LM26LVEB - National Semiconductor

May 16, 2008

LM26LV

1.6 V, LLP-6 Factory Preset Temperature Switch and

Temperature Sensor

General Description

The LM26LV is a low-voltage, precision, dual-output, low-

power temperature switch and temperature sensor. The tem-

perature trip point (TTRIP) can be preset at the factory to any

temperature in the range of 0°C to 150°C in 1°C increments.

Built-in temperature hysteresis (THYST) keeps the output sta-

ble in an environment of temperature instability.

In normal operation the LM26LV temperature switch outputs

assert when the die temperature exceeds TTRIP. The temper-

ature switch outputs will reset when the temperature falls

below a temperature equal to (TTRIP − THYST). The

OVERTEMP digital output, is active-high with a push-pull

structure, while the OVERTEMP digital output, is active-low

with an open-drain structure.

An analog output, VTEMP, delivers an analog output voltage

which is inversely proportional to the measured temperature.

Driving the TRIP TEST input high: (1) causes the digital out-

puts to be asserted for in-situ verification and, (2) causes the

threshold voltage to appear at the VTEMP output pin, which

could be used to verify the temperature trip point.

The LM26LV's low minimum supply voltage makes it ideal for

1.8 Volt system designs. Its wide operating range, low supply

current , and excellent accuracy provide a temperature switch

solution for a wide range of commercial and industrial appli-

cations.

Applications

■Cell phones

■Wireless Transceivers

■Digital Cameras

■Personal Digital Assistants (PDA's)

■Battery Management

■Automotive

■Disk Drives

■Games

■Appliances

Features

■Low 1.6V operation

■Low quiescent current

■Push-pull and open-drain temperature switch outputs

■Wide trip point range of 0°C to 150°C

■Very linear analog VTEMP temperature sensor output

■VTEMP output short-circuit protected

■Accurate over −50°C to 150°C temperature range

■2.2 mm by 2.5 mm (typ) LLP-6 package

■Excellent power supply noise rejection

Key Specifications

■ Supply Voltage 1.6V to 5.5V

■ Supply Current 8 μA (typ)

■ Accuracy, Trip Point

Temperature

0°C to 150°C ±2.2°C

■ Accuracy, VTEMP 0°C to 150°C ±2.3°C

0°C to 120°C ±2.2°C

−50°C to 0°C ±1.7°C

■ VTEMP Output Drive ±100 μA

■ Operating Temperature −50°C to 150°C

■ Hysteresis Temperature 4.5°C to 5.5°C

Connection Diagram

LLP-6

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Top View

See NS Package Number SDB06A

Typical Transfer Characteristic

VTEMP Analog Voltage vs Die Temperature

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LM26LV 1.6 V, LLP-6 Factory Preset Temperature Switch and Temperature Sensor

Block Diagram

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Pin Descriptions

No. Name Type Equivalent Circuit Description

1TRIP

TEST

Digital

Input

TRIP TEST pin. Active High input.

If TRIP TEST = 0 (Default) then:

VTEMP = VTS, Temperature Sensor Output Voltage

If TRIP TEST = 1 then:

OVERTEMP and OVERTEMP outputs are asserted and

VTEMP = VTRIP, Temperature Trip Voltage.

This pin may be left open if not used.

5 OVERTEMP Digital

Output

Over Temperature Switch output

Active High, Push-Pull

Asserted when the measured temperature exceeds the Trip

Point Temperature or if TRIP TEST = 1

This pin may be left open if not used.

3 OVERTEMP Digital

Output

Over Temperature Switch output

Active Low, Open-drain (See Section 2.1 regarding required pull-

up resistor.)

Asserted when the measured temperature exceeds the Trip

Point Temperature or if TRIP TEST = 1

This pin may be left open if not used.

6VTEMP

Analog

Output

VTEMP Analog Voltage Output

If TRIP TEST = 0 then

VTEMP = VTS, Temperature Sensor Output Voltage

If TRIP TEST = 1 then

VTEMP = VTRIP, Temperature Trip Voltage

This pin may be left open if not used.

