L497B [STMICROELECTRONICS]
HALL EFFECT PICKUP IGNITION CONTROLLER; 霍尔效应皮卡点火控制器
| 型号： | L497B |
| 厂家： | 
ST |
| 描述： | HALL EFFECT PICKUP IGNITION CONTROLLER |
| 文件： | 总11页 (文件大小：108K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
L497
HALL EFFECT PICKUP IGNITION CONTROLLER
.
.
.
.
DIRECT DRIVING OF THE EXTERNAL
POWER DARLINGTON
COIL CURRENT CHARGING ANGLE (dwell)
CONTROL
PROGRAMMECOIL CURRENT PEAKLIMITA-
TION
PROGRAMMABLE DWELL RECOVERY TIME
WHEN 94 % NOMINAL CURRENT NOT
REACHED
DIP16
SO16
ORDERING NUMBERS : L497B (DIP16)
L497D1 (SO16)
.
.
.
RPM OUTPUT
PERMANENT CONDUCTION PROTECTION
OVERVOLTAGE PROTECTION FOR EXTER-
NAL DARLINGTON
INTERNAL SUPPLY ZENER
REVERSE BATTERY PROTECTION
The device drives an NPN external darlington to
controlthecoil current providingthe requiredstored
energy with low dissipation.
.
.
A special feature of the L497 is the programmable
time for the recovery of the correct dwell ratio Td/T
when thecoil peakcurrent fails to reach 94 % of the
nominal value.In this wayonly one spark mayhave
an energylessthan 94 % ofthe nominaloneduring
fast accelerationor cold starts.
DESCRIPTION
The L497is anintegratedelectronicignitioncontrol-
ler for breakerless ignition systemsusing Hall effect
sensors.
BLOCK DIAGRAM
1/11
March 1998
L497
ABSOLUTE MAXIMUM RATINGS
Symbol
Parameter
Value
Unit
I3
D.C. Supply current
Transient Supply Current (tf fall time constant = 100ms)
200
800
mA
mA
V3
V6
I16
Supply Voltage
Int. Limited to Vz3
28
RPM Voltage
V
D.C. Driver Collector Current
Pulse ”
300
600
mA
mA
”(t <= 3ms)
V16
I7
Driver Collector Voltage
Auxiliary Zener Current
28
40
V
mA
I15
D.C. Overvoltage Zener Current
15
35
mA
mA
Pulse ”
” tfall = 300 s,
µ
trep Repetition Time > = 3ms
VR
Tj, Tstg
Ptot
Reverse Battery Voltage if Application Circuit of Fig. 4 is used
Junction and StorageTemperature Range
Power Dissipation
– 16
V
– 55 to 150
°C
1.2
0.65
W
W
at Taluminia = 90 C for SO-16
°
Tamb = 90 °C for DIP-16
PIN CONNECTION (top view)
THERMAL DATA
Symbol
Parameter
Thermal Resistance Junction-ambient for DIP-16
Rth j-alumin (*) Thermal Resistance Junction-alumina for SO-16
Value
Unit
Rth j-amb
Max
Max
90
50
C/W
°
°C/W
(*) Thermal resistance junction-aluminia with the device soldered on the middle of an aluminia supporting substrate mesuring
15 x 20 ; 0.65 mm thickness.
2/11
L497
PIN FUNCTIONS (refer to fig. 4)
Name
GND
Function
This pin must be connected to ground.
This pin must be connected to ground.
N
°
1
2
3
SIGNAL GND
POWER SUPPLY
Supply Voltage Input. An internal 7.5 V (typ) zener zener limits the voltage
at this pin. The external resistor R5 limits the current through the zener for
high supply voltages.
4
5
N.C.
This pin must be connected to ground or left open.
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-effect pickup 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 %. V5 is internally clamped to V3 and ground by diodes
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 R8 must limit the zener current, too, and R1 limits pin 6
current if RPM module pad is accidentally connected to VS.
7
8
AUX. ZENER
A 21 V (typ) General Purpose Zener. Its current must be limited by an
external resistor.
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 Icoll 94 % Inom
, just before the low transition of the
≤
hall-effect signal pulse.
