MAXIM MAX6625, MAX6626 User Manual

General Description

The MAX6625/MAX6626 combine a temperature sensor,
a programmable overtemperature alarm, and an I2C­compatible serial interface into single compact packages.
They convert their die temperatures into digital values
using internal analog-to-digital converters (ADCs). The
result of the conversion is held in a temperature register,
readable at any time through the serial interface. A dedi­cated alarm output, OT, activates if the conversion result
exceeds the value programmed in the high-temperature
register. A programmable fault queue sets the number of
faults that must occur before the alarm activates, prevent­ing spurious alarms in noisy environments. OT has pro­grammable output polarity and operating modes.

The MAX6625/MAX6626 feature a shutdown mode that
saves power by turning off everything but the power-on
reset and the I2C-compatible interface. Four separate
addresses can be configured with the ADD pin, allowing
up to four MAX6625/MAX6626 devices to be placed on
the same bus. The MAX6625P/MAX6626P OT outputs are
open drain, and the MAX6625R/MAX6626R OT outputs
include internal pullup resistors.

The MAX6625 has a 9-bit internal ADC and can function
as a replacement for the LM75 in most applications. The
MAX6626 has a 12-bit internal ADC. Both devices come
in the space-saving 6-pin SOT23 package, or the 6-pin
TDFN package.

Applications

Fan Control
Temperature Alarms
System Temperature Control
Industrial Equipment

Features

♦ 9-Bit Temperature-to-Digital Converter (MAX6625)

♦ 12-Bit Temperature-to-Digital Converter (MAX6626)

♦ I

2

C-Compatible Serial Interface

♦ Up to Four Devices on a Single Bus

♦ Versatile Alarm Output with Programmable Trip

Temperature and Hysteresis

♦ Low-Power Shutdown Mode

♦ Space-Saving TDFN or SOT23 Packages

♦ Lead-Free Version Available (TDFN Package)

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

________________________________________________________________ Maxim Integrated Products 1

GND

OT

**EP = EXPOSED PADDLE

SCL

16V

S

5 ADD

SDA

MAX6625
MAX6626

SOT236

TDFN-EP**

TOP VIEW

2

34

Pin Configuration

4

6

V

S

0.1µF

1

MAX6625
MAX6626

3

SCL

TO I

2

C

MASTER

10kΩ
(OMIT FOR MAX6625R
AND MAX6626R)

SDA

52

1kΩ

1kΩ

OT OUTPUT

Typical Operating Circuit

19-1841; Rev 4; 10/06

Note: All devices operate over the -55°C to +125°C temperature
range.

*For device options, see Selector Guide at end of data sheet.

Requires special solder temperature profile described in the
Absolute Maximum Ratings section.

**EP = Exposed paddle.

PART PIN-PACKAGE PKG CODE

MAX6625PMUT* 6 SOT23-6 U6F-6

MAX6625RMUT* 6 SOT23-6 U6F-6
MAX6625PMTT* 6 TDFN-EP** T633-1
MAX6625RMTT* 6 TDFN-EP** T633-1
MAX6626PMUT* 6 SOT23-6 U6F-6
MAX6626RMUT* 6 SOT23-6 U6F-6
MAX6626PMTT* 6 TDFN-EP** T633-1
MAX6626RMTT* 6 TDFN-EP** T633-1

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.

Ordering Information

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(+3V ≤ VS≤ +5.5V, T

A =

-55°C to +125°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.

VSto GND ................................................................-0.3V to +6V

OT, SCL, SDA to GND..............................................-0.3V to +6V

ADD to GND .................................................-0.3V to (V

S

+ 0.3V)

Current into Any Pin............................................................±5mA

OT Sink Current.................................................................. 20mA

Continuous Power Dissipation

6-Pin SOT23 (derate 9.1mW/°C above +70°C)............727mW

6-Pin TDFN (derate 23.8mW/°C above +70°C) .........1905mW

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

Storage Temperature Range .............................-60°C to +150°C

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

Lead Temperature .............................................................Note 1

Note 1: This device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device

can be exposed to during board-level solder attach and rework. This limit permits only the use of the solder profiles recom­mended in the industry-standard specification, IPC/JEDEC J-STD-020A, paragraph 7.6, Table 3 for IR/VPR and Convection
Reflow. Preheating is required. Hand or wave soldering is not allowed.

