19-1829; Rev 1; 6/01
KIT
ATION
EVALU
BLE
AVAILA
Low-Cost Precision Sensor
Signal Conditioner
General Description
Features
o
Provides Amplification, Calibration, and
Temperature Compensation
o
Accommodates Sensor Output Sensitivities
from 1mV/V to 40mV/V
o
Single Pin Digital Programming
o
No External Trim Components Required
o
16-Bit Offset and Span Calibration Resolution
o
Fully Analog Signal Path
o
On-Chip Lookup Table Supports Multipoint
Calibration Temperature Correction
o
Supports Both Current and Voltage Bridge
Excitation
o
Fast 3.2kHz Frequency Response
o
On-Chip Uncommitted Op Amp
o
Secure-Lock™ Prevents Data Corruption
o
Low 2mA Current Consumption
MAX1452
The MAX1452 is a highly integrated analog-sensor sig-
nal processor optimized for industrial and process con-
trol applications utilizing resistive element sensors.
The MAX1452 provides amplification, calibration, and
temperature compensation that enables an overall per-
formance approaching the inherent repeatability of the
sensor. The fully analog signal path introduces no
quantization noise in the output signal while enabling
digitally controlled trimming with the integrated 16-bit
DACs. Offset and span are calibrated using 16-bit
DACs, allowing sensor products to be truly inter-
changeable.
The MAX1452 architecture includes a programmable
sensor excitation, a 16-step programmable-gain ampli-
fier (PGA), a 768-byte (6144 bits) internal EEPROM,
four 16-bit DACs, an uncommitted op amp, and an on-
chip temperature sensor. In addition to offset and span
compensation. The MAX1452 provides a unique tem-
perature compensation strategy for offset TC and
FSOTC that was developed to provide a remarkable
degree of flexibility while minimizing testing costs.
The MAX1452 is packaged for the commercial, industri-
al, and automotive temperature ranges in 16-pin SSOP
packages.
Customization
Maxim can customize the MAX1452 for high-volume
dedicated applications. Using our dedicated cell library
of more than 2000 sensor-specific functional blocks,
Maxim can quickly provide a modified MAX1452 solu-
tion. Contact Maxim for further information.
PART
MAX1452CAE
MAX1452EAE
MAX1452AAE
MAX1452C/D
Ordering Information
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
-40°C to +125°C
0°C to +70°C
PIN-PACKAGE
16 SSOP
16 SSOP
16 SSOP
Dice*
Applications
Pressure Sensors
Transducers and Transmitters
Strain Gauges
Pressure Calibrators and Controllers
Resistive Elements Sensors
Accelerometers
Humidity Sensors
*Dice are tested at T
A
= +25°C, DC parameters only.
A detailed block diagram appears at the end of data sheet.
Pin Configuration
TOP VIEW
ISRC 1
OUT 2
V
SS
3
INM 4
BDR 5
INP 6
V
DD
7
TEST 8
MAX1452
(NOT TO SCALE)
16 FSOTC
15 AMP+
14 AMP-
13 AMPOUT
12 CLK1M
11 DIO
10 UNLOCK
9
V
DDF
Outputs Supported
4–20mA
0 to +5V (Rail-to-Rail
®
)
+0.5V to +4.5V Ratiometric
+2.5V to ±2.5V
Rail-to-Rail is a trademark of Nippon Motorola Ltd.
Secure-Lock is a trademark of Maxim Integrated Products.
SSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Low-Cost Precision Sensor
Signal Conditioner
MAX1452
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
DD
to V
SS
.........................................-0.3V, +6V
All Other Pins ...................................(V
SS
- 0.3V) to (V
DD
+ 0.3V)
Short-Circuit Duration, FSOTC, OUT, BDR,
AMPOUT .................................................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
16-Pin SSOP (derate 8.00mW/°C above +70°C) ..........640mW
Operating Temperature:
MAX1452CAE/MAX1452C/D ...............................0°C to +70°C
MAX1452EAE ...................................................-40°C to +85°C
MAX1452AAE .................................................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature.........................................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................ +300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
DD
= +5V, V
SS
= 0, T
A
= +25°C, unless otherwise noted.)
