________________General Description
The MAX6501–MAX6504 low-cost, fully integrated tem-
perature switches assert a logic signal when their die
temperature crosses a factory-programmed threshold.
Operating from a +2.7V to +5.5V supply, these devices
feature two on-chip, temperature-dependent voltage
references and a comparator. They are available with
factory-trimmed temperature trip thresholds from -45°C
to +115°C in 10°C increments, and are accurate to
±0.5°C (typ) or ±6°C (max). These devices require no
external components and typically consume 30µA sup-
ply current. Hysteresis is pin-selectable at +2°C or
+10°C.
The MAX6501/MAX6503 have an active-low, open-drain
output intended to interface with a microprocessor (µP)
reset input. The MAX6502/MAX6504 have an active-
high, push-pull output intended to directly drive fan-
control logic. The MAX6501/MAX6502 are offered with
hot-temperature thresholds (+35°C to +115°C), assert-
ing when the temperature is above the threshold. The
MAX6503/MAX6504 are offered with cold-temperature
thresholds (-45°C to +15°C), asserting when the tem-
perature is below the threshold.
The MAX6501–MAX6504 are offered in eight standard
temperature versions; contact the factory for pricing
and availability of nonstandard temperature versions.
They are available in 5-pin SOT23 and 7-pin TO-220
packages.
____________________________Features
o ±0.5°C (typical) Threshold Accuracy Over
Full Temperature Range
o No External Components Required
o Low Cost
o 30µA Supply Current
o Factory-Programmed Thresholds from
-45°C to +115°C in 10°C Increments
o Open-Drain Output (MAX6501/MAX6503)
Push-Pull Output (MAX6502/MAX6504)
o Pin-Selectable +2°C or +10°C Hysteresis
o SOT23-5 and TO220-7 Packages
MAX6501–MAX6504
†
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
________________________________________________________________ Maxim Integrated Products
1
19-1280; Rev 2; 11/99
Ordering Information
*These parts are offered in eight standard temperature versions
with a minimum order of 2,500 pieces. To complete the suffix
information, add P or N for positive or negative trip temperature,
and select an available trip point in degrees centigrade. For
example, the MAX6501UKP065-T describes a MAX6501 in a
SOT23-5 package with a +65°C threshold. Contact the factory for
pricing and availability of nonstandard temperature versions (mini-
mum order 10,000 pieces).
________________________Applications
µP Temperature Monitoring in High-Speed
Computers
Temperature Control
Temperature Alarms
Fan Control
Selector Guide and Pin Configurations appear at end of
data sheet.
PART*
MAX6501UK_ _ _ _-T
-55°C to +125°C
TEMP. RANGE
PIN-PACKAGE
5 SOT23-5
MAX6503UK_ _ _ _-T
-55°C to +125°C
5 SOT23-5
MAX6504UK_ _ _ _-T
-55°C to +125°C
5 SOT23-5
MAX6502UK_ _ _ _-T
-55°C to +125°C
5 SOT23-5
†
Patents Pending
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX6501CM_ _ _ _-T
-55°C to +125°C
7 TO-220-7
MAX6502CM_ _ _ _-T
-55°C to +125°C
7 TO-220-7
MAX6503CM_ _ _ _-T
-55°C to +125°C
7 TO-220-7
MAX6504CM_ _ _ _-T
-55°C to +125°C
7 TO-220-7
MAX6502
+2.7V TO +5.5V
GND
HYST
TOVER
µP
INT
GND
GND
V
CC
V
CC
Typical Operating Circuit
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
2
_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= +2.7V to +5.5V, R
PULL-UP
= 100k
Ω (MAX6501/MAX6503 only), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are
at T
A
= +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.
Note 1: 100% production tested at T
A
= +25°C. Specifications over temperature limits are guaranteed by design.
Note 2: The MAX6501–MAX6504 are available with internal, factory-programmed temperature trip thresholds from -45°C to +115°C
in +10°C increments (see Selector Guide).
Note 3: Guaranteed by design.
