MAXIM MAX6654 User Manual

19-1836; Rev 3; 5/06

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.

1°C Accurate Remote/Local Temperature

Sensor with SMBus Serial Interface

General Description

The MAX6654†is a precise digital thermometer that
reports the temperature of both a remote P-N junction
and its own die. The remote junction can be a diode-con­nected transistor—typically a low-cost, easily mounted
2N3904 NPN type or 2N3906 PNP type—that replaces
conventional thermistors or thermocouples. Remote
accuracy is ±1°C for multiple transistor manufacturers,
with no calibration needed. The remote junction can also
be a common-collector PNP, such as a substrate PNP of
a microprocessor (µP).

The 2-wire serial interface accepts standard System
Management Bus (SMBus)

TM

, Write Byte, Read Byte,
Send Byte, and Receive Byte commands to program the
alarm thresholds and to read temperature data.
Measurements can be done automatically and
autonomously, with the conversion rate programmed by
the user, or programmed to operate in a single-shot
mode. The adjustable conversion rate allows the user to
optimize supply current and temperature update rate to
match system needs. When the conversion rate is faster
than 1Hz, the conversion results are available as a 7-bit­plus-sign byte with a 1°C LSB. When the conversion rate
is 1Hz or slower, the MAX6654 enters the extended
mode. In this mode, 3 additional bits of temperature data
are available in the extended resolution register, provid­ing 10-bit-plus-sign resolution with a 0.125°C LSB. Single­shot conversions also have 0.125°C per LSB resolution
when the conversion rate is 1Hz or slower.

A parasitic resistance cancellation (PRC) mode can also
be invoked for conversion rates of 1Hz or slower by set­ting bit 4 of the configuration register to 1. In PRC mode,
the effect of series resistance on the leads of the external
diode is canceled. The 11-bit conversion in PRC mode is
performed in <500ms and is disabled for conversion
rates faster than 1Hz. The one-shot conversion is also 11
bits in <500ms.

The MAX6654 default low-temperature measurement
limit is 0°C. This can be extended to -64°C by setting bit
5 of the configuration register to 1.

The MAX6654 is available in a small, 16-pin QSOP sur­face-mount package.

Applications

Desktop Computers
Notebook Computers
Servers
Thin Clients

S.
Ps,

Is
a­ps
ts.

†SMBus is a trademark of Intel Corp.

________________________________________________________________ Maxim Integrated Products 1

Workstations
Test and Measurement
Multichip Modules

.

Features

♦ High Accuracy ±1°C (max) from +70°C to +100°C

(Remote)

♦ 11-Bit, 0.125°C Resolution

♦ Dual Channel: Measures Remote and Local

Temperature

♦ No Calibration Required

♦ Programmable Under/Overtemperature Alarms

2

♦ I

C™-Compatible/SMBus Interface

♦ +3V to +5.5V Supply Range

Ordering Information

PART TEMP RANGE

MAX6654MEE -55°C to +125°C

PIN­PACKAGE

16 QSOP

PKG
CODE

E16-1

Typical Operating Circuit

CPU

2200pF

0.1µF

DXP

DXN

V

CC

ADD0 ADD1

STBY

MAX6654

200Ω

SMBCLK

SMBDATA

ALERT

GND

+3V TO +5V SUPPLY

10k EACH

CLOCK

DATA

INTERRUPT TO µC

Pin Configuration

TOP VIEW

1

N.C. N.C.

V

2

CC

DXP

3

MAX6654

4

DXN

N.C.

5

ADD1

6

7

GND

GND

8

QSOP

16

15

14

13

12

11

10

9

STBY

SMBCLK

N.C.

SMBDATA

ALERT

ADD0

N.C.

MAX6654

MAX6654

1°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V and TA= +25°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.

