Rainbow Electronics MAX6642 User Manual

General Description

The MAX6642 is a precise, two-channel digital temper­ature sensor. It accurately measures the temperature of
its own die and a remote PN junction, and reports the
temperature data over a 2-wire serial interface. The
remote PN junction is typically a substrate PNP transis­tor on the die of a CPU, ASIC, GPU, or FPGA. The
remote PN junction can also be a discrete diode-con­nected small-signal transistor.

The 2-wire serial interface accepts standard system
management bus (SMBus™), Write Byte, Read Byte,
Send Byte, and Receive Byte commands to read the
temperature data and to program the alarm thresholds.
To enhance system reliability, the MAX6642 includes an
SMBus timeout. The temperature data format is 10 bit
with the least significant bit (LSB) corresponding to
+0.25°C. The ALERT output asserts when the local or
remote overtemperature thresholds are violated. A fault
queue may be used to prevent the ALERT output from
setting until two consecutive faults have been detected.

Measurements can be done autonomously or in a sin­gle-shot mode.

Remote accuracy is ±1°C maximum error between
+60°C and +100°C. The MAX6642 operates from -40°C
to +125°C, and measures remote temperatures
between 0°C and +150°C. The MAX6642 is available in
a 6-pin TDFN package.

Applications

Desktop Computers

Notebook Computers

Servers

Thin Clients

Test and Measurement

Workstations

Graphic Cards

Features

♦ Dual Channel: Measures Remote and Local

Temperature

♦ +0.25°C Resolution

♦ High Accuracy ±1°C (max) (Remote) and

±2°C (Local) from +60°C to +100°C

♦ Measures Remote Temperature Up to +150°C

♦ Programmable Overtemperature Alarm

Temperature Thresholds

♦ SMBus/I2CTM-Compatible Interface

♦ Tiny TDFN Package

MAX6642

±1°C, SMBus-Compatible Remote/Local

Temperature Sensor with Overtemperature Alarm

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-2920; Rev 0; 8/03

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.

Typical Operating Circuit

PART

MEASURED TEMP RANGE

TOP

MARK

MAX6642ATT90-T 0°C to +150°C

AFC

MAX6642ATT92-T 0°C to +150°C

AFD

MAX6642ATT94-T 0°C to +150°C

AFE

MAX6642ATT96-T 0°C to +150°C

AFF

MAX6642ATT98-T 0°C to +150°C

AEW

MAX6642ATT9A-T 0°C to +150°C

AFG

MAX6642ATT9C-T 0°C to +150°C

AFH

MAX6642ATT9E-T 0°C to +150°C AFI

Selector Guide

SMBus is a trademark of Intel Corp.
Purchase of I

2

C components of Maxim Integrated Products, Inc.
or one of its sublicensed Associated Companies, conveys a
license under the Philips I

2

C Patent Rights to use these compo-

nents in an I

2

C system, provided that the system conforms to the

I

2

C Standard Specification as defined by Philips.

Pin Configuration and Functional Diagram appear at end of
data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX6642ATT90-T -40°C to +125°C 6 TDFN

MAX6642ATT92-T -40°C to +125°C 6 TDFN

MAX6642ATT94-T -40°C to +125°C 6 TDFN

MAX6642ATT96-T -40°C to +125°C 6 TDFN

MAX6642ATT98-T -40°C to +125°C 6 TDFN

MAX6642ATT9A-T -40°C to +125°C 6 TDFN

MAX6642ATT9C-T -40°C to +125°C 6 TDFN

MAX6642ATT9E-T -40°C to +125°C 6 TDFN

0.1µF

V

CC

3.3V

47Ω

10kΩ EACH

2200pF

µP

DXP

MAX6642

GND

SDA

SCLK

ALERT

DATA

CLOCK

INTERRUPT TO µP

MAX6642

±1°C, SMBus-Compatible Remote/Local
Temperature Sensor with Overtemperature Alarm

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(V

CC

= +3.0V to +5.5V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at V

CC

= +3.3V and TA = +25°C.) (Note 1)

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 Referenced to GND
V

CC

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

DXP.............................................................-0.3V to (V

CC

+ 0.3V)

SCLK, SDA, ALERT ..................................................-0.3V to +6V

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

Continuous Power Dissipation (T

A

= +70°C)

6-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW

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

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

Operating Temperature Range .........................-40°C to +125°C

Storage Temperature Range .............................-65°C to +150°C

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

Supply Voltage V

Temperature Resolution

Remote Temperature Error V

Local Temperature Error V

Supply Sensitivity of Temperature
Error

Undervoltage Lockout Threshold UVLO Falling edge of VCC disables ADC 2.4 2.7 2.95 V

Undervoltage Lockout Hysteresis 90 mV

Power-On-Reset (POR) Threshold VCC falling edge 1.5 2.0 2.4 V

POR Threshold Hysteresis 90 mV

Standby Supply Current SMBus static 3 10 µA

Operating Current During conversion 0.5 1.0 mA

Average Operating Current 260 µA

Conversion Time t

Conversion Rate f

Remote-Diode Source Current I

ALERT

Output-Low Sink Current

Output-High Leakage Current VOH = V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CC

