MLX90308
Programmable Sensor Interface
Features and Benefits
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Microprocessor-controlled signal conditioning for bridge-type sensors
Suited for low-cost sensors: reduction of non-linearity by programmable coefficients
External or internal temperature sensor for compensating temperature errors
Versatile output signal ranges: 4, 5, 10, or 11V
DC
; 4 to 20 mA loop
Mass calibration easy with 2400 or 9600 baud UART
Power supply from 6 to 35V
DC
Applications
Pressure transducers
Accelerometers
Temperature sensor assemblies
Linear position sensors
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Ordering Information
Part No.
MLX90308
MLX90308
Temperature Suffix
L (-40C to +150C)
L (-40C to +150C)
Package code
DF (SOIC16w)
UF (die on foil)
Description
The MLX90308 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 MLX90308 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.
MLX902xx Name of Sensor Rev Y.X 22/Aug/98
3901090308
Page 1
Page 1
Apr/04
Rev 006
MLX90308
Programmable Sensor Interface
3901090308
Rev 006
Page 2
Apr/04
Figure 1. Functional Block Diagram
MLX90308
Programmable Sensor Interface
Table 1. MLX90308 Electrical Specifications
Parameter
Regulator & Consumption
Input voltage range
Supply current
Supply current
Regulated supply voltage
Regulated voltage
temperature coefficient
Supply rejection ratio
Instrumentation Amplifier
Differential input range
Differential input range
Common mode input range
Pin leakage current
Common mode rejection Ratio CMRR
Hardware gain
Coarse offset control Range
CSOF[1:0] = 00
CSOF[1:0] = 01
CSOF[1:0] = 10
CSOF[1:0] = 11
Fixed offset control range
High
Low
IA chopper frequency
Gain Stage
Course gain
(Fixed Gain = 1023)
CSGN = 000
CSGN = 001
CSGN = 010
* CSGN = 100 to 111: voltage mode
only, not applicable to current mode.
Output > 6.5V; MSB = 1
Output < 6.5V; MSB = 0
CSGN = 011
CSGN = 100*
CSGN = 101*
Page 3
Page 3
DC operating parameters: T
A
= -40 to 140
o
C, V
DD1
= 6 to 35V
DC
(unless otherwise specified).
Symbol
Test Conditions
Min
Typ
Max
Units
V
IN
I
DD
I
DD
V
REG
V
DD1
(Regulator connected)
@ T
A
= 100ºC Current Mode
@ T
A
= 100ºC Voltage Mode
6
2.1
35
V
mA
5.0
4.5
4.75
-600
5.2
mA
V
uV /
º
C
dB
PSRR
V
DD1
> 6V
90
VBP-VBN
VBP-VBN
IINV = 0
IINV = 1
1/2(VBP+VBN)
Pins VBP & VBN to GND, V
DD
=
-11.0
-32.0
38.0
32.0
11.0
65.0
8.0
mV/V
(Vdd)
mV/V
(Vdd)
%VDD
nA
dB
60
18
-15.3
-5.1
3.8
13.9
6.0
-7.0
300
22
-13.9
-3.8
5.1
15.3
8.0
-5.0
V/V
mV/V
mV/V
mV/V
mV/V
mV/V
mV/V
kHz
3.0
4.9
8.0
12.8
7.9
12.7
3.3
5.4
8.8
14.1
8.7
14.0
V/V
V/V
V/V
V/V
V/V
V/V
Apr/04
MLX902xx Name of Sensor Rev Y.X 22/Aug/98
3901090308
Rev 006
MLX90308
Programmable Sensor Interface
Table 1. MLX90308 Electrical Specifications (continued)
Parameter
Coarse gain
Fixed gain control range
Digital Mode & Current Mode Coarse Gain Stage
Course Gain
CSGN = 00
CSGN = 01
CSGN = 10
CSGN = 11
1.05
1.71
2.77
4.48
4.5
2.74
6.5
7.24
2.0
@ 0V output voltage
Over complete output range
CSGN[2:2] = 0
CSGN[2:2] = 1
Digital mode step size
Capacitive load VMO pin
Current Mode Output Stage
Fixed gain
Output current CMO pin
Current sense resistor
Digital mode current output span
Digital mode current step Size
Signal Path ( General)
Overall gain
Overall non-linearity
Ratiometry Error (4.75V – 5.25V)
Overall Gain < 250V/V
Overall Gain > 250V/V
3901090308
Rev 006
Page 4
DC operating parameters: T
A
= -40 to 140
o
C, V
DD1
= 6 to 35V
DC
(unless otherwise specified).
