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LM9040 Dual Lambda Sensor Interface Amplifier
OBSOLETE
LM9040
Dual Lambda Sensor Interface Amplifier
General Description
The LM9040 is a dual sensor interface circuit consisting of
two independent sampled input differential amplifiers de-
signed for use with conventional Lambda Oxygen Sensors.
The Lambda Sensor is used for monitoring the oxygen con-
centration in the exhaust of gasoline engines using catalytic
after treatment and will deliver a voltage signal which is de-
pendent on the air-fuel mixture. The gain of the amplifiers are
internally set and can directly convert the Lambda sensor
output voltage to a level suitable for A/D conversion in a sys-
tem using a 5V reference.
The input common mode voltage range of each amplifier is
±2V with respect to the IC ground pin. This will allow the IC
to connect to sensors which are remotely grounded at the
engine exhaust manifold or exhaust pipe.
Each amplifier is capable of independent default operation
should either, or both, of the leads to a sensor become open
circuited.
Noise filtering is provided by an internal switched capacitor
low pass filter as part of each amplifier, and by external com-
ponents.
The LM9040 is fully specified over the automotive tempera-
ture range of −40°C to +125°C and is provided in a 14-pin
Small Outline surface mount package.
December 2, 2009
Features
■
■
■
■
■
■
■
■
■
■
Single 5V supply operation
Common mode input voltage range of ±2V
Differential input voltage range of 50 mV to 950 mV
Sampled differential input
Switched capacitor low pass filter
Internal oscillator and V
BB
generator
Open input default operation
Cold sensor default operation
Low power consumption (42 mW max)
Gain set by design and guaranteed over the operating
temperature range
Applications
■
Closed loop emissions control
■
Catalytic converter monitoring
Connection Diagram
1237201
Top View
Ordering Information
LM9040M
See NS Package Number M14B
© 2009 National Semiconductor Corporation
12372
Print Date/Time: 2009/12/02 10:13:43
www.national.com
12372 Version 3 Revision 2
LM9040
Absolute Maximum Ratings
(Note
1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
Supply Voltage
Input Voltage Continuous (Note
2)
Input Voltage Transient t
≤
1 ms (Note
2)
ESD Susceptibility (Note
3)
Maximum Junction Temperature
Storage Temperature Range
−0.3V to +6.0V
±14V
±60V
±2000V
150°C
−65°C to +150°C
Lead Soldering Information
Vapor Phase (60 Seconds)
Infrared (15 Seconds)
215°C
220°C
Operating Ratings
Supply Voltage
Differential Input Voltage
Common Mode Voltage
Power Dissipation
4.75V to 5.25V
0V to +1V
±2V
42 mW
DC Electrical Characteristics
The following specifications apply for V
CC
= 5.0V, V
DIFF
= 500 mV, V
CM
= 0V, R
OSC
= 178 kΩ,
−40°C
≤
T
A
≤
+125°C, DC Test
Circuit
Figure 1,
unless otherwise specified.
Symbol
I
CC
Z
DIFF
Z
IO
V
OL
V
OC
V
OUT(ERROR)
V
OH
R
OUT
CMRR
(DC)
T
RISE
T
FALL
F
C
Parameter
Supply Current
Differential Input Impedance
Inverting Input to Ground Impedance
Output Low Voltage
V
OUT
Center
(V
OUT
)−(V
DIFF
• 4.53)
Output High Voltage
Output Resistance
DC Common Mode Error
Output Rise Time
Output Fall Time
Low Pass Filter −3 dB
−2V
≤
V
CM
≤
+2V
C
OUT
= 0.01 μF
C
OUT
= 0.01 μF
C
OUT
= 0.01 μF
400
Conditions
4.75V
≤
V
CC
≤
5.25V
4.75V
≤
V
CC
≤
5.25V
Non-Inverting Inputs Open
V
DIFF
= 0V, I
LOAD
= 2.0 μA
One, or Both, Input(s) Open
4.75V
≤
V
CC
≤
5.25V
50 mV
≤
V
DIFF
≤
950 mV, V
CM
= 0V
V
DIFF
= 5V, I
LOAD
= −2 μA
V
CC
− 0.1V
1500
3500
±4.5
1.2
1.2
700
V
CC
• 0.380
1.05
10.00
100
V
CC
• 0.425
±65
Min
Max
8.0
1.60
Units
mA
Meg
Ω
Meg
Ω
mV
V
mV
V
Ω
mV/V
ms
ms
Hz
Note 1:
Absolute Maximum Ratings indicate limits beyond which damage to the device may occur.
Note 2:
The input voltage must be applied through external 4 kΩ input resistors. See
Figure 2,
AC Test Circuit. Amplifier operation will be disrupted, but will not
be destructive.
Note 3:
ESD Rating is with Human Body Model: 100 pF discharged through a 1500Ω resistor.
1237203
1237202
FIGURE 2. AC Test Circuit
FIGURE 1. DC Test Circuit
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12372 Version 3 Revision 2
2
Print Date/Time: 2009/12/02 10:13:43
LM9040
Typical Performance Characteristics
Supply Current vs Temperature
F
CLOCK
(Normalized) vs R
OSC
1237204
1237205
F
CLOCK
(Normalized) vs V
CC
Output R vs Temperature
1237206
1237207
Z
DIFF
vs Temperature
F
C
vs Temperature
1237208
1237209
3
12372 Version 3 Revision 2
Print Date/Time: 2009/12/02 10:13:43
www.national.com
LM9040
Voltage Gain vs Frequency
PSRR vs Frequency
1237210
1237211
CMRR vs Frequency
1237212
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12372 Version 3 Revision 2
4
Print Date/Time: 2009/12/02 10:13:43
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