The LM26LV and LM26LV-Q1 are low-voltage, precision, dual-output, low-power temperature switches and temperature sensors. The temperature trip point (TTRIP) can be preset at the factory to any temperature in the range of 0°C to 150°C in 1°C increments. Built-in temperature hysteresis (THYST) keeps the output stable in an environment of temperature instability.
In normal operation the LM26LV or LM26LV-Q1 temperature switch outputs assert when the die temperature exceeds TTRIP. The temperature switch outputs will reset when the temperature falls below a temperature equal to (TTRIP – THYST). The OVERTEMP digital output, is active-high with a push-pull structure, while the OVERTEMP digital output, is active-low with an open-drain structure.
The analog output, VTEMP, delivers an analog output voltage with Negative Temperature Coefficient (NTC).
Driving the TRIP_TEST input high causes the digital outputs to be asserted for in-situ verification and causes the threshold voltage to appear at the VTEMP output pin, which could be used to verify the temperature trip point.
The LM26LV's and LM26LV-Q1's low minimum supply voltage makes them ideal for 1.8-V system designs. The wide operating range, low supply current, and excellent accuracy provide a temperature switch solution for a wide range of commercial and industrial applications.
PART NUMBER | PACKAGE | BODY SIZE (NOM) |
---|---|---|
LM26LV, LM26LV-Q1 | WSON (6) | 2.20 mm × 2.50 mm |
Changes from F Revision (February 2013) to G Revision
Changes from E Revision (February 2013) to F Revision
PIN | TYPE | DESCRIPTION | EQUIVALENT CIRCUIT | |
---|---|---|---|---|
NAME | NO. | |||
GND | 2 | GND | Power supply ground | — |
OVERTEMP | 5 | O | Overtemperature switch output. Active high, push-pull. Asserted when the measured temperature exceeds the trip point temperature or if TRIP_TEST = 1. This pin may be left open if not used. |
![]() |
OVERTEMP | 3 | O | Overtemperature switch output. Active low, open-drain (See Determining the Pullup Resistor Value). Asserted when the measured temperature exceeds the trip point temperature or if TRIP_TEST = 1. This pin may be left open if not used. |
![]() |
TRIP_TEST | 1 | I | TRIP_TEST pin. Active high input. If TRIP_TEST = 0 (Default) then: VTEMP = VTS, temperature sensor output voltage. If TRIP_TEST = 1 then: OVERTEMP and OVERTEMP outputs are asserted and VTEMP = VTRIP, temperature trip voltage. This pin may be left open if not used. |
![]() |
VDD | 4 | PWR | Positive supply voltage | — |
VTEMP | 6 | O | VTEMP analog voltage output. If TRIP_TEST = 0 then: VTEMP = VTS, temperature sensor output voltage. If TRIP_TEST = 1 then: VTEMP = VTRIP, temperature trip voltage. This pin may be left open if not used. |
![]() |
Thermal Pad | — | — | The best thermal conductivity between the device and the PCB is achieved by soldering the DAP of the package to the thermal pad on the PCB. The thermal pad can be a floating node. However, for improved noise immunity the thermal pad must be connected to the circuit GND node, preferably directly to pin 2 (GND) of the device. | — |
MIN | MAX | UNIT | |
---|---|---|---|
Supply voltage | –0.3 | 6 | V |
Voltage at OVERTEMP pin | –0.3 | 6 | V |
Voltage at OVERTEMP and VTEMP pins | –0.3 | VDD + 0.5 | V |
TRIP_TEST input voltage | –0.3 | VDD + 0.5 | V |
Output current, any output pin | –7 | 7 | mA |
Input current at any pin(2) | 5 | mA | |
