MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Features and Benefits
Application Examples
Programmable Sensor Interface IC with 4 to
20 mA current loop output
Power supply from 6 to 35VDC
External or internal temperature sensor for
compensating temperature errors
Industrial pressure transducers.
Strain gauges, accelerometers, position
sensors, etc.
Any bridge type sensor with current loop
output.
Ordering Information
Part No.
MLX90323
Temperature Code
K ( -40C to 125C )
1 Functional Diagram
Package Code
DF (SOIC16w)
2 General Description
The IC converts small changes of output voltage
of full Wheatstone resistive bridge (caused by
mechanical stimulus such as pressure, force,
torque, light or magnetic field) to large changes of
the IC output current. It removes parasitic DC
level (Offset) from the output bridge voltage and
amplifies this signal certain times (Gain). Offset
and Gain are temperature dependant, so IC allows
temperature compensation of bridge parasitic DC
shift and sensitivity. Temperature can be
measured either by internal or external (resistor)
temperature sensor. Values of Offset and Gain
and theire temperature dependency are gotten
during calibration process than stored in IC
EEPROM as long as some other parameters.
Special calibration mode allows easy end quick
calibration process.
The IC has industry standard 4 – 20 mA current
loop output interface and takes power directly from
2-wire signal line. IC works properly over wide
voltage range (from 6 to 35 V) at the signal line.
3901090323
Rev 001
Page 1 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Table of Contents
1 Functional Diagram ..........................................................................................................................................1
2 General Description..........................................................................................................................................1
3 Glossary of Terms ............................................................................................................................................3
4 Absolute Maximum Ratings..............................................................................................................................4
5 Pin Definitions and Descriptions.......................................................................................................................5
6 General Electrical Specifications......................................................................................................................6
7 Detailed General Description ...........................................................................................................................9
7.1 Understanding 4-20 mA current loop interface..........................................................................................9
7.2 Analog features..........................................................................................................................................9
7.3 Digital features .........................................................................................................................................10
7.4 Parameters calculation ............................................................................................................................11
7.5 Communications ......................................................................................................................................12
8 Unique Features .............................................................................................................................................21
9 Application Information...................................................................................................................................21
10 Standard information regarding manufacturability of Melexis products with different soldering processes 22
11 ESD Precautions ..........................................................................................................................................23
12 Package Information ....................................................................................................................................23
13 Disclaimer.....................................................................................................................................................24
3901090323
Rev 001
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Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
3 Glossary of Terms
CM
CMN
CMO
COMS
CR
CSGN
CSOF
DACFnew
DACFold
DARDIS
EOC
ETMI
ETPI
FET
FG
FLT
GNO
GNOF
GNTP
HS
IFIX
IINV
ILIM
MODSEL
MUX
OFC
PLL
POR
RX
SAR
STC
Tdiff
Text
TMI
TMP
TPI
Tref
TSTB
TX
UART
VBN
VBP
VDD
WCB
WDC
3901090323
Rev 001
Current Mode
Current Mode Negative (supply connection)
Current Output
Communication, Serial
Carriage Return
Coarse Gain
Coarse Offset
Filtered DAC value, new
Filtered DAC value, old
DAC Resistor Disable
End Of Conversion flag bit
Timer Interrupt Enable
Enable Temperature Interrupt
Field Effect Transistor
Fixed Gain
Filter Pin
Gain and Offset adjusted digitized signal
Gain, Offset
Temperature Gain / Offset Coarse adjustment
Hardware / Software limit
fixed current output value
input signal invert command bit
current limit
Mode Select
multiplexer
Offset Control
Phase Locked Loop
Power On Reset
receive
Successive Approximation Register
start A/D conversion
temperature difference
temperature, external
timer Interrupt
temperature signal
temperature interrupt
temperature reference
test mode pin
transmit
Universal Asynchronous Receiver / Transmitter
bridge, positive, input
bridge, negative, input
supply voltage
warn / cold boot
watch dog counter
Page 3 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
4 Absolute Maximum Ratings
Table 1. Absolute Maximum Ratings
Supply voltage VDD Max
6V
Supply voltage VDD Min
4.5V
Supply voltage (operating), VDD1 Max
35V
Reverse voltage protection
-0.7V
Output current, I
8mA
Output current (short to VDD), I
100mA
Output current (short to VSS), I
8mA
Power dissipation, PD
71mW
Operating temperature range, TA
Storage temperature range, TS
Maximum junction temperature, TJ
-40 to +125°
-55 to +150°C
150°C
Exceeding the absolute maximum ratings may cause permanent damage. Exposure to absolute-maximumrated conditions for extended periods may affect device reliability.
