MAX6501, MAX6502
Ultra Small Temperature
Switch with Pin−Selectable
Hysteresis
The MAX6501 and MAX6502 are SOT-23 temperature switches
that require no external components and the design is facilitated with
factory- programmed temperature thresholds. A choice of
factory-trimmed temperature trip points are available. Pin selectable
hysteresis of +2°C or +10°C allows flexibility to the design. These
parts typically consume only 17
µA
of current and operate over the
entire -55°C to +125°C temperature range while offering accuracies
of
"0.5°C
(typ) and
"4°C
(max).
The MAX6501 has an open drain, active low output, meant for
microprocessor reset control. The MAX6502 has a CMOS, active high
output designed to drive a logic level MOSFET to turn on a fan or
heater element.
The MAX6501/6502 are aimed for hot-temperature monitoring
(+45°C to +115°C). These devices assert a logic signal when the
temperature goes above the threshold.
The MAX6501 and MAX6502 are offered in five standard
temperature thresholds. Available in 5-Pin SOT-23A packages, these
parts are ideal for applications requiring high integration, small size,
low power and low installed cost.
Features
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5
4
1
2
SOT-23A
CASE 1212
3
PIN CONNECTIONS
GND 1
GND 2
HYST 3
MAX6501
MAX6502
5 T
OVER
(T
OVER
)*
4 V
CC
*For MAX6502
Note: 5-Pin SOT-23A is equivalent to EIAJ SC-74A
•
5-Pin SOT-23A
•
Factory-Programmed Thresholds from +45°C to +115°C in 10°C
•
•
•
•
•
•
•
•
•
•
•
Increments
Pin-Selectable +2°C or +10°C Hysteresis
"0.5°C
(Typ) Threshold Accuracy Over Full Temperature Range
No External Components Required
17
µA
Supply Current
Thermal Management in PCs and Servers
Over Temperature Fail Safe Circuits
Simple Fan Controller
Temperature Alarms
Projectors/Printers
Notebook Computers
Network Boxes
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 9 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 9 of this data sheet.
Typical Applications
©
Semiconductor Components Industries, LLC, 2003
1
February, 2003 - Rev. 2
Publication Order Number:
MAX6501/D
MAX6501, MAX6502
MAXIMUM RATINGS*
Rating
Supply Voltage
TOVER (MAX6501)
TOVER (MAX6502)
All Other Pins
Input Current (All Pins)
Output Current (All Pins)
Operating Temperature Range
Storage Temperature Range
Lead Temperature (Soldering, 10 seconds)
Power Dissipation (T
A
= +70°C)
(Derate 7.1 mW/°C Above +70°C)
Symbol
V
CC
-
-
-
-
Value
-0.3 to +7.0
-0.3 to +7.0
-0.3 to (V
CC
+0.3)
-0.3 to (V
CC
+0.3)
20
20
-55 to +125
-65 to +165
+300
571
Unit
V
V
V
V
mA
mA
°C
°C
°C
mW
-
-
T
stg
-
-
*Static-sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses
above 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 above 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
= +2.7 V to +5.5 V, R
PULL- UP
= 100 KΩ (MAX6501 only), C
COUPLING
= 100 pF from V
CC
to GND, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.
Characteristics
Supply Voltage Range
Supply Current
Temperature Threshold Accuracy
(Note 1)
Temperature Threshold Hysteresis
HYST Input Threshold
HYST Input Threshold
Output Voltage High
Test Conditions
-
-
+45°C to +65°C
+75°C to +115°C
HYST = GND
HYST = V
CC
-
-
I
SOURCE
= 500
µA,
V
CC
u
2.7 V
(MAX6502 Only)
I
SOURCE
= 800
µA,
V
CC
u
4.5 V
(MAX6502 Only)
I
SINK
= 1.2 mA, V
CC
u
2.7 V
I
SINK
= 3.2 mA, V
CC
u
4.5 V
V
CC
= 2.7 V, V
TOVER
= 5.5 V
(MAX6501 Only)
Symbol
V
CC
I
CC
∆T
TH
T
HYST
V
IH
V
IL
V
OH
Min
2.7
-
-4.0
-6.0
-
-
0.8 x V
CC
-
0.8 x V
CC
V
CC
-1.5
V
OL
-
Typ
-
17
"0.5
"0.5
2.0
10
-
-
-
-
-
-
10
Max
5.5
40
4.0
6.0
-
-
-
0.2 x V
CC
-
-
0.3
0.4
-
Unit
V
µA
°C
°C
V
V
V
Output Voltage Low
Open-Drain Output Leakage Current
-
-
-
V
nA
1. The MAX6501 and MAX6502 are available with internal, factory-programmed temperature trip thresholds from +45°C to +115°C in +10°C
increments.
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2
MAX6501, MAX6502
PIN DESCRIPTION
MAX6501
1,2
3
4
5
MAX6502
1,2
3
4
-
Name
GND
HYST
V
CC
TOVER
Description
Ground. Ground both pins together close to the chip. Pin 2 provides the lowest thermal
resistance to the die.