The duration of the slow recovery is given by :
tsrc = 12,9 R7 Csrc (ms)
where R7 is the biasing resistor at pin 12 (in K ) and C is the delay
Ω
src
capacitor at pin 8 (in F).
µ
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 Tp is given by :
Tp =16 Cp R7 (ms)
where R7 is the biasing resistor at pin 12 (in KΩ) and CP is the delay
capacitor at pin 9 (in F).
µ
10
11
DWELL CONTROL
TIMER
A capacitor CT connected between this pin and ground is charged when the
HAll effect output is High and is discharged at the High to Low transition of
the Hall effect signal.
The recommended value is 100 nF using a 62 KΩ resistor at pin 12.
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 VCW and VCT voltage determines the timing for the
dwell control. For the optimized operation of the device CT = CW; the
recommended value is 100 nF using a 62 KΩ resistor at pin 12.
12
13
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 K
.
Ω
CURRENT SENSING
Connection for the Coil Current Limitation. The current is measured on the
sensing resitor RS and taken through the divider R10/R11. The current
limitation value is given by :
R
10 + R11
Isens = 0.32
RS R11
3/11
L497
PIN FUNCTIONS (continued)
Name
Function
N
°
14
15
16
DRIVER EMITTER
OUTPUT
Current Driver for the External Darlington. To ensure stability and precision
of Tdesat Cc and R9 must be used. Recommended value for R9 is 2 KΩ in
order not to change the open loop gain of the system.
Rc may be added to Cc to obtain greater flexibility in various application
situations.
Cc and Rc values ranges are 1 to 100 nF and 5 to 30 KΩ depending on the
external darlington type.
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
R3/R2 defines the limitation value given by :
22.5
R3
Vovp
5.10−3 R2 22.5
+
=
+
DRIVER COLLECTOR The collector current of the internal driver which drives the external
INPUT
darlington is supplied through this pin. Then the external resistor R6 limits
the maximum current supplied to the base of the external darlington.
ELECTRICAL CHARACTERISTICS
(VS = 14.4 V, – 40 °C < Tj < 125 °C unless otherwise specified)
Symbol
Parameter
Min Op. Voltage
Test Conditions
Min.
Typ.
Max.
Unit
V3
I3
3.5
V
Supply Current
V3 = 6 V
V3 = 4 V
5
7
18
25
13
mA
mA
VS
VZ3
V5
Voltage Supply
28
8.2
0.6
V
V
Supply Clamping Zener Voltage IZ3 = 70 mA
6.8
7.5
Input Voltage
Low Status
High Status
V
V
2.5
I5
Input Current
V5 = LOW
– 400
– 50
A
µ
V16–14
Darlington Driver Sat. Current
I14 = 50 mA
I14 = 180 mA
0.5
0.9
V
V
VSENS
I11C
Current Limit. Sensing Voltage
CW Charge Current
VS = 6 to 16 V
260
320
370
mV
VS = 5.3 to 16V
V11 = 0.5V
– 11.0
– 9.3
– 7.8
µ
A
T = 10 to 33ms
I11D
CW Charge Current
VS = 5.3 to 16V
V11 = 0.5V
T = 10 to 33ms
0.5
7.8
90
0.7
1.0
µA
I11C / I11D
VS = 5.3 to 16V
V11 = 0.5V
T = 10 to 33ms
22.0
98.5
See Note 1
ISRC
ISENSE
Percentage of Output Current
Determining the Slow Recovery
Control Start (fig. 2), note 1
94
%
s
TSRC
Duration of Altered Small Contr.
Ratio after SRC Function Start
(fig. 2)
0.8
CSRC = 1
F
µ
R7 = 62 K
Ω
VZ15
TP
External Darlington over V Prot. I15 = 5 mA
19
18
22.5
21.5
26
25
V
V
Zener Voltage
I15 = 2 mA
Permanent Conduction Time
V5 = High
0.4
1.1
1.8
s
CP = 1 F
µ
R7 = 62KΩ
4/11
L497
ELECTRICAL CHARACTERISTICS (continued)
Symbol
Parameter
Test Conditions
Min.
Typ.
Max.