Supply Voltage (V
CC
) ...............................................-0.3V to +7V
TOVER (MAX6501) ...................................................-0.3V to +7V
TOVER (MAX6502) .....................................-0.3V to (V
CC
+ 0.3V)
TUNDER (MAX6503) ................................................-0.3V to +7V
TUNDER (MAX6504) ..................................-0.3V to (V
CC
+ 0.3V)
All Other Pins..............................................-0.3V to (V
CC
+ 0.3V)
Input Current (all pins) ........................................................20mA
Output Current (all pins) .....................................................20mA
Continuous Power Dissipation (T
A
= +70°C)
5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) .........571mW
Operating Temperature Range .........................-55°C to +125°C
Storage Temperature Range .............................-65°C to +165°C
Lead Temperature (soldering, 10sec) .............................+300°C
-45°C to -25°C
V
CC
= 2.7V, V
TUNDER
= 5.5V (MAX6503),
V
TOVER
= 5.5V (MAX6501)
-15°C to +15°C
HYST = GND
I
SOURCE
= 500µA, V
CC
> 2.7V
(MAX6502/MAX6504 only)
I
SINK
= 1.2mA, V
CC
> 2.7V
CONDITIONS
-6
±0.5
6
µA
30
85
I
CC
V
2.7
5.5
V
CC
Supply Voltage Range
Supply Current
nA
10
Open-Drain Output Leakage
Current
-4
±0.5
4
2
T
HYST
Temperature Threshold
Hysteresis
V
0.8 x V
CC
0.3
UNITS
MIN
TYP
MAX
SYMBOL
PARAMETER
+35°C to +65°C
+75°C to +115°C
-4
±0.5
4
°C
-6
±0.5
6
∆T
TH
Temperature Threshold
Accuracy (Note 2)
V
0.2 x V
CC
V
IL
HYST Input Threshold
(Note 3)
0.8 x V
CC
V
IH
I
SINK
= 3.2mA, V
CC
> 4.5V
V
0.4
V
OL
Output Voltage Low
HYST = V
CC
10
°C
I
SOURCE
= 800µA, V
CC
> 4.5V
(MAX6502/MAX6504 only)
V
CC
- 1.5
V
OH
Output Voltage High
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
_______________________________________________________________________________________
3
0
5
10
15
20
25
30
35
40
-55
5
-25
35
65
95
125
SUPPLY CURRENT
vs. TEMPERATURE
MAX6501 TOC01
TEMPERATURE (°C)
SUPPLY CURRENT (
µ
A)
0
100
200
300
400
500
600
700
800
-55
5
-25
35
65
95
125
MAX6502/MAX6504
OUTPUT SOURCE RESISTANCE
vs. TEMPERATURE
MAX6501 TOC02
TEMPERATURE (°C)
OUTPUT SOURCE RESISTANCE (
Ω
)
V
CC
= 2.7V
V
CC
= 5.0V
V
CC
= 3.3V
0
20
40
60
80
100
120
140
160
-55
5
-25
35
65
95
125
OUTPUT SINK RESISTANCE
vs. TEMPERATURE
MAX6501 TOC03
TEMPERATURE (°C)
OUTPUT SINK RESISTANCE (
Ω
)
V
CC
= 2.7V
V
CC
= 5.0V
V
CC
= 3.3V
+15°C/div
+100°C
+25°C
SOT23 THERMAL STEP RESPONSE
IN PERFLUORINATED FLUID
MAX6501 TOC4
5sec/div
MOUNTED ON 0.75in
2
OF 2 oz. COPPER
0
4
2
8
6
10
12
14
16
-5
15
-25
-45
35
55
75
95
115
HYSTERESIS
vs. TRIP TEMPERATURE
MAX6501 TOC8
TRIP TEMPERATURE (°C)
HYSTERESIS (
°C)
MAX6503
MAX6504
HYST = V
CC
MAX6501
MAX6502
HYST = V
CC
MAX6501
MAX6502
HYST = GND
MAX6503
MAX6504
HYST = GND
+12.5°C/div
+100°C
+25°C
SOT23 THERMAL STEP RESPONSE
IN STILL AIR
MAX6501 TOC5
20sec/div
MOUNTED ON 0.75in
2
OF 2 oz. COPPER
TRACE A: TOVER VOLTAGE, R
PULL-UP
= 100k
Ω
TRACE B: V
CC
PULSE DRIVEN FROM 3.3V CMOS LOGIC OUTPUT
MAX6501 START-UP AND POWER-DOWN
(T
< T
TH
)
B
A
MAX6501 TOC07
TRACE A: TOVER VOLTAGE, R
PULL-UP
= 100k
Ω
TRACE B: V
CC
PULSE DRIVEN FROM 3.3V CMOS LOGIC OUTPUT
MAX6501 START-UP DELAY
(T
> T
TH
)
B
A
MAX6501 TOC07A
__________________________________________Typical Operating Characteristics
(V
CC
= +5V, R
PULL-UP
= 100k
Ω (MAX6501/MAX6503), T
A
= +25°C, unless otherwise noted.)
