MAXIM MAX6633, MAX6634, MAX6635 Technical data

General Description

The MAX6633/MAX6634/MAX6635 combine a tempera­ture sensor, a programmable overtemperature alarm,
and an SMBus™/I

2

C™-compatible serial interface into
a single package. They convert their die temperatures
into digital values using internal analog-to-digital con­verters (ADCs). The result of the conversion is then held
in a temperature register as a 12-bit + sign value, allow­ing 0.0625°C resolution, readable at any time through
the serial interface. The devices are capable of reading
temperatures up to +150°C.

The MAX6633/MAX6634/MAX6635 feature a shutdown
mode that saves power by turning off everything except
the power-on reset (POR) and the serial interface. The
devices can be configured to separate addresses,
allowing multiple devices to be used on the same bus.

The MAX6633 has four address pins, allowing up to 16
devices to be connected to a single bus. The MAX6634
has three address pins, allowing up to eight devices to
be connected to a single bus. The MAX6635 has two
address pins, allowing up to four devices to be con­nected to a single bus.

The MAX6633/MAX6634/MAX6635 make temperature
data available for transfer over the serial interface. The
MAX6634 incorporates a dual-mode ALERT output
(open drain) and can serve as an upgraded alternative
to the LM75. The MAX6635 includes an ALERT output
and an OVERT output (both open drain) and can func­tion as an upgraded replacement for the LM76 in most
applications. The MAX6634/MAX6635 feature user-pro­grammable temperature thresholds. All three devices
come in an 8-pin SO package.

Applications

Battery Temperature Alarms

PC Temperature Control

Automotive Equipment

Features

♦ +3V to +5.5V Supply Range

♦ Accuracy

±1°C max (0°C to +50°C)
±1.5°C max (-20°C to +85°C)
±2.5°C max (-40°C to +125°C)
±2.5°C typ (+150°C)

♦ User-Programmable Temperature Thresholds

(MAX6634/MAX6635)

♦ User-Configurable Alarm Output(s)

(MAX6634/MAX6635)

♦ Ability to Respond to SMBus/I

2

C-Compatible Alert

Response Address (MAX6634/MAX6635)

♦ OVERT Output for System Shutdown (MAX6635)

♦ Multiple Devices per Bus

16 devices (MAX6633)
8 devices (MAX6634)
4 devices (MAX6635)

MAX6633/MAX6634/MAX6635

12-Bit Plus Sign Temperature Sensors with

SMBus/I2C-Compatible Serial Interface

________________________________________________________________

Maxim Integrated Products

1

Ordering Information

19-2120; Rev 0; 8/01

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.

EVALUATION KIT

AVAILABLE

SMBus is a trademark of Intel Corp.

I

2

C is a trademark of Philips Corp.

V

CC

V

CC

SCL

SDA

1

5

8

2

3

TO SYSTEM
SHUTDOWN

A0 A1 GND

+3.0V TO +5.5V

0.1μF

ALERT

OVERT

MAX6635

467

10kΩ 1kΩ 1kΩ 10kΩ

TO INTERRUPT
CONTROLLER

TO SMBus/I

2

C

MASTER

Typical Operating Circuit

Pin Configurations appear at end of data sheet.

PART TEMP. RANGE PIN-PACKAGE

MAX6633MSA -55°C to +150°C 8 SO

MAX6634MSA -55°C to +150°C 8 SO

MAX6635MSA -55°C to +150°C 8 SO

MAX6633/MAX6634/MAX6635

12-Bit Plus Sign Temperature Sensors with
SMBus/I2C-Compatible Serial Interface

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VCC= +3.0V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are VCC= +3.3V, TA= +25°C, unless other­wise noted.)

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.

