General Description
The MAX6687/MAX6688 comprise a remote-junction
temperature switch and a local temperature switch in a
single package. The remote-junction switch uses an
external P-N junction (typically a diode-connected transistor on the die of an external CPU, ASIC, or FPGA) as
a sensing element to measure the remote temperature.
The remote-junction temperature switch has a factoryprogrammed trip temperature threshold of either
+120°C or +125°C. The local temperature switch has a
pin-programmable temperature threshold that is set by
connecting pins S1 and S2 to ground, to VDD, or leaving them floating. Hysteresis for both local and remote
thresholds is 5°C. The MAX6687/MAX6688 do not
assert on transient (single-sample) faults or when
power is first applied.
The MAX6687 has two open-drain active-low outputs
while the MAX6688 has two push-pull active-high outputs. T
REMOTE
asserts a logic signal when the remote
temperature exceeds the factory-programmed +120°C
or +125°C trip threshold. T
LOCAL
is asserted when the
die temperature exceeds the pin-programmed threshold, which is controlled by pins S1 and S2. The local
thresholds are available in two ranges in 5°C increments. The two ranges are +40°C to +80°C and +75°C
to +115°C.
The MAX6687/MAX6688 operate from a 3.0V to 5.5V
power supply and are available in a space-saving 8-pin
µMAX package.
Applications
CPU Temperature Protection
FPGA Temperature Protection
Fan Control
Temperature Alarms
Features
♦ Pin-Programmable Local Temperature Threshold
in 5°C Increments in Two Distinct Ranges: +40°C
to +80°C and +75°C to +115°C
♦ Factory-Programmed Remote Threshold:
+120°C (L Suffix) or +125°C (H Suffix)
♦ Open-Drain Active-Low Outputs (MAX6687)
♦ CMOS Push-Pull, Active-High Outputs (MAX6688)
♦ ±1.5°C Accuracy
♦ 2Hz Temperature Sampling Rate
♦ 215µA Average Supply Current
♦ 3.0V to 5.5V Power-Supply Voltage
♦ 8-Pin µMAX Package
MAX6687/MAX6688
Local/Remote Temperature Switches in a
µMAX Package
________________________________________________________________ Maxim Integrated Products 1
Ordering Information
19-2636; Rev 2; 11/03
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.
Pin Configurations/Functional Diagrams/Selector Guide
appear at end of data sheet.
Typical Operating Circuit
3.3V
V
DD
DXP
MAX6687
C
S
DXN
µP µP
S1
S2
GND
T
REMOTE
T
LOCAL
3.3V
TO SYSTEM
SHUTDOWN
PART TEMP RANGE PIN-PACKAGE
MAX6687AU40L -40°C to +125°C 8 µMAX
MAX6687AU40H -40°C to +125°C 8 µMAX
MAX6687AU75L -40°C to +125°C 8 µMAX
MAX6687AU75H -40°C to +125°C 8 µMAX
MAX6688AU40L -40°C to +125°C 8 µMAX
MAX6688AU40H -40°C to +125°C 8 µMAX
MAX6688AU75L -40°C to +125°C 8 µMAX
MAX6688AU75H -40°C to +125°C 8 µMAX
C
S
DXP
DXN
S1
S2
3.3V
V
DD
MAX6688
GND
T
REMOTE
T
LOCAL
TO SYSTEM
SHUTDOWN
12V
N
MAX6687/MAX6688
Local/Remote Temperature Switches in a
µMAX Package
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VDD= 3V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VDD= 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.