Hysteresis Input. Connect HYST to GND for +2°C hysteresis, or connect to V
CC
for +10°C
hysteresis.
Supply Input (+2.7 V to +5.5 V). Recommend 100 pF or greater Coupling capacitor from V
CC
to GND.
Open-Drain, Active-Low Output. TOVER goes low when the die temperature exceeds the
factory-programmed temperature threshold. Connect to a 100 KΩ pull-up resistor. May be
pulled up to a voltage higher than V
CC
.
Push/Pull Active-High Output. TOVER goes high when the die temperature exceeds the
factory-programmed temperature threshold.
-
5
TOVER
Typical Operating Circuit
+2.7 V to +5.5 V
The MAX6501 is intended for applications with a
microprocessor reset input. The MAX6502 is intended for
applications of turning on a fan or heater element.
Hysteresis Input
100 pF
V
CC
V
CC
µP
INT
GND
MAX6502
TOVER
GND GND HYST
To prevent the output from “chattering’’ at or near the trip
point temperature, a selectable HYST input pin is provided.
Hysteresis can be externally selected at 2°C (HYST = GND)
or 10°C (HYST = V
DD
) by means of the CMOS compatible
HYST input pin. Do not let the HYST pin float as this could
cause increase supply current. The hysteresis does not
depend on the part’s programmed trip threshold.
Table 1. Factory-Programmed Threshold Range
Part Number
MAX6501
MAX6502
Threshold (T
TH
) Range
+45°C
t
T
TH
t
+115°C
+45°C
t
T
TH
t
+115°C
Thermal Considerations
DETAILED DESCRIPTION
The MAX6501 and MAX6502 integrate a temperature
sensor with a factory- programmed threshold switch. A logic
signal is asserted when the die temperature crosses the factory
programmed threshold. An external hysteresis input pin
allows the user to select either 2°C or 10°C hysteresis to give
further flexibility to the design of the application. The
MAX6501 and MAX6502 are intended for a temperature
range from 45°C to 115°C in a 10°C increment. The
MAX6501 has an open drain output and the MAX6502 has
a push/pull output stage.
With a very low 17
µA
supply current, the MAX6501 and
MAX6502 dissipates very little power. Thus, the die
temperature is basically the same as the package
temperature. To minimize the error in temperature readings,
the load current should be limited to a few milliamps. As an
example, the typical thermal resistance of a 5-Pin SOT-23A
package is 140°C/W. If the MAX6501 had to sink 1.0 mA,
and the output voltage is guaranteed to be less than 0.3 V,
then an additional 0.3 mW of power is dissipated within the
IC. This corresponds to a 0.042°C rise in die temperature in
the 5-Pin SOT-23A.
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MAX6501, MAX6502
Temperature monitoring accuracy depends on the
thermal resistance between the device being monitored and
the temperature switch die. Heat flows primarily through
the leads onto the die. Pin 2 provides the lowest thermal
resistance to the die. To achieve the best temperature
monitoring results, the MAX6501 and MAX6502 should
be placed closest to the device being monitored. In
addition, a short and wide copper trace from Pin 2 to the
device should be used. In some cases, the 5- Pin SOT- 23A
package can be placed directly under the socketed
microprocessor for improved thermal contact.
APPLICATIONS
The MAX6501 has an open drain output and is therefore
intended to interface as a microprocessor reset input.
Moreover, the combination of these two devices can be used
to implement a temperature window alarm by wire- ORing the
outputs and using an external pull up resistor. (See Figure 1)
+5 V
R
PULL- UP
100 k
100 pF
V
CC
Temperature Out of Range
100 pF
V
CC
MAX6501UKP115-T
MAX6501UKP055-T
GND GND HYST
GND GND HYST
Figure 1. Over and Under Temperature Alarm
The MAX6502 can be used to control a DC fan. The fan
turns on when the sensed temperature rises above the factory
set threshold and remains on until the temperature falls
below threshold minus the hysteresis selected. An additional
fail safe measure could be designed by using a second
MAX6502 with a higher temperature threshold to alert the
user of an impending thermal shutdown, should the
temperature continue to rise. (See Figure 2)
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MAX6501, MAX6502
+5 V
V
CC
100 pF
HEAT
MAX6502UKP095-T
GND
GND
TOVER
HYST
TEMPERATURE
FAULT
µP
FAN
CONTROL
HEAT
100 pF
V
CC
HYST
MAX6502UKP055-T
TOVER
GND GND
Figure 2. Fan Control Circuit with Over Temperature Alert
TOVER
+
−
Positive
Tempco
Reference
Negative
Tempco
Reference
HYST
Network
MAX6501
COLD
+
TOVER
−
Positive
Tempco
Reference
Negative
Tempco
Reference
HYST
Network
MAX6502
TEMP
COLD
+25°C
T
TH
HOT
V
TOVER
MAX6502
+25°C
T
TH
HOT
V
TOVER
MAX6501
With 100 kΩ Pull-Up
HYST
TEMP
HYST
Figure 3. Functional Block Diagrams
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