VCC, SDA, SCL......................................................-0.3V to +6.0V

All Other Pins ................................................-0.3V to V

CC

+0.3V

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

ESD Protection (Human Body Model)................................2000V

Continuous Power Dissipation (T

A

= +70°C)

8-Pin SO (derate 5.88mW/°C above +70°C)................471mW

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

Operating Temperature Range .........................-55°C to +150°C

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

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

TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS

Supply Range V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

CC

0°C ≤ T

= ≤ +50°C, VCC = +3.3V -1.0 ±0.4 +1.0

A

3.0 5.5 V

-20°C ≤ T

Accuracy (Note 1)

Power-Supply Rejection Ratio PSRR 0.2 0.5 °C/V

-40°C ≤ T

T

= -55°C, VCC = +3.3V ±1.5 +2.8

A

= +150°C, VCC = +3.3V ±2.5

T

A

= ≤ +85°C, VCC = +3.3V -1.5 ±0.6 +1.5

A

= ≤ 125°C, VCC = +3.3V -2.5 ±1.0 +2.5

A

POR Threshold Hysteresis 90 mV

Supply Current in Shutdown

Average Operating Current

Peak Operating Current (Note 2)

VCC = +3.0V, SMBus inactive 12 20

= +5.5V, SMBus inactive 20 30

V

CC

VCC = +3.0V, SMBus inactive 150

V

= +5.5V, SMBus inactive 200

CC

VCC = +3.0V, SMBus inactive 270 350

V

= +5.5V, SMBus inactive 350 700

CC

Conversion Rate 1.4 2 2.4 Hz

DIGITAL INTERFACE

Logic Input Low Voltage V

Logic Input High
Voltage

Input Leakage Current I

I_LEAK

Output Low Sink Current I

Output Leakage Current I

O_LEAK

Input Capacitance C

V

OL

VCC = +3.0V to +5.5V 0.65 V

IL

VCC = +3V 2.2 V

IH

VCC = +5.5V 2.4

VIN = GND or V

VOL = 0.6V (SMBDATA,

ALERT, OVERT)
ALERT, OVERT at V

IN

CC

6mA

CC

5pF

°C

µA

µA

µA

±1µA

±1µA

MAX6633/MAX6634/MAX6635

12-Bit Plus Sign Temperature Sensors with

SMBus/I2C-Compatible Serial Interface

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +3.0V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are VCC= +3.3V, TA= +25°C, unless other­wise noted.)

Note 1: Guaranteed by design and characterization.
Note 2: Peak operating current measured during conversion. See Figure 4.
Note 3: Guaranteed by design, not production tested.
Note 4: A master device must provide a hold time of at least 300ns for the SDA signal in order to bridge the undefined region of

SCL’s falling edge.

SMBus TIMING (Note 3, Figures 1, 2, and 3)

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

Data Setup Time t

Data Hold Time (Note 4) t

Receive SCL/SDA Rise Time t

SCL/SDA Fall Time (Note 4) t

Clock Low Period t

Clock High Period t

SMBus Timeout 25 48 ms

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

10 100 kHz

4.7 µs

300 ns

1µs

300 ns

SCL

t

BUF

t

SU:STA

HD:STA

SU:STO

SU: DAT

HD: DAT

R

F

LOW

HIGH

90% to 90% 4.7 µs

10% of SMBDATA to 90% of SMBCLK 4 µs

90% of SMBCLK to 10% of SMBDATA 4 µs

90% of SMBDATA to 10% of SMBCLK 250 ns

10% to 10% 4.7 µs

90% to 90% 4 µs

MAX6633/MAX6634/MAX6635

12-Bit Plus Sign Temperature Sensors with
SMBus/I2C-Compatible Serial Interface

4 _______________________________________________________________________________________

Typical Operating Characteristics

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

50

40

30

20

0

-55 550

110

165

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

MAX6633/4/5 toc01

TEMPERATURE (°C)

SHUTDOWN SUPPLY CURRENT (μA)

10

VCC = +5.5V

VCC = +3.3V

400

300

200

100

0

-55 550 110 165

AVERAGE SUPPLY CURRENT

vs. TEMPERATURE

MAX6633/4/5 toc02

TEMPERATURE (°C)

AVERAGE SUPPLY CURRENT (μA)

VCC = +5.5V

VCC = +3.3V

5

-1
10 10k 10M

TEMPERATURE ERROR

vs. SUPPLY NOISE FREQUENCY

0

MAX6633/4/5 toc03

SUPPLY NOISE FREQUENCY (Hz)

TEMPERATURE ERROR (°C)

3

2

1

4

VIN = SQUARE WAVE APPLIED TO
V

CC

WITH NO BYPASS

CAPACITOR

VIN = 200mVp-p

VIN = 200mVp-p

0

30

20

10

40

50

60

70

80

90

100

0 5 10 15 20

RESPONSE TO THERMAL SHOCK

MAX6633/4/5 toc04

TIME (s)