Voltages Referenced to GND
VDD, T
LOCAL
, T
REMOTE
............................................-0.3V to +6V
DXN .......................................................................-0.3V to +0.8V
All Other Pins..............................................-0.3V to (VDD+ 0.3V)
Input Current .........................................................................5mA
Output Current ....................................................................20mA
Continuous Power Dissipation (TA= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10s) .................................+300°C
Power-Supply Range V
Average Supply Current I
Supply Current During
Conversion
Power-On Reset (POR) Threshold POR V
POR Threshold Hysteresis 50 mV
Remote-Diode Temperature
Threshold Accuracy, Rising
Temperature
Internal Temperature Threshold
Accuracy, Rising Temperature
Temperature Threshold
Hysteresis
Temperature Threshold Supply
Sensitivity
Output Voltage High V
Output Voltage Low V
Logic Input Low Voltage
(S1, S2)
Logic Input High Voltage
(S1, S2)
Input Current (S1, S2) 10 µA
Open-Drain Output Leakage
Current
PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS
DD
DD
falling edge 1 1.5 2.0 V
DD
TA = +25°C, VDD = 3.3V -1.5 +1.5
∆T
∆T
T
HYST
V
V
TA = 0°C to +85°C, VDD = 3.3V -3.0 +3.0
TH
TA = -40°C to +125°C, VDD = 3.3V -5.0 +5.0
Temperature trip thresholds from +40°C to
+105°C, V
TH
Temperature trip thresholds +110°C and
+115°C, V
OHISOURCE
I
OL
SINK
IL
IH
V
OUT
DD
DD
= 1mA, MAX6688 V
= 1mA 0.2 V
= 5.5V, MAX6687 1 µA
3 5.5 V
215 500 µA
400 800 µA
= 3.3V
= 3.3V
-3.0 +3.0
-3.5 +3.5
5.0 °C
- 0.2 V
DD
1.8 V
0.6 °C/V
0.4 V
°C
°C
MAX6687/MAX6688
Local/Remote Temperature Switches in a
µMAX Package
_______________________________________________________________________________________ 3
Note 1: All parameters are tested at +25°C. Temperature specifications over a range of -40°C to +125°C are guaranteed by design.
ELECTRICAL CHARACTERISTICS (continued)
(VDD= 3V to 5.5V, TA= -40°C to +125°C, unless otherwise noted. Typical values are at VDD= 3.3V and TA= +25°C.) (Note 1)
Typical Operating Characteristics
(VDD= 3.3V, CS= 2200pF, TA= +25°C, unless otherwise noted.)
AVERAGE SUPPLY CURRENT
vs. AMBIENT TEMPERATURE
MAX6687/88 toc01
AMBIENT TEMPERATURE (°C)
AVERAGE SUPPLY CURRENT (µA)
1007550250-25
140
180
220
260
300
100
-50 125
AVERAGE SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX6687/88 toc02
SUPPLY VOLTAGE (V)
AVERAGE SUPPLY CURRENT (µA)
5.04.54.03.5
140
180
220
260
300
100
3.0 5.5
TA = +100°C
TA = -40°C
TA = +25°C
TEMPERATURE TRIP THRESHOLD ERROR
vs. C
S
CAPACITANCE
MAX6687/88 toc03
CS CAPACITANCE (nF)
TEMPERATURE TRIP THRESHOLD ERROR (°C)
10
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
0
1 100
MAX6688U40H
S1 = S2 = FLOAT
REMOTE TEMPERATURE TRIP THRESHOLD
ERROR vs. AMBIENT TEMPERATURE
MAX6687/88 toc04
AMBIENT TEMPERATURE (°C)
UPPER TRIP THRESHOLD ERROR (°C)
7550250-25
-4
-3
-2
-1
0
1
-5
-50 100
MAX6688U40H
T
REMOTE
TRIP = +125°C
Temperature Conversion Time 0.2 0.25 0.3 s
Temperature Sample Period 0.4 0.5 0.6 s
Current Sourcing for External
Diode
PARAMETER SYMBOL CONDITION MIN TYP MAX UNITS
High level 80 100 120
Low level 8 10 12
µA
MAX6687/MAX6688
Detailed Description
The MAX6687/MAX6688 sense the temperatures of
both a remote P-N junction and their own die. The
external P-N junction is typically a base-emitter junction
of a substrate PNP on a microprocessor, FPGA, or
ASIC die (see the Typical Operating Circuit).
The remote temperature switch has a factory-programmed trip temperature of either +120°C or +125°C
and is intended to be used for system shutdown when
the die temperature of a remote IC, such as a microprocessor, FPGA, or ASIC exceeds the factory-programmed thresholds.
The local temperature switch has a pin-programmable
threshold temperature (Table 1). This temperature
switch may be used for such functions as system shutdown or for turning on a cooling fan when board temperature exceeds the temperature limit. Two
temperature ranges are available for the local trip
threshold: +40°C to +80°C and +75°C to +115°C. S1
and S2 pins must be set to the desired trip temperature
before power is applied to the VDDpin. If S1 and S2
settings are changed after the power is turned on, the
local trip threshold remains set to the point where S1
and S2 were when power was applied.
Since the MAX6687/MAX6688 are often used for system shutdown, they are designed so that the outputs
do not change on transient faults or when power is first
applied. This eliminates the possibility that the IC could
erroneously shut a system down.