(All voltages are referenced to GND unless otherwise noted.)
V

CC

..........................................................................-0.3V to +6V

DXP, ADD_ ................................................-0.3V to (VCC + 0.3V)

DXN ......................................................................-0.3V to +0.8V

SMBCLK, SMBDATA,

ALERT, STBY.. ......................-0.3V to +6V

SMBDATA, ALERT Current .................................-1mA to +50mA

DXN Current ......................................................................±1mA

ESD Protection (all pins, Human Body Model). .................2000V

Continuous Power Dissipation (T

A

= +70°C)

16-Pin QSOP (derate 8.30mW/°C above +70°C).........667mW

Operating Temperature Range ........................-55°C to +125°C

Junction Temperature......................................................+150°C

Storage Temperature Range ............................-65°C to +165°C

Lead Temperature (soldering, 10s) .................................+300°C

PARAMETER

CONDITIONS

UNITS

TEMPERATURE-TO-DIGITAL CONVERTER

+60°C ≤ T

A

≤ +100°C, VCC = +3.3V

0°C ≤ T

A

≤ +100°C, VCC = +3.3V -2 +2

Accuracy (Local Sensor)

-55°C ≤ T

A

≤ +120°C, VCC = +3.3V -5 +5

°C

-1 +1

0°C ≤ T

RJ

≤ +100°C, VCC = +3.3V (Note 1) -2 +2Accuracy (Remote Sensor)

-5 +5

°C

Line Regulation 0.2 0.5 °C

+1 °C

Resolution (Legacy Mode) Conversion rate >1Hz

+8 Bits

°C

Resolution (Extended Mode) Conversion rate ≤1Hz

Bits

Undervoltage Lockout
Threshold

UVLO

V

CC

input, disables A/D conversion,

rising edge

V

Undervoltage Lockout
Hysteresis

mV

Supply Voltage Range V

CC

V

P ow er - O n Reset ( P O R) Thr eshol d

VCC, falling edge

V

POR Threshold Hysteresis

mV

Standby Current SMBus static +3 +10 µA

Operating Current During conversion

+1 mA

0.25 conversion/s (Note 3)

+70

Average Operating Current

2 conversion/s (Note 3)

µA

Conversion Time

From stop bit to conversion completed, in
legacy mode (Note 3)

ms

Conversion Timing Error ±25 %

High level

Remote Diode Current I

RJ

Low level +8

+12

µA

SYMBOL

MIN TYP MAX

-1.3 +1.3

+ 70° C ≤ T

- 55°C ≤ T

≤ + 100° C , V

R J

≤ +120°C , V

RJ

= + 3.3V ( N ote 1)

C C

= + 3.3V ( Notes 1, 2)

C C

+0.125

+11

+2.60 +2.80 +2.95

+3.0 +5.5

+1.5 +2.0 +2.5

t

CONV

+95 +125 +156

+80 +100 +120

+90

+90

+0.55

+40

+150 +250

+10

MAX6654

1°C Accurate Remote/Local Temperature

Sensor with SMBus Serial Interface

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at VCC= +3.3V and TA= +25°C.)

PARAMETER

CONDITIONS

UNITS

Logic Input Low Voltage V

IL

VCC = +3.0V to +5.5V

VCC = +3.0V

V

Logic Input High Voltage V

IH

VCC = +5.5V

V

Input Leakage Current I

LEAK

V

IN

= GND or V

CC

±2µA

VOL = +0.6V +6

Output Low Sink Current I

OL

V

OL

= +0.4V +1

mA

Input Capacitance C

in

+5 pF

Output High Leakage Current VOH = +5.5V +1 µA

Serial Clock Frequency f

SCL

(Note 4) 0

kHz

Bus Free Time Between STOP
and START Conditions

t

BUF

µs

START Condition Setup Time

µs

Repeat START Condition Setup
Time

90% to 90%

µs

START Condition Hold Time

10% of SMBDATA to 90% of SMBCLK +4 µs

STOP Condition Setup Time

90% of SMBCLK to 10% of SMBDATA662 +4 µs

Clock Low Period t

LOW

10% to 10%

µs

Clock High Period t

HIGH

90% to 90% +4 µs

Data Setup Time

90% of SMBDATA to 10% of SMBCLK

ns

Data Hold Time

(Note 5) 0 µs

Receive SCL/SDA Rise Time t

R

+1 µs

Receive SCL/SDA Fall Time t

F

ns

SMBus Timeout

SMBDATA and SMBCLK time low for reset
of serial interface

+40 ms

Note 1: +25°C ≤ TA≤ +85°C.
Note 2: If both the MAX6654 and the remote junction are below T

A

= -20°C, then VCC> 3.15V.