4VDD Power Positive Supply Voltage

2 GND Ground Power Supply Ground

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LM26LV

Typical Application

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LM26LV

Ordering Information

Order Number Temperature Trip

Point, °C

NS Package

Number Top Mark Transport Media

LM26LVCISD-150 150°C SDB06A 150 1000 Units on Tape and Reel

LM26LVCISDX-150 150°C SDB06A 150 4500 Units on Tape and Reel

LM26LVCISD-145 145°C SDB06A 145 1000 Units on Tape and Reel

LM26LVCISDX-145 145°C SDB06A 145 4500 Units on Tape and Reel

LM26LVCISD-140 140°C SDB06A 140 1000 Units on Tape and Reel

LM26LVCISDX-140 140°C SDB06A 140 4500 Units on Tape and Reel

LM26LVCISD-135 135°C SDB06A 135 1000 Units on Tape and Reel

LM26LVCISDX-135 135°C SDB06A 135 4500 Units on Tape and Reel

LM26LVCISD-130 130°C SDB06A 130 1000 Units on Tape and Reel

LM26LVCISDX-130 130°C SDB06A 130 4500 Units on Tape and Reel

LM26LVCISD-125 125°C SDB06A 125 1000 Units on Tape and Reel

LM26LVCISDX-125 125°C SDB06A 125 4500 Units on Tape and Reel

LM26LVCISD-120 120°C SDB06A 120 1000 Units on Tape and Reel

LM26LVCISDX-120 120°C SDB06A 120 4500 Units on Tape and Reel

LM26LVCISD-115 115°C SDB06A 115 1000 Units on Tape and Reel

LM26LVCISDX-115 115°C SDB06A 115 4500 Units on Tape and Reel

LM26LVCISD-110 110°C SDB06A 110 1000 Units on Tape and Reel

LM26LVCISDX-110 110°C SDB06A 110 4500 Units on Tape and Reel

LM26LVCISD-105 105°C SDB06A 105 1000 Units on Tape and Reel

LM26LVCISDX-105 105°C SDB06A 105 4500 Units on Tape and Reel

LM26LVCISD-100 100°C SDB06A 100 1000 Units on Tape and Reel

LM26LVCISDX-100 100°C SDB06A 100 4500 Units on Tape and Reel

LM26LVCISD-095 95°C SDB06A 095 1000 Units on Tape and Reel

LM26LVCISDX-095 95°C SDB06A 095 4500 Units on Tape and Reel

LM26LVCISD-090 90°C SDB06A 090 1000 Units on Tape and Reel

LM26LVCISDX-090 90°C SDB06A 090 4500 Units on Tape and Reel

LM26LVCISD-085 85°C SDB06A 085 1000 Units on Tape and Reel

LM26LVCISDX-085 85°C SDB06A 085 4500 Units on Tape and Reel

LM26LVCISD-080 80°C SDB06A 080 1000 Units on Tape and Reel

LM26LVCISDX-080 80°C SDB06A 080 4500 Units on Tape and Reel

LM26LVCISD-075 75°C SDB06A 075 1000 Units on Tape and Reel

LM26LVCISDX-075 75°C SDB06A 075 4500 Units on Tape and Reel

LM26LVCISD-070 70°C SDB06A 070 1000 Units on Tape and Reel

LM26LVCISDX-070 70°C SDB06A 070 4500 Units on Tape and Reel

LM26LVCISD-065 65°C SDB06A 065 1000 Units on Tape and Reel

LM26LVCISDX-065 65°C SDB06A 065 4500 Units on Tape and Reel

LM26LVCISD-060 60°C SDB06A 060 1000 Units on Tape and Reel

LM26LVCISDX-060 60°C SDB06A 060 4500 Units on Tape and Reel

LM26LVCISD-050 50°C SDB06A 050 1000 Units on Tape and Reel

LM26LVCISDX-050 50°C SDB06A 050 4500 Units on Tape and Reel

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LM26LV

Absolute Maximum Ratings (Note 1)
Supply Voltage −0.2V to +6.0V
Voltage at OVERTEMP pin −0.2V to +6.0V
Voltage at OVERTEMP and
  VTEMP pins −0.2V to (VDD + 0.5V)
TRIP TEST Input Voltage −0.2V to (VDD + 0.5V)
Output Current, any output pin ±7 mA
Input Current at any pin (Note 2) 5 mA
Storage Temperature −65°C to +150°C
Maximum Junction Temperature
  TJ(MAX) +155°C
ESD Susceptibility (Note 3) :  
  Human Body Model 4500V
  Machine Model 300V
Charged Device Model 1000V
Soldering process must comply with National's
Reflow Temperature Profile specifications. Refer to
www.national.com/packaging. (Note 4)
Operating Ratings  (Note 1)