3901090323
Rev 001
Page 4 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
5 Pin Definitions and Descriptions
Table 2. Pin Description
Pin
Signal
Name
1,2
Unused
3
TSTB
Test pin for Melexis production testing. (in normal application connected to
VDD)
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
control voltage for use with external circuitry. (unconnected when not used)
6,7
VBN,VBP
Bridge inputs, negative and positive.
8
TMP
Temperature sensor input. An external temperature sensor can be used in
conjunction with the internal one. The external sensor can provide a
temperature reading at the location of the bridge sensor.
9
VDD
Regulated supply voltage. Used for internal analog circuitry to ensure accurate
and stable signal manipulation.
10
FET
Regulator FET gate control. For generating a stable supply for the bridge
sensor and internal analog circuitry (generates regulated voltage for VDD).
11
VDD1
Unregulated supply voltage. Used for digital circuitry and to generate FET
output.
12
NC
Do not connect
13
CMO
Current output.
14
CMN
Current negative rail. Current return path.
15
GND
Power supply return.
16
COMS
Serial communications pin. Bi-directional serial communication signal for
reading and writing to the EEPROM.
3901090323
Rev 001
Description
1
COMS
16
2
GND
15
3
TSTB
CMN
14
4
FLT
CMO
13
5
OFC
6
VBN
VDD1
11
7
VBP
FET
10
8
TMP
VDD
9
12
Page 5 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
6 General Electrical Specifications
Table 3. MLX90323 Electrical Specifications
o
DC operating parameters: TA = -40 to 125 C, VDD1 = 6 to 35VDC (unless otherwise specified).
Parameter
Symbol
Test Conditions
Min
Typ
Max
Units
35
V
Regulator & Consumption
Input voltage range
VIN
VDD1 (Regulator connected)
Supply current
IDD
@ TA = 100ºC Current Mode
Regulated supply voltage VREG
6
2.1
4.5
Regulated voltage
temperature coefficient
Supply rejection ratio
4.75
mA
5.2
º
-600
PSRR
VDD1 > 6V
V
uV / C
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)
38.0
65.0
%VDD
Common mode
input range
Common mode
rejection Ratio
1/2(VBP+VBN)
CMRR
60
Hardware gain
Coarse offset
control Range
Fixed offset control range
dB
69
84
CSOF[1:0] = 00
-4.37
-3.97
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
High
1.71
2.29
mV/V
Low
-2.00
-1.43
mV/V
IA chopper frequency
300
V/V
mV/V
kHz
Gain Stage
Coarse gain
CSGN = 000
3.0
3.3
V/V
(Fixed Gain = 1023)
CSGN = 001
4.9
5.4
V/V
Coarse gain
CSGN = 010
8.0
8.8
V/V
Coarse gain
CSGN = 011
12.8
14.1
V/V
Fixed gain control range
0.480
0.970 V/V
Current Coarse Gain Stage
3901090323
Rev 001
Page 6 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Coarse 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
8.4
9.3
mA/V
Current Output Stage
Fixed gain
RSENSE = 24 ohm
Output current CMO pin
Current mode
Current sense resistor
27
mA
24
Ohms
Signal Path ( General)
Overall gain
Current sense res = 24Ω
Overall non-linearity
Bandwidth (-3dB)
39 nF (FLT to GND)
284
2625
mA/V
-0.25
0.25
%
4.2
KHz
2.8
3.5
Temperature Sensor & Amplifier
Temperature sensor sensitivity
390
Temperature sensor output voltage
uV/ºC
70
380
mV
Input voltage range TMP pin
GNTP[1,0] = 00
207
517
mV
@ VDD = 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
Monotonicity
Bit
Guaranteed By Design
Offset Error
10
LSB
10
Bit
ADC
Resolution
Guaranteed by design
Monotonicity
Offset error
10
LSB
On-Chip RC Oscillator and Clock
Trimmed RC oscillator frequency
86.9
Frequency temperature coefficient
88.7
26
Clock Stability with temperature compensation over full
temperature range
Ratio of f (microcontroller main
TURBO = 0
clock and (RC oscillator)
TURBO = 1
3901090323
Rev 001
87.8
Page 7 of 24
-3
kHz
Hz/ºC
+3
%
7
28
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
UART & COMS Pin
UART baud rate
COMS pin input levels
TURBO = 0
2400
Baud
TURBO = 1
9600
Baud
Low
0.3*VDD
V
High
COMS Pin Output Resistance
3901090323
Rev 001
0.7*VDD V
Low
100
Ohms
High
100
kOhms
Page 8 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
7 Detailed General Description
7.1 Understanding 4-20 mA current loop interface
MLX90323 IC is optimized for 4 - 20 mA industry standard current loop interface. The 4 - 20mA current loop
shown in Figure 1 is a common method of transmitting sensor information in many industrial applications.
