Melexis MLX90308 Technical data

查询MLX90308LUF供应商

Features and Benefits

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Microprocessor-controlled signal conditioning for bridge-type sensors

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Suited for low-cost sensors: reduction of non-linearity by programmable coefficients

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External or internal temperature sensor for compensating temperature errors

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Versatile output signal ranges: 4, 5, 10, or 11VDC; 4 to 20 mA loop

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Mass calibration easy with 2400 or 9600 baud UART

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Power supply from 6 to 35VDC

Applications

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Pressure transducers

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Accelerometers

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Temperature sensor assemblies

Linear position sensors

Ordering Information

Part No. Temperature Suffix Package code
MLX90308 L (-40C to +150C) DF (SOIC16w)
MLX90308 L (-40C to +150C)

MLX90308

Programmable Sensor Interface

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 re­programmable. 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.

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MLX90308

Programmable Sensor Interface

Figure 1. Functional Block Diagram

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MLX90308

Programmable Sensor Interface

Table 1. MLX90308 Electrical Specifications

DC operating parameters: TA = -40 to 140oC, V

Parameter Symbol Test Conditions Min Typ Max Units

Regulator & Consumption

= 6 to 35VDC (unless otherwise specified).

DD1

Input voltage range VIN V

(Regulator connected) 6 35 V

DD1

Supply current IDD @ TA = 100ºC Current Mode 2.1 mA

Supply current IDD @ TA = 100ºC Voltage Mode 5.0 mA

Regulated supply voltage V

Regulated voltage

4.5 4.75 5.2 V

REG

-600 uV / ºC

temperature coefficient
Supply rejection ratio PSRR V

> 6V 90 dB

DD1

Instrumentation Amplifier

Differential input range VBP-VBN IINV = 0 -11.0 32.0 mV/V

Differential input range VBP-VBN IINV = 1 -32.0 11.0 mV/V

Common mode input range 1/2(VBP+VBN) 38.0 65.0 %VDD

Pin leakage current Pins VBP & VBN to GND, VDD = 8.0 nA

Common mode rejection Ratio CMRR 60 dB

Hardware gain 18 22 V/V

Coarse offset control Range CSOF[1:0] = 00 -15.3 -13.9

CSOF[1:0] = 01 -5.1 -3.8

CSOF[1:0] = 10 3.8 5.1

CSOF[1:0] = 11 13.9 15.3

Fixed offset control range High 6.0 8.0

Low -7.0 -5.0

mV/V

mV/V

mV/V

mV/V

mV/V

mV/V

IA chopper frequency 300 kHz

(Vdd)

(Vdd)

Gain Stage

Course gain CSGN = 000 3.0 3.3 V/V

(Fixed Gain = 1023)

* CSGN = 100 to 111: voltage mode

CSGN = 001 4.9 5.4 V/V

CSGN = 010 8.0 8.8 V/V

CSGN = 011 12.8 14.1 V/V

only, not applicable to current mode.
Output > 6.5V; MSB = 1
Output < 6.5V; MSB = 0

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CSGN = 100*

CSGN = 101* 12.7 14.0 V/V

7.9 8.7

V/V

MLX90308

Programmable Sensor Interface

Table 1. MLX90308 Electrical Specifications (continued)

DC operating parameters: TA = -40 to 140oC, V

Parameter Test Conditions Min Typ Max Units

Coarse gain CSGN = 110* 20.4 23.0 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 = 111* 33.1 36.6 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

Voltage Mode Output Stage ( See Voltage Mode)

Output voltage span CSGN[2:2] = 0 4.5 6.5 V

Gain 2.74 3.04 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

Digital mode step size VDD = 5V, CSGN[2:2]=0 6.5 mV

Capacitive load VMO pin 10 nF

Current Mode Output Stage

Fixed gain R

Output current CMO pin Current mode 27 mA

Current sense resistor 24 Ohms

Digital mode current output span VDD = 5V 23 mA

CSGN[2:2] = 1 6.5 11 V

Gain 7.24 7.86 V/V

CSGN[2:2] = 1 11.0 V

VDD = 5V, CSGN[2:2]=1 11.0 mV

SENSE

= 6 to 35VDC (unless otherwise specified).

DD1

= 24 ohm 8.4 9.3 mA/V

Digital mode current step Size VDD = 5V,R

Signal Path ( General)

Overall gain Voltage mode 28 600 V/V

Overall non-linearity -0.25 0.25 %

Ratiometry Error (4.75V – 5.25V) Overall Gain < 250V/V -0.5 0.5 %

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Rev 006

Current mode = 24Ω 81 750 mA/V

Overall Gain > 250V/V

=24Ω 30 uA

SENSE

-1.3

+1.3

%

MLX90308

Programmable Sensor Interface

Table 1. MLX90308 Electrical Specifications (continued)

DC operating parameters: TA = -40 to 140oC, V

Parameter Test Conditions Min Typ Max Units

Bandwidth (-3dB) 39 nF connected from FLT to GND 2.8 3.5 4.2 KHz

= 6 to 35VDC (unless otherwise specified).