Specified Temperature Range:  TMIN ≤ TA ≤ TMAX
  LM26LV −50°C ≤ TA ≤ +150°C
Supply Voltage Range (VDD)+1.6 V to +5.5 V
Thermal Resistance (θJA) (Note 5)
  LLP-6 (Package SDB06A) 152 °C/W
Accuracy Characteristics
Trip Point Accuracy
Parameter Conditions Limits
(Note 7)
Units
(Limit)
Trip Point Accuracy (Note 8) 0 − 150°C VDD = 5.0 V ±2.2 °C (max)
VTEMP Analog Temperature Sensor Output Accuracy
There are four gains corresponding to each of the four Temperature Trip Point Ranges. Gain 1 is the sensor gain used for Tem-
perature Trip Point 0 - 69°C. Likewise Gain 2 is for Trip Points 70 - 109 °C; Gain 3 for 110 - 129 °C; and Gain 4 for 130 - 150 °C.
These limits do not include DC load regulation. These stated accuracy limits are with reference to the values in the LM26LV
Conversion Table.
Parameter Conditions Limits
(Note 7)
Units
(Limit)
VTEMP Temperature
Accuracy
(Note 8)
Gain 1: for Trip Point
Range 0 - 69°C
TA = 20°C to 40°C VDD = 1.6 to 5.5 V ±1.8
°C (max)
TA = 0°C to 70°C VDD = 1.6 to 5.5 V ±2.0
TA = 0°C to 90°C VDD = 1.6 to 5.5 V ±2.1
TA = 0°C to 120°C VDD = 1.6 to 5.5 V ±2.2
TA = 0°C to 150°C VDD = 1.6 to 5.5 V ±2.3
TA = −50°C to 0°C VDD = 1.7 to 5.5 V ±1.7
Gain 2: for Trip Point
Range 70 - 109°C
TA = 20°C to 40°C VDD = 1.8 to 5.5 V ±1.8
°C (max)
TA = 0°C to 70°C VDD = 1.9 to 5.5 V ±2.0
TA = 0°C to 90°C VDD = 1.9 to 5.5 V ±2.1
TA = 0°C to 120°C VDD = 1.9 to 5.5 V ±2.2
TA = 0°C to 150°C VDD = 1.9 to 5.5 V ±2.3
TA = −50°C to 0°C VDD = 2.3 to 5.5 V ±1.7
Gain 3: for Trip Point
Range 110 - 129°C
TA = 20°C to 40°C VDD = 2.3 to 5.5 V ±1.8
°C (max)
TA = 0°C to 70°C VDD = 2.5 to 5.5 V ±2.0
TA = 0°C to 90°C VDD = 2.5 to 5.5 V ±2.1
TA = 0°C to 120°C VDD = 2.5 to 5.5 V ±2.2
TA = 0°C to 150°C VDD = 2.5 to 5.5 V ±2.3
TA = −50°C to 0°C VDD = 3.0 to 5.5 V ±1.7
Gain 4: for Trip Point
Range 130 - 150°C
TA = 20°C to 40°C VDD = 2.7 to 5.5 V ±1.8
°C (max)
TA = 0°C to 70°C VDD = 3.0 to 5.5 V ±2.0
TA = 0°C to 90°C VDD = 3.0 to 5.5 V ±2.1
TA = 0°C to 120°C VDD = 3.0 to 5.5 V ±2.2
TA = 0°C to 150°C VDD = 3.0 to 5.5 V ±2.3
TA = −50°C to 0°C VDD = 3.6 to 5.5 V ±1.7
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LM26LV

Electrical Characteristics

Unless otherwise noted, these specifications apply for +VDD = +1.6V to +5.5V. Boldface limits apply for TA = TJ = TMIN to

TMAX ; all other limits TA = TJ = 25°C.

Symbol Parameter Conditions Typical

(Note 6)

Limits

(Note 7)

Units

(Limit)

GENERAL SPECIFICATIONS

ISQuiescent Power Supply

Current

816 μA (max)

Hysteresis 55.5 °C (max)

4.5 °C (Min)

OVERTEMP DIGITAL OUTPUT ACTIVE HIGH, PUSH-PULL

VOH Logic "1" Output Voltage

VDD ≥ 1.6V Source ≤ 340 μA

VDD − 0.2V V (min)

VDD ≥ 2.0V Source ≤ 498 μA

VDD ≥ 3.3V Source ≤ 780 μA

VDD ≥ 1.6V Source ≤ 600 μA

VDD − 0.45V V (min)

VDD ≥ 2.0V Source ≤ 980 μA

VDD ≥ 3.3V Source ≤ 1.6 mA

BOTH OVERTEMP and OVERTEMP DIGITAL OUTPUTS

VOL Logic "0" Output Voltage

VDD ≥ 1.6V Sink ≤ 385 μA

0.2

V (max)

VDD ≥ 2.0V Sink ≤ 500 μA

VDD ≥ 3.3V Sink ≤ 730 μA

VDD ≥ 1.6V Sink ≤ 690 μA

0.45

VDD ≥ 2.0V Sink ≤ 1.05 mA

VDD ≥ 3.3V Sink ≤ 1.62 mA

OVERTEMP DIGITAL OUTPUT ACTIVE LOW, OPEN DRAIN

IOH

Logic "1" Output Leakage

Current (Note 12)

TA = 30 °C 0.001 1μA (max)

TA = 150 °C 0.025

VTEMP ANALOG TEMPERATURE SENSOR OUTPUT

VTEMP Sensor Gain

Gain 1: If Trip Point = 0 - 69°C −5.1 mV/°C

Gain 2: If Trip Point = 70 - 109°C −7.7 mV/°C

Gain 3: If Trip Point = 110 - 129°C −10.3 mV/°C

Gain 4: If Trip Point = 130 - 150°C −12.8 mV/°C

VTEMP Load Regulation

(Note 10)