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Power-Supply Voltage V

S

3.0 5.5 V

I2C-compatible active 1 mA

I2C-compatible inactive

µAQuiescent Current I

C

Shutdown mode 1 µA

MAX6625 9

ADC Resolution

MAX6626 12

MAX6625 0.5

Temperature Resolution

MAX6626
TA = +25°C, VS = +3V to +3.6V ±1

0°C = TA ≤ +50°C, VS = +3.0V to +3.6V

Accuracy (Notes 2, 3)

0°C = T

A

≤ +70°C, VS = +3.0V to +3.6V

°C

Power-Supply Sensitivity VS = +3V to +5.5V 1

Conversion Time t

C

ms

OT Pullup Resistor R

P

MAX6625R, MAX6626R only 25 50 kΩ

OT Saturation Voltage (Note 4) V

L

I

OUT

= 4mA (Note 4) 0.8 V

OT Delay (Programmable through fault queue)

ms

T

HIGH

Default Temperature

80 °C

T

LOW

Default Temperature T

LOW

75 °C

I2C-COMPATIBLE I/O: SCL, SDA, ADD

VS < +3.6V 2

Input High Voltage V

IH

VS > +3.6V 3

V

Input Low Voltage V

IL

0.8 V

Input Hysteresis 0.2 V

250

0.0625

T

HIGH

133

1 × t

C

±1.5

±2.0

6 × t

Bits

°C/LSB

°C/V

C

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(+3V ≤ VS≤ +5.5V, T

A =

-55°C to +125°C, unless otherwise noted.)

Note 2: Guaranteed by design and characterization to ±5 sigma.
Note 3: Quantization error not included in specifications for temperature accuracy.
Note 4: Output current should be minimized for best temperature accuracy. Power dissipation within the MAX6625/MAX6626 causes

self-heating and temperature drift; see the Thermal Considerations section.

Note 5: 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.

Note 6: C

B

= total capacitance of one bus line in pF. Tested with CB= 400pF.

Note 7: Input filters on SDA, SCL, and ADD suppress noise spikes less than 50ns.

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

Input High Leakage Current I

IH

V

IN

= +5V ±1 µA

Input Low Leakage Current I

IL

V

IN

= 0 ±1 µA

Input Capacitance C

IN

10 pF

Output Low Voltage V

OL

I

OL

= 3mA 0.4 V

Output High Current I

OH

VOH = 5V 1 µA

I2C-COMPATIBLE TIMING

Serial Clock Frequency f

SCL

DC

kHz

Bus Free Time Between STOP
and START Conditions

t

BUF

1.3 µs

START Condition Hold Time

0.6 µs

STOP Condition Setup Time

0.6 µs

Clock Low Period t

LOW

1.3 µs

Clock High Period t

HIGH

0.6 µs

Data Setup Time

ns

Data Hold Time

(Note 5) 0 0.9 µs

Maximum Receive SCL/SDA
Rise Time

t

R

(Note 6)

ns

Minimum Receive SCL/SDA
Rise Time

t

R

(Note 6)

20 +

ns

Maximum Receive SCL/SDA
Fall Time

t

F

(Note 6)

ns

Minimum Receive SCL/SDA
Fall Time

t

F

(Note 6)

20 +

ns

Transmit SDA Fall Time t

F

CB = 400pF, IO = 3mA (Note 6)

20 +

ns

Pulse Width of Suppressed
Spike

t

SP

(Note 7) 50 ns

Figure 1. Serial Bus Timing

SCL

SDA

t

F

t

LOW

t

SU:DAT

t

HD:STA

t

HD:DAT

t

SU:STO

t

BUF

t

HIGH

t

R

t

HD:STA

t

SU:STO

t

SU:DAT

t

HD:DAT

100

300

0.1C

300

0.1C

0.1C

B

400

B

B

250

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

4 _______________________________________________________________________________________

Typical Operating Characteristics

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

Pin Description

0

20

60

40

80

100

-5 50101520

RESPONSE TO THERMAL SHOCK

TEMPERATURE vs. TIME

MAX6625 toc01

TIME (s)

OUTPUT TEMPERATURE (°C)