Maximum junction temperature, TJ(MAX) | 155 | °C | |
Storage temperature, Tstg | –65 | 150 | °C |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) | ±4500 | V |
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) | ±1000 | |||
Machine model (MM)(3) | ±300 |
VALUE | UNIT | |||
---|---|---|---|---|
V(ESD) | Electrostatic discharge | Human-body model (HBM), per AEC Q100-002(1) | ±4500 | V |
Charged-device model (CDM), per AEC Q100-011 | ±1000 | |||
Machine model (MM) | ±300 |
MIN | NOM | MAX | UNIT | ||
---|---|---|---|---|---|
VDD | Supply voltage | 1.6 | 5.5 | V | |
Supply current | 8 | µA | |||
TA | Specified ambient temperature | –50 | 150 | °C |
THERMAL METRIC(1) | LM26LV and LM26LV-Q1 | UNIT | |
---|---|---|---|
NGF (WSON) | |||
6 PINS | |||
RθJA | Junction-to-ambient thermal resistance | 100.7 | °C/W |
RθJC(top) | Junction-to-case (top) thermal resistance | 121.7 | °C/W |
RθJB | Junction-to-board thermal resistance | 70 | °C/W |
ψJT | Junction-to-top characterization parameter | 7.1 | °C/W |
ψJB | Junction-to-board characterization parameter | 70.3 | °C/W |
RθJC(bot) | Junction-to-case (bottom) thermal resistance | 15.9 | °C/W |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | ||
---|---|---|---|---|---|---|---|
GENERAL SPECIFICATIONS | |||||||
IS | Quiescent power supply current | 8 | 16 | µA | |||
Hysteresis | 4.5 | 5 | 5.5 | °C | |||
OVERTEMP DIGITAL OUTPUT—ACTIVE HIGH, PUSH-PULL | |||||||
VOH | Logic High output voltage | VDD ≥ 1.6 V, Source ≤ 340 µA | VDD – 0.2 | V | |||
VDD ≥ 2 V, Source ≤ 498 µA | VDD – 0.2 | ||||||
VDD ≥ 3.3 V, Source ≤ 780 µA | VDD – 0.2 | ||||||
VDD ≥ 1.6 V, Source ≤ 600 µA | VDD – 0.45 | ||||||
VDD ≥ 2 V, Source ≤ 980 µA | VDD – 0.45 | ||||||
VDD ≥ 3.3 V, Source ≤ 1.6 mA | VDD – 0.45 | ||||||
BOTH OVERTEMP AND OVERTEMP DIGITAL OUTPUTS | |||||||
VOL | Logic Low output voltage | VDD ≥ 1.6 V, Source ≤ 385 µA | 0.2 | V | |||
VDD ≥ 2 V, Source ≤ 500 µA | 0.2 | ||||||
VDD ≥ 3.3 V, Source ≤ 730 µA | 0.2 | ||||||
VDD ≥ 1.6 V, Source ≤ 690 µA | 0.45 | ||||||
VDD ≥ 2 V, Source ≤ 1.05 mA | 0.45 | ||||||
VDD ≥ 3.3 V, Source ≤ 1.62 mA | 0.45 | ||||||
OVERTEMP DIGITAL OUTPUT—ACTIVE LOW, OPEN DRAIN | |||||||
IOH | Logic High output leakage current(3) | TA = 30°C | 0.001 | 1 | µA | ||
TA = 150°C | 0.025 | 1 | |||||
VTEMP ANALOG TEMPERATURE SENSOR OUTPUT | |||||||
VTEMP sensor gain | Gain 1 (trip point = 0°C to 69°C) | –5.1 | mV/°C | ||||
Gain 2 (trip point = 70°C to 109°C) | –7.7 | ||||||
Gain 3 (trip point = 110°C to 129°C) | –10.3 | ||||||
Gain 4 (trip point = 130°C to 150°C) | –12.8 | ||||||
VTEMP load regulation(4) | 1.6 V ≤ VDD < 1.8 V | Source ≤ 90 µA, VDD – VTEMP ≥ 200 mV |
–1 | –0.1 | mV | ||
Sink ≤ 100 µA, VTEMP ≥ 260 mV | 0.1 | 1 | |||||
VDD ≥ 1.8 V | Source ≤ 120 µA, VDD – VTEMP ≥ 200 mV |
–1 | –0.1 | ||||
Sink ≤ 200 µA, VTEMP ≥ 260 mV | 0.1 | 1 | |||||
Source or sink = 100 µA | 1 | Ω | |||||
Supply to VTEMP DC line regulation(5) | VDD = 1.6 V to 5.5 V | 0.29 | mV | ||||
74 | µV/V | ||||||
–82 | dB | ||||||
CL | VTEMP output load capacitance | Without series resistor. See Capacitive Loads. | 1100 | pF | |||
TRIP_TEST DIGITAL INPUT | |||||||
VIH | Logic High threshold voltage | VDD – 0.5 | V | ||||
VIL | Logic Low threshold voltage | 0.5 | |||||
IIH | Logic High input current | 1.5 | 2.5 | µA | |||
IIL | Logic Low input current(3) | 0.001 | 1 | µA |
PARAMETER | TEST CONDITIONS | MIN | TYP | MAX | UNIT | |
---|---|---|---|---|---|---|