DD1

Noise, VDD = 5V, C

Temperature Sensor & - Amplifier

Temperature sensor sensitivity 390 uV/ºC

Temperature sensor output voltage

Temperature Sensor & Amplifier (continued).

Input voltage range TMP pin GNTP[1,0] = 00 207 517 mV

@ VDD = 5.0V

DAC

Resolution 10 Bit

Monotonicity Guaranteed By Design

Ratiometric output range (DAC output) 1 75 % VDD

Offset Error 10 LSB

Differential non-linearly 1 LSB

Integral non-linearity 2 LSB

ADC

=39nF, CL=10nF, RL =5KΩ, Analog Mode

FLT

70 380 mV

GNTP[1,0] = 01 145 367 mV

GNTP[1,0] = 10 101 263 mV

GNTP[1,0] = 11 71 186 mV

7.1

mVRMS

Resolution 10 Bit

Monotonicity

Ratiometric input range 1 75 % VDD

Offset error 10 LSB

Differential non-linearly 1 LSB

Integral non-linearity 2 LSB

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 26 Hz/ºC

Clock Stability with temperature compensation over full temperature range -3 +3 %

Ratio of f (microcontroller main clock
and (RC oscillator)

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TURBO = 0 7

TURBO = 1 28

Guaranteed by design

40 250 kHz

86.9 87.8 88.7 kHz

MLX90308

Programmable Sensor Interface

Table 1. MLX90308 Electrical Specifications (continued)

DC operating parameters: TA = -40 to 140oC, V

Parameter Test Conditions Min Typ Max Units

Input & Output Pins (I01 & I02)

= 6 to 35VDC (unless otherwise specified).

DD1

Digital input levels

Output Levels @ output current = 5mA low VDD-0.4 0.4 V

TSTB Pin

Input levels Low 0.5 V

Pull-up Resistor 66 kOhms

FLT Pin

Output resistance 1.24 kOhms

Output voltage range VDD = 5V 0.05 3.6 V

OFC Pin

Output voltage range VDD = 5V 0.05 3.75 V

Load capacitor 20 pf

UART & COMS Pin

UART baud rate TURBO = 0 2400 baud

Low
High VDD-0.5

@ Output current = 5mA high VDD

High VDD-0.5

TURBO = 1 9600 baud

0.5

V

COMS pin input levels Low 0.3*VDD V

COMS Pin Output Resistance Low 100 Ohms

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High 0.7*VDD V

High 100 kOhms

Unique Features

MLX90308

Programmable Sensor Interface

Customization

Melexis can customize the MLX90308 in both
hardware and firmware for unique requirements. The
hardware design provides 64 bytes of RAM, 3 kbytes
of ROM, and 48 bytes of EEPROM for use by the
firmware.

Special Information

The output of the sensor bridge is amplified via offset
and gain amplifiers and then converted to the correct
output signal form in one of the output stages.

The sensitivity and offset of the analog signal chain
are defined by numbers passed to the DAC interfaces
from the microcontroller core (GN[9:0] and OF[9:0]).
The wide range of bridge offset and gain is
accommodated by means of a 2-bit coarse adjustment
DAC in the offset adjustment (CSOF[1:0]), and a
similar one in the gain adjustment (CSGN[2:0]). The
signal path can be directed through the processor for
digital processing. Two I/O pins are available for
analog inputs or digital outputs. These pins can be
used for alarms on various points on the analog signal
path and built-in or external temperature values.

Programming and Setup

The MLX90308 needs to have the compensation
coefficients programmed for a particular bridge
sensor to create the sensor system.
Programming the EEPROM involves some
minimal communications interface circuitry,
Melexis’ setup software, and a PC. The
communications interface circuitry is available in
a development board. This circuitry
communicates with the PC via a standard RS­232 serial communications port.

Table 2. Absolute Maximum Ratings

Supply voltage (ratiometric) V
Supply voltage (ratiometric) VDD Min

Supply voltage (operating),
Reverse voltage protection -0.7V
Supply current, Current Mode, IDD 3.5mA
Supply current, Voltage Mode, IDD 4.5mA
Output current, I

8mA

VMO

Output current (short to VDD), I
Output current (short to VSS), I
Output voltage, V

+11V

VMO

Power dissipation, PD 71mW
Operating temperature range, T
Storage temperature range, TS
Maximum junction temperature, TJ 150°C

DD

V

Max

DD1

SCVMO

SCVMO

Max

A

6V

4.5V

35V

100mA

8mA

-40 to +140°

-55 to +150°

Cross Reference

There are no known devices which the MLX 90308
can replace.

