SGS Thomson Microelectronics L497, L497D1, L497B Datasheet

HALLEFFECT PICKUPIGNITION CONTROLLER

.DIRECT DRIVING OF THE EXTERNAL

POWERDARLINGTON

.

COIL CURRENT CHARGING ANGLE (dwell)
CONTROL

.

PROGRAMMECOILCURRENT PEAKLIMITA­TION

.PROGRAMMABLEDWELL RECOVERY TIME

WHEN 94 % NOMINAL CURRENT NOT
REACHED

.

RPMOUTPUT

.PERMANENTCONDUCTION PROTECTION

.

OVERVOLTAGE PROTECTION FOR EXTER­NAL DARLINGTON

.

INTERNALSUPPLYZENER

.REVERSEBATTERY PROTECTION

DES CRIPTION

TheL497is anintegratedelectronicignitioncontrol­lerforbreakerlessignitionsystemsusingHalleffect
sensors.

L4 97

DIP16 SO1 6

ORDERING NUMBERS : L497B(DIP16)

The device drives an NPN external darlington to
controlthecoilcurrentprovidingthe requiredstored
energywith lowdissipation.

A specialfeature of the L497 is the programmable
time for the recovery of the correctdwell ratio T
whenthecoil peakcurrentfailstoreach94 % ofthe
nominalvalue.Inthis wayonlyone sparkmayhave
anenergylessthan94 % ofthenominaloneduring
fast accelerationor coldstarts.

L497D1(SO16)

/T

d

BLOCK DI AGRAM

March 1998

1/11

L497

ABSOLUTE MAXIMUM RATINGS

Symbol Parameter Value Unit

200
800

3

300
600

15
35

1.2

0.65

V
V
I

V

I

V

T

j,Tstg

P

I

16

D.C. Supply current

3

Transient Supply Current (t
Supply Voltage Int. Limited to Vz

3

RPM Voltage 28 V

6

fall time constant = 100ms)

f

D.C. Driver Collector Current
Pulse ” ”(t <= 3ms)

Driver Collector Voltage 28 V

16

I

15

Auxiliary Zener Current 40 mA

7

D.C. Overvoltage Zener Current
Pulse ” ” t

Repetition Time > = 3ms

tr

ep

Reverse Battery Voltage if Application Circuit of Fig. 4 is used – 16 V

R

= 300µs,

fall

Junction and StorageTemperature Range – 55 to 150
Power Dissipation

tot

at T

=90°C for SO-16

aluminia

=90°C for DIP-16

T

amb

mA
mA

mA
mA

mA
mA

°C

W
W

PI N CONNECTIO N (top view)

THERMAL DATA

Symbol Parameter Value Unit

R

th j-amb

R

th j-alumin

(*) Thermal resist ance junction-aluminia w ith the device soldere d on the middle of an alum inia supporti ng substrate mesuring

15 x 20 ; 0.65 mm thicknes s.

Thermal Resistance Junction-ambient for DIP-16

(*)

Thermal Resistance Junction-alumina for SO-16

Max
Max

90
50

C/W

°
°C/W

2/11

PIN FUNCTIONS (refer to fig. 4)

L497

N

°

Name Function

1 GND This pin must be connected to ground.
2 SIGNAL GND This pin must be connected to ground.
3 POWER SUPPLY Supply Voltage Input. An internal 7.5 V (typ) zener zener limits the voltage

at this pin. The external resistor R

limits the current through the zener for

5

high supply voltages.
4 N.C. This pin must be connected to ground or left open.
5 HALL-EFFECT INPUT Hall-effect Pickup Signal Input. This input is dwell control circuit output in

order to enable the current driving into the coil. The spark occurs at the

high-to-low transition of the hall-effectpickup signal.

Furthermore this input signal enables the slow recovery and permanent

conduction protection circuits. The input signal, supplied by the open

collector output stage of the Hall effect sensor, has a duty-cycle typically

about 70 %. V

is internally clamped to V3and ground by diodes

5

6 RPM OUTPUT Open collector output which is at a low level when current flows in the

ignition coil. For high voltages protection of this output, connection to the

pin 7 zener is recommended.

In this situation R

current if RPM module pad is accidentally connected to V

must limit the zener current, too, and R1limits pin 6

8

.

S

7 AUX. ZENER A 21 V (typ) General Purpose Zener. Its current must be limited by an

external resistor.
8 RECOVERY TIME A capacitor connected between this pin and ground sets the slope of the

dwell time variation as it rises from zero to the correct value. This occurs

after the detection of I

coll

94 % I

≤

, just before the low transition of the

nom

hall-effect signal pulse.