PARAMETER
GENERAL CHARACTERISTICS
Supply Voltage
Supply Current
Oscillator Frequency
ANALOG INPUT
Input Impedance
Input Referred Offset Tempco
Input Referred Adjustable
Offset Range
Amplifier Gain Nonlinearity
Common-Mode Rejection Ratio
Input Referred Adjustable FSO
Range
ANALOG OUTPUT
Differential Signal-Gain Range
Selectable in 16 steps
Configuration [5:2] 0000bin
Configuration [5:2] 0001bin
Differential Signal Gain
Configuration [5:2] 0010bin
Configuration [5:2] 0100bin
Configuration [5:2] 1000bin
Maximum Output Voltage Swing
Output Voltage Low
Output Voltage High
Output Impedance at DC
Output Offset Ratio
∆V
OUT
/
∆Offset
0.90
No load from each supply
I
OUT
= 1mA sinking, T
A
= T
MIN
to T
MAX
I
OUT
= 1mA sourcing, T
A
= T
MIN
to T
MAX
4.75
34
47
58
82
133
39-
240
39
52
65
91
143
0.02
0.100
4.87
0.1
1.05
1.20
0.20
46
59
74
102
157
V
V
V
Ω
V/V
V/V
V/V
CMRR
R
IN
(Notes 2, 3)
Offset TC = 0 at minimum gain (Note 4)
Percent of +4V span, V
OUT
= +0.5V to 4.5V
Specified for common-mode voltages
between V
SS
and V
DD
(Note 2)
(Note 5)
1
±1
±150
0.01
90
1-40
MΩ
µV/°C
mV
%
dB
mV/V
V
DD
I
DD
f
OSC
(Note 1)
0.85
4.5
5.0
2.0
1
5.5
2.5
1.15
V
mA
MHz
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
2
_______________________________________________________________________________________
Low-Cost Precision Sensor
Signal Conditioner
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V, V
SS
= 0, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Output Offset TC Ratio
Step Response and IC
(63% Final Value)
Maximum Capacitive Load
Output Noise
BRIDGE DRIVE
Bridge Current
Current Mirror Ratio
V
SPAN
Range (Span Code)
DIGITAL–TO–ANALOG CONVERTERS
DAC Resolution
ODAC Bit Weight
OTCDAC Bit Weight
FSODAC Bit Weight
FSOTCDAC Bit Weight
COARSE OFFSET DAC
IRODAC Resolution
IRODAC Bit Weight
FSOTC BUFFER
Minimum Output Voltage Swing
Maximum Output Voltage Swing
Current Drive
INTERNAL RESISTORS
Current-Source Reference
Resistor
Current-Source Reference
Resistor Temperature Coefficient
FSOTC Resistor
FSOTC Resistor Temperature
Coefficient
R
ISRC
∆R
ISRC
R
FTC
∆R
FTC
75
1300
75
1300
kΩ
ppm/°C
kΩ
ppm/°C
No load
No load
V
FSOTC
= +2.5V
V
DD
- 1.0
-40
+40
V
SS
+
0.1
V
V
µA
∆V
OUT
/
∆Code
Including sign
Input referred, DAC reference =
V
DD
= +5.0V (Note 6)
4
9
bits
mV/bit
∆V
OUT
/
∆Code
∆V
OUT
/
∆Code
∆V
OUT
/
∆Code
∆V
OUT
/
∆Code
DAC reference = V
DD
= +5.0V
DAC reference = V
BDR
= +2.5V
DAC reference = V
DD
= +5.0V
DAC reference = V
BDR
= +2.5V
16
76
38
76
38
bits
µV/bit
µV/bit
µV/bit
µV/bit
I
BDR
AA
R
L
= 1.7kΩ
R
ISOURCE
= internal
T
A
= T
MIN
to T
MAX
0.1
10
4000
0.5
12
2
14
C000
mA
A/A
hex
DC to 1kHz (gain = minimum, source
impedance = 5kΩ V
DDF
filter)
SYMBOL
∆V
OUT
/
∆Offset
TC
CONDITIONS
MIN
0.9
TYP
1
150
1
0.5
MAX
1.2
UNITS
V/V
µs
µF
mV
RMS
MAX1452
3
_______________________________________________________________________________________
Low-Cost Precision Sensor
Signal Conditioner
MAX1452
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= +5V, V
SS
= 0, T
A
= +25°C, unless otherwise noted.)