Test Conditions
CSGN = 110*
CSGN = 111*
Min
20.4
33.1
0.480
Typ
Max
23.0
36.6
0.970
1.17
1.89
3.06
4.95
6.5
3.04
11
7.86
-0.2
Units
V/V
V/V
V/V
V/V
V/V
V/V
V/V
V
V/V
V
V/V
V
mA
uA
Voltage Mode Output Stage ( See Voltage Mode)
Output voltage span
CSGN[2:2] = 0
Gain
CSGN[2:2] = 1
Gain
Minimum output voltage
Output source current
Output sink current
Output resistance
Digital mode output span
20
25
6.5
11.0
6.5
11.0
10
R
SENSE
= 24 ohm
Current mode
V
DD
= 5V
V
DD
= 5V,R
SENSE
=24
Voltage mode
Current mode = 24
28
81
-0.25
-0.5
-1.3
23
30
600
750
0.25
0.5
+1.3
8.4
27
24
9.3
Ohms
V
V
mV
mV
nF
mA/V
mA
Ohms
mA
uA
V/V
mA/V
%
%
%
Apr/04
V
DD
= 5V, CSGN[2:2]=0
V
DD
= 5V, CSGN[2:2]=1
MLX90308
Programmable Sensor Interface
Table 1. MLX90308 Electrical Specifications (continued)
Parameter
Bandwidth (-3dB)
DC operating parameters: T
A
= -40 to 140
o
C, V
DD1
= 6 to 35V
DC
(unless otherwise specified).
Test Conditions
39 nF connected from FLT to GND
Min
2.8
Typ
3.5
Max
4.2
7.1
Units
KHz
mVRMS
Noise, V
DD
= 5V, C
FLT
=39nF, C
L
=10nF, R
L
=5K , Analog Mode
Temperature Sensor & - Amplifier
Temperature sensor sensitivity
Temperature sensor output voltage
Temperature Sensor & Amplifier (continued).
Input voltage range TMP pin
@ V
DD
= 5.0V
GNTP[1,0] = 00
GNTP[1,0] = 01
GNTP[1,0] = 10
GNTP[1,0] = 11
DAC
Resolution
Monotonicity
Ratiometric output range (DAC output)
Offset Error
Differential non-linearly
Integral non-linearity
ADC
Resolution
Monotonicity
Ratiometric input range
Offset error
Differential non-linearly
Integral non-linearity
On-Chip RC Oscillator and Clock
Untrimmed RC oscillator
frequency
Trimmed RC oscillator frequency
(Measured at TMP pin with TSTB pin pulled low after power up)
Frequency temperature coefficiency
Clock Stability with temperature compensation over full temperature range
Ratio of f (microcontroller main clock
and (RC oscillator)
TURBO = 0
TURBO = 1
Page 5
Page 5
390
70
380
uV/ºC
mV
207
145
101
71
517
367
263
186
mV
mV
mV
mV
10
Guaranteed By Design
1
10
1
2
75
Bit
% V
DD
LSB
LSB
LSB
10
Guaranteed by design
1
10
1
2
75
Bit
% V
DD
LSB
LSB
LSB
40
86.9
87.8
26
-3
7
28
250
88.7
kHz
kHz
Hz/ºC
+3
%
MLX902xx Name of Sensor Rev Y.X 22/Aug/98
3901090308
Apr/04
Rev 006
Analogue and Mixed Signal
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