MLX902xx Name of Sensor Rev Y.X 22/Aug/98 Page 1
MLX90314AB
Programmable Sensor Interface
3901090314
Page 1
Aug/02
Rev 004
Features and Benefits
s
Microprocessor-controlled signal conditioning for bridge-type sensors
s
Suited for low-cost sensors: reduction of non-linearity by programmable coefficients
s
External or internal temperature sensor for compensating temperature errors
s
Versatile output signal ranges: 4, 5, 10, or 11V
DC
; 4 to 20 mA loop
s
Mass calibration easy with 2400 or 9600 baud UART
s
Power supply from 6 to 35V
DC
Applications
s
Pressure transducers
s
Accelerometers
s
Temperature sensor assemblies
s
Linear position sensors
Ordering Information
Part No.
Temperature Suffix
Package
Option Code
MLX90314
L ( -40C to 150C ) DF (SOIC16w) AB
MLX90314
L ( -40C to 150C ) UF (die on foil) AB
Description
The MLX90314AB is a dedicated microcontroller which performs signal conditioning for sensors wired in bridge
or differential configurations. Sensors that can be used include thermistors, strain gauges, load cells, pressure
sensors, accelerometers, etc. The signal conditioning includes gain adjustment, offset control, high order
temperature and linearity compensation. Compensation values are stored in EEPROM and are re-
programmable. Programming is accomplished by using a PC, with an interface circuit (level shifting and glue
logic), and provided software.
The application circuits can provide an output of an absolute voltage, relative voltage, or current. The output can
be range limited with defined outputs when
the signal is beyond the programmed limits.
Other features include alarm outputs and
level steering. The robust electrical design
allows the MLX90314AB to be used where
most
signal
conditioning
and
sensor
interface circuits cannot be used. Voltage
regulation control is provided for absolute
voltage and current modes (external FET
required).
The standard package is a plastic SO16W.
The device is static-sensitive and requires
ESD precautions.
M
L
X
9
0
3
1
4
A
B
P
r
o
g
r
a
m
m
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b
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e
S
e
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s
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r
I
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3
9
0
1
0
9
0
3
1
4
P
a
g
e
2
A
u
g
/
0
2
R
e
v
0
0
4
x 35
GAIN
External
Temp Sensor
Internal
Temp Sensor
INV
x2
ADC
3.5V
0V
Temp Amp Gain
GNTP [1:0]
Temperature signal. Used by
microproscessor to perform
temperature linearity corrections.
Hardware Gain = 70
0.97V/V
0.48V/V
1.24kOhm
GAIN
Fine Gain DAC
ADC
DAC
Micro-
Processor
Analog
Digital
2-bit
CSGN
1-bit
CSGN
Supply Regulator
VDD
VBP
VBN
TMP
GND
VMO
IO1
IO2
COMS
FLT
OFC
OPA
0V
3.5V
DAC_Offset
Coarse Offset
VDD1
FET
GAIN
Voltage Mode
Current Mode
CMO
CMN
TSTB
Figure 1. Functional Block Diagram
MLX902xx Name of Sensor Rev Y.X 22/Aug/98 Page 3
MLX90314AB
Programmable Sensor Interface
3901090314
Page 3
Aug/02
Rev 004
Table 1. MLX90314 Electrical Specifications
DC operating parameters: T
A
= -40 to 140
o
C, V
DD1
= 6 to 35V
DC
(unless otherwise specified).
Parameter
Symbol Test Conditions
Min
Typ
Max Units
Regulator & Consumption
Input voltage range
V
IN
V
DD1
(Regulator connected)
6
35
V
Supply current
I
DD
@ T
A
= 100C Current Mode
2.1
mA
Supply current
I
DD
@ T
A
= 100C Voltage Mode
5.0 mA
Regulated supply voltage
V
REG
4.5
4.75
5.2 V
Regulated voltage
temperature coefficient
-600
uV /
C
Supply rejection ratio
PSRR
V
DD1
> 6V
90
dB
Instrumentation Amplifier
Differential input range
VBP-VBN IINV = 0
-2.88
8.38 mV/V
(Vdd)
Differential input range
VBP-VBN IINV = 1
-8.38
2.88 mV/V
(Vdd)
Common mode input range
1/2(VBP+VBN)
38.0
65.0 %VDD
Pin leakage current
Pins VBP & VBN to GND, V
DD
=
8.0 nA
Common mode rejection Ratio CMRR
60
dB
Hardware gain
69
84
V/V
Coarse offset control Range
CSOF[1:0] = 00
-4.37
-3.97 mV/V
CSOF[1:0] = 01
-1.46
-1.09 mV/V
CSOF[1:0] = 10
1.09
1.46 mV/V
CSOF[1:0] = 11
3.97
4.37 mV/V
Fixed offset control range
High
1.71
2.29 mV/V
Low
-2.00
-1.43 mV/V
IA chopper frequency
300
kHz
Gain Stage
Course gain
CSGN = 000
3.0
3.3 V/V
(Fixed Gain = 1023)
CSGN = 001
4.9
5.4 V/V
CSGN = 010
8.0
8.8 V/V
CSGN = 011
12.8
14.1 V/V
CSGN = 100*
7.9
8.7
V/V
CSGN = 101*
12.7
14.0 V/V
* CSGN = 100 to 111: voltage mode
only, not applicable to current mode.
