Rainbow Electronics MAX31723 User Manual

19-5629; Rev 0; 11/10

Digital Thermometers and Thermostats

General Description

The MAX31722/MAX31723 digital thermometers and thermostats with an SPI™/3-wire interface provide temperature readings that indicate the device temperature. No additional components are required; the devices are truly temperature-to-digital converters. Temperature readings are communicated from the device over an SPI interface or a 3-wire serial interface. The choice of interface is selectable by the user. For applications that require greater temperature resolution, the user can adjust the readout resolution from 9 to 12 bits. This is particularly useful in applications where thermal runaway conditions must be detected quickly. The thermostat has a dedicated open-drain output (TOUT). Two thermostat operating modes, comparator and interrupt, control thermostat operation based on user-defined nonvolatile trip points (T

3.7V supply rail.

HIGH

and T

). Both devices feature a 1.7V to

LOW

with SPI/3-Wire Interface

Features

S Temperature Measurements Require No External

Components

S Measures Temperatures from -55NC to +125NC

S MAX31722 Thermometer Accuracy is ±2.0NC

S MAX31723 Thermometer Accuracy is ±0.5NC

S Thermometer Resolution is Configurable from 9

to 12 Bits (0.5NC to 0.0625NC Resolution)

S Thermostat Output with User-Defined Nonvolatile

Thresholds

S Data is Read from/Written to by SPI (Mode 0 and 2)

or 3-Wire Serial Interface

S 1.7V to 3.7V Power-Supply Range

S Available in 8-Pin µMAX

Ordering Information

®

Package

MAX31722/MAX31723

Applications

Networking Equipment

Cellular Base Stations

Industrial Equipment

Any Thermally Sensitive Systems

PART TEMP RANGE PIN-PACKAGE

MAX31722MUA+

MAX31722MUA+T MAX31723MUA+ MAX31723MUA+T

+Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

-55NC to +125NC 8 FMAX

Functional Diagram

OVERSAMPLING

MODULATOR

CONFIGURATION/

STATUS REGISTER

TEMPERATURE

REGISTER

T

AND T

HIGH

LOW

REGISTERS

DIGITAL

DECIMATOR

MAX31722 MAX31723

TOUT

THERMOSTAT

COMPARATOR

V

SDI

SDO

SCLK

SERMODE

GND

PRECISION

V

DD

CE

REFERENCE

I/O CONTROL

AND

INPUT SENSE

SPI is a trademark of Motorola, Inc. µMAX is a registered trademark of Maxim Integrated Products, Inc.

_______________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Digital Thermometers and Thermostats with SPI/3-Wire Interface

ABSOLUTE MAXIMUM RATINGS

Voltage Range on VDD Relative to GND ..............-0.3V to +6.0V

Voltage Range on Any Other Pin Relative to GND ...-0.3V to +6.0V Continuous Power Dissipation (TA = +70NC)

FMAX (derate 4.5mW/NC above +70NC) ......................362mW

EEPROM Programming Temperature Range . ...-40NC to +85NC

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.

RECOMMENDED OPERATING CHARACTERISTICS

(TJ = -55NC to +125NC, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage V Input Logic-High V Input Logic-Low V

MAX31722/MAX31723

DC ELECTRICAL CHARACTERISTICS

(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

MAX31722 Thermometer Error T

MAX31723 Thermometer Error T

Resolution 9 12 Bits

Conversion Time t

Logic 0 Output (SDO, TOUT)

Logic 1 Output (SDO) V

Leakage Current I

Active Current I

Shutdown Current I

DD

ERR

CONVT

V

OL

OH

CC

CC1

(Note 1) 1.7 3.7 V (Note 1) 0.7 x V

IH

(Note 1) -0.3 0.3 x V

IL

-40NC to +85NC Q2.0

-55NC to +125NC Q3.0 0NC to +70NC Q0.5

-55NC to +125NC Q2.0

9-bit conversions 25 10-bit conversions 50 11-bit conversions 100 12-bit conversions 200 (Note 2) 0.4 V

(Note 3)

L

Active temperature conversions (Note 4) 1150 Communication only 100 EEPROM writes (-40NC to +85NC)

EEPROM writes during active temperature conversions (-40NC to +85NC)

Operating Junction Temperature Range ......... -55NC to +125NC

Storage Temperature Range ............................ -55NC to +125NC

Lead Temperature (soldering, 10s) ................................+300NC

Soldering Temperature (reflow) ......................................+260NC

V

DD

VDD -

0.4

-1 +1

+ 0.3 V

DD

1150

1200

2

V

NC

ms

V

FA

2

Digital Thermometers and Thermostats

with SPI/3-Wire Interface

AC ELECTRICAL CHARACTERISTICS: 3-WIRE INTERFACE

(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.) (Figures 1, 2)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Data to SCLK Setup t SCLK to Data Hold t SCLK to Data Valid t SCLK Low Time t SCLK High Time t SCLK Frequency t SCLK Rise and Fall tR, t CE to SCLK Setup t SCLK to CE Hold t CE Inactive Time t CE to Output High-Z t SCLK to Output High-Z t