Note 3: The conversion time doubles for the extended resolution mode. This causes the average operating current to approximately

double.

Note 4: The serial interface resets when SMBCLK is low for more than t

TIMEOUT

.

Note 5: Note that a transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SMBCLK’s

falling edge.

SYMBOL

t

SU:STA

t

HD:STA

t

SU:STO

t

SU: DAT

t

HD: DAT

MIN TYP MAX

+2.2

+2.6

+100

+4.7

+4.7

+50

+4.7

+250

+0.8

t

TIMEOUT

+25

+300

MAX6654

1°C Accurate Remote/Local Temperature
Sensor with SMBus Serial Interface

4 _______________________________________________________________________________________

Typical Operating Characteristics

(VCC= +3.3V to +5.5V, TA= +25°C, unless otherwise noted.)

-2

-1

1

0

2

-50 -10 10 30 50-30 70 90 110 130 150

TEMPERATURE ERROR vs.

REMOTE-DIODE TEMPERATURE

MAX6654 toc01

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

FAIRCHILD 2N3904

110k1M100 100M

TEMPERATURE ERROR vs.

POWER-SUPPLY NOISE FREQUENCY

MAX6654 toc02

FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

0

4

8

12

16

VIN = 500mVp-p LOCAL

VIN = 500mVp-p REMOTE

3

0

1k 10M

TEMPERATURE ERROR vs.

COMMON-MODE NOISE FREQUENCY

1

2

MAX6654 toc03

FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

100k

0

2

1

3

6

7

5

4

8

0 2030405010 60 70 80 90 100

TEMPERATURE ERROR vs.

DXP-DXN CAPACITANCE

MAX6654 toc04

DXP-DXN CAPACITANCE (nF)

TEMPERATURE ERROR (°C)

VCC = +5V

40

70

60

50

80

90

100

3.0 3.83.63.2 3.4 4.0 4.2 4.4 4.6 4.8 5.0

STANDBY SUPPLY CURRENT vs.

SUPPLY VOLTAGE

MAX6654 toc05

SUPPLY VOLTAGE (V)

STANDBY SUPPLY CURRENT (µA)

MAX6654

1°C Accurate Remote/Local Temperature

Sensor with SMBus Serial Interface

_______________________________________________________________________________________ 5

Pin Description

PIN NAME FUNCTION

1, 5, 9, 13, 16

N.C. No Connection. Not internally connected. May be used for PC board trace routing.

2V

CC

Supply Voltage Input. +3.0V to +5.5V. Bypass to GND with a 0.1µF capacitor. A 200Ω series
resistor is recommended but not required for additional noise filtering.

3 DXP

Combined Current Source and ADC Positive Input for Remote-Junction Channel. If a remote­sensing junction is not used, connect DXP to DXN.

4DXN

Combined Current Sink and ADC Negative Input. DXN is internally biased to a diode voltage above
ground.

6 ADD1 SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.

7, 8 GND Ground

10 ADD0 SMBus Slave Address Select Input. ADD0 and ADD1 are sampled upon power-up.

11 ALERT SMBus Alert (Interrupt) Output. Open drain.

12

SMBus Serial-Data Input/Output. Open drain.

14

SMBus Serial-Clock Input

15 STBY

Hardware standby input. Temperature and comparison threshold data are retained in standby
mode. Low = standby mode, high = operating mode.

SMBDATA

SMBCLK