Unit
V6SAT
RPM Output Saturation Voltage I6 = 18.5 mA
I6 = 25 mA
0.5
0.8
V
V
I6 leak
VZ7
RPM Output Leakage Current
Auxiliary Zener Voltage
Reference Voltage
VS = 20 V
I7 = 20 mA
50
27
A
µ
19
V
V12
1.20
1.25
1.30
V
Notes : 1.
td
T
1
td/t desaturation ratio is given by:
=
1 + I11C ⁄ I11D
Isense = Icoil when the external Darlington is in theactive region.
2.
APPLICATION INFORMATION
Figure 1 : Main Waveforms.
5/11
L497
DWELL ANGLE CONTROL
TRANSIENT RESPONSE
The ignition system must deliver constant energy
evenduringthe conditionof accelerationand decel-
erationof themotorbelow80Hz/s.Theseconditions
can be simulated by means of a signal gene-rator
with a linearly modulated frequency between 1 Hz
and 200 Hz (this corresponds to a changebetween
30 and 6000 RPM for a 4 cylinders engine).
The dwell angle control circuit calculates the con-
ductiontime D for the outputtransistor in relation to
the speed of rotation, to the supply voltage and to
the characteristicsof the coil.
On the negativeedge of the Hall-effect input signal
thecapacitorCW beginsdischargingwitha constant
currentl11D. Whenthe setpeakvalueof thecoilcur-
rent is reached, this capacitor charges with a con-
stant current I11C = 13.3 x I11D, and the coil current
is kept constant by desaturationof the driven stage
and the external darlington.
CURRENT LIMIT
Thecurrentin thecoilis monitoredbymeasuringthe
Isense current flowing in the sensing resistor Rs on
the emitter of the external darlington. Isense is given
by :
The capacitor CT starts charging on the posi-
tive.edge of the Hall-effect input signal with a con-
stant current I10C. The dwell angle, and conse-
quentlythe starting point of the coilcurrent conduc-
tion, is decidedby the comparisonbetweenV10 and
V11.
Isense = Icoil + I14
Whenthevoltagedrop acrossRs reachestheinter-
nal comparatorthresholdvaluethefeedbackloopis
activated and Isense kept constant (fig.1) forcing the
external darlington in the active region. In this con-
dition :
A positive hysteresis is added to the dwell compa-
rator to avoid spurious effectsand CT is rapidly dis-
charged on the negative edge of Hall-effects input
signal.
Isense = Icoil
Whenaprecisepeakcoilcurrentis requiredRs must
be trimmed or anauxiliary resistor divider(R10, R11)
In this way the average voltage on CW increasesif
the motor speed decreases and viceversa in order
added :
0.320 R10
td
T
Icpeak(A) =
+ 1
to maintainconstanttheratio atanymotorspeed.
R11
RS)
td
T
D
T
SLOW RECOVERY CONTROL (fig. 2)
is kept constant (and not
= cost) to control
If Isense hasnot reached 94 % of the nominal value
just before thenegativeedge of theHall-effectinput
signal, the capacitor Csrc and CW are quickly dis-
chargedas longas thepick-up signalis ”low”. At the
next positive transition of the input signal the load
currentstartsimmediately, producingthe maximum
achievable Tdesat; then the voltage on CSRC in-
creaseslinearlyuntil thestandbyis reached.During
thisrecoverytime theCSRC voltageis convertedinto
a current which, substrated from the charging cur-
rentof thedwellcapacitor, producesa Tdesat modu-
lation. This means that the Tdesat decreasesslowly
untilitsvaluereaches,aftera timeTSRC, thenominal
7% value.
the power dissipation and to have sufficient time to
avoid low energy sparks during acceleration.
DESATURATIONTIMES IN STATIC
CONDITIONS
In staticconditionsandif CT =CW asrecommended
andif the valuesof the applicationcircuit offig.4 are
used.
td
1
=
T
1 + I11C / I11D
DESATURATIONTIMES IN LOW AND HIGH
FREQUENCY OPERATION
The time TSRC is given by:
Due to the upperlimit of the voltagerange of pin 11,
if the components of fig.4 are used, below 10 Hz
(300 RPM for a 4 cylinder engine) the OFF time
reachesits maximum value (about 50 ms)and then
the circuit graduallyloses control of the dwell angle
becauseD = T – 50 ms.
