LM94022 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-todigital 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 batterypowered 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. Applications n n n n n Battery Management Automotive Disk Drives Games Appliances Features n n n n n n n n 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 j Supply Voltage 1.5V to 5.5V j Supply Current 5.4 µA (typ) j Temperature Accuracy j Operating Temperature n Cell phones n Wireless Transceivers Connection Diagram ± 50 µA ± 1.5˚C ± 1.8˚C ± 2.1˚C ± 2.7˚C j Output Drive 20˚C to 40˚C -50˚C to 70˚C -50˚C to 90˚C -50˚C to 150˚C −50˚C to 150˚C Typical Transfer Characteristic SC70-5 Output Voltage vs Temperature 20143001 Top View See NS Package Number MAA05A 20143024 © 2005 National Semiconductor Corporation DS201430 www.national.com LM94022 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output May 2005 LM94022 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 ± 1.5˚C to ± 2.7˚C ± 1.5˚C to ± 2.7˚C MAA05A 22B 3000 Units on Tape and Reel MAA05A 22B 9000 Units on Tape and Reel LM94022BIMG LM94022BIMGX Pin Descriptions Label Pin Number 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 www.national.com 2 Supply Voltage Machine Model Soldering process must comply with National’s Reflow Temperature Profile specifications. Refer to www.national.com/packaging. (Note 4) −0.2V to +6.0V Voltage at Output Pin −0.2V to (VDD + 0.5V) ± 7 mA Output Current Voltage at GS0 and GS1 Input Pins Storage Temperature Operating Ratings(Note 1) −0.2V to +6.0V Input Current at any pin (Note 2) 5 mA Specified Temperature Range: −65˚C to +150˚C Maximum Junction Temperature (TJMAX) Supply Voltage Range (VDD) +150˚C TMIN ≤ TA ≤ TMAX −50˚C ≤ TA ≤ +150˚C LM94022 +1.5 V to +5.5 V Thermal Resistance (θJA) (Note 5) SC-70 ESD Susceptibility (Note 3) : Human Body Model 250V 415˚C/W 2500V 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 Temperature Error (Note 8) Conditions GS1=0 GS0=0 TA = +20˚C to +40˚C; VDD = 1.5V to 5.5V TA = +0˚C to +70˚C; VDD = 1.5V to 5.5V TA = +0˚C to +90˚C; VDD = 1.5V to 5.5V TA = +0˚C to +120˚C; VDD = 1.5V to 5.5V TA = +0˚C to +150˚C; VDD = 1.5V to 5.5V TA = −50˚C to +0˚C; VDD = 1.6V to 5.5V GS1=0 GS0=1 TA = +20˚C to +40˚C; VDD = 1.8V to 5.5V TA = +0˚C to +70˚C; VDD = 1.9V to 5.5V TA = +0˚C to +90˚C; VDD = 1.9V to 5.5V TA = +0˚C to +120˚C; VDD = 1.9V to 5.5V TA = +0˚C to +150˚C; VDD = 1.9V to 5.5V TA = −50˚C to +0˚C; VDD = 2.3V to 5.5V GS1=1 GS0=0 TA = +20˚C to +40˚C; VDD = 2.2V to 5.5V TA = +0˚C to +70˚C; VDD = 2.4V to 5.5V TA = +0˚C to +90˚C; VDD = 2.4V to 5.5V TA = +0˚C to +120˚C; VDD = 2.4V to 5.5V TA = +0˚C to +150˚C; VDD = 2.4V to 5.5V TA = −50˚C to +0˚C; VDD = 3.0V to 5.5V GS1=1 GS0=1 TA = +20˚C to +40˚C; VDD = 2.7V to 5.5V TA = +0˚C to +70˚C; VDD = 3.0V to 5.5V TA = +0˚C to +90˚C; VDD = 3.0V to 5.5V TA = +0˚C to +120˚C; VDD = 3.0V to 5.5V TA = 0˚C to +150˚C; VDD = 3.0V to 5.5V TA = −50˚C to +0˚C; VDD = 3.6V to 5.5V 3 Limits (Note 7) Units (Limit) ± 1.5 ± 1.8 ± 2.1 ± 2.4 ± 2.7 ± 1.8 ± 1.5 ± 1.8 ± 2.1 ± 2.4 ± 2.7 ± 1.8 ± 1.5 ± 1.8 ± 2.1 ± 2.4 ± 2.7 ± 1.8 ± 1.5 ± 1.8 ± 2.1 ± 2.4 ± 2.7 ± 1.8 ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) ˚C (max) www.national.com LM94022 Absolute Maximum Ratings (Note 1) LM94022 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 Sensor Gain Load Regulation (Note 10) Conditions Typical (Note 6) -5.5 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, (VDD - VOUT) ≥ 200mV -0.22 Line Regulation (Note 13) CL Supply Current mV/˚C mV/˚C 0.26 -1 mV (max) 1 mV (max) 200 µV/V 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 9 µA (max) Output Load Capacitance Power-on Time (Note 11) Units (Limit) GS1 = 0, GS0 = 0 Sink ≤ 50 µA, (VDD - VOUT) ≥ 200mV IS Limits (Note 7) 1100 pF (max) CL= 0 pF 0.7 5 ms (max) CL=1100 pF 0.8 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. www.national.com 4 Temperature Error vs. Temperature Minimum Operating Temperature vs. Supply Voltage 20143007 20143006 Supply Current vs. Temperature Supply Current vs. Supply Voltage 20143004 20143005 Load Regulation, Sourcing Current Load Regulation, Sinking Current 20143040 20143041 5 www.national.com LM94022 Typical Performance Characteristics LM94022 Typical Performance Characteristics (Continued) Change in Vout vs. Overhead Voltage Supply-Noise Gain vs. Frequency 20143042 20143043 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 6 The output voltages in this table apply for VDD = 5V. 