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July 2007
LM27A
±3°C Accurate, 120°C-150°C Factory Preset Thermostat
(LM27 in Die Form)
General Description
This datasheet applies to the LM27A, which is the die form of
the LM27. The LM27 is available in the SOT23-5 package.
Please refer to the LM27 datasheet for detailed specifications
pertaining to the packaged part.
The LM27A is a precision, single digital-output, low-power
thermostat comprised of an internal reference, DAC, temper-
ature sensor and comparator. Utilizing factory programming,
it can be manufactured with different trip points as well as
different digital output functionality. The trip point (TOS) can
be preset at the factory to any temperature in the range of
+120°C to +150°C in 1°C increments. The LM27A has two
digital output pads, one digital input (HYST) and one analog
output (VTEMP). One digitial output is an active-high, push-pull
output and the other is an active-low, open-drain output. Ei-
ther of the outputs (but not both) are available.
The LM27A is available in either an overtemperature shut-
down or an undertemperature shutdown option. An LM27A
with overtemperature shutdown is configured so that its ther-
mostat outputs (OS and OS) will go active when a rising
temperature crosses the trip point and the hysteresis will ap-
ply to a falling temperature. The thermostat outputs of an
LM27A with an undertemperature shutdown (US and US) will
trip on a falling temperature and hysteresis will apply on a
rising temperature. For example, when the LM27A is preset
as an overtemperature shutdown, the active-high output (OS)
will go HIGH and the active-low output (OS) will go LOW to
indicate that the die temperature is over the internally preset
TOS . The outputs will reset to their normal states when the
temperature goes below (TOS–THYST). Similarly, when pre-
programmed as an undertemperature shutdown the active-
high output (US) will go HIGH and the active-low output
(US) will go LOW to indicate that the temperature is below
TUS . The outputs will reset when the temperature is above
(TUS+THYST). The typical hysteresis, THYST, can be set to 2°C
or 10°C and is controlled by the state of the HYST pin. The
VTEMP analog output provides a voltage that is proportional to
temperature and has a −10.7mV/°C output slope.
Standard parts are available, see ordering information for de-
tails. For other part options, contact a National Semiconductor
Distributor or Sales Representative for information on mini-
mum-order qualification.
Applications
Microprocessor Thermal Management
Appliances
Portable Battery Powered Systems
Fan Control
Industrial Process Control
HVAC Systems
Electronic System Protection
Features
Internal comparator with pin selectable 2°C or 10°C
hysteresis
No external components required
Open-drain or push-pull digital output; supports CMOS
logic levels
Internal temperature sensor with VTEMP output pin
VTEMP output allows after-assembly system testing
Internal voltage reference and DAC for trip-point setting
Excellent power supply noise rejection
AEC-Q100 Qualified
Key Specifications
■ Power Supply Voltage
■ Power Supply Current
■ Hysteresis Temperature
■ Temperature Trip Point Accuracy
2.7V to 5.5V
40µA(max)
15µA(typ)
2°C or 10°C(typ)
±3°C (max)
© 2007 National Semiconductor Corporation 201530
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Ordering Information
For more detailed information on the suffix meaning see the part number template at the end of the Electrical Characteristics
Section. Contact National Semiconductor for other set points and output options.
Order Number
NS Package Number
Trip Point Setting
Output Function
Transport Media
LM27-2PL MDA
Die form, no package
145°C
Push-Pull (OS)
Open-Drain (OS)
400 units in waffle
trays
Connection Diagram
LM27A
Bond Pad Layout
TOP VIEW
1130µm x 902µm
Bond Pad Mechanical Dimensions
Dimensions of bond pad coordinates are in micrometers.
Origin of coordinates: center of die.
X-Direction is in the longitudinal axis of the die.
Coordinates refer to center of Bond Pad.
Opening sizes for bond pads 1 through 6 are 85 µm × 85 µm.
Pin#
1
2
3
4
5
6
BACK
X
–437 µm
–437 µm
–437 µm
+437 µm
+437 µm
+437 µm
20153002
Y
+225 µm
0
–220 µm
–220 µm
+5 µm
+225 µm
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Pin Descriptions
Pin Number
1
2
(Note 8)
3
(Note 8)
4
5
6
7 - 14
BACK
Pin Name
HYST
OS
US
OS
US
V+
GND
VTEMP
NC
Backside
Function
Connection
Hysteresis control, digital input
GND for 10°C or V+ for 2°C
Overtemperature Shutdown push-
pull active-high thermostat digital
output
Controller interrupt, system or power supply shutdown
Undertemperature Shutdown push-
pull active-high thermostat digital
output
System or power supply shutdown
Overtemperature Shutdown open-
drain active-low thermostat digital
output
Controller interrupt, system or power supply shutdown;
pull-up resistor 10kΩ
Undertemperature Shutdown open-
drain active low thermostat digital
output
System or power supply shutdown; pull-up resistor
10kΩ
Supply input
2.7V to 5.5V with a 0.1µF bypass capacitor. For PSRR
information see Section Titled NOISE
CONSIDERATIONS.
Power supply ground
System ground
Analog output voltage proportional to Leave floating or connect to a high impedance node.
temperature
Do not connect
Can go to GND connection (Note: GND must be
connected. The back is not a system ground connection).
