LM94022QBIMGX - Texas Instruments High-Performance Analog

LM94022

LM94022/LM94022Q 1.5V, SC70, Multi-Gain Analog Temperature Sensor with

Class-AB Output

Literature Number: SNIS140C

LM94022/LM94022Q

March 17, 2009

1.5V, SC70, Multi-Gain Analog Temperature Sensor with

Class-AB Output

General Description

The LM94022 is a precision analog output CMOS integrated-

circuit temperature sensor that operates at a supply voltage

as low as 1.5 Volts. A class-AB output structure gives the

LM94022 strong output source and sink current capability for

driving heavy loads. For example, it is well suited to source

the input of a sample-and-hold analog-to-digital converter

with its transient load requirements. While operating over the

wide temperature range of −50°C to +150°C, the LM94022

delivers an output voltage that is inversely porportional to

measured temperature. The LM94022's low supply current

makes it ideal for battery-powered systems as well as general

temperature sensing applications.

Two logic inputs, Gain Select 1 (GS1) and Gain Select 0

(GS0), select the gain of the temperature-to-voltage output

transfer function. Four slopes are selectable: −5.5 mV/°C,

−8.2 mV/°C, −10.9 mV/°C, and −13.6 mV/°C. In the lowest

gain configuration (GS1 and GS0 both tied low), the LM94022

can operate with a 1.5V supply while measuring temperature

over the full −50°C to +150°C operating range. Tying both

inputs high causes the transfer function to have the largest

gain of −13.6 mV/°C for maximum temperature sensitivity.

The gain-select inputs can be tied directly to VDD or Ground

without any pull-up or pull-down resistors, reducing compo-

nent count and board area. These inputs can also be driven

by logic signals allowing the system to optimize the gain dur-

ing operation or system diagnostics.

Applications

■Cell phones

■Wireless Transceivers

■Battery Management

■Automotive

■Disk Drives

■Games

■Appliances

Features

■LM94022Q is AEC-Q100 Grade 0 qualified and is

manufactured on an Automotive Grade Flow.

■Low 1.5V operation

■Push-pull output with 50µA source current capability

■Four selectable gains

■Very accurate over wide temperature range of −50°C to

+150°C

■Low quiescent current

■Output is short-circuit protected

■Extremely small SC70 package

■Footprint compatible with the industry-standard LM20

temperature sensor

Key Specifications

■ Supply Voltage 1.5V to 5.5V

■ Supply Current 5.4 μA (typ)

■ Output Drive ±50 μA

■ Temperature

Accuracy

20°C to 40°C

-50°C to 70°C

-50°C to 90°C

-50°C to 150°C

±1.5°C

±1.8°C

±2.1°C

±2.7°C

■ Operating

Temperature −50°C to 150°C

Connection Diagram

SC70-5

20143001

Top View

See NS Package Number MAA05A

Typical Transfer Characteristic

Output Voltage vs Temperature

20143024

LM94022/LM94022Q 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output

Typical Application

Full-Range Celsius Temperature Sensor (−50°C to +150°C)

Operating from a Single Battery Cell

20143002

Ordering Information

Order Temperature NS Package Device

Number Accuracy Number Marking Transport Media Features

LM94022BIMG ±1.5°C to ±2.7°C MAA05A 22B 3000 Units on Tape

and Reel

LM94022BIMGX ±1.5°C to ±2.7°C MAA05A 22B 9000 Units on Tape

and Reel

LM94022QBIMG ±1.5°C to ±2.7°C MAA05A 22Q 3000 Units on Tape

and Reel

AEC-Q100 Grade 0

Qualified. Automotive-

Grade Production Flow.

LM94022QBIMGX ±1.5°C to ±2.7°C MAA05A 22Q 9000 Units on Tape

and Reel

AEC-Q100 Grade 0

Qualified. Automotive-

Grade Production Flow.

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LM94022/LM94022Q

Pin Descriptions

Label Pin

Numb

Type

Equivalent Circuit

Function

GS1 5 Logic Input Gain Select 1 - One of two inputs for selecting the

slope of the output response

GS0 1 Logic Input Gain Select 0 - One of two inputs for selecting the

slope of the output response

OUT 3 Analog Output Outputs a voltage which is inversely proportional to

temperature

VDD 4 Power Positive Supply Voltage

GND 2 Ground Power Supply Ground

3 www.national.com

LM94022/LM94022Q

Absolute Maximum Ratings (Note 1)

Supply Voltage −0.3V to +6.0V

Voltage at Output Pin −0.3V to (VDD + 0.5V)

