NSC LM94022

LM94022/LM94022Q
1.5V, SC70, Multi-Gain Analog Temperature Sensor with
Class-AB Output
General Description
The LM94022 is a precision analog output CMOS integratedcircuit 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 component count and board area. These inputs can also be driven
by logic signals allowing the system to optimize the gain during operation or system diagnostics.
■ 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
■ Supply Current
■ Output Drive
■ Temperature
Accuracy
Applications
■
■
■
■
Cell phones
Wireless Transceivers
Battery Management
Automotive
1.5V to 5.5V
5.4 μA (typ)
±50 μA
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
Connection Diagram
−50°C to 150°C
Typical Transfer Characteristic
SC70-5
Output Voltage vs Temperature
20143001
Top View
See NS Package Number MAA05A
20143024
© 2007 National Semiconductor Corporation
201430
www.national.com
LM94022/LM94022Q 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output
December 6, 2007
LM94022/LM94022Q
Typical Application
Full-Range Celsius Temperature Sensor (−50°C to +150°C)
Operating from a Single Battery Cell
20143002
Ordering Information
Order
Number
Temperature
Accuracy
NS Package
Number
Device
Marking
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. AutomotiveGrade Production Flow.
LM94022QBIMGX
±1.5°C to ±2.7°C
MAA05A
22Q
9000 Units on Tape
and Reel
AEC-Q100 Grade 0
Qualified. AutomotiveGrade Production Flow.
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2
Transport Media
Features
Label
Pin
Numb
er
Type
Function
Equivalent Circuit
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
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LM94022/LM94022Q
Pin Descriptions
LM94022/LM94022Q
Machine Model
Soldering process must comply with National's
Reflow Temperature Profile specifications. Refer to
www.national.com/packaging. (Note 4)
Absolute Maximum Ratings (Note 1)
Supply Voltage
Voltage at Output Pin
Output Current
Voltage at GS0 and GS1 Input Pins
Input Current at any pin (Note 2)
Storage Temperature
Maximum Junction Temperature
(TJMAX)
ESD Susceptibility (Note 3) :
Human Body Model
−0.2V to +6.0V
−0.2V to (VDD + 0.5V)
±7 mA
−0.2V to +6.0V
5 mA
−65°C to +150°C
Operating Ratings
(Note 1)
Specified Temperature Range:
LM94022
TMIN ≤ TA ≤ TMAX
−50°C ≤ TA ≤ +150°C
Supply Voltage Range (VDD)
+150°C
+1.5 V to +5.5 V
Thermal Resistance (θJA) (Note 5)
SC-70
2500V
250V
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
Temperature Error GS1=0
(Note 8)
GS0=0
GS1=0
GS0=1
GS1=1
GS0=0
GS1=1
GS0=1
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Limits
(Note 7)
Units
(Limit)
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)
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)
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)
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)
4
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
Sensor Gain
Load Regulation
(Note 10)
Conditions
Typical
(Note 6)
Limits (Note 7)
Units
(Limit)
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
Source ≤ 50 μA,
-0.22
-1
mV (max)
Sink ≤ 50 μA,
0.26
1
mV (max)
mV/°C
(VDD - VOUT) ≥ 200mV
VOUT ≥ 200mV
Line Regulation
(Note 13)
IS
Supply Current
μV/V
200
TA = +30°C to +150°C,
5.4
8.1
μA (max)
TA = -50°C to +150°C,
5.4
9
μA (max)
5
ms (max)
(VDD - VOUT) ≥ 100mV
(VDD - VOUT) ≥ 100mV
CL
Output Load Capacitance
Power-on Time
(Note 11)
1100
CL= 0 pF
0.7
CL=1100 pF
0.8
pF (max)
10
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 12)
0.001
1
μA (max)
IIL
Logic "0" Input Current
(Note 12)
0.001
1
μA (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: Guaranteed by design.
Note 12: 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.
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 5.0.
