ture 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 con-
verters (ADCs). The result of the conversion is then held
in a temperature register as a 12-bit + sign value, allow-
ing 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 con-
nected 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 func-
tion as an upgraded replacement for the LM76 in most
applications. The MAX6634/MAX6635 feature user-pro-
grammable temperature thresholds. All three devices
come in an 8-pin SO package.
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)
Ordering Information
PART
MAX6633MSA
MAX6634MSA
MAX6635MSA
TEMP. RANGE
-55°C to +150°C
-55°C to +150°C
-55°C to +150°C
PIN-PACKAGE
8 SO
8 SO
8 SO
Typical Operating Circuit
V
CC
0.1µF
+3.0V TO +5.5V
8
V
CC
10kΩ
5
1
2
3
TO SMBus/I
2
C
MASTER
1kΩ
1kΩ
10kΩ
Applications
●
Battery Temperature Alarms
●
PC Temperature Control
ALERT
MAX6635
SDA
SCL
TO INTERRUPT
CONTROLLER
Pin Configurations appear at end of data sheet.
7
6
OVERT
A0 A1 GND
4
TO SYSTEM
SHUTDOWN
19-2120; Rev 1; 4/14
MAX6633/MAX6634/
MAX6635
Absolute Maximum Ratings
12-Bit Plus Sign Temperature Sensors
with SMBus/I
2
C-Compatible Serial Interface
V
CC
, 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
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.
Electrical Characteristics
(V
CC
= +3.0V to +5.5V, T
A
= -55°C to +125°C, unless otherwise noted. Typical values are V
CC
= +3.3V, T
A
= +25°C, unless other-
wise noted.)
PARAMETER
Supply Range
SYMBOL
V
CC
0°C
≤ T
A
= ≤ +50°C,
V
CC
= +3.3V
-20°C
≤ T
A
= ≤ +85°C,
V
CC
= +3.3V
Accuracy (Note 1)
-40°C
≤T
A
= ≤ 125°C,
V
CC
= +3.3V
T
A
= -55°C, V
CC
= +3.3V
T
A
= +150°C, V
CC
= +3.3V
Power-Supply Rejection Ratio
POR Threshold Hysteresis
Supply Current in Shutdown
Average Operating Current
Peak Operating Current (Note 2)
Conversion Rate
DIGITAL INTERFACE
Logic Input Low Voltage
Logic Input High
Voltage
Input Leakage Current
Output Low Sink Current
Output Leakage Current
Input Capacitance
V
IL
V
IH
I
I_LEAK
IOL
I
O_LEAK
C
IN
V
CC
= +3.0V to +5.5V
V
CC
= +3V
V
CC
= +5.5V
V
IN
= GND or V
CC
V
OL
= 0.6V (SMBDATA,
ALERT, OVERT)
ALERT, OVERT at V
CC
5
6
±1
2.2
2.4
±1
0.65
V
V
µA
mA
µA
pF
V
CC
= +3.0V, SMBus inactive
V
CC
= +5.5V, SMBus inactive
V
CC
= +3.0V, SMBus inactive
V
CC
= +5.5V, SMBus inactive
V
CC
= +3.0V, SMBus inactive
V
CC
= +5.5V, SMBus inactive
1.4
PSRR
CONDITIONS
MIN
3.0
-1.0
-1.5
-2.5
-2.8
±0.4
±0.6
±1.0
±1.5
±2.5
0.2
90
12
20
150
200
270
350
2
350
700
2.4
20
30
0.5
°C/V
mV
µA
µA
µA
Hz
TYP
MAX
5.5
+1.0
+1.5
+2.5
+2.8
°C
UNITS
V
TEMPERATURE-TO-DIGITAL CONVERTER CHARACTERISTICS
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MAX6633/MAX6634/
MAX6635
Electrical Characteristics (continued)
12-Bit Plus Sign Temperature Sensors
with SMBus/I
2
C-Compatible Serial Interface
(V
CC
= +3.0V to +5.5V, T
A
= -55°C to +125°C, unless otherwise noted. Typical values are V
CC
= +3.3V, T
A
= +25°C, unless other-
wise noted.)