The duration of the slow recovery is given by :

= 12,9 R7C

t

src

where R

7

(ms)

src

is the biasing resistor at pin 12 (in KΩ) and C

is the delay

src

capacitor at pin 8 (inµF).
9 MAX CONDUCTION

TIME

A capacitor connected between this pin and ground determines the

intervention delay of the permanent conduction protection. After this delay

time the coil current is slowly reduced to zero.

Delay Time T

T

=16 CpR7(ms)

p

where R

is given by :

p

is the biasing resistor at pin 12 (in KΩ) and CPis the delay

7

capacitor at pin 9 (inµF).

10 DWELL CONTROL

TIMER

A capacitor C

HAll effect output is High and is discharged at the High to Low transition of

connected between this pin and ground is charged when the

T

the Hall effect signal.

The recommended value is 100 nF using a 62 KΩ resistor at pin 12.

11 DWELL CONTROL The average voltage on the capacitor CW connected between this pin and

ground depends on the motor speed and the voltage supply. The

comparison between V

dwell control. For the optimized operation of the device C

and VCTvoltage determines the timing for the

CW

=CW; the

T

recommended value is 100 nF using a 62 KΩ resistor at pin 12.

12 BIAS CURRENT A resistor connected between this pin and ground sets the internal current

used to drive the external capacitors of the dwell control

(pin 10 and 11) permanent conduction protection (pin 9) and slow recovery

time (pin 8). The recommended value is 62 KΩ.

13 CURRENT SENSING Connection for the Coil Current Limitation. The current is measured on the

sensing resitor R

and taken through the divider R10/R11. The current

S

limitation value is given by :

I

sens

= 0.32 ⋅

R

10

RS⋅ R

+ R

11

11

3/11

L497

PIN FUNCTIONS (continued)

N

°

14 DRIVER EMITTER

Name Function

Current Driver for the External Darlington. To ensure stability and precision

OUTPUT

of T

desatCc

and R9must be used. Recommended value for R9is 2 KΩ in

order not to change the open loop gain of the system.

may be added to Ccto obtain greater flexibility in various application

R

c

situations.

and Rcvalues ranges are 1 to 100 nF and 5 to 30 KΩ depending on the

C

c

external darlington type.

15 OVERVOLTAGE LIMIT The darlington is protected against overvoltage by means of an internal

zener available at this pin and connected to pin 14. The internal divider

defines the limitation value given by :

R

3/R2

22.5

16 DRIVER COLLECTOR

INPUT



V

ovp

=

+



R

3



The collector current of the internal driver which drives the external

darlington is supplied through this pin. Then the external resistor R

5.10



−3

R

22.5

+

2




the maximum current supplied to the base of the external darlington.

ELECTRICAL CHARACTERISTICS

= 14.4V, – 40 °C<Tj< 125 °C unless otherwise specified)

(V

S

Symbol Parameter Test Conditions Min. Typ. Max. Unit

V

I

V

V

V

Min Op. Voltage 3.5 V

3

Supply Current V3=6V

3

Voltage Supply 28 V

S

Supply Clamping Zener Voltage IZ3= 70 mA 6.8 7.5 8.2 V

Z3

Input Voltage Low Status

5

V

=4V

3

5
7

18 25

13

0.6 V

High Status 2.5

Input Current V5= LOW – 400 – 50

5

Darlington Driver Sat. Current I14=50mA

= 180 mA

I

14

Current Limit. Sensing Voltage VS= 6 to 16 V 260 320 370 mV
CWCharge Current VS= 5.3 to 16V

V

= 0.5V

11

– 11.0 – 9.3 – 7.8 µ

0.5

0.9

V

V

I

16–14

SENS

I

11C

T = 10 to 33ms

I

11D

CW Charge Current VS= 5.3 to 16V

= 0.5V

V

11

0.5 0.7 1.0

T = 10 to 33ms

I

11C/I11D

VS = 5.3 to 16V

= 0.5V

V

11

7.8 22.0

T = 10 to 33ms See Note 1

I

SRC

I

SENSE

T

SRC

V

Z15

T

Percentage of Output Current
Determining the Slow Recovery
Control Start (fig. 2), note 1

Duration of Altered Small Contr.
Ratio after SRC Function Start
(fig. 2)

External Darlington over V Prot.
Zener Voltage

Permanent Conduction Time V5= High

P

=1µF

C

SRC

=62K

R

7

I15=5mA

=2mA

I

15

=1µF

C

P

= 62KΩ

R

7

Ω

90 94 98.5 %

0.8 s

19
18

22.5

21.5

26
25

0.4 1.1 1.8 s

6

limits

mA
mA

V

A

µ

V
V

A

µA

V
V

4/11