Output Current ±7 mA

Voltage at GS0 and GS1 Input Pins −0.3V to +6.0V

Input Current at any pin (Note 2) 5 mA

Storage Temperature −65°C to +150°C

Maximum Junction Temperature

(TJMAX)+150°C

ESD Susceptibility (Note 3) :

Human Body Model 2500V

Machine Model 250V

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

LM94022 −50°C ≤ TA ≤ +150°C

Supply Voltage Range (VDD)+1.5 V to +5.5 V

Thermal Resistance (θJA) (Note 5)

SC-70 415°C/W

Accuracy Characteristics

These limits do not include DC load regulation. These stated accuracy limits are with reference to the values in the LM94022

Transfer Table.

Parameter Conditions Limits

(Note 7)

Units

(Limit)

Temperature Error

(Note 8)

GS1=0

GS0=0

TA = +20°C to +40°C; VDD = 1.5V to 5.5V ±1.5 °C (max)

TA = +0°C to +70°C; VDD = 1.5V to 5.5V ±1.8 °C (max)

TA = +0°C to +90°C; VDD = 1.5V to 5.5V ±2.1 °C (max)

TA = +0°C to +120°C; VDD = 1.5V to 5.5V ±2.4 °C (max)

TA = +0°C to +150°C; VDD = 1.5V to 5.5V ±2.7 °C (max)

TA = −50°C to +0°C; VDD = 1.6V to 5.5V ±1.8 °C (max)

GS1=0

GS0=1

TA = +20°C to +40°C; VDD = 1.8V to 5.5V ±1.5 °C (max)

TA = +0°C to +70°C; VDD = 1.9V to 5.5V ±1.8 °C (max)

TA = +0°C to +90°C; VDD = 1.9V to 5.5V ±2.1 °C (max)

TA = +0°C to +120°C; VDD = 1.9V to 5.5V ±2.4 °C (max)

TA = +0°C to +150°C; VDD = 1.9V to 5.5V ±2.7 °C (max)

TA = −50°C to +0°C; VDD = 2.3V to 5.5V ±1.8 °C (max)

GS1=1

GS0=0

TA = +20°C to +40°C; VDD = 2.2V to 5.5V ±1.5 °C (max)

TA = +0°C to +70°C; VDD = 2.4V to 5.5V ±1.8 °C (max)

TA = +0°C to +90°C; VDD = 2.4V to 5.5V ±2.1 °C (max)

TA = +0°C to +120°C; VDD = 2.4V to 5.5V ±2.4 °C (max)

TA = +0°C to +150°C; VDD = 2.4V to 5.5V ±2.7 °C (max)

TA = −50°C to +0°C; VDD = 3.0V to 5.5V ±1.8 °C (max)

GS1=1

GS0=1

TA = +20°C to +40°C; VDD = 2.7V to 5.5V ±1.5 °C (max)

TA = +0°C to +70°C; VDD = 3.0V to 5.5V ±1.8 °C (max)

TA = +0°C to +90°C; VDD = 3.0V to 5.5V ±2.1 °C (max)

TA = +0°C to +120°C; VDD = 3.0V to 5.5V ±2.4 °C (max)

TA = 0°C to +150°C; VDD = 3.0V to 5.5V ±2.7 °C (max)

TA = −50°C to +0°C; VDD = 3.6V to 5.5V ±1.8 °C (max)

www.national.com 4

LM94022/LM94022Q

Electrical Characteristics

Unless otherwise noted, these specifications apply for +VDD = +1.5V 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)

Sensor Gain GS1 = 0, GS0 = 0 -5.5 mV/°C

GS1 = 0, GS1 = 1 -8.2 mV/°C

GS1 = 1, GS0 = 0 -10.9 mV/°C

GS1 = 1, GS0 = 1 -13.6 mV/°C

Load Regulation

(Note 10)

Source ≤ 50 μA,

(VDD - VOUT) ≥ 200mV

-0.22 -1 mV (max)

Sink ≤ 50 μA,

VOUT ≥ 200mV

0.26 1mV (max)

Line Regulation

(Note 11)

200 μV/V

ISSupply Current TA = +30°C to +150°C,

(VDD - VOUT) ≥ 100mV

5.4 8.1 μA (max)

TA = -50°C to +150°C,

(VDD - VOUT) ≥ 100mV

5.4 9μA (max)

CLOutput Load Capacitance 1100 pF (max)

Power-on Time (Note 12) CL= 0 pF to 1100 pF 0.7 1.9 ms (max)

VIH GS1 and GS0 Input Logic

"1" Threshold Voltage

VDD- 0.5V V (min)

VIL GS1 and GS0 Input Logic

"0" Threshold Voltage

0.5 V (max)

IIH Logic "1" Input Current

(Note 13)

0.001 1μA (max)

IIL Logic "0" Input Current

(Note 13)

0.001 1μA (max)

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 > V+), the current at that pin should be limited to 5 mA.

Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged

directly into each pin.

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

Note 5: The junction to ambient thermal 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 Transfer 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 thermal resistance.

Note 10: Source currents are flowing out of the LM94022. Sink currents are flowing into the LM94022.

Note 11: 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 5.0.

Note 12: Guaranteed by design and characterization.

Note 13: The input current is leakage only and is highest at high temperature. It is typically only 0.001µA. The 1µA limit is solely based on a testing limitation and

does not reflect the actual performance of the part.

5 www.national.com

LM94022/LM94022Q

Typical Performance Characteristics

Temperature Error vs. Temperature

20143007

Minimum Operating Temperature vs. Supply Voltage

20143006

Supply Current vs. Temperature

20143004

Supply Current vs. Supply Voltage

20143005

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LM94022/LM94022Q

Load Regulation, Sourcing Current

20143040

Load Regulation, Sinking Current

20143041

Change in Vout vs. Overhead Voltage

20143042

Supply-Noise Gain vs. Frequency

20143043

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LM94022/LM94022Q

Output Voltage vs. Supply Voltage

Gain Select = 00

20143034

Output Voltage vs. Supply Voltage

Gain Select = 01

20143035

Output Voltage vs. Supply Voltage

Gain Select = 10

20143036

Output Voltage vs. Supply Voltage

Gain Select = 11

20143037

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LM94022/LM94022Q

1.0 LM94022 Transfer Function

The LM94022 has four selectable gains, each of which can

be selected by the GS1 and GS0 input pins. The output volt-

age for each gain, across the complete operating temperature

range is shown in the LM94022 Transfer Table, below. This

table is the reference from which the LM94022 accuracy

specifications (listed in the Electrical Characteristics section)

are determined. This table can be used, for example, in a host

processor look-up table. A file containing this data is available

for download at www.national.com/appinfo/tempsensors.

LM94022 Transfer Table

The output voltages in this table apply for VDD = 5V.

Temperat

ure

(°C)

GS = 00

(mV)

GS = 01

(mV)

GS = 10

(mV)

GS = 11

(mV)

-50 1299 1955 2616 3277

-49 1294 1949 2607 3266

-48 1289 1942 2598 3254

-47 1284 1935 2589 3243

-46 1278 1928 2580 3232

-45 1273 1921 2571 3221

-44 1268 1915 2562 3210

-43 1263 1908 2553 3199

-42 1257 1900 2543 3186

-41 1252 1892 2533 3173

-40 1247 1885 2522 3160

-39 1242 1877 2512 3147

-38 1236 1869 2501 3134

-37 1231 1861 2491 3121

-36 1226 1853 2481 3108

-35 1221 1845 2470 3095

-34 1215 1838 2460 3082

-33 1210 1830 2449 3069

-32 1205 1822 2439 3056

-31 1200 1814 2429 3043

-30 1194 1806 2418 3030

-29 1189 1798 2408 3017

-28 1184 1790 2397 3004

-27 1178 1783 2387 2991

-26 1173 1775 2376 2978

-25 1168 1767 2366 2965

-24 1162 1759 2355 2952

-23 1157 1751 2345 2938

-22 1152 1743 2334 2925

-21 1146 1735 2324 2912

-20 1141 1727 2313 2899

-19 1136 1719 2302 2886

-18 1130 1711 2292 2873

-17 1125 1703 2281 2859

-16 1120 1695 2271 2846

-15 1114 1687 2260 2833

-14 1109 1679 2250 2820

Temperat

ure

(°C)

GS = 00

(mV)

GS = 01

(mV)

GS = 10

(mV)

GS = 11

(mV)

