LM27A NSC [National Semiconductor], LM27A Datasheet

LM27A

Manufacturer Part Number

LM27A

Description

Manufacturer

NSC [National Semiconductor]

Datasheets

1.LM27-2PLMDA.pdf (10 pages)

2.LM27A.pdf (10 pages)

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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 (T

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 (V

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

temperature goes below (T

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

or 10°C and is controlled by the state of the HYST pin. The

temperature and has a −10.7mV/°C output slope.

TEMP

. The outputs will reset to their normal states when the

. The outputs will reset when the temperature is above

analog output provides a voltage that is proportional to

HYST

TEMP

). The typical hysteresis, T

). One digitial output is an active-high, push-pull

–T

HYST

). Similarly, when pre-

HYST

201530

, can be set to 2°C

) can

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

■

Features

■

Key Specifications

■

Microprocessor Thermal Management

Appliances

Portable Battery Powered Systems

Fan Control

Industrial Process Control

HVAC Systems

Electronic System Protection

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 V

Internal voltage reference and DAC for trip-point setting

Excellent power supply noise rejection

AEC-Q100 Qualified

Power Supply Voltage

Power Supply Current

Hysteresis Temperature

Temperature Trip Point Accuracy

TEMP

output allows after-assembly system testing

TEMP

2°C or 10°C(typ)

output pin

www.national.com

2.7V to 5.5V

±3°C (max)

40µA(max)

15µA(typ)

July 2007

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