Transmitting sensor information via a current loop is particularly useful when the information has to be sent to
a remote location over long distances. The loop operation is straightforward: a sensor’s output voltage is first
converted to a proportional current, with 4mA normally representing the sensor’s zero-level output, and 20mA
representing the sensor’s full-scale output. Then, a receiver at the remote end converts the 4-20mA current
back into a voltage which in turn can be further processed by a controller module.
Sensor
MLX90323
VB
Signal Line
SLP
Positive
Signal processor / Controller
Transmission Line
E
INP
INM
GND
4 – 20 mA
R
Current loop
power source
Output voltage for
further processing
SLN Signal Line
Negative
Figure 1. Current loop interface diagram
7.2 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).
Oscillator
The MLX90323 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.
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).
3901090323
Rev 001
Page 9 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
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.
7.3 Digital features
Microprocessor, LX11 Core, Interrupt Controller, Memories
The LX11 microcontroller core is described in its own datasheet. As an overview, this implementation of the
LX11 RISC core has following resources:
Two accumulators, one index and two interrupt accumulators.
15 - 8 bit I/O ports to internal resources.
64 byte RAM.
4 kbytes ROM : 3 kbytes is available for customer's application firmware. 1k is reserved for test.
48 x 8 bit EEPROM.
Four interrupt sources, two UART interrupts and two timers.
UART
The serial link is a potentially full-duplex UART. It is receive-buffered, in that it can receive a second byte
before a previously received byte has been read from the receiving register. However, if the first byte is not
read by the time the reception of the second byte is completed, the first byte will be lost. The UART's baud
rate depends on the RC-oscillator's frequency and the "TURBO"-bit (see output port). Transmitted and
received data has the following structure: start bit = 0, 8 bits of data, stop bit = 1.
Sending Data
Writing a byte to port 1 automatically starts a transmission sequence. The TX Interrupt is set when the STOPbit of the byte is latched on the serial line.
Receiving Data
Reception is initialized by a 1 to 0 transition on the serial line (i.e., a START-bit). The baud rate period (i.e.,
the duration of one bit) is divided into 16 phases. The first six and last seven phases of a bit are not used.
The decision on the bit-value is then the result of a majority vote of phase 7, 8 and 9 (i.e., the center of the
bit).
Spike synchronization is avoided by de-bouncing on the incoming data and a verification of the START-bit
value. The RX Interrupt is set when the stop bit is latched in the UART.
Timer
The clock of the timers TMI and TPI is taken directly from the main oscillator. The timers are never reloaded,
so the next interrupt will take place 2x oscillator pulses after the first interrupt.
Watch Dog
An internal watch dog will reset the whole circuit in case of a software crash. If the watch dog counter is not
reset at least once every 26 milliseconds (@ 2.46 MHz main clock), the microcontroller and all the
peripherals will be reset.
Temperature Processing
Temperature reading controls the temperature compensation. This temperature reading is filtered as
designated by the user. The filter adjusts the temperature reading by factoring in a portion of the previous
value. This helps to minimize the effect of noise when using an external temperature sensor. The filter
equation is:
If measured_temp > Temp_f(n) then
n_factor
Temp_f(n+1) = Temp_f(n) + [measured_temp - Temp_f(n)] / [2
]
If measured_temp < Temp_f(n), then
3901090323
Rev 001
Page 10 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
n_factor
Temp_f(n+1) = Temp_f(n) - [measured_temp - Temp_f(n)] [2
]
Temp_f(n+1) = new filtered temperature value
Temp_f(n) = previous filtered temperature value
Measured_temp = Value from temperature A to D
N_factor = Filter value set by the user (four LSB’s of byte 25 of EEPROM), range 0-6.
The filtered temperature value, Temp_f, is stored in RAM bytes 58 and 59. The data is a 10 bit value, left
justified in a 16 bit field.
