MAX6603 查看數據表（PDF） - Maxim Integrated

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MAX6603

Dual-Channel, Platinum RTD-to-Voltage Signal Conditioner

Maxim Integrated 

Dual-Channel, Platinum RTD-to-Voltage

Signal Conditioner

Pin Description

PIN

NAME

FUNCTION

1

VCC

Power-Supply Input. Bypass to GND with a 0.1µF capacitor as close to VCC as possible.

2

RS2-

Sense Resistor 2 Negative Input

3

RS2+

Sense Resistor 2 Positive Input

4

RS1+

Sense Resistor 1 Positive Input

5

RS1-

Sense Resistor 1 Negative Input

6

GND

Ground

7

DG1

Diagnostic Output Signal 1. DG1 asserts low upon fault detection.

8

OUT1

Output Analog Voltage 1. OUT1 is high impedance upon DG1 assertion.

9

OUT2

Output Analog Voltage 2. OUT2 is high impedance upon DG2 assertion.

10

DG2

Diagnostic Output Signal 2. DG2 asserts low upon fault detection.

—

EP

Exposed Pad. Connect to GND.

Functional Block Diagram

VCC

RS1+

VCC

RSRC

ESD

CLAMP

MAX6603

AMP

RS1-

ESD

CLAMP

VCC

IEXC

HI-V

DETECT

FAULT

DETECT

OUT1

DG1

RSRC

RS2+

ESD

CLAMP

AMP

RS2-

ESD

CLAMP

IEXC

HI-V

DETECT

FAULT

DETECT

OUT2

DG2

GND

Detailed Description

The MAX6603 converts a Deutsche Institute for Normung

(DIN) standard 200Ω Pt RTD to a high-level analog volt-

age without the need for external trims or precise dis-

crete components. The Pt RTD resistance conveys

temperature information approximated by the Callendar-

Van Dusen equation and is represented in Figure 1:

R(T) = RO[1 + AT + BT2+ CT3]

where: R(T) = Resistance of Pt RTD at temperature (T)

R0 = Base resistance in ohms at 0°C

T = Temperature in °C

A = 3.9083 E-3 °C-1 (alpha coefficient 1)

B = -5.7750 E-7 °C-2 (alpha coefficient 2)

C = 0 (approximation for temperatures > 0°C)

(Alpha coefficients can vary depending on

standards.)

The MAX6603 applies a constant excitation current of

1mA (typ) through the Pt RTD, generating a voltage

drop that is amplified and results in a high-level output

voltage. The excitation current (IEXC) typically varies

ratiometrically by 0.2mA/V (typ) with respect to VCC,

and therefore, the amplified signal is ratiometric to the

power supply. The voltage amplification from input to

output is 5 (typ). The output voltage is applied to a

ratiometric ADC to produce a digital value independent

of supply voltage. For ADCs that use VCC as their refer-

ence voltage, sudden changes in the supply voltage do

not affect the microcontroller’s reading of the tempera-

ture. Ratiometricity simplifies the connection to most

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