DC

CDH

CDD

CL

CH

CLK

CC

CCH

CWH

CDZ

CCZ

AC ELECTRICAL CHARACTERISTICS: SPI INTERFACE

(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.) (Figures 3, 4)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Data to SCLK Setup t SCLK to Data Hold t SCLK to Data Valid t SCLK Low Time t SCLK High Time t SCLK Frequency t SCLK Rise and Fall tR, t CE to SCLK Setup t SCLK to CE Hold t CE Inactive Time t CE to Output High-Z t

DC

CDH

CDD

CL

CH

CLK

CC

CCH

CWH

CDZ

(Notes 5, 6) 35 ns (Notes 5, 6) 35 ns (Notes 5, 6, 7) 80 ns (Note 6) 100 ns (Note 6) 100 ns (Note 6) DC 5.0 MHz

F

(Note 6) 400 ns (Note 6) 100 ns (Note 6) 400 ns (Notes 5, 6) 40 ns (Notes 5, 6) 40 ns

(Notes 5, 6) 35 ns (Notes 5, 6) 35 ns (Notes 5, 6, 7) 80 ns (Note 6) 100 ns (Note 6) 100 ns (Note 6) DC 5.0 MHz

F

(Note 6) 400 ns (Note 6) 100 ns (Note 6) 400 ns (Notes 5, 6) 40 ns

MAX31722/MAX31723

200 ns

AC ELECTRICAL CHARACTERISTICS: EEPROM

(VDD = 1.7V to 3.7V, TJ = -55NC to +125NC, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

EEPROM Write Cycle Time t

EEPROM Write Endurance N

Note 1: All voltages are referenced to ground. Currents entering the IC are specified positive, and currents exiting the IC are negative. Note 2: Logic 0 voltages are specified at a sink current of 3mA. Note 3: Logic 1 voltages are specified at a source current of 1mA. Note 4: ICC specified with SCLK = VDD and CE = GND. Note 5: Measured at VIH = 0.7V x VDD or VIL = 0.3 x VDD and 10ms maximum rise and fall times. Note 6: Measured with 50pF load. Note 7: Measured at VOH = 0.7 x VDD or VOL = 0.3 x VDD. Measured from the 50% point of SCLK to the VOH minimum of SDO. Note 8: VDD must be > 2.0V during EEPROM write cycles.

WR

EEWR

-40NC to +85NC (Note 8)

-40NC P TA P +85NC (Note 8) TA = +25NC (Note 8)

20,000 80,000

15 ms

Cycles

3

Digital Thermometers and Thermostats with SPI/3-Wire Interface

CE

SCLK

I/O*

*I/O IS SDI AND SDO CONNECTED TOGETHER.

t

CC

t

CDH

t

DC

A0 A1 A7 D0 D1

WRITE ADDRESS BYTE

Figure 1. Timing Diagram: 3-Wire Read Data Transfer

MAX31722/MAX31723

CE

t

CC

t

CL

t

CCZ

t

CDD

READ DATA BIT

t

R

CCH

t

F

t

CWH

CDD

t

CDZ

SCLK

t

CDH

t

DC

I/O*

*I/O IS SDI AND SDO CONNECTED TOGETHER.

A0 A1 A7 D0

WRITE ADDRESS BYTE WRITE DATA

Figure 2. Timing Diagram: 3-Wire Write Data Transfer

4

t

CH

Digital Thermometers and Thermostats

with SPI/3-Wire Interface

MAX31722/MAX31723

CE

SCLK

SDI

SDO

NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.

t

CC

t

CDH

t

DC

A7 A6 A0

WRITE ADDRESS BYTE READ DATA BYTE

Figure 3. Timing Diagram: SPI Read Data Transfer

CE

t

CC

t

CDD

D7 D6 D1 D0

t

CL

R

t

F

CDD

t

CCH

t

CDZ

t

CWH

SCLK

SDI

NOTE: SCLK CAN BE EITHER POLARITY, TIMING SHOWN FOR CPOL = 1.

t

CDH

t

DC

A7 A6 A0 D7 D0

WRITE ADDRESS BYTE WRITE DATA BYTE

Figure 4. Timing Diagram: SPI Write Data Transfer

t

CH

t

CDH

5