7.4 Parameters calculation
The parameters OF and GN represent, respectively, offset correction and span control, while OFTCi and
GNTCi represent their temperature coefficients (thermal zero shift and thermal span shift). After reset, the
firmware continuously calculates the offset and gain DAC settings as follows: The EEPROM holds
parameters GN, OF, OFTCi and GNTCi, where “i” is the gap number and can be 1 < i < 4. The transfer
function is described below.
Vout = FG * DAC_GAIN * CSGN[2:0] * {Vin+DAC_OFFSET+CSOF}
Iout = FG * DAC_GAIN * CSGN[1:0] * {Vin+DAC_OFFSET+CSOF} * 8.85mA/V
FG = Hardware Gain (~72V/V). Part of the hardware design, and not changeable
CSGN = Course Gain, part of byte 2 in EEPROM.
CSOF = Coarse Offset, part of byte 2 in EEPROM.
GAIN
DAC_GAIN (new value) ~ GN[9:0] + [GNTCi * dT]
GN[9:0] = Fixed Gain, bytes 3 and 17 in EEPROM.
GNTCi = Gain TC for a given temperature segment I. GNTCiL and GNTCiH in
dT = Temp. change within the appropriate gap
EEPROM table.
How to calculate gain in the first temp. gap?:
DAC_GAIN = GN[9:0] - GNTC1 * (T1 – Temp_f1)
How to calculate gain in the other temp. gaps?:
2nd gap: DAC_GAIN = GN[9:0] + GNTC2 * (Temp_f2 – T1)
3rd gap: DAC_GAIN = DAC_GAIN2 + GNTC3 * (Temp_f3 – T2)
4th gap: DAC_GAIN = DAC_GAIN3 + GNTC4 * (Temp_f4 – T3)
Where:
Temp_f = Filtered temp (previously described)
If GNTC1 > 2047 => DAC_GAIN
If GNTC2,3,4 > 2047 => DAC_GAIN ↓
[V/V]
(0.97 − 0.48) *
GN [9 : 0]
+ 0.48 = DAC _ GAIN
1023
OFFSET
DAC_OFFSET (new value) ~ OF[9:0]+[OFTCi* dT]
3901090323
Rev 001
Page 11 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
OF[9:0] = Fixed Gain, bytes 4 and 17 in EEPROM.
OFTCi = Offset for a given temperature segment I. OFTCiL and OFTCiH in EEPROM table.
dT = Temp. change within the appropriate gap.
Calculation of the offset for a given temperature segment is performed the same way as for the gain.
(1.83 − −1.57) *
OF [9 : 0]
− 1.57 = DAC _ OFFSET [mV/V]
1023
7.5 Communications
The MLX90323 firmware transfers a complete byte of data into and from the memory based on a simple
command structure. The commands allow data to be read and written to and from the EEPROM and read
from the RAM. RAM data that can be read includes the current digitized temperature and digitized GNO. The
commands are described below. Melexis provides setup software for programming the MLX90323.
UART Commands
The commands can be divided into three parts: (1) downloading of data from the ASIC, (2) uploading of data
to the ASIC and (3) the reset command.
All the commands have the same identification bits. The two MSB’s of the sent byte indicate the command
while the last six MSB’s designate the desired address. The commands are coded as followed:
11 to read a RAM byte.
10 to read an EEPROM byte.
01 to write in the EEPROM.
00 to write in the RAM.
The addresses can include 0-63 for the RAM, 0-47 for the EEPROM, and 63 for the EEPROM, RESET
Command (read).
Downloading Command
With one byte, data can be downloaded from the ASIC. The ASIC will automatically send the value of the
desired byte.
Uploading Command
Writing to the RAM or EEPROM involves a simple handshaking protocol in which each byte transmitted is
acknowledged by the firmware. The first byte transmitted to the firmware includes both command and
address. The firmware acknowledges receipt of the command and address byte by echoing the same
information back to the transmitter. This “echo” also indicates that the firmware is ready to receive the byte of
data to be stored in RAM or EEPROM. Next, the byte of value to be stored is transmitted and, if successfully
received and stored by the firmware, is acknowledged by a “data received signal,” which is two bytes of value
BCh. If the “data received signal” is not observed, it may be assumed that no value has been stored in RAM
or EEPROM.
Reset Command
Reading the address 63 of the EEPROM resets the ASIC and generates a received receipt indication.