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. Temperature (˚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 LM94022 Transfer Table The output voltages in this table apply for VDD = 5V. Temperature (˚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 7 -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 35 843 1283 1723 2163 www.national.com LM94022 1.0 LM94022 Transfer Function LM94022 1.0 LM94022 Transfer Function The output voltages in this table apply for VDD = 5V. Temperature (˚C) GS = 00 (mV) GS = 01 (mV) GS = 10 (mV) GS = 11 (mV) (Continued) The output voltages in this table apply for VDD = 5V. 81 585 898 1212 1525 82 579 890 1201 1511 Temperature (˚C) GS = 00 (mV) GS = 01 (mV) GS = 10 (mV) GS = 11 (mV) 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 128 314 495 676 858 129 308 487 665 843 (Continued) LM94022 Transfer Table www.national.com 8 Although the LM94022 is very linear, its response does have a slight downward parabolic shape. This shape is very accurately 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 twopoint equation: (Continued) LM94022 Transfer Table (Continued) The output voltages in this table apply for VDD = 5V. Temperature (˚C) GS = 00 (mV) GS = 01 (mV) GS = 10 (mV) GS = 11 (mV) 130 302 478 653 829 131 296 469 642 814 132 291 460 630 800 133 285 452 618 786 134 279 443 607 771 135 273 434 595 757 136 267 425 584 742 137 261 416 572 728 138 255 408 560 713 139 249 399 549 699 140 243 390 537 684 141 237 381 525 670 142 231 372 514 655 143 225 363 502 640 144 219 354 490 626 145 213 346 479 611 146 207 337 467 597 147 201 328 455 582 148 195 319 443 568 149 189 310 432 553 150 183 301 420 538 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. 9 www.national.com LM94022 1.0 LM94022 Transfer Function LM94022 2.0 Mounting and Thermal Conductivity For operation in very noisy environments, some bypass capacitance should be present on the supply within approximately 2 inches of the LM94022. 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. 4.0 Capacitive Loads 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. 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 FIGURE 1. LM94022 Thermal Resistance CLOAD 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. 3.0 Output and Noise Considerations 5.0 Output Voltage Shift 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 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 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. www.national.com 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 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 possible shift. 10 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). 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 is present, the gain can be increased as high as -13.6 mV/˚C. The larger gain is optimal for reducing the effects of 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 functionality of the LM94022. 11 www.national.com LM94022 6.0 Selectable Gain for Optimization and In Situ Testing LM94022 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 12 inches (millimeters) unless otherwise noted 5-Lead SC70 Molded Package Order Number LM94022BIMG, LM94022BIMGX NS Package Number MAA05A National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. For the most current product information visit us at www.national.com. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. BANNED SUBSTANCE COMPLIANCE National Semiconductor manufactures products and uses packing materials that meet the provisions of the Customer Products Stewardship Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned Substances’’ as defined in CSP-9-111S2. National Semiconductor Americas Customer Support Center Email: [email protected] Tel: 1-800-272-9959 www.national.com National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: [email protected] National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: [email protected] Tel: 81-3-5639-7560 LM94022 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output Physical Dimensions