1.6V ≤ VDD < 1.8V

Source ≤ 90 μA

(VDD − VTEMP) ≥ 200 mV −0.1 −1 mV (max)

Sink ≤ 100 μA

VTEMP ≥ 260 mV 0.1 1mV (max)

VDD ≥ 1.8V

Source ≤ 120 μA

(VDD − VTEMP) ≥ 200 mV −0.1 −1 mV (max)

Sink ≤ 200 μA

VTEMP ≥ 260 mV 0.1 1mV (max)

Source or Sink = 100 μA1 Ohm

VDD Supply- to-VTEMP

DC Line Regulation

(Note 13)

VDD = +1.6V to +5.5V

0.29 mV

74 μV/V

−82 dB

VTEMP Output Load

Capacitance Without series resistor. See Section 4.2 1100 pF (max)

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LM26LV

Electrical Characteristics

Unless otherwise noted, these specifications apply for +VDD = +1.6V to +5.5V. Boldface limits apply for TA = TJ = TMIN to

TMAX ; all other limits TA = TJ = 25°C.

Symbol Parameter Conditions Typical

(Note 6)

Limits

(Note 7)

Units

(Limit)

TRIP TEST DIGITAL INPUT

VIH Logic "1" Threshold Voltage VDD− 0.5 V (min)

VIL Logic "0" Threshold Voltage 0.5 V (max)

IIH Logic "1" Input Current 1.5 2.5 μA (max)

IIL

Logic "0" Input Current

(Note 12)

0.001 1μA (max)

TIMING

tEN

Time from Power On to Digital

Output Enabled. See

definition below.

(Note 11).

1.1 2.3 ms (max)

tVTEMP

Time from Power On to

Analog Temperature Valid.

See definition below.

(Note 11)

0.9 10 ms (max)

Definitions of tEN and tVTEMP

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LM26LV

Notes

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 power supplies (VI < GND or VI > VDD), the current at that pin should be limited to 5 mA.

Note 3: The Human Body Model (HBM) is a 100 pF capacitor charged to the specified voltage then discharged through a 1.5 kΩ resistor into each pin. The

Machine Model (MM) is a 200 pF capacitor charged to the specified voltage then discharged directly into each pin. The Charged Device Model (CDM) is a specified

circuit characterizing an ESD event that occurs when a device acquires charge through some triboelectric (frictional) or electrostatic induction processes and then

abruptly touches a grounded object or surface.

Note 4: Reflow temperature profiles are different for lead-free and non-lead-free packages.

Note 5: The junction to ambient temperature resistance (θJA) is specified without a heat sink in still air.

Note 6: Typicals are at TJ = TA = 25°C and represent most likely parametric norm.

Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).

Note 8: Accuracy is defined as the error between the measured and reference output voltages, tabulated in the Conversion Table at the specified conditions of

supply gain setting, voltage, and temperature (expressed in °C). Accuracy limits include line regulation within the specified conditions. Accuracy limits do not

include load regulation; they assume no DC load.

Note 9: Changes in output due to self heating can be computed by multiplying the internal dissipation by the temperature resistance.

Note 10: Source currents are flowing out of the LM26LV. Sink currents are flowing into the LM26LV.

Note 11: Guaranteed by design.

Note 12: The 1 µA 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 1 nA typical current at 25°C would increase to 16 nA at 85°C.

Note 13: Line regulation (DC) is calculated by subtracting the output voltage at the highest supply voltage from the output voltage at the lowest supply voltage.

The typical DC line regulation specification does not include the output voltage shift discussed in Section 4.3.

Note 14: The curves shown represent typical performance under worst-case conditions. Performance improves with larger overhead (VDD − VTEMP), larger VDD,

and lower temperatures.

Note 15: The curves shown represent typical performance under worst-case conditions. Performance improves with larger VTEMP, larger VDD and lower

temperatures.

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LM26LV

Typical Performance Characteristics

VTEMP Output Temperature Error vs. Temperature

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Minimum Operating Temperature vs. Supply Voltage

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Supply Current vs. Temperature

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Supply Current vs. Supply Voltage

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Load Regulation, 100 mV Overhead

T = 80°C Sourcing Current (Note 14)

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Load Regulation, 200 mV Overhead

T = 80°C Sourcing Current (Note 14)

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LM26LV

Load Regulation, 400 mV Overhead

T = 80°C Sourcing Current (Note 14)

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Load Regulation, 1.72V Overhead

T = 150°C, VDD = 2.4V

Sourcing Current (Note 14)

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Load Regulation, VDD = 1.6V

Sinking Current (Note 15)

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Load Regulation, VDD = 1.8V

Sinking Current (Note 15)

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Load Regulation, VDD = 2.4V

Sinking Current (Note 15)

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Change in VTEMP vs. Overhead Voltage