-13 1104 1671 2239 2807

-12 1098 1663 2228 2793

-11 1093 1656 2218 2780

-10 1088 1648 2207 2767

-9 1082 1639 2197 2754

-8 1077 1631 2186 2740

-7 1072 1623 2175 2727

-6 1066 1615 2164 2714

-5 1061 1607 2154 2700

-4 1055 1599 2143 2687

-3 1050 1591 2132 2674

-2 1044 1583 2122 2660

-1 1039 1575 2111 2647

0 1034 1567 2100 2633

1 1028 1559 2089 2620

2 1023 1551 2079 2607

3 1017 1543 2068 2593

4 1012 1535 2057 2580

5 1007 1527 2047 2567

6 1001 1519 2036 2553

7 996 1511 2025 2540

8 990 1502 2014 2527

9 985 1494 2004 2513

10 980 1486 1993 2500

11 974 1478 1982 2486

12 969 1470 1971 2473

13 963 1462 1961 2459

14 958 1454 1950 2446

15 952 1446 1939 2433

16 947 1438 1928 2419

17 941 1430 1918 2406

18 936 1421 1907 2392

19 931 1413 1896 2379

20 925 1405 1885 2365

21 920 1397 1874 2352

22 914 1389 1864 2338

23 909 1381 1853 2325

24 903 1373 1842 2311

25 898 1365 1831 2298

26 892 1356 1820 2285

27 887 1348 1810 2271

28 882 1340 1799 2258

29 876 1332 1788 2244

30 871 1324 1777 2231

31 865 1316 1766 2217

32 860 1308 1756 2204

33 854 1299 1745 2190

34 849 1291 1734 2176

9 www.national.com

LM94022/LM94022Q

Temperat

ure

(°C)

GS = 00

(mV)

GS = 01

(mV)

GS = 10

(mV)

GS = 11

(mV)

35 843 1283 1723 2163

36 838 1275 1712 2149

37 832 1267 1701 2136

38 827 1258 1690 2122

39 821 1250 1679 2108

40 816 1242 1668 2095

41 810 1234 1657 2081

42 804 1225 1646 2067

43 799 1217 1635 2054

44 793 1209 1624 2040

45 788 1201 1613 2026

46 782 1192 1602 2012

47 777 1184 1591 1999

48 771 1176 1580 1985

49 766 1167 1569 1971

50 760 1159 1558 1958

51 754 1151 1547 1944

52 749 1143 1536 1930

53 743 1134 1525 1916

54 738 1126 1514 1902

55 732 1118 1503 1888

56 726 1109 1492 1875

57 721 1101 1481 1861

58 715 1093 1470 1847

59 710 1084 1459 1833

60 704 1076 1448 1819

61 698 1067 1436 1805

62 693 1059 1425 1791

63 687 1051 1414 1777

64 681 1042 1403 1763

65 676 1034 1391 1749

66 670 1025 1380 1735

67 664 1017 1369 1721

68 659 1008 1358 1707

69 653 1000 1346 1693

70 647 991 1335 1679

71 642 983 1324 1665

72 636 974 1313 1651

73 630 966 1301 1637

74 625 957 1290 1623

75 619 949 1279 1609

76 613 941 1268 1595

77 608 932 1257 1581

78 602 924 1245 1567

79 596 915 1234 1553

80 591 907 1223 1539

81 585 898 1212 1525

82 579 890 1201 1511

Temperat

ure

(°C)

GS = 00

(mV)

GS = 01

(mV)

GS = 10

(mV)

GS = 11

(mV)

83 574 881 1189 1497

84 568 873 1178 1483

85 562 865 1167 1469

86 557 856 1155 1455

87 551 848 1144 1441

88 545 839 1133 1427

89 539 831 1122 1413

90 534 822 1110 1399

91 528 814 1099 1385

92 522 805 1088 1371

93 517 797 1076 1356

94 511 788 1065 1342

95 505 779 1054 1328

96 499 771 1042 1314

97 494 762 1031 1300

98 488 754 1020 1286

99 482 745 1008 1272

100 476 737 997 1257

101 471 728 986 1243

102 465 720 974 1229

103 459 711 963 1215

104 453 702 951 1201

105 448 694 940 1186

106 442 685 929 1172

107 436 677 917 1158

108 430 668 906 1144

109 425 660 895 1130

110 419 651 883 1115

111 413 642 872 1101

112 407 634 860 1087

113 401 625 849 1073

114 396 617 837 1058

115 390 608 826 1044

116 384 599 814 1030

117 378 591 803 1015

118 372 582 791 1001

119 367 573 780 987

120 361 565 769 973

121 355 556 757 958

122 349 547 745 944

123 343 539 734 929

124 337 530 722 915

125 332 521 711 901

126 326 513 699 886

127 320 504 688 872

128 314 495 676 858

129 308 487 665 843

130 302 478 653 829

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LM94022/LM94022Q

Temperat

ure

(°C)

GS = 00

(mV)

GS = 01

(mV)

GS = 10

(mV)

GS = 11

(mV)

