1

L1

L

R

L6

S2

Short Circuit Detector

Detects excessive current (Ish > 25 A) flowing in the shunt

resistor RS. The detection takes place after a time delay of t3

(t3 = 55 ms). In this case, the relay will be turned off. The

circuit is reset by switching S1 to the off position.

Operation with Short Circuit Detection

Pin 6 has to be left open and a capacitor C2 has to be

connected between Pin 1 and Pin 2.

Operation without Short Circuit Detection

L2 L3

L4 L5

PARTS LIST

R1 = 75 kΩ

Relay–Coil Resistance

R2 = 3.3 kΩ

Range 60 Ω to 800 Ω

R3 = 220 Ω

RS = 30 mΩ

Wire Resistor

Note: Per text connect

jumper JU–1 bypass

C1 = 5.6 µF

short circuit detector

C2 = 0.047 µF

C2 may be deleted also.

APPLICATION INFORMATION

1. The flashing cycle is started by closing S1. The switch

positionissensedacrossresistorR2andRLampbyInput 8.

Rst = R2 + RLamp.

The condition for the start is: Rst < 3.6 kΩ.

For correct operation, leakage resistance from Pin 8 to

ground must be greater than 5.6 kΩ.

2.

Flashing frequency:

fn =

1

R1C1Kn

3. Flashing frequency in the case of one defective lightbulb

of 21 W:

fF =

1

R1C1KF

Kn = 2,2KF

4. t1: delay at the moment when S1 is closed and first flash

t1: t1 = K1R1C

5. t2: defective lightbulb detection delay t2 = K2R1C1

6. t3: short circuit detection delay t3 = K1R1C1

In the case of short circuit – it is assumed that the voltage

(VPin2–VPin1) ≥ 8.0 V. The relay will be turned off after delay

t3. The circuit is reset by switching S1 to the off position.

The capacitor C2 is not obligatory when the short circuit

7. detector is not used. In this case Pin 6 has to be connected

to Pin 2.

When overvoltage is sensed (VPin2 – VPin1) the relay is

8. turned off to protect the relay and the lightbulbs against

excessive currents.

MOTOROLA ANALOG IC DEVICE DATA

3

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