TEMPERATURE (°C)

VCC = +5.5V
DEVICE IMMERSED IN +85°C
FLUORINERT BATH

3

2

0

-2

-3

-40 400 80 120 160

TEMPERATURE ERROR

vs. TEMPERATURE

MAX6633/4/5 toc05

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

VCC = +3.3V

VCC = +5.5V

Detailed Description

The MAX6633/MAX6634/MAX6635 continuously con­vert their die temperatures into digital values using their
integrated ADCs. The resulting data is readable at any
time through the SMBus/I

2

C-compatible serial interface.
The device functions as a slave on the SMBus inter­face, supporting Write Byte, Write Word, Read Byte,
and Read Word commands. Separate addresses can
be configured using the individual address pins.
Figures 5, 6, and 7 show the functional diagrams of the
MAX6633/MAX6634/MAX6635, respectively.

SMBus/I2C-Compatible Operation

The MAX6633/MAX6634/MAX6635 are readable and
programmable through their SMBus/I2C-compatible
serial interface. Figures 1, 2, and 3 show the timing
details of the clock (SCL) and data (SDA) signals. The
devices function as slaves on the SMBus and support
Write Byte, Write Word, Read Byte, and Read Word
commands. Figure 8 is the MAX6633/MAX6634/
MAX6635 programmer’s model.

Addressing

Separate addresses can be configured using the indi­vidual address pins. The address of each device is
selected by connecting the address (A_) pins to one of
two potentials: GND or VCC. The MAX6635 makes two
address pins available (A0, A1), allowing up to four
devices to be connected to a single bus line. The
MAX6634 makes three address pins available (A0, A1,
A2), allowing up to eight devices to be connected to a
single bus line. The MAX6633 makes four address pins
available (A0, A1, A2, A3), allowing as many as 16

devices to be connected to a single bus line. Table 1
shows the full SMBus/I

2

C address for each device type.

Control Registers (MAX6633)

Three registers control the operation of the MAX6633
(Figure 5 and Tables 2 through 6). The Pointer register
is the first addressed and determines which of the other
two registers is acted upon. The other two are the
Temperature and Configuration registers. The tempera­ture value is stored as 12 bits plus a sign bit, read only,
and contains the latest temperature data. The true reg­ister length is 16 bits, with the lower 3 unused in this
part. The digital temperature data contained in the tem­perature register is in °C, using a two’s-complement
format with 1LSB corresponding to 0.0625°C.

The Configuration register is 8 bits, read/write, and
contains the SMBus timeout disable bit, fault queue
enable bit, and the shutdown bit.

Control Registers (MAX6634)

Six registers control the operation of the MAX6634
(Figure 6 and Tables 2 through 7). The pointer register
is the first addressed and determines which of the other
five registers is acted upon. The other five are the
Temperature, Configuration, High-Temperature
(T

HIGH

), Low-Temperature (T

LOW

), and Hysteresis

(T

HYST

) registers. The temperature value is stored as
12 bits plus a sign bit, read only, and contains the lat­est temperature data. The true register length is 16 bits,
with the lowest 2 used as status bits, and the third bit
(D2) is unused. The digital temperature data contained
in the temperature register is in °C, using a two’s-com­plement format with 1LSB corresponding to 0.0625°C.

MAX6633/MAX6634/MAX6635

12-Bit Plus Sign Temperature Sensors with

SMBus/I2C-Compatible Serial Interface

_______________________________________________________________________________________ 5

Pin Description

PIN

MAX6633 MAX6634 MAX6635

1 1 1 SDA Serial Data Input/Output. Open drain.

2 2 2 SCL Serial Clock Input

3 — — A3 Address Pin

4 4 4 GND Ground

5 5 — A2 Address Pin

6 6 6 A1 Address Pin

7 7 7 A0 Address Pin

888 V

—3 5 ALERT ALERT Output. Open drain.
—— 3 OVERT OVERT Output. Open drain.

NAME FUNCTION

CC

Supply Voltage Input. +3.0V to +5.5V. Bypass VCC to GND
with a 0.1µF capacitor.