131 296 469 642 814

132 291 460 630 800

133 285 452 618 786

134 279 443 607 771

135 273 434 595 757

136 267 425 584 742

137 261 416 572 728

138 255 408 560 713

139 249 399 549 699

140 243 390 537 684

141 237 381 525 670

142 231 372 514 655

143 225 363 502 640

144 219 354 490 626

145 213 346 479 611

146 207 337 467 597

147 201 328 455 582

148 195 319 443 568

149 189 310 432 553

150 183 301 420 538

Although the LM94022 is very linear, its response does have

a slight downward parabolic shape. This shape is very accu-

rately reflected in the LM94022 Transfer Table. For a linear

approximation, a line can easily be calculated over the de-

sired temperature range from the Table 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 the Gain Setting at GS1 = 0 and GS0 = 0, over a tem-

perature 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.

11 www.national.com

LM94022/LM94022Q

2.0 Mounting and Thermal

Conductivity

The LM94022 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 thermal conductivity, the backside of the

LM94022 die is directly attached to the GND pin (Pin 2). The

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

LM94022 will also affect the temperature reading.

Alternatively, the LM94022 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 LM94022

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 output to ground or VDD, the output from the LM94022 will

not be correct. Printed-circuit coatings are often used to en-

sure that moisture cannot corrode the leads or circuit 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 LM94022's die temperature is

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

rent, ILis 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 Select = 11, VOUT = 2.231 mV,

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

showing a self-heating error of only 0.021°C. Since the

LM94022's junction temperature is the actual temperature

being measured, care should be taken to minimize the load

current that the LM94022 is required to drive. Figure 1 shows

the thermal resistance of the LM94022.

Device Number NS Package

Number

Thermal

Resistance (θJA)

LM94022BIMG MAA05A 415°C/W

FIGURE 1. LM94022 Thermal Resistance

3.0 Output and Noise

Considerations

A push-pull output gives the LM94022 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 LM94022 is ideal for this and other

applications which require strong source or sink current.

The LM94022's supply-noise gain (the ratio of the AC signal

on VOUT to the AC signal on VDD) was measured during bench

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

mance 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 LM94022.

4.0 Capacitive Loads

The LM94022 handles capacitive loading well. In an extreme-

ly noisy environment, or when driving a switched sampling

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

minimize noise coupling. Without any precautions, the

LM94022 can drive a capacitive load less than or equal to

1100 pF as shown in Figure 2. For capacitive loads greater

than 1100 pF, a series resistor may be required on the output,

as shown in Figure 3.

20143015

FIGURE 2. LM94022 No Decoupling Required for

Capacitive Loads Less than 1100 pF.

20143033

CLOAD Minimum RS

1.1 nF to 99 nF 3 kΩ

100 nF to 999 nF 1.5 kΩ

1 μF800 Ω

FIGURE 3. LM94022 with series resistor for capacitive

Loading greater than 1100 pF.

5.0 Output Voltage Shift

The LM94022 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 VOUT. The shift typically occurs when VDD-

VOUT = 1.0V.

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

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

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

20°C, VOUT is always monotonic. The accuracy specifications

in the Electrical Characteristics table already include this pos-

sible shift.

6.0 Selectable Gain for Optimization

and In Situ Testing

The Gain Select digital inputs can be tied to the rails or can

be driven from digital outputs such as microcontroller GPIO

pins. In low-supply voltage applications, the ability to reduce

the gain to -5.5 mV/°C allows the LM94022 to operate over

the full -50 °C to 150 °C range. When a larger supply voltage

www.national.com 12

LM94022/LM94022Q

is present, the gain can be increased as high as -13.6 mV/°

C. The larger gain is optimal for reducing the effects of noise

(for example, noise coupling on the output line or quantization

noise induced by an analog-to-digital converter which may be

sampling the LM94022 output).

Another application advantage of the digitally selectable gain

is the ability to perform dynamic testing of the LM94022 while

it is running in a system. By toggling the logic levels of the

gain select pins and monitoring the resultant change in the

output voltage level, the host system can verify the function-

ality of the LM94022.

13 www.national.com

LM94022/LM94022Q

7.0 Applications Circuits

20143018

FIGURE 4. Celsius Thermostat

20143019

FIGURE 5. Conserving Power Dissipation with Shutdown

20143028

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 LM94022 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

www.national.com 14

LM94022/LM94022Q

Physical Dimensions inches (millimeters) unless otherwise noted

5-Lead SC70 Molded Package

Order Number LM94022BIMG, LM94022BIMGX, LM94022QBIMG, LM94022QBIMGX

NS Package Number MAA05A

15 www.national.com

LM94022/LM94022Q

Notes

LM94022/LM94022Q 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output

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