LM1949 [TI]
注入器驱动控制器;
| 型号： | LM1949 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 注入器驱动控制器 驱动 控制器 |
| 文件： | 总17页 (文件大小：883K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LM1949
www.ti.com
SNLS349C –FEB 1995–REVISED MARCH 2013
LM1949 Injector Drive Controller
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1
FEATURES
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 (Figure 19–Figure 22).
This guarantees opening of 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 consumed by the system is
dramatically 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.
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Low Voltage Supply (3V–5.5V)
22 mA Output Drive Current
No RFI Radiation
Adaptable to All Injector Current Levels
Highly Accurate Operation
TTL/CMOS Compatible Input Logic Levels
Short Circuit Protection
High Impedance Input
Externally Set Holding Current, IH
Internally Set Peak Current (4 × IH)
Externally Set Time-Out
Can be Modified for Full Switching Operation
Available in Plastic 8-Pin PDIP
APPLICATIONS
Normally powered from a 5V ± 10% supply, the IC is
typically 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.
•
•
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Fuel Injection
Throttle Body Injection
Solenoid Controls
Air and Fluid Valves
DC Motor Drives
The LM1949 is available in the plastic PDIP, (contact
factory for other package options).
Typical Application
Figure 1. Typical Application and Test Circuit
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 1995–2013, Texas Instruments Incorporated
LM1949
SNLS349C –FEB 1995–REVISED MARCH 2013
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IN
1
2
8
7
TIMER
OUT
SUPPLY
SUPPLY
GND
COMP
3
4
6
5
SENSE
INPUT
SENSE
GND
Figure 2. Package Number P0008E
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
(1)(2)
Absolute Maximum Ratings
Supply Voltage
8V
1235 mW
(3)
Power Dissipation
Input Voltage Range
−0.3V to VCC
−40°C to +125°C
−65°C to +150°C
150°C
Operating Temperature Range
Storage Temperature Range
Junction Temperature
Lead Temp. (Soldering 10 sec.)
260°C
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
(3) 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.
Electrical Characteristics
(VCC = 5.5V, VIN = 2.4V, TJ = 25°C, Figure 1, unless otherwise specified.)
Symbol
Parameter
Supply Current
Conditions
Min
Typ
Max
Units
ICC
Off
VIN = 0V
11
28
23
54
mA
mA
mA
V
Peak
Pin 8 = 0V
Pin 8 Open
VCC = 5.5V
VCC = 3.0V
VCC = 5.5V
VCC = 3.0V
Hold
16
26
VOH
Input On Level
1.4
1.2
1.35
1.15
3
2.4
1.6
V
VOL
Input Off Level
1.0
0.7
V
V
IB
Input Current
Output Current
Peak
−25
+25
µA
IOP
Pin 8 = 0V
Pin 8 Open
−10
−22
−5
mA
mA
V
Hold
−1.5
VS
VP
Output Saturation Voltage 10 mA, VIN = 0V
Sense Input
0.2
0.4
Peak Threshold
Hold Reference
Time-out, t
VCC = 4.75V
350
88
386
94
415
102
110
mV
mV
%
VH
t
t ÷ RTCT
90
100
2
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SNLS349C –FEB 1995–REVISED MARCH 2013
Typical Performance Characteristics
Output Current vs
Supply Voltage
Supply Current vs
Supply Voltage
Figure 3.
Figure 4.
Quiescent Current vs
Supply Voltage
Input Voltage Thresholds
vs Supply Voltage
Figure 5.
Figure 6.
Sense Input Peak Voltage
vs Supply Voltage
Sense Input Hold Voltage
vs Supply Voltage
Figure 7.
Figure 8.
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Typical Performance Characteristics (continued)
Normalized Timer Function
vs Supply Voltage
Quiescent Supply Current
vs Junction Temperature
Figure 9.
Figure 10.
Quiescent Supply Current
vs Junction Temperature
Output Current vs
Junction Temperature
Figure 11.
Figure 12.
Input Voltage Thresholds
vs Junction Temperature
Sense Input Peak Voltage
vs Junction Temperature
Figure 13.
Figure 14.