PARAMETER
Temperature ADC Resolution
Offset
Gain
Nonlinearity
Lowest Digital Output
Highest Digital Output
UNCOMMITTED OP AMP
Open Loop Gain
Input Common-Mode Range
Output Swing
Output Voltage High
Output Voltage Low
Offset
Unity Gain Bandwidth
EEPROM
Maximum Erase/Write Cycles
Minimum Erase Time
(Note 7)
(Note 8)
10k
6
Cycles
ms
No load, T
A
= T
MIN
to T
MAX
1mA source, T
A
= T
MIN
to T
MAX
1mA sink, T
A
= T
MIN
to T
MAX
V
IN+
= +2.5V, unity gain buffer
-20
2
R
L
= 100kΩ
V
SS
V
SS
+
0.02
4.85
4.90
0.05
0.15
+20
90
V
DD
V
DD
-
0.02
dB
V
V
V
V
mV
MHz
SYMBOL
CONDITIONS
MIN
TYP
8
±3
1.45
±0.5
00
AF
MAX
UNITS
bits
LSB
°C/bit
LSB
hex
hex
TEMPERATURE-TO-DIGITAL CONVERTER
Excludes sensor or load current.
All electronics temperature errors are compensated together with sensors errors.
The sensor and the MAX1452 must be at the same temperature during calibration and use.
This is the maximum allowable sensor offset.
This is the sensor's sensitivity normalized to its drive voltage, assuming a desired full span output of +4V and a bridge volt-
age of +2.5V.
Note 6:
Bit weight is ratiometric to V
DD
.
Note 7:
Programming of the EEPROM at room temperature is recommended.
Note 8:
Allow a minimum of 6ms elapsed time before sending any command.
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
4
_______________________________________________________________________________________
Low-Cost Precision Sensor
Signal Conditioner
MAX1452
Typical Operating Characteristics
(V
DD
= +5V, T
A
= +25°C, unless otherwise noted.)
OFFSET DAC DNL
MAX1452 toc01
AMPLIFIER GAIN NONLINEARITY
OUTPUT ERROR FROM STRAIGHT LINE (mV)
ODAC = 6800hex
OTCDAC = 0
FSODAC = 4000hex
FSOTCDAC = 8000hex
IRO = 2hex
PGA = 0
MAX1452 toc02
5.0
5.0
2.5
DNL (mV)
2.5
0
0
-2.5
-2.5
-5.0
0
10k
20k
30k
40k
50k
60k
70k
DAC CODE
-5.0
-50
-25
0
25
50
OUTPUT NOISE
MAX1452 toc03
INPUT VOLTAGE [INP-INM] (mV)
OUT
10mV/div
400µs/div
C = 4.7µF, R
LOAD
= 1kΩ
Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
ISRC
OUT
V
SS
INM
BDR
INP
V
DD
TEST
Bridge Drive Current Mode Setting
High ESD and Scan Path Output Signal. May need a 0.1µF capacitor, in noisy environments.
OUT may be parallel connected to DIO.
Negative Supply Voltage
Bridge Negative Input. Can be swapped to INP by configuration register.
Bridge Drive
Bridge Positive Input. Can be swapped to INM by configuration register.
Positive Supply Voltage. Connect a 0.1µF capacitor from V
DD
to V
SS
.
Internally Connected. Connect to V
SS
.
FUNCTION
_______________________________________________________________________________________
5
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