MAX1458 データシートの表示（PDF） - Maxim Integrated

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MAX1458

1%-Accurate, Digitally Trimmed Sensor Signal Conditioner

Maxim Integrated 

MAX1458

1%-Accurate, Digitally Trimmed

Sensor Signal Conditioner

Pin Description

PIN

1

2

3, 11

4

5

6

7

8

9

10

12

13

14

15

16

NAME

SCLK

CS

I.C.

TEMP

FSOTC

DIO

WE

VSS

ISRC

OUT

INM

BDRIVE

INP

VDD

LIMIT

FUNCTION

Data Clock Input. Used only during programming/testing. Internally pulled to VSS with a 1MΩ (typical)

resistor. Data is clocked in on the rising edge of the clock. The maximum SCLK frequency is 10kHz.

Chip-Select Input. The MAX1458 is selected when this pin is high. When low, OUT and DIO become high

impedance. Internally pulled to VDD with a 1MΩ (typical) resistor. Leave unconnected for normal operation.

Internally Connected. Leave unconnected.

Temperature Sensor Output. An internal temperature sensor (a 100kΩ, 4600ppm/°C TC resistor) which can

provide a temperature-dependent voltage.

Buffered FSOTC DAC Output. An internal 75kΩ resistor (RFTC) connects FSOTC to ISRC (see Functional

Diagram). Optionally, external resistors can be used in place of or in parallel with RFTC and RISRC.

Data Input/Output. Used only during programming/testing. Internally pulled to VSS with a 1MΩ (typical)

resistor. High impedance when CS is low.

Dual-Function Input Pin. Used to enable EEPROM erase/write operations. Also used to set the DAC

refreshrate mode. Internally pulled to VDD with a 1MΩ (typical) resistor. Refer to the Chip-Select (CS) and

Write-Enable (WE) section.

Negative Power-Supply Input

Current-Source Reference. An internal 75kΩ resistor (RISRC) connects ISRC to VSS (see Functional

Diagram). Optionally, external resistors can be used in place of or in parallel with RFTC and RISRC.

PGA Output Voltage

Negative Sensor Input. Input impedance >1MΩ. Rail-to-rail input range.

Sensor Excitation Current Output. This current source drives the bridge.

Positive Sensor Input. Input impedance >1MΩ. Rail-to-rail input range.

Positive Power-Supply Input. Connect a 0.1μF capacitor from VDD to VSS.

Voltage Limit Input. This pin sets the maximum voltage at OUT. If left unconnected, the output voltage will be

limited to 4.6V (VDD = 5V). Connect to VDD for maximum output swing. The acceptable range is 4.5V ≤

VLIMIT ≤ VDD.

Detailed Description

The MAX1458 provides an analog amplification path for

the sensor signal. Calibration and temperature compen-

sation are achieved by varying the offset and gain of a

programmable-gain amplifier (PGA) and by varying the

sensor bridge current. The PGA uses a switchedcapac

itor CMOS technology, with an input-referred coarse off-

set trimming range of approximately ±63mV (9mV steps).

An additional output-referred fine offset trim is provided

by the Offset DAC (approximately 2.8mV steps). The

PGA provides eight gain values from +41V/V to +230V/V.

The bridge current source is programmable from 0.1mA

to 2mA.

The MAX1458 uses four 12-bit DACs and one 3-bit DAC,

with calibration coefficients stored by the user in an inter-

nal 128-bit EEPROM. This memory contains the following

information as 12-bit-wide words:

●● Configuration register

●● Offset calibration coefficient

●● Offset temperature error compensation coefficient

●● FSO (full-span output) calibration coefficient

●● FSO temperature error compensation coefficient

●● 24 user-defined bits for customer programming of

manufacturing data (e.g., serial number and date) Figure

1 shows a typical pressure-sensor output and defines the

offset, full-scale, and full-span output values as a function

of voltage.

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