MAX1452AAE(2001) Ver la hoja de datos (PDF) - Maxim Integrated

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MAX1452AAE
(Rev.:2001)

Low-Cost Precision Sensor Signal Conditioner

Maxim Integrated 

Low-Cost Precision Sensor

Signal Conditioner

SENSOR

G 2N4392

5

BDR

6 INP

7

VDD

9

VDDF

OUT 2

MAX1452

FSOTC

16

4 INM

ISRC 1

TEST VSS

83

IN 1

MAX6105

2 5V

GND

1kΩ

3

RSTC

0.1µF 0.1µF

RISRC

0.1µF

SD

0.1µF

VPWR

+12V TO +40V

OUT

GND

Figure 3. Basic Nonratiometric Output Configuration

Typical Nonratiometric

Operating Circuit

(12VDC < VPWR < 40VDC)

Nonratiometric output configuration enables the sensor

power to vary over a wide range. A high performance

voltage reference, such as the MAX6105, is incorporat-

ed in the circuit to provide a stable supply and refer-

ence for MAX1452 operation. A typical example is

shown in Figure 3. Nonratiometric operation is valuable

when wide ranges of input voltage are to be expected

and the system A/D or readout device does not enable

ratiometric operation.

Typical 2-Wire, Loop Powered,

4–20mA Operating Circuit

Process Control systems benefit from a 4–20mA current

loop output format for noise immunity, long cable runs,

and 2-wire sensor operation. The loop voltages can

range from 12VDC to 40VDC and are inherently nonra-

tiometric. The low current consumption of the MAX1452

allows it to operate from loop power with a simple

4–20mA drive circuit efficiently generated using the

integrated uncommitted op amp (Figure 4).

Internal Calibration Registers (ICRs)

The MAX1452 has five 16-bit internal calibration regis-

ters that are loaded from EEPROM, or loaded from the

serial digital interface.

Data can be loaded into the internal calibration regis-

ters under three different circumstances.

Normal Operation, Power-On Initialization Sequence

• The MAX1452 has been calibrated, the Secure-

Lock byte is set (CL[7:0] = FFhex) and UNLOCK is

low.

• Power is applied to the device.

• The power-on reset functions have completed.

• Registers CONFIG, OTCDAC, and FSOTCDAC are

refreshed from EEPROM.

• Registers ODAC, and FSODAC are refreshed from

the temperature indexed EEPROM locations.

Normal Operation, Continuous Refresh

• The MAX1452 has been calibrated, the Secure-

Lock byte has been set (CL[7:0] = FFhex) and

UNLOCK is low.

• Power is applied to the device.

• The power-on reset functions have completed.

• The temperature index timer reaches a 1ms time

period.

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