LM94022BIMGX

LM94022/LM94022Q 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output December 6, 2007 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 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 −50°C to 150°C Applications ■ ■ ■ ■ Cell phones Wireless Transceivers Battery Management Automotive ■ Operating Temperature Connection Diagram SC70-5 Typical Transfer Characteristic Output Voltage vs Temperature 20143001 Top View See NS Package Number MAA05A 20143024 © 2007 National Semiconductor Corporation 201430 www.national.com 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 LM94022BIMG LM94022BIMGX LM94022QBIMG Temperature Accuracy ±1.5°C to ±2.7°C ±1.5°C to ±2.7°C ±1.5°C to ±2.7°C NS Package Number MAA05A MAA05A MAA05A Device Marking 22B 22B 22Q Transport Media 3000 Units on Tape and Reel 9000 Units on Tape and Reel 3000 Units on Tape and Reel 9000 Units on Tape and Reel AEC-Q100 Grade 0 Qualified. AutomotiveGrade Production Flow. AEC-Q100 Grade 0 Qualified. AutomotiveGrade Production Flow. Features LM94022QBIMGX ±1.5°C to ±2.7°C MAA05A 22Q www.national.com 2 LM94022/LM94022Q Pin Descriptions Label Pin Numb er 5 Type Equivalent Circuit Logic Input Gain Select 1 - One of two inputs for selecting the slope of the output response Function GS1 GS0 OUT 1 3 Logic Input Analog Output Gain Select 0 - One of two inputs for selecting the slope of the output response Outputs a voltage which is inversely proportional to temperature VDD GND 4 2 Power Ground Positive Supply Voltage Power Supply Ground 3 www.national.com LM94022/LM94022Q 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 +150°C 2500V Machine Model Soldering process must comply with National's Reflow Temperature Profile specifications. Refer to www.national.com/packaging. (Note 4) 250V Operating Ratings Specified Temperature Range: LM94022 Supply Voltage Range (VDD) (Note 1) −50°C ≤ TA ≤ +150°C  TMIN ≤ TA ≤ TMAX +1.5 V to +5.5 V 415°C/W Thermal Resistance (θJA) (Note 5) SC-70 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 GS1=0 (Note 8) GS0=0 Conditions 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 Limits (Note 7) ±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 Units (Limit) °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 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 Sensor Gain Conditions GS1 = 0, GS0 = 0 GS1 = 0, GS1 = 1 GS1 = 1, GS0 = 0 GS1 = 1, GS0 = 1 Load Regulation (Note 10) Source ≤ 50 μA, Sink ≤ 50 μA, Line Regulation (Note 13) IS Supply Current TA = +30°C to +150°C, (VDD - VOUT) ≥ 100mV TA = -50°C to +150°C, CL Output Load Capacitance Power-on Time (Note 11) VIH VIL IIH IIL GS1 and GS0 Input Logic "1" Threshold Voltage GS1 and GS0 Input Logic "0" Threshold Voltage Logic "1" Input Current (Note 12) Logic "0" Input Current (Note 12) 0.001 0.001 CL= 0 pF CL=1100 pF (VDD - VOUT) ≥ 100mV 1100 0.7 0.8 5 10 VDD- 0.5V 0.5 1 1 (VDD - VOUT) ≥ 200mV 0.26 200 5.4 5.4 8.1 9 1 mV (max) μV/V μA (max) μA (max) pF (max) ms (max) ms (max) V (min) V (max) μA (max) μA (max) VOUT ≥ 200mV Typical (Note 6) -5.5 -8.2 -10.9 -13.6 -0.22 -1 Limits (Note 7) Units (Limit) mV/°C mV/°C mV/°C mV/°C mV (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 www.national.com 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 20143005 www.national.com 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 20143037 www.national.com 8 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 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. Temperat GS = 00 ure (mV) (°C) -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 1104 1098 1093 1088 1082 1077 1072 1066 1061 1055 1050 1044 1039 1034 1028 1023 1017 1012 1007 1001 996 990 985 980 974 969 963 958 952 947 941 936 931 925 920 914 909 903 898 892 887 882 876 871 865 860 854 849 GS = 01 (mV) 1671 1663 1656 1648 1639 1631 1623 1615 1607 1599 1591 1583 1575 1567 1559 1551 1543 1535 1527 1519 1511 1502 1494 1486 1478 1470 1462 1454 1446 1438 1430 1421 1413 1405 1397 1389 1381 1373 1365 1356 1348 1340 1332 1324 1316 1308 