DEVICE IMMERSED IN +85°C
FLUORINERT BATH

80

120

100

160

140

180

200

-55 5 35-25 65 95 125

STATIC QUIESCENT SUPPLY CURRENT

vs. TEMPERATURE

MAX6625 toc02

TEMPERATURE (°C)

INPUT CURRENT (µA)

80

120

100

160

140

180

200

-55 5 35-25 65 95 125

DYNAMIC QUIESCENT SUPPLY CURRENT

vs. TEMPERATURE

MAX6625 toc03

TEMPERATURE (°C)

INPUT CURRENT (µA)

-5

-2

-3

-4

0

-1

4

3

2

1

5

-50 -25 0 25 50 75 100 125

TEMPERATURE ERROR

vs. TEMPERATURE

MAX6625 toc04

TEMPERATURE (°C)

TEMPERATURE ERROR (°C)

MAXIMUM LIMIT

±5 SIGMA RANGE

MINIMUM LIMIT

PIN NAME FUNCTION

1 SDA I2C-Compatible Serial Bidirectional Data Line

2 GND Power-Supply Ground

3 SCL I2C-Compatible Clock Input

4 OT Temperature Alarm Output

5 ADD I2C-Compatible Address Set Pin: Ground (0), VS (1), SDA (2), SCL (3); see Table 1.

6VSPower-Supply Input, +3V to +5.5V. Bypass VS to GND with a 0.1µF capacitor.

—EP

Exposed Paddle. Internally connected to GND. Connect to a large ground plane for maximum thermal
dissipation.

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

_______________________________________________________________________________________ 5

Detailed Description

The MAX6625/MAX6626 continuously convert their die
temperatures into digital values using their self-con­tained delta-sigma ADCs. The resulting data is read­able at any time through the I2C-compatible serial
interface. A dedicated alarm output asserts if the result
exceeds the value in the programmable high-tempera­ture register. A programmable fault queue sets the
number of faults that must occur before the alarm
asserts, preventing spurious alarms in noisy environ­ments. The alarm output polarity is selectable and
deasserts based on either of two operating modes,
comparator or interrupt. In comparator mode, the OT
output deasserts if the temperature conversion result
falls below the programmable low-temperature register
value (subject to the fault queue conditions) providing
adjustable hysteresis. In interrupt mode, the OT output
deasserts when any register is read through the serial
interface. Each conversion cycle takes about 130ms. At
power-up, the temperature register is set to 8000H until
the first conversion is completed.

The MAX6625/MAX6626 feature a shutdown mode,
accessible through the serial interface, that saves power
by turning off everything but the power-on reset and the
I2C-compatible interface. While in shutdown mode, the
temperature register is set to 8000H. The device func-

tions as a slave on the I

2

C-compatible bus supporting
Write Byte, Write Word, Read Byte, and Read Word com­mands. Four separate addresses can be configured with
the ADD pin, allowing up to four MAX6625/MAX6626
devices to be placed on the same bus. Figure 2 shows
the functional diagram of the MAX6625/MAX6626.

Serial interface

I2C-Compatible Operation

The MAX6625/MAX6626 are readable and programma­ble through their I2C-compatible serial interface.
Figures 3 and 4 show the timing details of the clock
(SCL) and data (SDA) signals. The device functions as
a slave on the I2C-compatible bus and supports Write
Byte, Write Word, Read Byte, and Read Word com­mands.

Addressing

Four separate addresses can be configured with the
ADD pin, allowing up to four MAX6625/MAX6626s to be
placed on the same bus. The address is selected by
connecting the ADD pin to either of four places: GND
(address 0), VS(address 1), SDA (address 2), or SCL
(address 3). Table 1 shows the full I2C-compatible
address for each state.

MAX6625
MAX6626

TEMPERATURE REGISTER

T

HIGH

REGISTER

+Vs

OT

GND
SDA
SCL
ADD

SERIAL BUS INTERFACE

T

LOW

REGISTER

SET-POINT

COMPARATOR

ADDRESS
POINTER
REGISTER

BANDGAP

REGISTER

ADC

REFERENCE

TEMP SIGNAL

FAULT
QUEUE

COUNTER

CONFIGURATION REGISTER

MAX665_ R

ONLY

Figure 2. Functional Diagram

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

6 _______________________________________________________________________________________

Figure 3. I2C-Compatible Timing Diagram

ADDRESS

BYTE

ADDRESS

BYTE

ADDRESS

BYTE

(a) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FROM CONFIGURATION REGISTER