5
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LM94022/LM94022Q
Electrical Characteristics
LM94022/LM94022Q
Typical Performance Characteristics
Temperature Error vs. Temperature
Minimum Operating Temperature vs. Supply Voltage
20143007
20143006
Supply Current vs. Temperature
Supply Current vs. Supply Voltage
20143004
www.national.com
20143005
6
LM94022/LM94022Q
Load Regulation, Sourcing Current
Load Regulation, Sinking Current
20143040
20143041
Change in Vout vs. Overhead Voltage
Supply-Noise Gain vs. Frequency
20143042
20143043
7
www.national.com
LM94022/LM94022Q
Output Voltage vs. Supply Voltage
Gain Select = 00
Output Voltage vs. Supply Voltage
Gain Select = 01
20143034
20143035
Output Voltage vs. Supply Voltage
Gain Select = 10
Output Voltage vs. Supply Voltage
Gain Select = 11
20143036
www.national.com
20143037
8
Temperat GS = 00
ure
(mV)
(°C)
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
The output voltages in this table apply for VDD = 5V.
Temperat GS = 00
GS = 01
GS = 10
GS = 11
ure
(mV)
(mV)
(mV)
(mV)
(°C)
-6
1066
1615
2164
2714
-5
1061
1607
2154
2700
-4
1055
1599
2143
2687
-3
1050
1591
2132
2674
-50
1299
1955
2616
3277
-2
1044
1583
2122
2660
-49
1294
1949
2607
3266
-1
1039
1575
2111
2647
-48
1289
1942
2598
3254
0
1034
1567
2100
2633
-47
1284
1935
2589
3243
1
1028
1559
2089
2620
-46
1278
1928
2580
3232
2
1023
1551
2079
2607
-45
1273
1921
2571
3221
3
1017
1543
2068
2593
-44
1268
1915
2562
3210
4
1012
1535
2057
2580
-43
1263
1908
2553
3199
5
1007
1527
2047
2567
-42
1257
1900
2543
3186
6
1001
1519
2036
2553
-41
1252
1892
2533
3173
7
996
1511
2025
2540
-40
1247
1885
2522
3160
8
990
1502
2014
2527
-39
1242
1877
2512
3147
9
985
1494
2004
2513
-38
1236
1869
2501
3134
10
980
1486
1993
2500
-37
1231
1861
2491
3121
11
974
1478
1982
2486
-36
1226
1853
2481
3108
12
969
1470
1971
2473
-35
1221
1845
2470
3095
13
963
1462
1961
2459
-34
1215
1838
2460
3082
14
958
1454
1950
2446
-33
1210
1830
2449
3069
15
952
1446
1939
2433
-32
1205
1822
2439
3056
16
947
1438
1928
2419
-31
1200
1814
2429
3043
17
941
1430
1918
2406
-30
1194
1806
2418
3030
18
936
1421
1907
2392
-29
1189
1798
2408
3017
19
931
1413
1896
2379
-28
1184
1790
2397
3004
20
925
1405
1885
2365
-27
1178
1783
2387
2991
21
920
1397
1874
2352
-26
1173
1775
2376
2978
22
914
1389
1864
2338
-25
1168
1767
2366
2965
23
909
1381
1853
2325
-24
1162
1759
2355
2952
24
903
1373
1842
2311
-23
1157
1751
2345
2938
25
898
1365
1831
2298
-22
1152
1743
2334
2925
26
892
1356
1820
2285
-21
1146
1735
2324
2912
27
887
1348
1810
2271
-20
1141
1727
2313
2899
28
882
1340
1799
2258
-19
1136
1719
2302
2886
29
876
1332
1788
2244
-18
1130
1711
2292
2873
30
871
1324
1777
2231
-17
1125
1703
2281
2859
31
865
1316
1766
2217
-16
1120
1695
2271
2846
32
860
1308
1756
2204
-15
1114
1687
2260
2833
33
854
1299
1745
2190
-14
1109
1679
2250
2820
34
849
1291
1734
2176
The LM94022 has four selectable gains, each of which can
be selected by the GS1 and GS0 input pins. The output voltage 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
9
www.national.com
LM94022/LM94022Q
1.0 LM94022 Transfer Function
LM94022/LM94022Q
Temperat GS = 00
ure
(mV)
(°C)
GS = 01
(mV)
GS = 10
(mV)
GS = 11
(mV)
Temperat GS = 00
ure
(mV)
(°C)
GS = 01
(mV)
GS = 10
(mV)
GS = 11
(mV)
35
843
1283
1723
2163
83
574
881
1189
1497
36
838
1275
1712
2149
84
568
873
1178
1483
37
832
1267
1701
2136
85
562
865
1167
1469
38
827
1258
1690
2122
86
557
856
1155
1455
39
821
1250
1679
2108
87
551
848
1144
1441
40
816
1242
1668
2095
88
545
839
1133
1427
41
810
1234
1657
2081
89
539
831
1122
1413
42
804
1225
1646
2067
90
534
822
1110
1399
43
799
1217
1635
2054
91
528
814
1099
1385
44
793
1209
1624
2040
92
522
805
1088
1371
45
788
1201
1613
2026
93
517
797
1076
1356
46
782
1192
1602
2012
94
511
788
1065
1342
47
777
1184
1591
1999
95
505
779
1054
1328
48
771
1176
1580
1985
96
499
771
1042
1314
49
766
1167
1569
1971
97
494
762
1031
1300
50
760
1159
1558
1958
98
488
754
1020
1286
51
754
1151
1547
1944
99
482
745
1008
1272
52
749
1143
1536
1930
100
476
737
997
1257
53
743
1134
1525
1916
101
471
728
986
1243
54
738
1126
1514
1902
102
465
720
974
1229
55
732
1118
1503
1888
103
459
711
963
1215
56
726
1109
1492
1875
104
453
702
951
1201