Immediately before reset, the ASIC sends a value of BCh to the UART, indicating that the reset has been
received.
EEPROM Data
All user-settable variables are stored in the EEPROM within the MLX90323. The EEPROM is always reprogrammable. Changes to data in the EEPROM do not take effect until the device is reset via a soft reset or
power cycle. 12 bit variables are stored on 1.5 bytes. The 4 MSB’s are stored in a separate byte and shared
with the four MSB’s of another 12-bit variable.
3901090323
Rev 001
Page 12 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Clock Temperature Stabilization
To provide a stable clock frequency from the internal clock over the entire operating temperature range, three
separate clock adjust values are used. Shifts in operating frequency over temperature do not effect the
performance but do, however, cause the communications baud rate to change.
The firmware monitors the internal temperature sensor to determine which of three temperature ranges the
device currently is in. Each temperature range has a factory set clock adjust value, ClkTC1, ClkTC2, and
ClkTC3. The temperature ranges are also factory set. The Ctemp1 and Ctemp2 values differentiate the three
ranges. In order for the temperature A to D value to be scaled consistently with what was used during factory
programming, the CLKgntp (temperature amplifier gain) valued is stored. The Cadj value stored in byte 1 of
the EEPROM is used to control the internal clock frequency while the chip boots.
Unused Bytes
There are eight unused bytes in the EEPROM address map. These bytes can be used by the user to store
information such as a serial number, assembly date code, production line, etc. Melexis doesn’t guarantee that
these bytes will be available to the user in future revisions of the firmware.
EEPROM Checksum
A checksum test is used to ensure the contents of the EEPROM. The eight bit sum of all of the EEPROM
addresses should have a remainder of 0FFh when the checksum test is enabled (mode byte). Byte 47 is
used to make the sum remainder totals 0FFh. If the checksum test fails, the output will be driven to a user
defined value, Faultval. When the checksum test is enabled, the checksum is verified at initialization of RAM
after a reset.
RAM Data
All the coefficients (pressure, temperature) are compacted in a manner similar to that used for the EEPROM.
They are stored on 12 bits (instead of keeping 16 bits for each coefficient). All the measurements are stored
on 16 bits. The user must have access to the RAM and the EEPROM, while interrupt reading of the serial
port. Therefore, bytes must be kept available for the return address, the A-accu and the B-accu, when an
interrupt occurs. The RAM keeps the same structure in the both modes.
Table 4. Examples of Fixed Point Signed
Numbers
3901090323
Rev 001
Decimal
Value
Hexadecimal
Equivalent
Fixed Point
Signed Number
Equivalent
0
0000h
+0.00
1023
3FFh
+0.9990234
1024
400h
+1.000
2047
7FFh
+1.9990234
2048
800h
-0.000
3071
0BFFh
-0.9990234
Page 13 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
3072
0C00h
-1.000
4095
0FFFh
-1.9990234
Data Range
Various data are arranged as follows:
Temperature points: 10 bits, 0-03FF in high-low order.
Pressure points: 10 bits, 0-03FF in high-low order.
GN1: 10 bits, 0-03FF in high-low order.
OF1: 10 bits, 0-03FF in high-low order.
GNTCi: signed 12 bits (with MSB for the sign), [-1.9990234, +1.9990234].
OFTCi: signed 12 bits (with MSB for the sign), [-1.9990234, +1.9990234].
3901090323
Rev 001
Page 14 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Table 5. EEPROM Byte Definitions
Byte
Designation
Note
0
Turbo mode, temp
selection
Bit 1: (0 = internal temp, 1 = external temp)
Bit 3: (0 = Turbo mode active, 1 = not active)
Bit 0-2-4-5-6-7: unused
1
Cadj
Controls system clock during boot.
2
Coarse Control
Contents described in Table 6.
3
GN1L
The eight LSB's of the Fixed Gain, GN[7:0].
4
OF1L
The eight LSB's of Fixed Offset OF[7:0].
5
GNTC1L
The eight LSB's of the first gain TC GNTC1[7:0].
6
OFTC1L
The eight LSB's of the first offset TC OFTC1[7:0].
7
TR1L
The eight LSB's of the first temperature point, T1[7:0].
8
GNTC2L
P5L
The eight LSB's of the second gain TC GNTC2[7:0].
The eight LSB's of Pressure Point 5 P5[7:0].
9
OFTC2L
The eight LSB's of the second offset TC OFTC2[7:0].