(b) CONFIGURATION REGISTER WRITE

(c) T

HIGH

AND T

LOW

WRITE

POINTER

BYTE

POINTER

BYTE

POINTER

BYTE

MOST-SIGNIFICANT

DATA BYTE

LEAST-SIGNIFICANT

DATA BYTE

CONFIGURATION

BYTE

ADDRESS

BYTE

DATA

BYTE

ACK BY

MAX6625

ACK BY

MAX6625

ACK BY

MAX6625

ACK BY

MAX6625

ACK BY

MAX6625

ACK BY

MAX6625

ACK BY

MAX6625

START

BY

MASTER

START

BY

MASTER

START

BY

MASTER

REPEAT

START

BY

MASTER

NO

ACK BY

MASTER

STOP

COND BY

MASTER

ACK BY

MAX6625

ACK BY

MAX6625

STOP

COND BY

MASTER

STOP

COND BY

MASTER

ACK BY

MAX6625

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

_______________________________________________________________________________________ 7

Figure 4. I2C-Compatible Timing Diagram

ADDRESS

BYTE

ADDRESS BYTE

ADDRESS

BYTE

ADDRESS

BYTE

DATA

BYTE

(a) TYPICAL 2-BYTE READ FROM PRESET POINTER LOCATION SUCH AS TEMP, T

HIGH

, T

LOW

(b) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FOR 2-BYTE REGISTER SUCH AS TEMP, T

HIGH

, T

LOW

(c) TYPICAL 1-BYTE READ FROM CONFIGURATION REGISTER WITH PRESET POINTER

MOST-SIGNIFICANT

DATA BYTE

LEAST-SIGNIFICANT

DATA BYTE

POINTER BYTE

MOST-SIGNIFICANT

DATA BYTE

LEAST-SIGNIFICANT

DATA BYTE

ACK BY

MAX6625

ACK BY

MASTER

ACK BY

MAX6625

ACK BY

MAX6625

ACK BY

MASTER

ACK BY

MAX6625

ACK BY

MASTER

START

BY

MASTER

START

BY

MASTER

REPEAT

START

BY

MASTER

START

BY

MASTER

STOP

COND BY

MASTER

STOP

COND BY

MASTER

STOP

COND BY

MASTER

NO ACK BY

MASTER

NO

ACK BY

MASTER

NO

ACK BY

MASTER

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

8 _______________________________________________________________________________________

Control Registers

Five registers control the operation of the MAX6625/
MAX6626 (Figure 5 and Tables 2 through 7). The point­er register should be the first addressed and deter­mines which of the other four registers are acted on.
The other four are the temperature, configuration, high­temperature (T

HIGH

), and low-temperature (T

LOW

) reg­isters. The temperature register is 9 bits for the
MAX6625 and 12 bits for the MAX6626, read only, and
contains the latest temperature data. The register
length is 16 bits with the unused bits masked to zero.
The digital temperature data contained in the tempera­ture register is in °C, using a two’s-complement format
with 1 LSB corresponding to 0.5°C for the MAX6625
and 0.0625°C for the MAX6626 (Table 8).

The configuration register is 8 bits, read/write, and con­tains the fault queue depth, the temperature alarm
polarity select bit, the interrupt mode select bit, and the
shutdown control bit. The high-temperature register is
9 bits, read/write, and contains the value that triggers

the overtemperature alarm. The low-temperature regis­ter is 9 bits, read/write, and contains the value to which
the temperature must fall before the overtemperature
alarm is deasserted, if in comparator mode.

Temperature Conversion

An on-chip bandgap reference produces a signal pro­portional to absolute temperature (PTAT), as well as the
temperature-stable reference voltage necessary for the
analog-to-digital conversion. The PTAT signal is digi­tized by the on-board ADC to a resolution of 0.5°C for
the MAX6625, and 0.0625°C for the MAX6626. The
resulting digital value is placed in the temperature reg­ister. The temperature conversion runs continuously
and asynchronously from the I

2

C-compatible interface
at a rate of 133ms per conversion. When the tempera­ture register is read, the most recently completed con­version result is provided and the currently active
conversion is aborted. When the bus transaction is fin­ished by an I2C-compatible stop condition conversions
resume.