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LM26LV

VTEMP Supply-Noise Gain vs. Frequency

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VTEMP vs. Supply Voltage

Gain 1: For Trip Points

0 - 69°C

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VTEMP vs. Supply Voltage

Gain 2: For Trip Points

70 - 109°C

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VTEMP vs. Supply Voltage

Gain 3: For Trip Points

110 - 129°C

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VTEMP vs. Supply Voltage

Gain 4: For Trip Points

130 - 150°C

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LM26LV

1.0 LM26LV VTEMP vs Die

Temperature Conversion Table

The LM26LV has one out of four possible factory-set gains,

Gain 1 through Gain 4, depending on the range of the Tem-

perature Trip Point. The VTEMP temperature sensor voltage,

in millivolts, at each discrete die temperature over the com-

plete operating temperature range, and for each of the four

Temperature Trip Point ranges, is shown in the Conversion

Table below. This table is the reference from which the

LM26LV accuracy specifications (listed in the Electrical Char-

acteristics section) are determined. This table can be used,

for example, in a host processor look-up table. See Section

1.1.1 for the parabolic equation used in the Conversion Table.

VTEMP Temperature Sensor Output Voltage vs Die

Temperature Conversion Table

The VTEMP temperature sensor output voltage, in mV, vs Die

Temperature, in °C, for each of the four gains corresponding

to each of the four Temperature Trip Point Ranges. Gain 1 is

the sensor gain used for Temperature Trip Point 0 - 69°C.

Likewise Gain 2 is for Trip Points 70 - 109 °C; Gain 3 for 110

- 129 °C; and Gain 4 for 130 - 150 °C. VDD = 5.0V. The values

in bold font are for the Trip Point range.

Die

Temp.,

°C

VTEMP, Analog Output Voltage, mV

Gain 1:

for

TTRIP =

0-69°C

Gain 2:

for

TTRIP =

70-109°C

Gain 3:

for

TTRIP =

110-129°C

Gain 4:

