Document
LM1949
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SNLS349C – FEB 1995 – REVISED MARCH 2013
LM1949 Injector Drive Controller
Check for Samples: LM1949
FEATURES
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•2 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
• Fuel Injection • Throttle Body Injection • Solenoid Controls • Air and Fluid Valves • DC Motor Drives
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.
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.
The LM1949 is available in the plastic PDIP, (contact factory for other package options).
Typical Application
Figure 1. Typical Application and Test Circuit
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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.
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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
www.ti.com
IN 1 OUT 2
COMP 3
SENSE INPUT
4
LM1949N
8 TIMER
7 SUPPLY
6
SUPPLY GND
5
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.
Absolute Maximum Ratings (1)(2)
Supply Voltage Power Dissipation (3) Input Voltage Range Operating Temperature Range Storage Temperature Range Junction Temperature Lead Temp. (Soldering 10 sec.)
8V 1235 mW −0.3V to VCC −40°C to +125°C −65°C to +150°C
150°C 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
Conditions
ICC
Supply Current
Off
VIN = 0V
Peak
Pin 8 = 0V
Hold
Pin 8 Open
VOH
Input On Level
VCC = 5.5V
VCC = 3.0V
VOL
Input Off Level
VCC = 5.5V
VCC = 3.0V
IB
Input Current
IOP
Output Current
Peak
Pin 8 = 0V
Hold
Pin 8 Open
VS
Output Saturation Voltage 10 mA, VIN = 0V
VP
Sense Input
Peak Threshold
VCC = 4.75V
VH
Hold Reference
t
Time-out, t
t ÷ RTCT
Min
Typ
Max
Units
11
23
mA
28
54
mA
16
26
mA
1.4
2.4
V
1.2
1.6
V
1.0
1.35
V
0.7
1.15
V
−25
3
+25
µA
−10
−22
−1.5
−5
0.2
mA
mA
0.4
V
350
386
415
mV
88
94
102
mV
90
100
110
%
2
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Copyright © 1995–2013, Texas Instruments Incorporated
www.ti.com
LM1949
SNLS349C – FEB 1995 – REVISED MARCH 2013
Typical Performance Characteristics
Output Current vs Supply Voltage
Supply Current vs Supply Voltage
Figure 3.
Quiescent Current vs Supply Voltage
Figure 4.
Input Voltage .