PARAMETER
Serial Clock Frequency
Bus Free Time Between STOP
and START Condition
START Condition Setup Time
Repeat START Condition Setup
Time
START Condition Hold Time
STOP Condition Setup Time
Data Setup Time
Data Hold Time (Note 4)
Receive SCL/SDA Rise Time
SCL/SDA Fall Time (Note 4)
Clock Low Period
Clock High Period
SMBus Timeout
Note
Note
Note
Note
1:
2:
3:
4:
t
SU:STA
t
HD:STA
t
SU:STO
t
SU:DAT
t
HD:DAT
t
R
t
F
t
LOW
t
HIGH
10% to 10%
90% to 90%
4.7
4
25
48
90% to 90%
10% of SMBDATA to 90% of SMBCLK
90% of SMBCLK to 10% of SMBDATA
90% of SMBDATA to 10% of SMBCLK
SYMBOL
f
SCL
t
BUF
CONDITIONS
MIN
10
4.7
4.7
4.7
4
4
250
300
1
300
TYP
MAX
100
UNITS
kHz
µs
µs
µs
µs
µs
ns
ns
µs
ns
µs
µs
ms
SMBus TIMING
(Note
3) (Figures 1, 2, and 3)
Guaranteed by design and characterization.
Peak operating current measured during conversion. See Figure 4.
Guaranteed by design, not production tested.
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.
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MAX6633/MAX6634/
MAX6635
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
12-Bit Plus Sign Temperature Sensors
with SMBus/I
2
C-Compatible Serial Interface
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX6633/4/5 toc01
AVERAGE SUPPLY CURRENT
vs. TEMPERATURE
MAX6633/4/5 toc02
SHUTDOWN SUPPLY CURRENT (µA)
AVERAGE SUPPLY CURRENT (µA)
TEMPERATURE ERROR (°C)
40
30
20
10
0
V
CC
= +5.5V
4
3
2
1
0
-1
300
V
CC
= +5.5V
200
V
IN
= SQUARE WAVE APPLIED TO
V
CC
WITH NO BYPASS
CAPACITOR
V
IN
= 200mVp-p
100
V
CC
= +3.3V
-55
0
55
110
165
V
CC
= +3.3V
V
IN
= 200mVp-p
0
-55
0
55
110
165
10
10k
SUPPLY NOISE FREQUENCY (Hz)
10M
TEMPERATURE (°C)
TEMPERATURE (°C)
MAX6633/4/5 toc04
100
90
80
TEMPERATURE (
°
C)
70
60
50
40
30
20
10
0
0
RESPONSE TO THERMAL SHOCK
3
TEMPERATURE ERROR (
°
C)
TEMPERATURE ERROR
vs. TEMPERATURE
MAX6633/4/5 toc05
2
V
CC
= +3.3V
0
V
CC
= +5.5V
-2
V
CC
= +5.5V
DEVICE IMMERSED IN +85
°
C
FLUORINERT BATH
5
10
TIME (s)
15
20
-3
-40
0
40
80
120
160
TEMPERATURE (°C)
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MAX6633/4/5 toc03
50
400
5
TEMPERATURE ERROR
vs. SUPPLY NOISE FREQUENCY
MAX6633/MAX6634/
MAX6635
Pin Description
PIN
MAX6633
1
2
3
4
5
6
7
8
—
—
MAX6634
1
2
—
4
5
6
7
8
3
—
MAX6635
1
2
—
4
—
6
7
8
5
3
NAME
SDA
SCL
A3
GND
A2
A1
A0
V
CC
ALERT
OVERT
12-Bit Plus Sign Temperature Sensors
with SMBus/I
2
C-Compatible Serial Interface
FUNCTION
Serial Data Input/Output. Open drain.
Serial Clock Input
Address Pin
Ground
Address Pin
Address Pin
Address Pin
Supply Voltage Input. +3.0V to +5.5V. Bypass V
CC
to GND
with a 0.1µF capacitor.
ALERT
Output. Open drain.
OVERT
Output. Open drain.
Detailed Description
The MAX6633/MAX6634/MAX6635 continuously con-
vert 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 inter-
face, 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.
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)
SMBus/I
2
C-Compatible Operation
The MAX6633/MAX6634/MAX6635 are readable and
programmable through their SMBus/I
2
C-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.
Three registers control the operation of the MAX6633
(Figure 5 and Tables 2 through 6). The Pointer regis-
ter 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 tempera-
ture value is stored as 12 bits plus a sign bit, read only,
and contains the latest temperature data. The true regis-
ter 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
1 LSB corresponding to 0.0625°C.
The Configuration register is 8 bits, read/write, and con-
tains the SMBus timeout disable bit, fault queue enable
bit, and the shutdown bit.
Control Registers (MAX6634)
Addressing
Separate addresses can be configured using the indi-
vidual address pins. The address of each device is
selected by connecting the address (A_) pins to one
of two potentials: GND or V
CC
. 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
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
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