for

TTRIP =

130-150°C

−50 1312 1967 2623 3278

−49 1307 1960 2613 3266

−48 1302 1952 2603 3253

−47 1297 1945 2593 3241

−46 1292 1937 2583 3229

−45 1287 1930 2573 3216

−44 1282 1922 2563 3204

−43 1277 1915 2553 3191

−42 1272 1908 2543 3179

−41 1267 1900 2533 3166

−40 1262 1893 2523 3154

−39 1257 1885 2513 3141

−38 1252 1878 2503 3129

−37 1247 1870 2493 3116

−36 1242 1863 2483 3104

−35 1237 1855 2473 3091

−34 1232 1848 2463 3079

−33 1227 1840 2453 3066

−32 1222 1833 2443 3054

−31 1217 1825 2433 3041

−30 1212 1818 2423 3029

−29 1207 1810 2413 3016

−28 1202 1803 2403 3004

−27 1197 1795 2393 2991

−26 1192 1788 2383 2979

−25 1187 1780 2373 2966

−24 1182 1773 2363 2954

−23 1177 1765 2353 2941

−22 1172 1757 2343 2929

−21 1167 1750 2333 2916

−20 1162 1742 2323 2903

−19 1157 1735 2313 2891

−18 1152 1727 2303 2878

−17 1147 1720 2293 2866

−16 1142 1712 2283 2853

−15 1137 1705 2272 2841

−14 1132 1697 2262 2828

−13 1127 1690 2252 2815

−12 1122 1682 2242 2803

−11 1116 1674 2232 2790

−10 1111 1667 2222 2777

−9 1106 1659 2212 2765

−8 1101 1652 2202 2752

−7 1096 1644 2192 2740

−6 1091 1637 2182 2727

−5 1086 1629 2171 2714

−4 1081 1621 2161 2702

−3 1076 1614 2151 2689

−2 1071 1606 2141 2676

−1 1066 1599 2131 2664

01061 1591 2121 2651

11056 1583 2111 2638

21051 1576 2101 2626

31046 1568 2090 2613

41041 1561 2080 2600

51035 1553 2070 2587

61030 1545 2060 2575

71025 1538 2050 2562

81020 1530 2040 2549

91015 1522 2029 2537

10 1010 1515 2019 2524

11 1005 1507 2009 2511

12 1000 1499 1999 2498

13 995 1492 1989 2486

14 990 1484 1978 2473

15 985 1477 1968 2460

16 980 1469 1958 2447

17 974 1461 1948 2435

18 969 1454 1938 2422

19 964 1446 1927 2409

20 959 1438 1917 2396

21 954 1431 1907 2383

22 949 1423 1897 2371

23 944 1415 1886 2358

24 939 1407 1876 2345

25 934 1400 1866 2332

26 928 1392 1856 2319

27 923 1384 1845 2307

28 918 1377 1835 2294

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LM26LV

29 913 1369 1825 2281

30 908 1361 1815 2268

31 903 1354 1804 2255

32 898 1346 1794 2242

33 892 1338 1784 2230

34 887 1331 1774 2217

35 882 1323 1763 2204

36 877 1315 1753 2191

37 872 1307 1743 2178

38 867 1300 1732 2165

39 862 1292 1722 2152

40 856 1284 1712 2139

41 851 1276 1701 2127

42 846 1269 1691 2114

43 841 1261 1681 2101

44 836 1253 1670 2088

45 831 1245 1660 2075

46 825 1238 1650 2062

47 820 1230 1639 2049

48 815 1222 1629 2036

49 810 1214 1619 2023

50 805 1207 1608 2010

51 800 1199 1598 1997

52 794 1191 1588 1984

53 789 1183 1577 1971

54 784 1176 1567 1958

55 779 1168 1557 1946

56 774 1160 1546 1933

57 769 1152 1536 1920

58 763 1144 1525 1907

59 758 1137 1515 1894

60 753 1129 1505 1881

61 748 1121 1494 1868

62 743 1113 1484 1855

63 737 1105 1473 1842

64 732 1098 1463 1829

65 727 1090 1453 1816

66 722 1082 1442 1803

67 717 1074 1432 1790

68 711 1066 1421 1776

69 706 1059 1411 1763

70 701 1051 1400 1750

71 696 1043 1390 1737

72 690 1035 1380 1724

73 685 1027 1369 1711

74 680 1019 1359 1698

75 675 1012 1348 1685

76 670 1004 1338 1672

77 664 996 1327 1659

78 659 988 1317 1646

79 654 980 1306 1633

80 649 972 1296 1620

81 643 964 1285 1607

82 638 957 1275 1593

83 633 949 1264 1580

84 628 941 1254 1567

85 622 933 1243 1554

86 617 925 1233 1541

87 612 917 1222 1528

88 607 909 1212 1515

89 601 901 1201 1501

90 596 894 1191 1488

91 591 886 1180 1475

92 586 878 1170 1462

93 580 870 1159 1449

94 575 862 1149 1436

95 570 854 1138 1422

96 564 846 1128 1409

97 559 838 1117 1396

98 554 830 1106 1383

99 549 822 1096 1370

100 543 814 1085 1357

101 538 807 1075 1343

102 533 799 1064 1330

103 527 791 1054 1317

104 522 783 1043 1304

105 517 775 1032 1290

106 512 767 1022 1277

107 506 759 1011 1264

108 501 751 1001 1251

109 496 743 990 1237

110 490 735 979 1224

111 485 727 969 1211

112 480 719 958 1198

113 474 711 948 1184

114 469 703 937 1171

115 464 695 926 1158

116 459 687 916 1145

117 453 679 905 1131

118 448 671 894 1118

119 443 663 884 1105

120 437 655 873 1091

121 432 647 862 1078

122 427 639 852 1065

123 421 631 841 1051

124 416 623 831 1038

125 411 615 820 1025

126 405 607 809 1011

127 400 599 798 998

128 395 591 788 985

129 389 583 777 971

130 384 575 766 958

13 www.national.com

LM26LV

131 379 567 756 945

132 373 559 745 931

133 368 551 734 918

134 362 543 724 904

135 357 535 713 891

136 352 527 702 878

137 346 519 691 864

138 341 511 681 851

139 336 503 670 837

140 330 495 659 824

141 325 487 649 811

142 320 479 638 797

143 314 471 627 784

144 309 463 616 770

145 303 455 606 757

146 298 447 595 743

147 293 438 584 730

148 287 430 573 716

149 282 422 562 703

150 277 414 552 690

1.1 VTEMP vs DIE TEMPERATURE APPROXIMATIONS

The LM26LV's VTEMP analog temperature output is very lin-

ear. The Conversion Table above and the equation in Section

1.1.1 represent the most accurate typical performance of the

VTEMP voltage output vs Temperature.

1.1.1 The Second-Order Equation (Parabolic)

The data from the Conversion Table, or the equation below,

when plotted, has an umbrella-shaped parabolic curve.

VTEMP is in mV.

1.1.2 The First-Order Approximation (Linear)

For a quicker approximation, although less accurate than the

second-order, over the full operating temperature range the

linear formula below can be used. Using this formula, with the

constant and slope in the following set of equations, the best-

fit VTEMP vs Die Temperature performance can be calculated

with an approximation error less than 18 mV. VTEMP is in mV.

1.1.3 First-Order Approximation (Linear) over Small

Temperature Range

For a linear approximation, a line can easily be calculated

over the desired temperature range from the Conversion Ta-

ble using the two-point equation:

Where V is in mV, T is in °C, T1 and V1 are the coordinates of

the lowest temperature, T2 and V2 are the coordinates of the

highest temperature.