The MAX6687/MAX6688 provide noise immunity by
integration and oversampling of the diode voltage, but
good design practice includes routing the DXP and
DXN lines away from noise sources, such as highspeed digital lines, switching regulators, inductors, and
transformers. The DXP and DXN traces should be
paired together and surrounded by a ground plane
whenever possible.
Local/Remote Temperature Switches in a
µMAX Package
4 _______________________________________________________________________________________
Pin Description
PIN
MAX6687 MAX6688
11VDDPower-Supply Input. Bypass to GND with a 0.1µF capacitor.
2 2 GND Ground
3 3 DXP
44DXN
5 — T
— 5T
6 — T
— 6T
77S1
88S2
NAME FUNCTION
This pin connects to the positive (anode) terminal of the external P-N sense junction. It sources
current into the external junction. A 2200pF capacitor should be connected across DXP and
DXN.
This pin connects to the negative (cathode) terminal of the external P-N sense junction. It sinks
current from the external junction. A 2200pF capacitor should be connected across DXP and
DXN. DXN must be connected to the GND pin at the pin.
Open-Drain Active-Low Output. T
REMOTE
REMOTE
LOCAL
LOCAL
programmed temperature threshold, either +120°C or +125°C. Connect a pullup resistor
(typically 10kΩ) between T
CMOS Push-Pull, Active-High Output. T
factory-programmed temperature threshold, either +120°C or +125°C.
Open-Drain Active-Low Output. T
programmable temperature threshold set by S1 and S2. Connect a pullup resistor (typically
10kΩ) between T
CMOS Push-Pull, Active-High Output. T
pin-programmable temperature threshold set by S1 and S2.
Threshold Select Input. Used in conjunction with S2 to set the local threshold temperature
(Table 1). It can be connected to V
Threshold Select Input. Used in conjunction with S1 to set the local threshold temperature
(Table 1). It can be connected to V
goes low when the temperature exceeds the factory-
REMOTE
and a positive power supply up to 5.5V.
REMOTE
goes high when the temperature exceeds the
REMOTE
goes low when the temperature exceeds the pin-
LOCAL
and a positive power supply up to 5.5V.
LOCAL
goes high when the temperature exceeds the
LOCAL
, GND, or left floating.
DD
, GND, or left floating.
DD
Applications Information
Remote-Diode selection
The MAX6687/MAX6688 are optimized to measure the
die temperature of CPUs and other ICs that have onchip temperature-sensing diodes. These on-chip
diodes are substrate PNPs with their collectors grounded. Connect the base of the PNP to DXN and the emitter to DXP. When using a discrete, diode-connected
NPN or PNP as a sensing diode, use a good-quality
small-signal device. Examples are listed in Table 2.
Tight specifications for forward current gain indicate
the manufacturer has good process controls and that
the devices have consistent VBEcharacteristics.
Always use a transistor for the sensing junction; diodes
do not work.
The MAX6687/MAX6688 are optimized for use with
thermal-sensing transistors with an ideality factor of
1.008. Different ideality factors cause predictable, usually small deviations in trip temperature thresholds.
Noise-Filtering Capacitors
A quality ceramic capacitor must be connected across
the DXP/DXN inputs to maintain temperature threshold
accuracy by filtering out noise. The capacitor should be
located physically close to the DXP/DXN pins and
should typically have a value of 2200pF. Larger capacitor values can cause temperature measurement errors.
A 50% increase from the recommended capacitor
value can cause up to ±1°C error.
Sensing Circuit Board and
Ambient Temperature
Temperature switches like the MAX6687/MAX6688 that
sense their own die (local) temperatures must be
mounted on or close to the object whose temperature
they are intended to measure. The MAX6687/MAX6688
can accurately measure the temperature of a circuit
board to which they are soldered because the package
leads provide a good thermal path between the circuit
board and their own die. If the MAX6687/MAX6688 are
intended to be triggered by the temperature of a heatgenerating component on the circuit board, they should
be mounted as close as possible to that component
and should share supply and ground traces (if they are
not noisy) with that component where possible. The
thermal path between the plastic package and the die
is not as good as the path through the package leads,
so the MAX6687/MAX6688 are less sensitive to the surrounding air temperature than they are to the temperature of their package leads, but they can be
successfully used to respond to the ambient temperature if the circuit board is designed to track the ambient
temperature.