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Typical Performance Characteristics (continued)
Sense Input Hold Voltage
vs Junction Temperature
Normalized Timer Function
vs Junction Temperature
Figure 15.
Figure 16.
LM1949N Junction
Temperature Rise Above
Ambient
vs
Supply Voltage
Figure 17.
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Typical Circuit Waveforms
Figure 18.
APPLICATION HINTS
The injector driver integrated circuits were designed to be used in conjunction with an external controller. The
LM1949 derives its input signal from either a control oriented processor (COPS™), microprocessor, or some
other system. This input signal, in the form of a square wave with a variable duty cycle and/or variable frequency,
is applied to Pin 1. In a typical system, input frequency is proportional to engine RPM. Duty cycle is proportional
to the engine load. The circuits discussed are suitable for use in either open or closed loop systems. In closed
loop systems, the engine exhaust is monitored and the air-to-fuel mixture is varied (via the duty cycle) to
maintain a perfect, or stochiometric, ratio.
INJECTORS
Injectors and solenoids are available in a vast array of sizes and characteristics. Therefore, it is necessary to be
able to design a drive system to suit each type of solenoid. The purpose of this section is to enable any system
designer to use and modify the LM1949 and associated circuitry to meet the system specifications.
Fuel injectors can usually be modeled by a simple RL circuit. Figure 19 shows such a model for a typical fuel
injector. In actual operation, the value of L1 will depend upon the status of the solenoid. In other words, L1 will
change depending upon whether the solenoid is open or closed. This effect, if pronounced enough, can be a
valuable aid in determining the current necessary to open a particular type of injector. The change in inductance
manifests itself as a breakpoint in the initial rise of solenoid current. The waveforms at the sense input show this
occurring at approximately 130 mV. Thus, the current necessary to overcome the constrictive forces of that
particular injector is 1.3 amperes.
Figure 19. Model of a Typical Fuel Injector
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PEAK AND HOLD CURRENTS
The peak and hold currents are determined by the value of the sense resistor RS. The driver IC, when initiated by
a logic 1 signal at Pin 1, initially drives Darlington transistor Q1 into saturation. The injector current will rise
exponentially from zero at a rate dependent upon L1, R1, the battery voltage and the saturation voltage of Q1.
The drop across the sense resistor is created by the solenoid current, and when this drop reaches the peak
threshold level, typically 385 mV, the IC is tripped from the peak state into the hold state. The IC now behaves
more as an op amp and drives Q1 within a closed loop system to maintain the hold reference voltage, typically 94
mV, across RS. Once the injector current drops from the peak level to the hold level, it remains there for the
duration of the input signal at Pin 1. This mode of operation is preferable when working with solenoids, since the
current required to overcome kinetic and constriction forces is often a factor of four or more times the current
necessary to hold the injector open. By holding the injector current at one fourth of the peak current, power
dissipation in the solenoids and Q1 is reduced by at least the same factor.
In the circuit of Figure 1, it was known that the type of injector shown opens when the current exceeds 1.3 amps
and closes when the current then falls below 0.3 amps. In order to guarantee injector operation over the life and
temperature range of the system, a peak current of approximately 4 amps was chosen. This led to a value of RS
of 0.1Ω. Dividing the peak and hold thresholds by this factor gives peak and hold currents through the solenoid of
3.85 amps and 0.94 amps respectively.
Different types of solenoids may require different values of current. The sense resistor RS may be changed
accordingly. An 8-amp peak injector would use RS equal to .05Ω, etc. Note that for large currents above one
amp, IR drops within the component leads or printed circuit board may create substantial errors unless
appropriate care is taken. The sense input and sense ground leads (Pins 4 and 5 respectively), should be Kelvin
connected to RS. High current should not be allowed to flow through any part of these traces or connections. An
easy solution to this problem on double-sided PC boards (without plated-through holes) is to have the high
current trace and sense trace attach to the RS lead from opposite sides of the board.
