CA3165 Ver la hoja de datos (PDF) - Intersil

Número de pieza

componentes Descripción

Fabricante

CA3165

Electronic Switching Circuit

Intersil 

CA3165

+13V

R1

820

200

220

1W

1W

5%

±5%

6

5

CA3165E 4

TOP

7

VIEW

3

8

2

0.01µF

C6

C3

0.01µF

L1 SENSOR COIL,

INDUCTANCE ≈ 100µH,

UNLOADED Q ≈ 53

1

R6

220

6490 ± 0.15%

C2

L1

1500pF

SILVER

MICA

METALLIC TRIGGER WHEEL,

ONE TOOTH PER CYLINDER

VOUT

ALL RESISTORS 1/2 W ±5%

UNLESS OTHERWISE SPECIFIED

RESISTOR VALUES IN OHMS

FIGURE 6. TYPICAL IGNITION SYSTEM USING THE CA3165E

Application Information

Figure 5 and Figure 6 show the application of the CA3165 in

a typical ignition system. The oscillator on the chip operates

at about 400kHz as determined by the tuned circuit L1, C2.

The amplitude of the oscillation is detected on the chip and

applied to a Schmitt trigger which sets the terminal voltage

as shown in the chart in Figure 1 and Figure 2 for the

unloaded condition of the oscillator. As a metallic tooth in the

rotor passes the coil L1, eddy-current losses occur which

reduce the Q of the resonant circuit and decrease the ampli-

tude of the oscillations to a level below that of a reference in

the detector circuit. The output terminals are then switched

to states as shown in the chart in Figure 1 and Figure 2 for

the loaded condition of the oscillator. The oscillation is main-

tained at this lower amplitude by switching in additional feed-

back in the oscillator circuit. The fact that the oscillator

continues to operate at some minimum level during this

dwell period eliminates timing variations which would occur if

the oscillator had to be restarted by random noise.

Spark occurs as terminal 4 is switched from high to low. The

output amplifier clamps terminal 4 low through the regulator

during the duration of the spark.

The Dwell period represents the time that terminal 10

(CA3165E1) or terminal 6 (CA3165E) is high, terminal 4 is

low, and the coil is charged.

The value of the oscillator feedback, resistor, RF, is selected

to set the dwell period. With a sintered-iron 8 f-tooth rotor, a

typical value of RF is 6500Ω for 28.5 degrees of dwell out of

a 45 degree cycle. For a star-type rotor and a particular coil

in a typical distributor, the feedback resistor would be larger

(typically 8800Ω) depending on clearances, coil geometry

and tooth shape.

For typical F-Tooth Rotor with Rod Sensor and 113µH of coil

inductance, the Q and frequency with respect to rotor posi-

tion was measured for the following positions

CENTER 46 at 377kHz

SLOT

6 at 390kHz

FIRE

15 at 381kHz

(Free air Q = 55.7 at 375kHz.)

OSCILLATOR

OSC

LOADED

DWELL

PERIOD

OSC

UN-

LOADED

HIGH

DETECTOR

TERM 10

LOW

HIGH

TERM 4

LOW

SPARK

DWELL

COIL

CHARGE

DWELL

FIGURE 7. TIMING SEQUENCE

10-30

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