Output > 6.5V; MSB = 1
Output < 6.5V; MSB = 0
MLX90314AB
Programmable Sensor Interface
3901090314
Page 4
Aug/02
Rev 004
Table 1. MLX90314 Electrical Specifications (continued)
DC operating parameters: T
A
= -40 to 140
o
C, V
DD1
= 6 to 35V
DC
(unless otherwise specified).
Parameter
Test Conditions
Min
Typ
Max
Units
Coarse gain
CSGN = 110*
20.4
23.0
V/V
CSGN = 111*
33.1
36.6
V/V
Fixed gain control range
0.480
0.970 V/V
Digital Mode & Current Mode Coarse Gain Stage
Course Gain
CSGN = 00
1.05
1.17
V/V
CSGN = 01
1.71
1.89
V/V
CSGN = 10
2.77
3.06
V/V
CSGN = 11
4.48
4.95
V/V
Output voltage span
CSGN[2:2] = 0
4.5
6.5
V
Gain
2.74
3.04
V/V
CSGN[2:2] = 1
6.5
11
V
Gain
7.24
7.86
V/V
Minimum output voltage
-0.2
V
Output source current
2.0
mA
Output sink current
@ 0V output voltage
20
uA
Output resistance
Over complete output range
25
Ohms
Digital mode output span
CSGN[2:2] = 0
6.5
V
CSGN[2:2] = 1
11.0
V
Digital mode step size
V
DD
= 5V, CSGN[2:2]=0
6.5
mV
V
DD
= 5V, CSGN[2:2]=1
11.0
mV
Capacitive load VMO pin
10
nF
Current Mode Output Stage
Fixed gain
R
SENSE
= 24 ohm
8.4
9.3
mA/V
Output current CMO pin
Current mode
27
mA
Current sense resistor
24
Ohms
Digital mode current output span
V
DD
= 5V
23
mA
Digital mode current step Size
V
DD
= 5V,R
SENSE
=24
30
uA
Signal Path ( General)
Overall gain
Voltage mode
98
2100
V/V
Current mode = 24
284
2625
mA/V
Overall non-linearity
-0.25
0.25
%
Ratiometry Error (4.75V 5.25V)
Overall Gain < 250V/V
-1.75
1.75
%
Overall Gain > 250V/V
-4.6
+4.6
%
Voltage Mode Output Stage ( See Voltage Mode)
MLX902xx Name of Sensor Rev Y.X 22/Aug/98 Page 5
MLX90314AB
Programmable Sensor Interface
3901090314
Page 5
Aug/02
Rev 004
Table 1. MLX90314 Electrical Specifications (continued)
DC operating parameters: T
A
= -40 to 140
o
C, V
DD1
= 6 to 35V
DC
(unless otherwise specified).
Parameter
Test Conditions
Min
Typ
Max Units
Bandwidth (-3dB)
39 nF connected from FLT to GND 2.8
3.5
4.2
KHz
18.0
mVRMS
Temperature Sensor & - Amplifier
Temperature sensor sensitivity
390
uV/C
Temperature sensor output voltage
70
380
mV
Temperature Sensor & Amplifier (continued).
Input voltage range TMP pin
GNTP[1,0] = 00
207
517 mV
@ V
DD
= 5.0V
GNTP[1,0] = 01
145
367 mV
GNTP[1,0] = 10
101
263 mV
GNTP[1,0] = 11
71
186 mV
DAC
Resolution
10
Bit
Monotonicity
Guaranteed By Design
Ratiometric output range (DAC output)
1
75
% V
DD
Offset Error
10
LSB
Differential non-linearly
1
LSB
Integral non-linearity
2
LSB
ADC
Resolution
10
Bit
Monotonicity
Guaranteed by design
Ratiometric input range
1
75
% V
DD
Offset error
10
LSB
Differential non-linearly
1
LSB
Integral non-linearity
2
LSB
On-Chip RC Oscillator and Clock
Untrimmed RC oscillator
frequency
40
250 kHz
Trimmed RC oscillator frequency
(Measured at TMP pin with TSTB pin pulled low after power up)
86.9
87.8
88.7 kHz
Frequency temperature coefficiency
26
Hz/C
Clock Stability with temperature compensation over full temperature range
-3
+3
%
Ratio of f (microcontroller main clock
and (RC oscillator)
TURBO = 0
7
TURBO = 1
28
Noise, V
DD
= 5V, C
FLT
=39nF, C
L
=10nF, R
L
=5K
,
Analog Mode (Max. gain)
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