TIMER FUNCTION
The purpose of the timer function is to limit the power dissipated by the injector or solenoid under certain
conditions. Specifically, when the battery voltage is low due to engine cranking, or just undercharged, there may
not be sufficient voltage available for the injector to achieve the peak current. In the Figure 18 waveforms under
the low battery condition, the injector current can be seen to be leveling out at 3 amps, or 1 amp below the
normal threshold. Since continuous operation at 3 amps may overheat the injectors, the timer function on the IC
will force the transition into the hold state after one time constant (the time constant is equal to RTx CT), or when
the voltage on the TIMER pin (Pin 8) is greater than typically VSUPPLY x 63%. The timer is reset at the end of
each input pulse. For systems where the timer function is not needed, it can be disabled by grounding the TIMER
Pin (Pin 8). For systems where the initial peak state is not required, (i.e., where the solenoid current rises
immediately to the hold level), the timer can be used to disable the peak function. This is done by setting the time
constant equal to zero, (i.e., CT = 0). Leaving RT in place is recommended. The timer will then complete its time-
out and disable the peak condition before the solenoid current has had a chance to rise above the hold level.
The actual range of the timer in injection systems will probably never vary much from the 3.9 milliseconds shown
in Figure 1. However, the actual useful range of the timer extends from microseconds to seconds, depending on
the component values chosen. The useful range of RT is approximately 1k to 240k. The capacitor CT is limited
only by stray capacitances for low values and by leakages for large values.
The timing capacitor is reset (discharged) when the IN pin (Pin 1) is below the VOL(MIN) threshold. The capacitor
reset time at the end of each controller pulse is determined by the supply voltage and the timing capacitor value.
The IC resets the capacitor to an initial voltage (VBE) by discharging it with a current of approximately 15 mA.
Thus, a 0.1 µF cap is reset in approximately 25 µs.
COMPENSATION
Compensation of the error amplifier provides stability for the circuit during the hold state. External compensation
(from Pin 2 to Pin 3) allows each design to be tailored for the characteristics of the system and/or type of
Darlington power device used. In the vast majority of designs, the value or type of the compensation capacitor is
not critical. Values of 100 pF to 0.1 µF work well with the circuit of Figure 1. The value shown of 0.1 µF (disc)
provides a close optimum in choice between economy, speed, and noise immunity. In some systems, increased
phase and gain margin may be acquired by bypassing the collector of Q1 to ground with an appropriately rated
0.1 µF capacitor. This is, however, rarely necessary.
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FLYBACK ZENER
The purpose of zener Z1 is twofold. Since the load is inductive, a voltage spike is produced at the collector of Q1
anytime the injector is reduced. This occurs at the peak-to-hold transition, (when the current is reduced to one
fourth of its peak value), and also at the end of each input pulse, (when the current is reduced to zero). The
zener provides a current path for the inductive kickback, limiting the voltage spike to the zener value and
preventing Q1 from damaging voltage levels. Thus, the rated zener voltage at the system peak current must be
less than the minimum breakdown of Q1. Also, even while Z1 is conducting the majority of the injector current
during the peak-to-hold transition (see Figure 20), Q1 is operating at the hold current level. This fact is easily
overlooked and, as described in the following text, can be corrected if necessary. Since the error amplifier in the
IC demands 94 mV across RS, Q1 will be biased to provide exactly that. Thus, the safe operating area (SOA) of
Q1 must include the hold current with a VCE of Z1 volts. For systems where this is not desired, the zener anode
may be reconnected to the top of RS as shown in Figure 21. Since the voltage across the sense resistor now
accurately portrays the injector current at all times, the error amplifier keeps Q1 off until the injector current has
decayed to the proper value. The disadvantage of this particular configuration is that the ungrounded zener is
more difficult to heat sink if that becomes necessary.
The second purpose of Z1 is to provide system transient protection. Automotive systems are susceptible to a vast
array of voltage transients on the battery line. Though their duration is usually only milliseconds long, Q1 could
suffer permanent damage unless buffered by the injector and Z1. There is one reason why a zener is preferred
over a clamp diode back to the battery line, the other reason being long decay times.