Chip Information
TRANSISTOR COUNT: 7765
PROCESS: BiCMOS
MAX6687/MAX6688
Local/Remote Temperature Switches in a
µMAX Package
_______________________________________________________________________________________ 5
Table 1. Local Temperature Trip Threshold Selection
Table 2. Sensor Transistor Manufacturers
S1 S2
GND GND +40 +75
GND FLOAT +45 +80
GND V
FLOAT GND +55 +90
FLOAT FLOAT +60 +95
FLOAT V
V
DD
V
DD
V
DD
DD
DD
GND +70 +105
FLOAT +75 +110
V
DD
MAX6687AUA40L/MAX6687AUA40H/
MAX6688AUA40L/MAX6688AUA40H
LOCALTEMPERATURE TRIP THRESHOLD (°C) LOCAL TEMPERATURE TRIP THRESHOLD (°C)
+50 +85
+65 +100
+80 +115
MAX6687AUA75L/MAX6687AUA75H/
MAX6688AUA75L/MAX6688AUA75H
Central Semiconductor (USA) CMPT3904
Rohm Semiconductor (Japan) SST3904
Samsung (Korea) KST3904-TF
Siemens (Germany) SMBT3904
MANUFACTURER MODEL NO.
MAX6687/MAX6688
Local/Remote Temperature Switches in a
µMAX Package
6 _______________________________________________________________________________________
Pin Configurations
Selector Guide
Figure 1a. MAX6687 Functional Block Diagram
Figure 1b. MAX6688 Functional Block Diagram
Functional Block Diagrams
TOP VIEW
1
V
DD
2
MAX6687
DXP
3
4
DXN
µMAX
V
DD
T
REMOTE
+120°C OR +125°C
DXP
DXN
S1
S2
REMOTE
TEMPERATURE
CONVERTER
T
REMOTE
+40°C OR +115°C
MAX6687
LOCAL
TEMPERATURE
CONVERTER
GND
87S2
S1GND
6
T
LOCAL
5
T
REMOTE
T
REMOTE
N
T
LOCAL
N
V
DXP
DXN
DXP
DXN
1
DD
2
87S2
S1GND
MAX6688
3
4
6
T
LOCAL
5
T
REMOTE
µMAX
T
REMOTE
+120°C OR +125°C
REMOTE
TEMPERATURE
CONVERTER
S1
S2
T
REMOTE
+40°C OR +115°C
V
DD
LOCAL
TEMPERATURE
CONVERTER
GND
DIGITAL
DRIVER
MAX6688
DIGITAL
DRIVER
T
REMOTE
T
LOCAL
PART OUTPUTS
REMOTE TRIP THRESHOLD
LOCAL TRIP THRESHOLD RANGE
(°C)
MAX6687AU40L Open drain, active low +120 +40 to +80
MAX6687AU40H Open drain, active low +125 +40 to +80
MAX6687AU75L Open drain, active low +120 +75 to +115
MAX6687AU75H Open drain, active low +125 +75 to +115
MAX6688AU40L Push pull, active high +120 +40 to +80
MAX6688AU40H Push pull, active high +125 +40 to +80
MAX6688AU75L Push pull, active high +120 +75 to +115
MAX6688AU75H Push pull, active high +125 +75 to +115
(°C)
MAX6687/MAX6688
Local/Remote Temperature Switches in a
µMAX Package
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 _____________________ 7
© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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.)
0.6±0.1
0.6±0.1
8
b
E H
A1
A
ÿ 0.50±0.1
1
D
TOP VIEW
A2
e
FRONT VIEW
4X S
BOTTOM VIEW
c
L
SIDE VIEW
8
1
DIM
A
A1
A2
b
c
D
e
E
H
L
α
S
INCHES
MIN
-
0.002
0.030
0.010
0.005
0.116
0.0256 BSC
0.116
0.188
0.016
0∞
0.0207 BSC
0.043
0.006
0.037
0.014
0.007
0.120
0.120
0.198
0.026
MAX
6∞
MILLIMETERS
MIN
0.05 0.15
0.25 0.36
0.13 0.18
2.95 3.05
2.95 3.05
4.78
0.41
MAX
- 1.10
0.950.75
0.65 BSC
5.03
0.66
0.5250 BSC
8LUMAXD.EPS
6∞0∞
α
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
REV.DOCUMENT CONTROL NO.APPROVAL
21-0036
1
J
1
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