0
10
20
30
40
50
60
-5
-4
-3
-2
-1
0
1
2
3
4
5
TRIP THRESHOLD ACCURACY
MAX6501 TOC-A
ACCURACY (°C)
PERCENTAGE OF PARTS SAMPLED (%)
SAMPLE SIZE = 300
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
4
_______________________________________________________________________________________
Pin Description
1, 2
1, 2
Ground. Not internally connected. Tie both ground pins togeth-
er close to the chip. Pin 2 provides the lowest thermal resis-
tance to the die.
1, 2
PIN
1, 2
GND
3
3
Hysteresis Input. Connect HYST to GND for +2°C hysteresis, or
connect to V
CC
for +10°C hysteresis.
3
3
HYST
4
4
Supply Input (+2.7V to +5.5V)
5
—
Open-Drain, Active-Low Output. TOVER goes low when the die
temperature exceeds the factory-programmed temperature
threshold. Connect to a 100k
Ω pull-up resistor. May be pulled
up to a voltage higher than V
CC
.
—
—
TOVER
4
4
V
CC
—
5
Push-Pull Active-High Output. TOVER goes high when the die tem-
perature exceeds the factory-programmed temperature threshold.
—
—
Open-Drain, Active-Low Output. TUNDER goes low when the
die temperature goes below the factory-programmed tempera-
ture threshold. Connect to a 100k
Ω pull-up resistor. May be
pulled up to a voltage higher than V
CC
.
5
—
TUNDER
—
—
Push-Pull Active-High Output. TUNDER goes high when the die tem-
perature falls below the factory-programmed temperature threshold.
—
5
TUNDER
—
—
TOVER
MAX6502
MAX6501
MAX6503
MAX6504
NAME
FUNCTION
________________General Description
The MAX6501–MAX6504 fully integrated temperature
switches incorporate two temperature-dependent refer-
ences and a comparator. One reference exhibits a pos-
itive temperature coefficient and the other a negative
temperature coefficient (Figure 1). The temperature at
which the two reference voltages are equal determines
the temperature trip point. Pin-selectable +2°C or
+10°C hysteresis keeps the output from oscillating
when the die temperature approaches the threshold
temperature. The MAX6501/MAX6503 have an active-
low, open-drain output structure that can only sink cur-
rent. The MAX6502/MAX6504 have an active-high,
push-pull output structure that can sink or source cur-
rent. The internal power-on reset circuit guarantees the
output is at T
TH
= +25°C state at start-up for 50µs.
The MAX6501–MAX6504 are available with factory-
preset temperature thresholds from -45°C to +115°C in
10°C increments. Table 1 lists the available temperature
threshold ranges. The MAX6501/MAX6503 outputs are
intended to interface with a microprocessor (µP) reset
input (Figure 2). The MAX6502/MAX6504 outputs are
intended for applications such as driving a fan control
(Figure 3).
Hysteresis Input
The HYST pin is a CMOS-compatible input that selects
hysteresis at either a high level (+10°C for HYST = V
CC
)
or a low level (+2°C for HYST = GND). Hysteresis pre-
vents the output from oscillating when the temperature
approaches the trip point. The HYST pin should not
float. Drive HYST close to ground or V
CC
. Other input
voltages cause increased supply current. The actual
amount of hysteresis depends on the part’s pro-
grammed trip threshold. (See the Typical Operating
Characteristics graphs.)