10
TR2L
P4L
The eight LSB's of the second temperature point T2[7:0].
The eight LSB's of Pressure Point 4 (or Signature) P4[7:0].
11
GNTC3L
The eight LSB's of the third gain TC GNTC3[7:0].
3901090323
Rev 001
Page 15 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Table 5. EEPROM Byte Definitions (continued)
Byte
Designation
Note
12
OFTC3L or
P3L
The eight LSB's of the third offset TC OFTC3[7:0]
The eight LSB's of Pressure Point 2 (or Signature) P2[7:0].
13
TR3L
The eight LSB's of the third temperature point T3[7:0].
14
GNTC4L or
P2L
The eight LSB's of the fourth gain TC GNTC4[7:0].
The eight LSB's of Pressure Point 2 P2[7:0].
15
OFTC4L
The eight LSB's of the fourth offset TC OFTC4.
16
PoffL
The eight LSB's of Pressure (output signal) Ordinate
Poff[7:0].
Upper four bits
Lower four bits
17
GN1[9:8]
OF1[9:8]
Two MSB's of fixed gain
GN[9:8].
Two MSB's of fixed offset
OF[9:8]
18
GNTC1[11:8]
OFTC1[11:8]
Four MSB's of first gain TC
GNTC1[11:8].
Four MSB's of the first offset
TC OFTC1[11:8].
19
TR1[9:8]
GNTC2[11:8]
Two MSB's, first temperature
point T1[9:8] or
Four MSB's, Pressure
Four MSB's, second gain
TC GNTC2[11:8] or
TC GNTC2[11:8] or
Two MSB's Pressure Point 5
P5[9:8].
Four MSB's second offset
TC OFTC2[11:8] or
Two MSB's second
temperature point T2[9:8] or
Two MSB's Pressure Point 4
P4[9:8].
Four MSB's third gain TC
GNTC3[11:8] or
Four MSB's third offset
TC OFTC3[11:8] or
Two MSB's Pressure Point 3
P3[9:8].
P5[9:8]
20
OFTC2[11:8]
TR2[9:8]
P4[9:8]
21
GNTC3[11:8]
OFTC3[11:8]
P3[9:8]
22
TR3[9:8]
GNTC4[11:8] Two MSB's third
temperature point t3[9:8] or
P2[9:8]
Four MSB's fourth gain TC
GNTC4[11:8] or
Two MSB's Pressure
Point 2 P2[9:8].
23
OFTC4[11:8]
Poff[9:8]
Two MSB's Pressure
3901090323
Rev 001
Four MSB's fourth offset TC
ordinate
OFTC4[11:8] or
Page 16 of 24
Poff[9:8].
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Table 5. EEPROM Byte Definitions (continued)
Byte
Designation
Note
24
PNB_TNB
Number of temperature and pressure gaps.
25
n_factor
Temperature filter coefficient, four LSB's. Four MSB's
must all be zero.
26
Not used
This byte is not used.
32
ClkTC1
Value of Cadj at low temperature (Don’t change; factory
set).
33
ClkTC2
Value of Cadj at mid temperature (Don’t change; factory
set).
34
ClkTC3
Value of Cadj at high temperature Don’t change; factory
set).
35
Ctemp1
First Cadj temperature point, eight MSB’s of the 10 bit
internal temperature value (set at factory; do not
change).
36
Ctemp2
Second Cadj temperature point, eight MSB’s of the 10
bit internal temperature value (set at factory; do not
change).
37-38
Not used
These bytes are not used and are available to the user.
39
CLKgntp
Setting for temperature amplifier for clock temperature
adjustment temperature reading (factory set, do not
change).
40-41
Faultval
Value sent to output if checksum test fails is a 10 bit
value.
42-46
Not Used
These bytes are not used and are available to the user.
47
Checksum
EEPROM checksum; value needed to make all bytes
add to 0FFh. Must be set by user if checksum test is
active.
3901090323
Rev 001
Page 17 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Table 6. Bit Definitions, Coarse Control , Byte 2
Bit Symbol Function
7
IINV
Invert signal sign.
6
GNTP1 Gain & offset of temperature
amplifier.
5
GNTP0 GNTP = 0 to 3.
4
CSOF 1 Coarse offset of signal amplifier.
3
CSOF 0 CSOF = 0 to 3.
2
CSGN2 Coarse gain of signal amplifier.