Note: Only connect to one of the output pads, Pad 2 or Pad 3, not both. Either push-pull (Pad 2) or open-drain (Pad 3) can be used
but they can not both be used on the same die.
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Absolute Maximum Ratings (Note 1)
Input Voltage
Input Current at any pin (Note 2)
Package Input Current(Note 2)
Storage Temperature
ESD Susceptibility (Note 3)
Human Body Model
Machine Model
6.0V
5mA
20mA
−65°C to + 175°C
2500V
250V
Operating Ratings (Note 1)
Specified Temperature Range
LM27A
Positive Supply Voltage (V+)
Maximum VOUT
TMIN TA TMAX
−40°C TA +150°C
+2.7V to +5.5V
+5.5V
LM27A Electrical Characteristics
The following specifications apply for V+ = 2.7VDC to 5.5VDC, and VTEMP load current = 0µA unless otherwise specified. Boldface
limits apply for TA = TJ = TMIN to TMAX; all other limits TA = TJ = 25°C unless otherwise specified.
Typical
LM27A
Units
Symbol
Parameter
Conditions
(Note 4)
Limits
(Limits)
(Note 5)
Temperature Sensor
Trip Point Accuracy (Includes VREF, DAC, +120°C<TA<+150°C
Comparator Offset, and Temperature
Sensitivity errors)
±3 °C (max)
Trip Point Hysteresis
HYST = GND
10
°C
HYST = V+
2
°C
VTEMP Output Temperature Sensitivity
VTEMP Temperature Sensitivity Error to
Equation:
VO = (−3.552×10−6×(T−30)2+
(−10.695×10−3×(T−30))+
1.8386V
VTEMP Load Regulation
−30°C TA 150°C,
2.7V V+ 5.5V
−55°C TA 150°C,
4.5V V+ 5.5V
TA = 25°C
Source 1 μA
Sink 40 μA
−10.82
0.070
±3
±3
±2.5
0.7
mV/°C
°C (max)
°C (max)
°C (max)
mV
mV (max)
VTEMP Line Regulation
IS Supply Current
+2.7V V+ +5.5V,
−0.2
mV/V
−30°C TA +120°C
15 22 µA (max)
40 µA (max)
Digital Output and Input
IOUT(“1”)
Logical “1” Output Leakage Current (Note V+ = +5.0V
7)
0.001
1
µA (max)
VOUT(“0”) Logical “0” Output Voltage
IOUT = +1.2mA and
V+2.7V; IOUT = +3.2mA
and V+4.5V; (Note 6)
0.4 V (max)
VOUT(“1”) Logical “1” Push-Pull Output Voltage
VIH HYST Input Logical ”1“ Threshold
Voltage
ISOURCE = 500µA, V+ 2.7V
ISOURCE = 800µA, V+4.5V
0.8 × V+
V+ − 1.5
0.8 × V+
V (min)
V (min)
V (min)
VIL HYST Input Logical ”0“ Threshold
Voltage
0.2 × V+
V (max)
tEN tENABLE: Time from Power-On to Digital VDD = 3.3V ±5%
Output (OS or OS) Enabled
350 µs (min)
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Definition of tENABLE
20153024
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed
specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test
conditions.
Note 2: When the input voltage (VI) at any pin exceeds the power supply (VI < GND or VI > V+), the current at that pin should be limited to 5mA. The 20mA
maximum package input current rating limits the number of pins that can safely exceed the power supplies with an input current of 5mA to four. Under normal
operating conditions the maximum current that pins 2, 4 or 5 can handle is limited to 5mA each.
Note 3: The human body model is a 100pF capacitor discharge through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged
directly into each pin.
Note 4: Typicals are at TJ = TA = 25°C and represent most likely parametric norm.
Note 5: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).
Note 6: Care should be taken to include the effects of self heating when setting the maximum output load current. Self heating is not included in the trip point
accuracy specification.
Note 7: The 1µA limit is based on a testing limitation and does not reflect the actual performance of the part. Expect to see a doubling of the current for every
15°C increase in temperature. For example, the 1nA typical current at 25°C would increase to 16nA at 85°C.
Note 8: Only connect to one of the output pads, number 2 or number 3, not both. Either push-pull (Pad 2) or open-drain (Pad 3) can be used but they can not
both be used on the same die.
Part Number Template
The series of digits labeled xyz in the part number LM27-xyz MDA, describe the set point value and the function of the output as
follows:
The place holders xy describe the set point temperature as shown in the following table.
x (10x)
y (1x)
Temperature (°C)
x (10x)
y (1x)
Temperature (°C)
-H
0
-S
7
-J
1
-T
8
-K
2
-V
9
-L
3
Z-
12
-N
4
1-
13
-P
5
2-
14
-R
6
3-
15
The value of z describes the assignment/function of the output as shown in the following table:
Value of z
Digital Output Function
L Overtemperature shutdown: active-high OS output or active-low OS output
N Undertemperature shutdown: active-high US or active-low US output.
For example:
• The part number LM27-2SL MDA would have TOS = 147°C, and is programmed as an overtemperature shutdown output.
• The part number LM27-ZLN MDA would have TUS = 123°C, and is programmed as an undertemperature shutdown output.
Active-high open-drain and active-low push-pull options are available, please contact National Semiconductor for more information.
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