Table 1. Factory-Programmed Threshold
Range
+35°C < T
TH
< +115°C
+35°C < T
TH
< +115°C
THRESHOLD (T
TH
) RANGE
-45°C < T
TH
< +15°C
-45°C < T
TH
< +15°C
MAX6503
MAX6504
MAX6501
MAX6502
PART
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
_______________________________________________________________________________________
5
POSITIVE
TEMPCO
REFERENCE
NEGATIVE
TEMPCO
REFERENCE
HYST
NETWORK
TOVER
HYST
TOVER
TEMP
COLD
+25°C
T
TH
V
MAX6501
POSITIVE
TEMPCO
REFERENCE
NEGATIVE
TEMPCO
REFERENCE
HYST
NETWORK
TOVER
HYST
TOVER
TEMP
COLD
+25°C
T
TH
HOT
HOT
V
POSITIVE
TEMPCO
REFERENCE
NEGATIVE
TEMPCO
REFERENCE
HYST
NETWORK
TUNDER
HYST
TUNDER
TEMP
COLD
T
TH
+25°C
HOT
V
POSITIVE
TEMPCO
REFERENCE
NEGATIVE
TEMPCO
REFERENCE
HYST
NETWORK
TUNDER
HYST
TUNDER
TEMP
COLD
T
TH
+25°C
HOT
V
MAX6502
MAX6503
MAX6504
MAX6501
WITH 100k
Ω PULL-UP
MAX6504
MAX6503
WITH 100k
Ω PULL-UP
MAX6502
Figure 1. Block and Functional Diagrams
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
6
_______________________________________________________________________________________
Applications Information
Thermal Considerations
The MAX6501–MAX6504 supply current is typically
30µA. 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 monitor-
ing is good thermal contact between the MAX6501–
MAX6504 package and the device being monitored. In
some applications, the SOT23-5 package may be small
enough to fit underneath a socketed µP, allowing the
device to monitor the µP’s temperature directly. The
TO-220 package can monitor the temperature of a heat
sink directly, and presents the lower thermal resistance
of the two packages. Use the monitor’s output to reset
the µP, assert an interrupt, or trigger an external alarm.
Accurate temperature monitoring depends on the thermal
resistance between the device being monitored and the
MAX6501–MAX6504 die. Heat flows in and out of plastic
packages, primarily through the leads. Pin 2 of the
SOT23-5 package provides the lowest thermal resistance
to the die. Short, wide copper traces leading to the tem-
perature 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
DISSIPATION
x
θ
JA
where P
DISSIPATION
is the power dissipated by the
MAX6501–MAX6504, and
θ
JA
is the package’s thermal
resistance.
The typical thermal resistance is 140°C/W for the
SOT23-5 package and 75°C/W for the TO-220 pack-
age. To limit the effects of self-heating, minimize the
output currents. For example, if the MAX6501 or
MAX6503 sink 1mA, the output voltage is guaranteed to
be less than 0.3V. Therefore, an additional 0.3mW of
power is dissipated within the IC. This corresponds to a
0.042°C shift in the die temperature in the SOT23-5.
Temperature-Window Alarm
The MAX6501–MAX6504 temperature switch outputs
assert when the die temperature is outside the factory-
programmed range. Combining the outputs of two
devices creates an over/undertemperature alarm. The
MAX6501/MAX6503 and the MAX6502/MAX6504 are
designed to form two complementary pairs, each con-
taining one cold trip-point output and one hot trip-point
output. The assertion of either output alerts the system to
an out-of-range temperature. The MAX6502/MAX6504
push/pull output stages can be ORed to produce a ther-
mal out-of-range alarm. More favorably, a MAX6501/
MAX6503 can be directly wire-ORed with a single exter-
nal resistor to accomplish the same task (Figure 4).
The temperature window alarms shown in Figure 4 can
be used to accurately determine when a device’s tem-
perature falls out of the -5°C to +75°C range. The ther-
mal-overrange signal can be used to assert a thermal
shutdown, power-up, recalibration, or other temperature-
dependent function.
Low-Cost, Fail-Safe
Temperature Monitor
In high-performance/high-reliability applications, multiple
temperature monitoring is important. The high-level
integration and low cost of the MAX6501–MAX6504
facilitate the use of multiple temperature monitors to in-
crease system reliability. Figure 5’s application uses two
MAX6502s with different temperature thresholds to ensure
that fault conditions that can overheat the monitored
device cause no permanent damage. The first tempera-
ture monitor activates the fan when the die temperature
exceeds +45°C. The second MAX6502 triggers a system
shutdown if the die temperature reaches +75°C. The
second temperature monitor’s output asserts when a
wide variety of destructive fault conditions occur, includ-
ing latchups, short circuits, and cooling-system failures.