CSGN = 0 to 7. If CSGN > 3,
CSGN1 output range = 0 to 10V. If
CSGN <= 3, output range = 0 to
CSGN0 5V.
1
0
Table 7. RAM Byte Definitions
Byte
Functions
0
Not used
1
GN1L
Fixed gain number (8LSB).
2
OF1L
Fixed offset number (8LSB).
3
GNTC1L
First gain TC (8LSB).
4
OFTC1L
First offset TC (8LSB).
5
TR1L
First temperature point.
6
GNTC2L
P5L
Second gain TC.
Pressure point 5 (8LSB).
7
OFTC2L
Second offset TC.
8
TR2L
P4L
Second temperature point.
Pressure Point 4 (or Signature) (8LSB).
9
GNTC3L
Third gain TC.
10
OFTC3L
P3L
Third offset TC.
Pressure Point 2 (or Signature) (8LSB).
3901090323
Rev 001
Remarks
Page 18 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
Byte
Functions
Remarks
TR3L
GNTC4L
Third temperature point.
Fourth gain TC.
P2L
Pressure Point 1 (8LSB).
13
14
OFTC4L
DIGMOP1L
Fourth offset TC.
Fixed pressure (8LSB).
15
GN1[9:8]
OF1[9:8]
Two MSB's of fixed gain
GN[9:8].
Two MSB's of fixed offset
OF[9:8].
16
GNTC1
[11:8]
OFTC1[11:8]
Four MSB's of first gain TC
GNTC1[11:8].
Four MSB's of the first
offset TC OFTC1[11:8]
17
TR1[9:8]
GNTC2[11:8]
Two MSB's, first temperature
gain
point T1[9:8] or
Four MSB's, second
11
12
P5[9:8]
18
OFTC2[11:8]
TR2[9:8]
Four MSB's, second offset TC
OFTC2[11:8] or
TC GNTC2[11:8] or
Two MSB's, Pressure
Point 5 P5[9:8]
Two MSB's, second temp.
point T2[9:8] or
P4[9:8]
19
GNTC3[11:8] OFTC3[11:8]
Four MSB's, Third Gain TC
GNTC3[11:8] or
Two MSB's, Pressure
Point 4 P4[9:8].
Four MSB's Third Offset
TC OFTC3[11:8] or
Two MSB's, third temperature
point t3[9:8] or
Two MSB's Pressure
Point 3 P3[9:8]
Four MSB's, Fourth Gain
TC GNTC4[11:8] or
Four MSB's Fourth Offset TC
OFTC4[11:8] or
Two MSB's, Pressure
Point 2 P2[9:8].
Two MSB's Pressure
Point 1 P1[9:8].
P3[9:8]
20
TR3[9:8]
GNTC4[11:8]
P2[9:8]
21
OFTC4[11:8]
P1[9:8]
22
PNB_TNB
Same as EEPROM.
23
N_Factor
Temperature filter coefficient — 4 LSB’s, 4 MSB = 0
24
Not Used
25-26
GN
Offset Ordinate of the current gap.
27-28
OF
Gain Ordinate of the current gap.
Taddress
29
35-36
A_16
4 bits for the max. temperature address of the current gap;
4 bits for the min. temperature address of the current gap.
16 bits A Register.
37-38
B_16
16 bits B Register.
39-42
RESULT_32
32 bits result (for 16 bit multiplication).
3901090323
Rev 001
Page 19 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
43-44
Tempo1
Measured temperature, internal or external, and temporary
variable 1.
45
Tempo2
Temporary variable 2.
46-47
Signal_In
Digitized signal value, analog and digital mode
48
Coms_backup
Address saved when command is send.
49
P3_copy
Port 3 setting copy.
50
Adsav1
Address saved at interrupt.
51-52
Aaccsav
A-Accumulators saved at interrupt.
53
Baccsav
B-Accumulators saved at interrupt.
54-55
DAC_gain
DAC gain (GN).
56-57
DAC_offset
DAC offset (OF).
58-59
Temp_f
60-61
Signal_Out
Filtered temperature. This is a 10 bit number that is left
justified in a 16 bit field.
Digitized linearity corrected signal value. Digital mode only.
62-63
Adsav2
Address saved when call.
Note: Because of space considerations, the measured temperature can’t be kept in the RAM at all times. If
the measured temperature is to be available, the temperature filter variable, N_Factor, must be set to 6.
3901090323
Rev 001
Page 20 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
8 Unique Features
Customization
Melexis can customize the MLX90323 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.