57
721
1101
1481
1861
105
448
694
940
1186
58
715
1093
1470
1847
106
442
685
929
1172
59
710
1084
1459
1833
107
436
677
917
1158
60
704
1076
1448
1819
108
430
668
906
1144
61
698
1067
1436
1805
109
425
660
895
1130
62
693
1059
1425
1791
110
419
651
883
1115
63
687
1051
1414
1777
111
413
642
872
1101
64
681
1042
1403
1763
112
407
634
860
1087
65
676
1034
1391
1749
113
401
625
849
1073
66
670
1025
1380
1735
114
396
617
837
1058
67
664
1017
1369
1721
115
390
608
826
1044
68
659
1008
1358
1707
116
384
599
814
1030
69
653
1000
1346
1693
117
378
591
803
1015
70
647
991
1335
1679
118
372
582
791
1001
71
642
983
1324
1665
119
367
573
780
987
72
636
974
1313
1651
120
361
565
769
973
73
630
966
1301
1637
121
355
556
757
958
74
625
957
1290
1623
122
349
547
745
944
75
619
949
1279
1609
123
343
539
734
929
76
613
941
1268
1595
124
337
530
722
915
77
608
932
1257
1581
125
332
521
711
901
78
602
924
1245
1567
126
326
513
699
886
79
596
915
1234
1553
127
320
504
688
872
80
591
907
1223
1539
128
314
495
676
858
81
585
898
1212
1525
129
308
487
665
843
82
579
890
1201
1511
130
302
478
653
829
www.national.com
10
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
rately reflected in the LM94022 Transfer Table. For a linear
approximation, a line can easily be calculated over the desired 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 temperature range of 20°C to 50°C, we would proceed as follows:
Using this method of linear approximation, the transfer function can be approximated for one or more temperature ranges
of interest.
Although the LM94022 is very linear, its response does have
a slight downward parabolic shape. This shape is very accu-
11
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LM94022/LM94022Q
Temperat GS = 00
ure
(mV)
(°C)
LM94022/LM94022Q
4.0 Capacitive Loads
2.0 Mounting and Thermal
Conductivity
The LM94022 handles capacitive loading well. In an extremely 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.
The LM94022 can be applied easily in the same way as other
integrated-circuit temperature sensors. It can be glued or cemented 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 sealedend 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 condensation 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 ensure that moisture cannot corrode the leads or circuit traces.
The thermal resistance junction to ambient (θJA) is the parameter used to calculate the rise of a device junction temperature due to its power dissipation. The equation used to
calculate the rise in the LM94022's die temperature is
20143015
FIGURE 2. LM94022 No Decoupling Required for
Capacitive Loads Less than 1100 pF.
where TA is the ambient temperature, IQ is the quiescent current, 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
20143033
Minimum RS
1.1 nF to 99 nF
3 kΩ
100 nF to 999 nF
1.5 kΩ
1 μF
800 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 voltage 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 VDDVOUT = 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 possible shift.
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 example, driving dynamic loads like an input stage on an analogto-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 discussion 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 Performance Characteristics section. A load capacitor on the output
can help to filter noise.
For operation in very noisy environments, some bypass capacitance should be present on the supply within approximately 2 inches of the LM94022.
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CLOAD
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
12
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 functionality of the LM94022.
13
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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
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
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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
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LM94022/LM94022Q 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output
Notes
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