Figure 20. Circuit Waveforms
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Figure 21. Alternate Configuration for Zener Z1
POWER DISSIPATION
The power dissipation of the system shown in Figure 1 is dependent upon several external factors, including the
frequency and duty cycle of the input waveform to Pin 1. Calculations are made more difficult since there are
many discontinuities and breakpoints in the power waveforms of the various components, most notably at the
peak-to-hold transition. Some generalizations can be made for normal operation. For example, in a typical cycle
of operation, the majority of dissipation occurs during the hold state. The hold state is usually much longer than
the peak state, and in the peak state nearly all power is stored as energy in the magnetic field of the injector,
later to be dumped mostly through the zener. While this assumption is less accurate in the case of low battery
voltage, it nevertheless gives an unexpectedly accurate set of approximations for general operation.
The following nomenclature refers to Figure 1. Typical values are given in parentheses:
RS
VH
VP
VZ
= Sense Resistor (0, 1Ω)
= Sense Input Hold Voltage (.094V)
= Sense Input Peak Voltage (.385V)
= Z1 Zener Breakdown Voltage (33V)
VBATT = Battery Voltage (14V)
L1
R1
n
= Injector Inductance (.002H)
= Injector Resistance (1Ω)
= Duty Cycle of Input Voltage of Pin 1 (0 to 1)
= Frequency of Input (10 Hz to 200 Hz)
f
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Q1 Power Dissipation:
(1)
SWITCHING INJECTOR DRIVER CIRCUIT
The power dissipation of the system, and especially of Q1, can be reduced by employing a switching injector
driver circuit. Since the injector load is mainly inductive, transistor Q1 can be rapidly switched on and off in a
manner similar to switching regulators. The solenoid inductance will naturally integrate the voltage to produce the
required injector current, while the power consumed by Q1 will be reduced. A note of caution: The large
amplitude switching voltages that are present on the injector can and do generate a tremendous amount of radio
frequency interference (RFI). Because of this, switching circuits are not recommended. The extra cost of
shielding can easily exceed the savings of reduced power. In systems where switching circuits are mandatory,
extensive field testing is required to guarantee that RFI cannot create problems with engine control or
entertainment equipment within the vicinity.
The LM1949 can be easily modified to function as a switcher. Accomplished with the circuit of Figure 23, the only
additional components required are two external resistors, RA and RB. Additionally, the zener needs to be
reconnected, as shown, to RS. The amount of ripple on the hold current is easily controlled by the resistor ratio of
RA to RB. RB is kept small so that sense input bias current (typically 0.3 mA) has negligible effect on VH. Duty
cycle and frequency of oscillation during the hold state are dependent on the injector characteristics, RA, RB, and
the zener voltage as shown in the following equations.
(2)
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As shown, the power dissipation by Q1 in this manner is substantially reduced. Measurements made with a
thermocouple on the bench indicated better than a fourfold reduction in power in Q1. However, the power
dissipation of the zener (which is independent of the zener voltage chosen) is increased over the circuit of
Figure 1.
Figure 22. Switching Application Circuit
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Figure 23. LM1949 Simplified Internal Schematic
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SNLS349C –FEB 1995–REVISED MARCH 2013
REVISION HISTORY
Changes from Revision B (March 2013) to Revision C
Page
•
Changed layout of National Data Sheet to TI format .......................................................................................................... 12
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PACKAGE OPTION ADDENDUM
www.ti.com
27-May-2022
PACKAGING INFORMATION
Orderable Device
Status Package Type Package Pins Package
Eco Plan
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
Samples
Drawing
Qty
(1)
(2)
(3)
(4/5)
(6)
LM1949N/NOPB
ACTIVE
PDIP
P
8
40
RoHS & Green
NIPDAU
Level-1-NA-UNLIM
-55 to 125
LM
1949N
Samples
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6)
Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
1-Jun-2022
TUBE
T - Tube
height
L - Tube length
W - Tube
width
B - Alignment groove width
*All dimensions are nominal
Device
Package Name Package Type
PDIP
Pins
SPQ
L (mm)
W (mm)
T (µm)
B (mm)
LM1949N/NOPB
P
8
40
502
14
11938
4.32
Pack Materials-Page 1
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相关型号：
LM1949N/NOPB
IC 0.022 A BUF OR INV BASED PRPHL DRVR, PDIP8, MINI, PLASTIC, DIP-8, Peripheral Driver
NSC
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