MAX6502
+5V
TOVER
GND
GND
V
CC
HYST
µP
FAN
HEAT
V
CC
Figure 3. Overtemperature Fan Control
MAX6501
+3.3V
GND
HYST
GND
V
CC
µP
HEAT
V
CC
R
PULL-UP
100k
TOVER
INT
SHUTDOWN
OR
RESET
Figure 2. Microprocessor Alarm/Reset
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
_______________________________________________________________________________________
7
MAX6503_ _N005
MAX6501_ _P075
+5V
HYST
HYST
GND
GND
V
CC
GND
GND
V
CC
R
PULL-UP
100k
TOVER
TUNDER
OUT OF RANGE
MAX6502_ _P075
HYST
GND
GND
+5V
MAX6504_ _N005
GND
GND
HYST
V
CC
V
CC
TOVER
TUNDER
OUT OF RANGE
OVERTEMP
UNDERTEMP
Figure 4. Temperature-Window Alarms
MAX6502_ _P075
GND
GND
HYST
+5V
MAX6502_ _P045
GND
GND
HYST
V
CC
V
CC
TOVER
TOVER
TEMPERATURE
FAULT
FAN
CONTROL
µP
HEAT
HEAT
Figure 5. Low-Power, High-Reliability, Fail-Safe Temperature
Monitor
Table 2. Device Marking Codes for SOT23-5 Package
MAX6502UKP115
2.5k
ACFY
MAX6502UKP105
10k
ACFZ
MAX6504UKP015
10k
ADKE
MAX6504UKP005
2.5k
ABZY
MAX6504UKN005
10k
ACAT
MAX6504UKN015
2.5k
ACGD
MAX6504UKN025
10k
ACAV
MAX6504UKN035
10k
ACAW
MAX6504UKN045
10k
ACAX
DEVICE
MINIMUM
ORDER
CODE
MAX6503UKP015
10k
ACAM
MAX6503UKP005
2.5k
ABZX
MAX6503UKN005
10k
ACAN
MAX6503UKN015
2.5k
ACFX
MAX6503UKN025
10k
ACAP
MAX6503UKN035
10k
ACAQ
MAX6503UKN045
10k
ADIZ
MAX6502UKP095
2.5k
ABZW
MAX6502UKP085
2.5k
ACGA
MAX6502UKP075
2.5k
ACGB
MAX6502UKP065
2.5k
ABZV
MAX6502UKP055
2.5k
ACGC
MAX6502UKP045
2.5k
ABZU
MAX6502UKP035
10k
ABZG
MAX6501UKP115
2.5k
ACAG
MAX6501UKP105
10k
ACFU
MAX6501UKP095
2.5k
ABZT
MAX6501UKP085
2.5k
ACDP
MAX6501UKP075
2.5k
ACFV
MAX6501UKP065
2.5k
ABZS
MAX6501UKP055
2.5k
ACFW
MAX6501UKP045
2.5k
ABZR
MAX6501UKP035
10k
ABZF
DEVICE
MINIMUM
ORDER
CODE
MAX6501–MAX6504
Low-Cost, +2.7V to +5.5V, Micropower
Temperature Switches in SOT23 and TO-220
GND
V
CC
HYST
( ) ARE FOR MAX6502.
1
5 TOVER
(TOVER)
GND
MAX6501
MAX6502
SOT23-5
TOP VIEW
2
3
4
GND
V
CC
HYST
( ) ARE FOR MAX6504.
1
5 TUNDER
(TUNDER)
GND
MAX6503
MAX6504
SOT23-5
2
3
4
GND TOVER
(TOVER)
HYST
GND
MAX6501
MAX6502
TO-220-7
GND
V
CC
HYST
GND
MAX6503
MAX6504
TO-220-7
TUNDER
(TUNDER)
1 2 3 4 5 6 7
1 2 3 4 5 6 7
V
CC
Pin Configurations
Chip Information
TRANSISTOR COUNT: 237
SUBSTRATE CONNECTED TO GND
PART
MAX6501 MAX6502 MAX6503 MAX6504
OUTPUT
STAGE
Open-
Drain
Push-Pull
Open-
Drain
Push-Pull
TRIP TEMP
THRESHOLD
Hot
Hot
Cold
Cold
STANDARD TEMPERATURE THRESHOLDS (
°C)
Selector Guide
-45
-35
-25
-15
-5
+5
+15
+35
+45
+55
+65
+75
+85
+95
+105
+115
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.