ESD Precautions

Observe standard ESD control procedures for CMOS
semiconductors.

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MLX90308

Programmable Sensor Interface

Table 3. Pin Description

Signal

Pin

Name

1,2 I/O1, 2 Bi-directional I/O. Can also be used as input to A/D converter. I/O can be

3 TSTB Test pin for Melexis production testing. (in normal application connected to
4 FLT Filter pin; allows for connection of a capacitor to the internal analog path.

5 OFC Offset control output. Provides access to the internal programmed offset
6,7 VBN,VBP Bridge inputs, negative and positive.

8 TMP Temperature sensor input. An external temperature sensor can be used in

9 VDD Regulated supply voltage. Used for internal analog circuitry to ensure accurate
10 FET Regulator FET gate control. For generating a stable supply for the bridge
11 V

Unregulated supply voltage. Used for digital circuitry and to generate FET

DD1

12 VMO Voltage mode output. Compensated sensor output voltage.

Description

controlled by serial communications or by firmware as alarm inputs or level
out. (unconnected when not used)

VDD)

control voltage for use with external circuitry. (unconnected when not used)

conjunction with the internal one. The external sensor can provide a
temperature reading at the location of the bridge sensor.

and stable signal manipulation.
sensor and internal analog circuitry (generates regulated voltage for VDD).
output.

13 CMO Current mode output. Compensated sensor output for current mode operation.
14 CMN Current mode negative rail. Current mode return path.
15 GND Power supply return.
16 COMS Serial communications pin. Bi-directional serial communication signal for

reading and writing to the EEPROM.

1

2

3

4

5

6

7

8 9

IO1

IO2

TSTB

FLT

OFC

VBN

VBP

TMP

COMS

GND

CMN

CMO

VMO

VDD1

FET

VDD

16

15

14

13

12

11

10

Figure 2. Pinout (SO16W (LW) Package)

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MLX90308

Programmable Sensor Interface

Analog Features

Supply Regulator

A bandgap-stabilized supply-regulator is on-chip while
the pass-transistor is external. The bridge-type sensor
is typically powered by the regulated supply (typically

4.75V). For ratiometric operation, the supply-regulator
can be disabled by connecting together the
unregulated and regulated supply pins.

Oscillator

The MLX90308 contains a programmable on-chip RC
oscillator. No external components are needed to set
the frequency (87.8 kHz +/-1%). The MCU-clock is
generated by a PLL (phase locked loop tuned for 614
kHz or 2.46 Mhz) which locks on the basic oscillator.

The frequency of the internal clock is stabilized over
the full temperature range, which is divided into three
regions, each region having a separate digital clock
setting. All of the clock frequency programming is
done by Melexis during final test of the component.
The device uses the internal temperature sensor to
determine which temperature range setting to use.

A/D and D/A

Power-On Reset

The Power-On Reset (POR) initializes the state of the
digital part after power up. The reset circuitry is
completely internal. The chip is completely reset and
fully operational 3.5 ms from the time the supply crosses

3.5 volts. The POR circuitry will issue another POR if
the supply voltage goes below this threshold for 1.0 us.

Test Mode

For 100% testability, a "TEST" pin is provided. If the pin
is pulled low, then the monitor program is entered and
the chip changes its functionality. In all other
applications, this pin should be pulled high or left
floating (internal pull-up).

Temperature Sense

The temperature measurement, TPO, is generated from
the external or internal temperature sensor. This is
converted to a 10-bit number for use in calculating the
signal compensation factors. A 2-bit coarse adjustment
GNTP[1:0] is used for the temperature signal gain &
offset adjustment.

Conversions using only one DAC

For saving chip area, the "Offset DAC" is multiplexed
in various ways. Both "fine offset" and "digital mode"
signals are stored on a capacitor. An ADC-loop is
available by using a comparator and SAR.

D/A

Before changing to another capacitor, the DAC output
should be settled to the new value. For example,
MODSEL moves the analog multiplexer to the so­called "open state 0." At the same time, the 10 bit mux
selects OF[9:0] for the offset-DAC. After the DAC
settling time, the analog multiplexer is moved to its
final state and the DAC-output is stored on a
capacitor.

A/D

The S/W-Signal MODSEL connects the SAR-output to
the DAC and the DAC-output to the comparator. The
SARegister is initialized by a rising edge of STC (S/W
signal). At the end of the A/D conversion, the
EOC flag is set to 1 and the controller can read the
ADC values.

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