Overtemperature Alarm

The dedicated overtemperature output pin, OT, has
programmable polarity and two modes: comparator
and interrupt. Polarity and mode are selected through
the configuration register, and alarm activity is gov­erned by a fault queue. Fault queue depth is also
selected through the configuration register (Tables 5
and 6). The MAX6625P/MAX6626P OT output is open

POINTER REGISTER

(SELECTS REGISTER FOR

COMMUNICATION)

INTERFACE

SDA

SCL

DATA

ADDRESS

REGISTER SELECT

CONFIGURATION

(READ-WRITE, SETS OPERATING MODES)

POINTER = 00000001

T

LOW

SET-POINT

(READ-WRITE)

POINTER = 00000010

TEMPERATURE

(READ ONLY)

POINTER = 00000000

T

HIGH

SET-POINT

(READ-WRITE)

POINTER = 00000011

Figure 5. MAX6625/MAX6626 Programmers Model

ADD CONNECTION

I2C-COMPATIBLE ADDRESS

GND 100 1000

V

S

100 1001

SDA 100 1010

SCL 100 1011

Table 1. Address Selection

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

_______________________________________________________________________________________ 9

D7

D2 D1 D0

0

0

Register select

(see Table 3)

Table 2. Pointer Register

D7 to D2: Read all zeros, cannot be written.

PART D15

D14

D13

D12

D11

D10D9D8D7D6D5D4D3D2–D0

MAX6625

0000 0

MAX6625

MSB

Bit

Bit

0

Table 4. Temperature Register

D7

D2 D1 D0

0

Fault

OT

Mode

Shutdown

Table 5. Configuration Register

All defaults = 0.
D0: 0 = Normal operation, 1 = Shutdown.
D1: 0 = Comparator mode, 1 = Interrupt mode.
D2: 0 = Active low, 1 = Active high.
D7 to D5: Reserved locations, always write zeros.

D4 D3 NO. OF FAULTS

0 0 1 (default)

01 2

10 4

11 6

Table 6. Fault Queue Depth

D1 D0 REGISTER

0 0 Temperature (default)

0 1 Configuration

10T

LOW

11T

HIGH

Table 3. Register Select

D6 to D0, MAX6625: Read all zeros, cannot be written.
D2 to D0, MAX6626: Read all zeros, cannot be written.
D15: MSB is the sign bit.

1 LSB = 0.5°C for the MAX6625.
1 LSB = 0.0.0625°C for the MAX6626.
Temperature is stored in two’s-complement format.

D6 D5 D4 D3

0000

MSB

(Sign)

(Sign)

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB

11

10

Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB

D6 D5 D4 D3

Comparator

00

Queue

Depth

Polarity

or Interrupt

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

10 ______________________________________________________________________________________

D15

D14

D13

D12

D11

D10D9D8D7D6D5D4D3D2D1D0

MSB

0000000

Table 7. T

HIGH

and T

LOW

Registers

D6 to D0: Read all zeros, cannot be written.
D15: MSB is the sign bit.
Default: T

HIGH

= +80°C (5000H), T

LOW

= +75°C (4B00H).

LSB = 0.5°C.

DIGITAL OUTPUT CODE

MAX6625 MAX6626

BINARY BINARY

TEMPERATURE

(°C)

MSB LSB

HEX

MSB LSB

HEX

+125.0000 0111 1101 0000 0000 7D00 0111 1101 0000 0000 7D00

+124.9375 0111 1100 1000 0000 7C80 0111 1100 1111 0000 7CF0

+25.0000 0001 1001 0000 0000 1900 0001 1001 0000 0000 1900

+0.5000 0000 0000 1000 0000 0080 0000 0000 1000 0000 0080

0.0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0000

-0.5000 1111 1111 1000 0000 FF80 1111 1111 1000 0000 FF80

-25.0000 1110 0111 0000 0000 E700 1110 0111 0000 0000 E700

-55.0000 1100 1001 0000 0000 C900 1100 1001 0000 0000 C900

∗ 1000 0000 0000 0000 8000 1000 0000 0000 0000 8000

Table 8. Output Code vs. Temperature

*8000H is the default value at power-up and after coming out of shutdown.

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 LSB

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

______________________________________________________________________________________ 11

drain, and the MAX6625R/MAX6626R output includes
an internal 35kΩ (typ) pullup resistor. Figure 6 shows
the OT alarm operation and reset details.