For example, if we want to determine the equation of a line

with Gain 4, over a temperature range of 20°C to 50°C, we

would proceed as follows:

Using this method of linear approximation, the transfer func-

tion can be approximated for one or more temperature ranges

of interest.

www.national.com 14

LM26LV

2.0 OVERTEMP and OVERTEMP

Digital Outputs

The OVERTEMP Active High, Push-Pull Output and the

OVERTEMP Active Low, Open-Drain Output both assert at

the same time whenever the Die Temperature reaches the

factory preset Temperature Trip Point. They also assert si-

multaneously whenever the TRIP TEST pin is set high. Both

outputs de-assert when the die temperature goes below the

Temperature Trip Point - Hysteresis. These two types of dig-

ital outputs enable the user the flexibility to choose the type

of output that is most suitable for his design.

Either the OVERTEMP or the OVERTEMP Digital Output pins

can be left open if not used.

2.1 OVERTEMP OPEN-DRAIN DIGITAL OUTPUT

The OVERTEMP Active Low, Open-Drain Digital Output, if

used, requires a pull-up resistor between this pin and VDD.

The following section shows how to determine the pull-up re-

sistor value.

Determining the Pull-up Resistor Value

20204752

The Pull-up resistor value is calculated at the condition of

maximum total current, iT, through the resistor. The total cur-

rent is:

where,

iTiT is the maximum total current through the Pull-up

Resistor at VOL.

iLiL is the load current, which is very low for typical

digital inputs.

VOUT VOUT is the Voltage at the OVERTEMP pin. Use

VOL for calculating the Pull-up resistor.

VDD(Max) VDD(Max) is the maximum power supply voltage to be

used in the customer's system.

The pull-up resistor maximum value can be found by using

the following formula:

EXAMPLE CALCULATION

Suppose we have, for our example, a VDD of 3.3 V ± 0.3V, a

CMOS digital input as a load, a VOL of 0.2 V.

(1) We see that for VOL of 0.2 V the electrical specification for

OVERTEMP shows a maximim isink of 385 µA.

(2) Let iL= 1 µA, then iT is about 386 µA max. If we select

35 µA as the current limit then iT for the calculation becomes

35 µA

(3) We notice that VDD(Max) is 3.3V + 0.3V = 3.6V and then

calculate the pull-up resistor as

RPull-up = (3.6 − 0.2)/35 µA = 97k

(4) Based on this calculated value, we select the closest re-

sistor value in the tolerance family we are using.

In our example, if we are using 5% resistor values, then the

next closest value is 100 kΩ.

2.2 NOISE IMMUNITY

The LM26LV is virtually immune from false triggers on the

OVERTEMP and OVERTEMP digital outputs due to noise on

the power supply. Test have been conducted showing that,

with the die temperature within 0.5°C of the temperature trip

point, and the severe test of a 3 Vpp square wave "noise"

signal injected on the VDD line, over the VDD range of 2V to

5V, there were no false triggers.

3.0 TRIP TEST Digital Input

The TRIP TEST pin simply provides a means to test the

OVERTEMP and OVERTEMP digital outputs electronically

by causing them to assert, at any operating temperature, as

a result of forcing the TRIP TEST pin high.

When the TRIP TEST pin is pulled high the VTEMP pin will be

at the VTRIP voltage.

If not used, the TRIP TEST pin may either be left open or

grounded.

4.0 VTEMP Analog Temperature

Sensor Output

The VTEMP push-pull output provides the ability to sink and

source significant current. This is beneficial when, for exam-

ple, driving dynamic loads like an input stage on an analog-

to-digital converter (ADC). In these applications the source

current is required to quickly charge the input capacitor of the

ADC. See the Applications Circuits section for more discus-

sion of this topic. The LM26LV is ideal for this and other

applications which require strong source or sink current.

4.1 NOISE CONSIDERATIONS

The LM26LV's supply-noise gain (the ratio of the AC signal

on VTEMP to the AC signal on VDD) was measured during

bench tests. It's typical attenuation is shown in the Typical

Performance Characteristics section. A load capacitor on the

output can help to filter noise.

For operation in very noisy environments, some bypass ca-

pacitance should be present on the supply within approxi-

mately 2 inches of the LM26LV.

4.2 CAPACITIVE LOADS

The VTEMP Output handles capacitive loading well. In an ex-

tremely noisy environment, or when driving a switched sam-

pling input on an ADC, it may be necessary to add some

filtering to minimize noise coupling. Without any precautions,

the VTEMP can drive a capacitive load less than or equal to

1100 pF as shown in Figure 1. For capacitive loads greater

than 1100 pF, a series resistor is required on the output, as

shown in Figure 2, to maintain stable conditions.

15 www.national.com

LM26LV

20204715

FIGURE 1. LM26LV No Decoupling Required for

Capacitive Loads Less than 1100 pF.

20204733

CLOAD RS

1.1 nF to 99 nF 3 kΩ

100 nF to 999 nF 1.5 kΩ

1 μF800 Ω

FIGURE 2. LM26LV with series resistor for capacitive

loading greater than 1100 pF.