Trsc = 12.9 R7 CSRC (ms)
where R7 isthebiasingresistor at pin12 (inKΩ)and
Csrc the capacitor at pin 8 (in µF).
Over 200Hz (6000RPMfor a 4 cylinderengine)the
availabletimeforthe conductionis lessthan3.5ms.
If theused coilis 6 mH, 6A, theOFFtimeis reduced
to zero and the circuit losesthe dwell angle control.
6/11
L497
Figure 2 : SRC : Icoil Failure and Time Dependence of Active Region.
HJ : Input signal
C : Coil current
VCM : Voltage on capacitor CSRC.
DST : Percentage of imposed desaturation time.
I
Figure 3 : PermanentConduction Protection.
PERMANENT CONDUCTION PROTECTION
(fig. 3)
necessaryto avoid undesired sparks. When the in-
put signal goes low again CP is swiftly discharged
and the current control loop operatesnormally.
The permanent conductionprotection circuit moni-
torstheinputperiod,chargingCPwitha costantcur-
rent whenthe sensorsignal is high and discharging
it whenthe sensorsignal is low. If the inputremains
highfor a time longerthan TP thevoltageacrossCP
reachesan internallyfixedvalueforcingtheslowde-
crease of coil current to zero. A slow decrease is
The delay time TP is given by :
TP (sec) = 18 CP R7
Where R7 isthe biasing resistoron pin12 (in K) and
Cp the delay capacitor at pin 9 (in µF).
7/11
L497
OTHER APPLICATION NOTES
DUMP PROTECTION
work is mandatory for stability during the high vol-
tage condition.
Load dump protection must be implemented by an
external zener if this function is necessary. In fig. 4
DZ2 protects the driver stage, the connection be-
tween pin 6 and 7 protects the output transistor of
pin 6. MoreoverDZ1 protectsboth thepowersupply
input (pin 3) and Hall-effect sensor.
Ro Co values depend on the darlington used in the
application.
Moreover the resistor R13 is suggested to limit the
overvoltage even when supply voltage is discon-
nected during the high voltage condition.
Resistor R4 is necessaryto limit DZ1 current during
load dump.
REVERSE BATTERY PROTECTION
Dueto thepresenceof externalimpedanceat pin 6,
3, 16, 15 L497 is protected against reverse battery
voltage.
OVERVOLTAGELIMITATION
The external darlington collector voltage is sensed
by the voltage divider R2, R3. The voltage limitation
increases rising R2 or decreasing R3.
NEGATIVE SPIKE PROTECTION
If correct operation is requested also during short
negativespikes,thediodeDS andcapacitorCs must
be used.
Due to the active circuit used, an Ro Co series net-
Figure 4 : ApplicationCircuit.
8/11
L497
DIP16 PACKAGE MECHANICAL DATA
mm
inch
TYP.
DIM.
MIN.
0.51
0.77
TYP.
MAX.
MIN.
0.020
0.030
MAX.
a1
B
b
1.65
0.065
0.787
0.5
0.020
0.010
b1
D
E
e
0.25
20
8.5
2.54
17.78
0.335
0.100
0.700
e3
F
7.1
5.1
0.280
0.201
I
L
3.3
0.130
Z
1.27
0.050
9/11
L497
SO16 PACKAGE MECHANICAL DATA
mm
inch
TYP.
DIM.
MIN.
TYP.
MAX.
1.75
0.2
MIN.
MAX.
0.069
0.008
0.063
0.018
0.010
A
a1
a2
b
0.1
0.004
1.6
0.35
0.19
0.46
0.25
0.014
0.007
b1
C
0.5
0.020
c1
D
45° (typ.)
9.8
5.8
10
0.386
0.228
0.394
0.244
E
6.2
e
1.27
8.89
0.050
0.350
e3
F
3.8
0.5
4.0
0.150
0.020
0.157
0.050
0.024
L
1.27
0.62
M
S
8
(max.)
°
10/11
L497
Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility for
the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its
use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics. Specification
mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously
supplied. SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems
without express written approval of SGS-THOMSON Microelectronics.
1998 SGS-THOMSON Microelectronics – Printed in Italy – All Rights Reserved
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11/11
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