Fault Queue

A programmable fault queue on the MAX6625/
MAX6626 eliminates spurious alarm activity in noisy
environments. The queue sets the number of consecu­tive out-of-tolerance temperature readings that must
occur before the OT alarm output is toggled. An out-of­tolerance reading is above T

HIGH

or below T

LOW

. The
fault queue depth defaults to one at power-up and may
be programmed to one, two, four, or six consecutive
conversions. Any time the conversion result is in toler­ance, and OT is not asserted, the queue is cleared,
even if it contains some out-of-tolerance counts.
Additionally, the fault queue automatically clears at
power-up, in shutdown, or if a master writes to any of
the T

HIGH

, T

LOW

, or configuration registers. Whenever

the fault queue is cleared, OT is deasserted.

For example, the fault queue is set to four, two consec­utive out-of-tolerance readings have occurred, and the
master writes to the T

LOW

register. The fault queue is
cleared and begins to look for four new consecutive
out-of-tolerance conversions.

Comparator Mode

In comparator mode, OT is asserted when the number
of consecutive conversions exceeding the value in the
T

HIGH

register is equal to the depth of the fault queue.

OT deasserts when the number of consecutive conver­sions less than the value in the T

LOW

register is equal

to the depth of the fault queue. T

HIGH

minus T

LOW

is

the effective hysteresis of the OT output.

For example, if T

HIGH

is set to +100°C, T

LOW

is set to
+80°C, and the fault queue depth is set to four, OT
does not assert until four consecutive conversions
exceed +100°C. Then, OT does not deassert until four
consecutive conversions are less than +80°C.

Comparator mode allows autonomous clearing of an OT
fault without the intervention of a master and is ideal to
use for driving a cooling fan (Figure 7).

Interrupt Mode

In interrupt mode, the MAX6625/MAX6626 look for a
T

HIGH

or a T

LOW

fault based on previous fault activity.
The OT pin asserts an alarm for an undertemperature
fault, as well as for an overtemperature fault, depending
on certain conditions. If the fault queue is cleared at
power-up, the IC looks for a T

HIGH

fault. After a T

HIGH

fault, the IC looks for a T

LOW

fault. After a T

LOW

fault,

the IC looks for a T

HIGH

fault, and it bounces back and
forth if properly deasserted each time. Once either fault
has occurred, it remains active indefinitely until
deasserted by a read of any register, and the device
then begins to look for a fault of the opposite type. Also,
if the fault queue is cleared, OT is deasserted and the
IC once again looks for a T

HIGH

fault. The activation of

any fault is subject to the depth of the fault queue.

DIE

TEMPERATURE

TIME

** *

T

HIGH

T

LOW

OT

(COMPARATOR MODE)

OT

(INTERRUPT MODE)

TEMPERATURE RESPONSE
SHOWN WITH OT SET FOR

ACTIVE LOW

*THIS ASSUMES DEASSERTION OF OT BY A
MASTER THROUGH THE SERIAL INTERFACE.
SEE INTERRUPT MODE SECTION.

Figure 6. OT Alarm Output and Reset Diagram

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

12 ______________________________________________________________________________________

Example 1: If T

HIGH

is set to +100°C, T

LOW

is set to
+80°C, and the fault queue depth is set to four, OT
does not assert until four consecutive conversions
exceed +100°C. If the temperature is then read through
the I2C-compatible interface, OT deasserts. OT asserts
again when four consecutive conversions are less than
+80°C.

Example 2: If T

HIGH

is set to +100°C, T

LOW

is set to
+80°C, and the fault queue depth is set to four, OT
does not assert until four consecutive conversions
exceed +100°C. If the T

HIGH

register is then changed
to +120°C, OT deasserts and the IC looks for a new
T

HIGH

fault.

Shutdown

The MAX6625/MAX6626 offer a low-power shutdown
mode. Enter shutdown mode by programming the shut­down bit of the control register high. In shutdown, the
temperature register is set to 8000H and the ADC is
turned off, reducing the device current draw to 1µA
(typ). After coming out of shutdown, the temperature
register continues to read 8000H until the first conver­sion result appears. The fault queue is held in reset
during shutdown.

