National Semiconductor LM1949 Technical data
LM1949
Injector Drive Controller
LM1949 Injector Drive Controller
February 1995
General Description
The LM1949 linear integrated circuit serves as an excellent
control of fuel injector drive circuitry in modern automotive
systems. The IC is designed to control an external power
NPN Darlington transistor that drives the high current injector solenoid. The current required to open a solenoid is
several times greater than the current necessary to merely
hold it open; therefore, the LM1949, by directly sensing the
actual solenoid current, initially saturates the driver until the
“peak” injector current is four times that of the idle or “holding” current (
the injector. The current is then automatically reduced to the
sufficient holding level for the duration of the input pulse. In
this way, the total power consumedbythesystemisdramatically reduced. Also, a higher degree of correlation of fuel to
the input voltage pulse (or duty cycle) is achieved, since
opening and closing delays of the solenoid will be reduced.
Normally powered from a 5V
cally operable over the entire temperature range (−55˚C to
+125˚C ambient) with supplies as low as 3 volts. This is
particularly useful under “cold crank” conditions when the
battery voltage may drop low enough to deregulate the 5-volt
power supply.
The LM1949 is available in the plastic miniDIP, (contact
factory for other package options).
Figure 3–Figure 7
). This guarantees opening of
±
10% supply, the IC is typi-
Typical Application Circuit
Features
n Low voltage supply (3V–5.5V)
n 22 mA output drive current
n No RFI radiation
n Adaptable to all injector current levels
n Highly accurate operation
n TTL/CMOS compatible input logic levels
n Short circuit protection
n High impedance input
n Externally set holding current, I
n Internally set peak current (4 x IH)
n Externally set time-out
n Can be modified for full switching operation
n Available in plastic 8-pin minDIP
H
Applications
n Fuel injection
n Throttle body injection
n Solenoid controls
n Air and fluid valves
n DC motor drives
Order Number LM1949M or LM1949N
See NS Package Number M08A or N08E
FIGURE 1. Typical Application and Test Circuit
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00506201
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
LM1949
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage 8V
Input Voltage Range −0.3V to V
Operating Temperature Range −40˚C to +125˚C
Storage Temperature Range −65˚C to +150˚C
Junction Temperature 150˚C
Lead Temp. (Soldering 10 sec.) 260˚C
Power Dissipation (Note 2) 1235 mW
Electrical Characteristics
(VCC= 5.5V, VIN= 2.4V, TJ= 25˚C,
Symbol Parameter Conditions Min Typ Max Units
I
CC
Supply Current
Off V
Peak Pin 8 = 0V 28 54 mA
Hold Pin 8 Open 16 26 mA
V
OH
V
OL
I
B
I
OP
Input On Level VCC= 5.5V 1.4 2.4 V
Input Off Level VCC= 5.5V 1.0 1.35 V
Input Current −25 3 +25 µA
Output Current
Peak Pin 8 = 0V −10 −22 mA
Hold Pin 8 Open −1.5 −5 mA
V
S
Output Saturation Voltage 10 mA, VIN= 0V 0.2 0.4 V
Sense Input
V
P
V
H
Peak Threshold VCC= 4.75V 350 386 415 mV
Hold Reference 88 94 102 mV
t Time-out, t t ÷ R
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2: For operation in ambient temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and a thermal resistance
of 100˚C/W junction to ambient.
Figure 1
, unless otherwise specified.)
=0V 11 23 mA
IN
V
= 3.0V 1.2 1.6 V
CC
V
= 3.0V 0.7 1.15 V
CC
TCT
90 100 110 %
CC
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Typical Circuit Waveforms
LM1949
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LM1949
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FIGURE 2. LM1949 Circuit
Schematic Diagram
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