4.3 VOLTAGE SHIFT

The LM26LV is very linear over temperature and supply volt-

age range. Due to the intrinsic behavior of an NMOS/PMOS

rail-to-rail buffer, a slight shift in the output can occur when

the supply voltage is ramped over the operating range of the

device. The location of the shift is determined by the relative

levels of VDD and VTEMP. The shift typically occurs when

VDD − VTEMP = 1.0V.

This slight shift (a few millivolts) takes place over a wide

change (approximately 200 mV) in VDD or VTEMP. Since the

shift takes place over a wide temperature change of 5°C to

20°C, VTEMP is always monotonic. The accuracy specifica-

tions in the Electrical Characteristics table already includes

this possible shift.

5.0 Mounting and Temperature

Conductivity

The LM26LV can be applied easily in the same way as other

integrated-circuit temperature sensors. It can be glued or ce-

mented to a surface.

To ensure good temperature conductivity, the backside of the

LM26LV die is directly attached to the GND pin (Pin 2). The

temperatures of the lands and traces to the other leads of the

LM26LV will also affect the temperature reading.

Alternatively, the LM26LV can be mounted inside a sealed-

end metal tube, and can then be dipped into a bath or screwed

into a threaded hole in a tank. As with any IC, the LM26LV

and accompanying wiring and circuits must be kept insulated

and dry, to avoid leakage and corrosion. This is especially true

if the circuit may operate at cold temperatures where con-

densation can occur. If moisture creates a short circuit from

the VTEMP output to ground or VDD, the VTEMP output from the

LM26LV will not be correct. Printed-circuit coatings are often

used to ensure that moisture cannot corrode the leads or cir-

cuit traces.

The thermal resistance junction-to-ambient (θJA) is the pa-

rameter used to calculate the rise of a device junction tem-

perature due to its power dissipation. The equation used to

calculate the rise in the LM26LV's die temperature is

where TA is the ambient temperature, IQ is the quiescent cur-

rent, IL is the load current on the output, and VO is the output

voltage. For example, in an application where TA = 30 °C,

VDD = 5 V, IDD = 9 μA, Gain 4, VTEMP = 2231 mV, and

IL = 2 μA, the junction temperature would be 30.021 °C, show-

ing a self-heating error of only 0.021°C. Since the LM26LV's

junction temperature is the actual temperature being mea-

sured, care should be taken to minimize the load current that

the VTEMP output is required to drive. If The OVERTEMP out-

put is used with a 100 k pull-up resistor, and this output is

asserted (low), then for this example the additional contribu-

tion is [(152° C/W)x(5V)2/100k] = 0.038°C for a total self-

heating error of 0.059°C. Figure 3 shows the thermal

resistance of the LM26LV.

Device Number NS Package

Number

Thermal

Resistance (θJA)

LM26LVCISD SDB06A 152° C/W

FIGURE 3. LM26LV Thermal Resistance

www.national.com 16

LM26LV

6.0 Applications Circuits

20204761

FIGURE 4. Temperature Switch Using Push-Pull Output

20204762

FIGURE 5. Temperature Switch Using Open-Drain Output

20204728

Most CMOS ADCs found in microcontrollers and ASICs have a sampled data comparator input structure. When the ADC charges

the sampling cap, it requires instantaneous charge from the output of the analog source such as the LM26LV temperature sensor

and many op amps. This requirement is easily accommodated by the addition of a capacitor (CFILTER). The size of CFILTER depends

on the size of the sampling capacitor and the sampling frequency. Since not all ADCs have identical input stages, the charge

requirements will vary. This general ADC application is shown as an example only.

FIGURE 6. Suggested Connection to a Sampling Analog-to-Digital Converter Input Stage

17 www.national.com

LM26LV

20204718

FIGURE 7. Celsius Temperature Switch

20204760

FIGURE 8. TRIP TEST Digital Output Test Circuit

20204765

The TRIP TEST pin, normally used to check the operation of the OVERTEMP and OVERTEMP pins, may be used to latch the

outputs whenever the temperature exceeds the programmed limit and causes the digital outputs to assert. As shown in the figure,

when OVERTEMP goes high the TRIP TEST input is also pulled high and causes OVERTEMP output to latch high and the

OVERTEMP output to latch low. Momentarily switching the TRIP TEST input low will reset the LM26LV to normal operation. The

resistor limits the current out of the OVERTEMP output pin.

FIGURE 9. Latch Circuit using OVERTEMP Output

www.national.com 18

LM26LV

Physical Dimensions inches (millimeters) unless otherwise noted

6-Lead LLP-6 Package

Order Number LM26LVCISD, LM26LVCISDX

NS Package Number SDB06A

19 www.national.com

LM26LV

Notes

LM26LV 1.6 V, LLP-6 Factory Preset Temperature Switch and Temperature Sensor

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