Thermal Considerations

The MAX6625/MAX6626 supply current is less than
1mA when the I2C-compatible interface is active. When
used to drive high-impedance loads, the devices dissi­pate negligible power; therefore, the die temperature is
essentially the same as the package temperature. The

key to accurate temperature monitoring is good thermal
contact between the MAX6625/MAX6626 package and
the monitored device or circuit. In some applications,
the 6-pin SOT23 package may be small enough to fit
underneath a socketed µP, allowing the device to moni­tor the µP’s temperature directly. Heat flows in and out
of plastic packages primarily through the leads. Short,
wide copper traces leading to the temperature monitor
ensure that heat transfers quickly and reliably. The rise
in die temperature due to self-heating is given by the
following formula:

∆T

J

= P

D

✕

θ

JA

where PDis the power dissipated by the MAX6625/
MAX6626, and θJAis the package’s thermal resistance.

The typical thermal resistance is +110°C/W for the 6­pin SOT23 package. To limit the effects of self-heating,
minimize the output currents. For example, if the
MAX6625/MAX6626 sink 4mA with the maximum OT V

L

specification of 0.8V, an additional 3.2mW of power is
dissipated within the IC. This corresponds to a 0.35°C
rise in the die temperature.

Applications

Figure 7 shows the MAX6625/MAX6626 used as a tem­perature-triggered fan controller. Figure 8 shows the
MAX6625/MAX6626 used as a thermostat to control a
heating element.

4

6

+V

S

+3V TO +5V

+12V

OT

MAX6625R
MAX6626R

2

12V 300mA
FAN MOTOR

LOGIC LEVEL
MOSFET

Figure 7. Fan Controller

Figure 8. Simple Thermostat

+V

S

+3V TO +5V

6

4k

MAX6625P
MAX6626P

3

5

OT

2N3904

HEATER

RELAY
5VDC, 20mA
125VAC, 1A

HEATER
SUPPLY

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

______________________________________________________________________________________ 13

TRANSISTOR COUNT: 7513

PROCESS: BiCMOS

Chip Information

PART

ALARM

OUTPUT

(bits)

M A X 6 62 5P Open drain 9

MAX6625R

9

M A X 6 62 6P Open drain 12

MAX6626R

12

Selector Guide

Internal pullup

Internal pullup

RESOLUTION

TOP

MARK

AAHY

AAHZ

AANP

AANQ

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

14 ______________________________________________________________________________________

6LSOT.EPS

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

______________________________________________________________________________________ 15

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

MAX6625/MAX6626

9-Bit/12-Bit Temperature Sensors with
I2C-Compatible Serial Interface in a SOT23

16 ______________________________________________________________________________________

6, 8, &10L, DFN THIN.EPS

H

1

2

21-0137

PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

9-Bit/12-Bit Temperature Sensors with

I2C-Compatible Serial Interface in a SOT23

MAX6625/MAX6626

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 17

© 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.

Package Information (continued)

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages

.)

COMMON DIMENSIONS

SYMBOL

MIN. MAX.

A 0.70 0.80

D 2.90 3.10
E 2.90 3.10

A1

0.00 0.05

L 0.20 0.40

PKG. CODE N D2 E2 e JEDEC SPEC b [(N/2)-1] x e

PACKAGE VARIATIONS

0.25 MIN.k

A2 0.20 REF.

2.30±0.101.50±0.106T633-1 0.95 BSC MO229 / WEEA 1.90 REF0.40±0.05

1.95 REF0.30±0.050.65 BSC2.30±0.108T833-1

2.00 REF0.25±0.050.50 BSC2.30±0.1010T1033-1

2.40 REF0.20±0.05- - - - 0.40 BSC1.70±0.10 2.30±0.1014T1433-1

1.50±0.10

1.50±0.10

MO229 / WEEC

MO229 / WEED-3

0.40 BSC - - - - 0.20±0.05 2.40 REFT1433-2 14 2.30±0.101.70±0.10

T633-2 6 1.50±0.10 2.30±0.10

0.95 BSC MO229 / WEEA

0.40±0.05 1.90 REF

T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF

-DRAWING NOT TO SCALE-

H

2

2

21-0137

PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm

2.30±0.10

MO229 / WEED-3

2.00 REF0.25±0.05

0.50 BSC

1.50±0.1010T1033-2

Revision History

Pages changed at Rev 4: 1, 2, 15, 16, 17