1299 1291 GS = 10 (mV) 2239 2228 2218 2207 2197 2186 2175 2164 2154 2143 2132 2122 2111 2100 2089 2079 2068 2057 2047 2036 2025 2014 2004 1993 1982 1971 1961 1950 1939 1928 1918 1907 1896 1885 1874 1864 1853 1842 1831 1820 1810 1799 1788 1777 1766 1756 1745 1734 GS = 11 (mV) 2807 2793 2780 2767 2754 2740 2727 2714 2700 2687 2674 2660 2647 2633 2620 2607 2593 2580 2567 2553 2540 2527 2513 2500 2486 2473 2459 2446 2433 2419 2406 2392 2379 2365 2352 2338 2325 2311 2298 2285 2271 2258 2244 2231 2217 2204 2190 2176 LM94022 Transfer Table 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) -50 -49 -48 -47 -46 -45 -44 -43 -42 -41 -40 -39 -38 -37 -36 -35 -34 -33 -32 -31 -30 -29 -28 -27 -26 -25 -24 -23 -22 -21 -20 -19 -18 -17 -16 -15 -14 1299 1294 1289 1284 1278 1273 1268 1263 1257 1252 1247 1242 1236 1231 1226 1221 1215 1210 1205 1200 1194 1189 1184 1178 1173 1168 1162 1157 1152 1146 1141 1136 1130 1125 1120 1114 1109 1955 1949 1942 1935 1928 1921 1915 1908 1900 1892 1885 1877 1869 1861 1853 1845 1838 1830 1822 1814 1806 1798 1790 1783 1775 1767 1759 1751 1743 1735 1727 1719 1711 1703 1695 1687 1679 2616 2607 2598 2589 2580 2571 2562 2553 2543 2533 2522 2512 2501 2491 2481 2470 2460 2449 2439 2429 2418 2408 2397 2387 2376 2366 2355 2345 2334 2324 2313 2302 2292 2281 2271 2260 2250 3277 3266 3254 3243 3232 3221 3210 3199 3186 3173 3160 3147 3134 3121 3108 3095 3082 3069 3056 3043 3030 3017 3004 2991 2978 2965 2952 2938 2925 2912 2899 2886 2873 2859 2846 2833 2820 9 www.national.com LM94022/LM94022Q Temperat GS = 00 ure (mV) (°C) 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 843 838 832 827 821 816 810 804 799 793 788 782 777 771 766 760 754 749 743 738 732 726 721 715 710 704 698 693 687 681 676 670 664 659 653 647 642 636 630 625 619 613 608 602 596 591 585 579 GS = 01 (mV) 1283 1275 1267 1258 1250 1242 1234 1225 1217 1209 1201 1192 1184 1176 1167 1159 1151 1143 1134 1126 1118 1109 1101 1093 1084 1076 1067 1059 1051 1042 1034 1025 1017 1008 1000 991 983 974 966 957 949 941 932 924 915 907 898 890 GS = 10 (mV) 1723 1712 1701 1690 1679 1668 1657 1646 1635 1624 1613 1602 1591 1580 1569 1558 1547 1536 1525 1514 1503 1492 1481 1470 1459 1448 1436 1425 1414 1403 1391 1380 1369 1358 1346 1335 1324 1313 1301 1290 1279 1268 1257 1245 1234 1223 1212 1201 GS = 11 (mV) 2163 2149 2136 2122 2108 2095 2081 2067 2054 2040 2026 2012 1999 1985 1971 1958 1944 1930 1916 1902 1888 1875 1861 1847 1833 1819 1805 1791 1777 1763 1749 1735 1721 1707 1693 1679 1665 1651 1637 1623 1609 1595 1581 1567 1553 1539 1525 1511 Temperat GS = 00 ure (mV) (°C) 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 574 568 562 557 551 545 539 534 528 522 517 511 505 499 494 488 482 476 471 465 459 453 448 442 436 430 425 419 413 407 401 396 390 384 378 372 367 361 355 349 343 337 332 326 320 314 308 302 GS = 01 (mV) 881 873 865 856 848 839 831 822 814 805 797 788 779 771 762 754 745 737 728 720 711 702 694 685 677 668 660 651 642 634 625 617 608 599 591 582 573 565 556 547 539 530 521 513 504 495 487 478 GS = 10 (mV) 1189 1178 1167 1155 1144 1133 1122 1110 1099 1088 1076 1065 1054 1042 1031 1020 1008 997 986 974 963 951 940 929 917 906 895 883 872 860 849 837 826 814 803 791 780 769 757 745 734 722 711 699 688 676 665 653 GS = 11 (mV) 1497 1483 1469 1455 1441 1427 1413 1399 1385 1371 1356 1342 1328 1314 1300 1286 1272 1257 1243 1229 1215 1201 1186 1172 1158 1144 1130 1115 1101 1087 1073 1058 1044 1030 1015 1001 987 973 958 944 929 915 901 886 872 858 843 829 www.national.com 10 LM94022/LM94022Q Temperat GS = 00 ure (mV) (°C) 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 296 291 285 279 273 267 261 255 249 243 237 231 225 219 213 207 201 195 189 183 GS = 01 (mV) 469 460 452 443 434 425 416 408 399 390 381 372 363 354 346 337 328 319 310 301 GS = 10 (mV) 642 630 618 607 595 584 572 560 549 537 525 514 502 490 479 467 455 443 432 420 GS = 11 (mV) 814 800 786 771 757 742 728 713 699 684 670 655 640 626 611 597 582 568 553 538 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 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 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 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. 