= 3.3V

CC

= 3.3V

CC

CONV

CONV

RJ

From stop bit to conversion completion 106 125 143 ms

High level 80 100 120

Low level 8 10 12

VOL = 0.4V 1

V

= 0.6V 4

OL

CC

3.0 5.5 V

0.25 °C

10 Bits

TRJ = +60°C to +100°C,

= +25°C to +85°C

T

A

TRJ = 0°C to +125°C -3.0 +3.0

T

= +125°C to +150°C -3.5 +3.5

RJ

TA = +60°C to +100°C -2.0 +2.0

= 0°C to +125°C -3.0 +3.0

T

A

-1.0 +1.0

±0.2 °C/V

8Hz

1µA

°C

°C

µA

mA

MAX6642

±1°C, SMBus-Compatible Remote/Local

Temperature Sensor with Overtemperature Alarm

_______________________________________________________________________________________ 3

Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2: Timing specifications guaranteed by design.
Note 3: The serial interface resets when SCLK is low for more than t

TIMEOUT

.

Note 4: A transition must internally provide at least a hold time to bridge the undefined region (300ns max) of SCLK’s falling edge.

ELECTRICAL CHARACTERISTICS (continued)

(V

CC

= +3.0V to +5.5V, TA = -40°C to +125°C, unless otherwise specified. Typical values are at V

CC

= +3.3V and TA = +25°C.) (Note 1)

SMBus-COMPATIBLE INTERFACE (SCLK and SDA)

Logic Input Low Voltage V

Logic Input High Voltage V

Input Leakage Current I

Output Low Sink Current I

Input Capacitance C

SMBus TIMING (Note 2)

Serial Clock Frequency f

Bus Free Time Between STOP
and START Condition

START Condition Setup Time 4.7 µs

Repeat START Condition Setup
Time

START Condition Hold Time t

STOP Condition Setup Time t

Clock Low Period t

Clock High Period t

Data Setup Time t

Receive SCLK/SDA Rise Time t

Receive SCLK/SDA Fall Time t

Pulse Width of Spike Suppressed t

SMBus Timeout t

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IL

VCC = 3.0V 2.2 V

IH

LEAK

OL

SCLK

t

BUF

t

SU:STA

HD:STA

SU:STO

LOW

HIGH

HD:DAT

SP

TIMEOUT

VIN = GND or 5.5V -1 +1 µA

VOL = 0.6V 6 mA

IN

(Note 3) 100 kHz

90% to 90% 50 ns

10% of SDA to 90% of SCLK 4 µs

90% of SCLK to 90% of SDA 4 µs

10% to 10% 4.7 µs

90% to 90% 4 µs

(Note 4) 250 µs

R

F

SDA low period for interface reset 20 28 40 ms

0.8 V

5pF

4.7 µs

1µs

300 ns

050ns

MAX6642

±1°C, SMBus-Compatible Remote/Local
Temperature Sensor with Overtemperature Alarm

4 _______________________________________________________________________________________

Typical Operating Characteristics

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

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0.01 0.1 1 10 100

STANDBY SUPPLY CURRENT

vs. CLOCK FREQUENCY

MAX6642 toc01

CLOCK FREQUENCY (kHz)

SUPPLY CURRENT (µA)

-4

-2

-3

0

-1

1

2

REMOTE TEMPERATURE ERROR

vs. REMOTE-DIODE TEMPERATURE

MAX6642 toc02

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

0507525 100 125

2N3906

-3

-1

-2

1

0

2

3

0125

LOCAL TEMPERATURE ERROR

vs. DIE TEMPERATURE

MAX 6642 toc03

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

5025 75 100

-1.5

-0.5

-1.0

0.5

0

1.5

1.0

2.0

0.0001 0.01 0.10.001 1 10 100

TEMPERATURE ERROR

vs. POWER-SUPPLY NOISE FREQUENCY

MAX6642 toc04

FREQUENCY (kHz)

TEMPERATURE ERROR (°C)

VIN = 100mV

P-P

SQUARE WAVE

APPLIED TO V

CC

WITH NO BYPASS CAPACITOR

LOCAL ERROR

REMOTE ERROR

0

30

20

10

40

50

60

70

80

90

100

0.001 0.10.01 1 10 100

TEMPERATURE ERROR

vs. DXP NOISE FREQUENCY

MAX6642 toc05

FREQUENCY (kHz)

TEMPERATURE ERROR (°C)

LOCAL ERROR

REMOTE ERROR

VIN = AC-COUPLED TO DXP
V

IN

= 100mV

P-P

SQUARE WAVE

-6.0

-5.0

-4.0

-3.0

-2.0

-1.0

0

1.0

2.0

0.1 1 10 100

TEMPERATURE ERROR

vs. DXP-GND CAPACITANCE

MAX6642 toc06

DXP-GND CAPACITANCE (nF)

TEMPERATURE ERROR (°C)