Programming and Setup
The MLX90323 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 RS-232 serial communications
port.
9 Application Information
Supply
5K
VDD
FET VDD1
100 nF
COMS
100 nF
CMO
100 nF
VBP
75 Ohms
VBN
TMP
FLT
Depends on
stability of the
current loop
39 nF
GND CMN
24 Ohms
Ground
3901090323
Rev 001
Page 21 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
10 Standard information regarding manufacturability of Melexis
products with different soldering processes
Our products are classified and qualified regarding soldering technology, solderability and moisture sensitivity
level according to following test methods:
Reflow Soldering SMD’s (Surface Mount Devices)
•
•
IPC/JEDEC J-STD-020
Moisture/Reflow Sensitivity Classification for Nonhermetic Solid State Surface Mount Devices
(classification reflow profiles according to table 5-2)
EIA/JEDEC JESD22-A113
Preconditioning of Nonhermetic Surface Mount Devices Prior to Reliability Testing
(reflow profiles according to table 2)
Wave Soldering SMD’s (Surface Mount Devices) and THD’s (Through Hole Devices)
•
•
EN60749-20
Resistance of plastic- encapsulated SMD’s to combined effect of moisture and soldering heat
EIA/JEDEC JESD22-B106 and EN60749-15
Resistance to soldering temperature for through-hole mounted devices
Iron Soldering THD’s (Through Hole Devices)
•
EN60749-15
Resistance to soldering temperature for through-hole mounted devices
Solderability SMD’s (Surface Mount Devices) and THD’s (Through Hole Devices)
•
EIA/JEDEC JESD22-B102 and EN60749-21
Solderability
For all soldering technologies deviating from above mentioned standard conditions (regarding peak
temperature, temperature gradient, temperature profile etc) additional classification and qualification tests
have to be agreed upon with Melexis.
The application of Wave Soldering for SMD’s is allowed only after consulting Melexis regarding assurance of
adhesive strength between device and board.
Melexis is contributing to global environmental conservation by promoting lead free solutions. For more
information on qualifications of RoHS compliant products (RoHS = European directive on the Restriction Of
the use of certain Hazardous Substances) please visit the quality page on our website:
http://www.melexis.com/quality.asp
3901090323
Rev 001
Page 22 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
11 ESD Precautions
Electronic semiconductor products are sensitive to Electro Static Discharge (ESD).
Always observe Electro Static Discharge control procedures whenever handling semiconductor products.
12 Package Information
10.65
10.00
7.60
7.40
0.32
0.23
1.27
0.40
0.51
0.33
1.27
0o to
8o
Notes:
10.50
10.10
1. All dimensions in millimeters.
2. Body dimensions do not include mold flash or
protrusion, which are not to exceed 0.15mm.
2.65
2.35
0.010
min.
3901090323
Rev 001
Page 23 of 24
Data Sheet
March/08
MLX90323
4 – 20 mA Loop Sensor Interface
with Signal Conditioning and EEPROM
13 Disclaimer
Devices sold by Melexis are covered by the warranty and patent indemnification provisions appearing in its
Term of Sale. Melexis makes no warranty, express, statutory, implied, or by description regarding the
information set forth herein or regarding the freedom of the described devices from patent infringement.
Melexis reserves the right to change specifications and prices at any time and without notice. Therefore, prior
to designing this product into a system, it is necessary to check with Melexis for current information. This
product is intended for use in normal commercial applications. Applications requiring extended temperature
range, unusual environmental requirements, or high reliability applications, such as military, medical lifesupport or life-sustaining equipment are specifically not recommended without additional processing by
Melexis for each application.
The information furnished by Melexis is believed to be correct and accurate. However, Melexis shall not be
liable to recipient or any third party for any damages, including but not limited to personal injury, property
damage, loss of profits, loss of use, interrupt of business or indirect, special incidental or consequential
damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical
data herein. No obligation or liability to recipient or any third party shall arise or flow out of Melexis’ rendering
of technical or other services.
© 2005 Melexis NV. All rights reserved.
For the latest version of this document, go to our website at
www.melexis.com
Or for additional information contact Melexis Direct:
Europe, Africa, Asia:
Phone: +32 1367 0495
E-mail: [email protected]
America:
Phone: +1 603 223 2362
E-mail: [email protected]
ISO/TS 16949 and ISO14001 Certified
3901090323
Rev 001
Page 24 of 24
Data Sheet
March/08