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 LM94022BIMG NS Package Number MAA05A Thermal Resistance (θJA) 415°C/W 20143033 CLOAD 1.1 nF to 99 nF 100 nF to 999 nF 1 μF Minimum RS 3 kΩ 1.5 kΩ 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. 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 functionality 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 1.5V, SC70, Multi-Gain Analog Temperature Sensor with Class-AB Output Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers Audio Clock Conditioners Data Converters Displays Ethernet Interface LVDS Power Management Switching Regulators LDOs LED Lighting PowerWise Serial Digital Interface (SDI) Temperature Sensors Wireless (PLL/VCO) www.national.com/amplifiers www.national.com/audio www.national.com/timing www.national.com/adc www.national.com/displays www.national.com/ethernet www.national.com/interface www.national.com/lvds www.national.com/power www.national.com/switchers www.national.com/ldo www.national.com/led www.national.com/powerwise www.national.com/sdi www.national.com/tempsensors www.national.com/wireless WEBENCH Analog University App Notes Distributors Green Compliance Packaging Design Support www.national.com/webench www.national.com/AU www.national.com/appnotes www.national.com/contacts www.national.com/quality/green www.national.com/packaging www.national.com/quality www.national.com/refdesigns www.national.com/feedback Quality and Reliability Reference Designs Feedback THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. NATIONAL MAKES NO REPRESENTATIONS OR WARRANTIES WITH RESPECT TO THE ACCURACY OR COMPLETENESS OF THE CONTENTS OF THIS PUBLICATION AND RESERVES THE RIGHT TO MAKE CHANGES TO SPECIFICATIONS AND PRODUCT DESCRIPTIONS AT ANY TIME WITHOUT NOTICE. NO LICENSE, WHETHER EXPRESS, IMPLIED, ARISING BY ESTOPPEL OR OTHERWISE, TO ANY INTELLECTUAL PROPERTY RIGHTS IS GRANTED BY THIS DOCUMENT. TESTING AND OTHER QUALITY CONTROLS ARE USED TO THE EXTENT NATIONAL DEEMS NECESSARY TO SUPPORT NATIONAL’S PRODUCT WARRANTY. EXCEPT WHERE MANDATED BY GOVERNMENT REQUIREMENTS, TESTING OF ALL PARAMETERS OF EACH PRODUCT IS NOT NECESSARILY PERFORMED. NATIONAL ASSUMES NO LIABILITY FOR APPLICATIONS ASSISTANCE OR BUYER PRODUCT DESIGN. BUYERS ARE RESPONSIBLE FOR THEIR PRODUCTS AND APPLICATIONS USING NATIONAL COMPONENTS. PRIOR TO USING OR DISTRIBUTING ANY PRODUCTS THAT INCLUDE NATIONAL COMPONENTS, BUYERS SHOULD PROVIDE ADEQUATE DESIGN, TESTING AND OPERATING SAFEGUARDS. EXCEPT AS PROVIDED IN NATIONAL’S TERMS AND CONDITIONS OF SALE FOR SUCH PRODUCTS, NATIONAL ASSUMES NO LIABILITY WHATSOEVER, AND NATIONAL DISCLAIMS ANY EXPRESS OR IMPLIED WARRANTY RELATING TO THE SALE AND/OR USE OF NATIONAL PRODUCTS INCLUDING LIABILITY OR WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER INTELLECTUAL PROPERTY RIGHT. LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS PRIOR WRITTEN APPROVAL OF THE CHIEF EXECUTIVE OFFICER AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: Life support devices or systems are devices 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. A critical component is any component in 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. National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. Copyright© 2007 National Semiconductor Corporation For the most current product information visit us at www.national.com National Semiconductor Americas Customer Support Center Email: new.feedback@nsc.com Tel: 1-800-272-9959 National Semiconductor Europe Customer Support Center Fax: +49 (0) 180-530-85-86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +49 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 National Semiconductor Asia Pacific Customer Support Center Email: ap.support@nsc.com National Semiconductor Japan Customer Support Center Fax: 81-3-5639-7507 Email: jpn.feedback@nsc.com Tel: 81-3-5639-7560 www.national.com