tEN | Time from power ON to digital output enabled(1) | 1.1 | 2.3 | ms | ||
tVTEMP | Time from power ON to analog temperature valid(1) | CL = 0 pF to 1100 pF | 1 | 2.9 | ms |
PARAMETER | TEST CONDITIONS | MIN | MAX | UNIT | |
---|---|---|---|---|---|
TRIP POINT ACCURACY | |||||
Trip point accuracy(2) | TA = 0°C to 150°C, VDD = 5 V | –2.2 | 2.2 | °C | |
VTEMP ANALOG TEMPERATURE SENSOR OUTPUT ACCURACY(3) | |||||
VTEMP temperature accuracy(2) | Gain 1 trip point = 0°C to 69°C |
TA = 20°C to 40°C, VDD = 1.6 V to 5.5 V | –1.8 | 1.8 | °C |
TA = 0°C to 70°C, VDD = 1.6 V to 5.5 V | –2 | 2 | |||
TA = 0°C to 90°C, VDD = 1.6 V to 5.5 V | –2.1 | 2.1 | |||
TA = 0°C to 120°C, VDD = 1.6 V to 5.5 V | –2.2 | 2.2 | |||
TA = 0°C to 150°C, VDD = 1.6 V to 5.5 V | –2.3 | 2.3 | |||
TA = –50°C to 0°C, VDD = 1.7 V to 5.5 V | –1.7 | 1.7 | |||
Gain 2 trip point = 70°C to 109°C |
TA = 20°C to 40°C, VDD = 1.8 V to 5.5 V | –1.8 | 1.8 | ||
TA = 0°C to 70°C, VDD = 1.9 V to 5.5 V | –2 | 2 | |||
TA = 0°C to 90°C, VDD = 1.9 V to 5.5 V | –2.1 | 2.1 | |||
TA = 0°C to 120°C, VDD = 1.9 V to 5.5 V | –2.2 | 2.2 | |||
TA = 0°C to 150°C, VDD = 1.9 V to 5.5 V | –2.3 | 2.3 | |||
TA = –50°C to 0°C, VDD = 2.3 V to 5.5 V | –1.7 | 1.7 | |||
Gain 3 trip point = 110°C to 129°C |
TA = 20°C to 40°C, VDD = 2.3 V to 5.5 V | –1.8 | 1.8 | ||
TA = 0°C to 70°C, VDD = 2.5 V to 5.5 V | –2 | 2 | |||
TA = 0°C to 90°C, VDD = 2.5 V to 5.5 V | –2.1 | 2.1 | |||
TA = 0°C to 120°C, VDD = 2.5 V to 5.5 V | –2.2 | 2.2 | |||
TA = 0°C to 150°C, VDD = 2.5 V to 5.5 V | –2.3 | 2.3 | |||
TA = –50°C to 0°C, VDD = 3 V to 5.5 V | –1.7 | 1.7 | |||
Gain 4 trip point = 130°C to 150°C |
TA = 20°C to 40°C, VDD = 2.7 V to 5.5 V | –1.8 | 1.8 | ||
TA = 0°C to 70°C, VDD = 3 V to 5.5 V | –2 | 2 | |||
TA = 0°C to 90°C, VDD = 3 V to 5.5 V | –2.1 | 2.1 | |||
TA = 0°C to 120°C, VDD = 3 V to 5.5 V | –2.2 | 2.2 | |||
TA = 0°C to 150°C, VDD = 3 V to 5.5 V | –2.3 | 2.3 | |||
TA = –50°C to 0°C, VDD = 3.6 V to 5.5 V | –1.7 | 1.7 |
100-mV overhead | TA = 80°C | Sourcing current |
VDD = 1.6 V | Sinking Current |
VDD = 2.4 V | Sinking Current |
Gain 2 (Trip Points = 70°C to 109°C) |
Gain 4 (Trip Points = 130°C to 150°C) |
200-mV overhead | TA = 80°C | Sourcing Current |
1.72-V overhead TA = 150°C | VDD = 2.4 V Sourcing current |
VDD = 1.8 V | Sinking Current |
Gain 1 (Trip Points = 0°C tp 69°C) |
Gain 3 (Trip Points = 110°C to 129°C) |
The LM26LV and LM26LV-Q1 are precision, dual-output, temperature switches with analog temperature sensor output. The trip temperature (TTRIP) is factory selected by the order number. The VTEMP class AB analog output provides a voltage that is proportional to temperature. The LM26LV and LM26LV-Q1 include an internal reference DAC (TEMP THRESHOLD), analog temperature sensor and analog comparator. The reference DAC is connected to one of the comparator inputs. The reference DAC output voltage (VTRIP) is preprogrammed by TI. The result of the reference DAC voltage and the temperature sensor output comparison is provided on two output pins OVERTEMP and OVERTEMP.
The VTEMP output has a programmable gain. The output gain has 4 possible settings as described in Table 1. The gain setting is dependent on the temperature trip point selected.
Built-in temperature hysteresis (THYST) prevents the digital outputs from oscillating. The OVERTEMP and OVERTEMP activates when the die temperature exceeds TTRIP and releases when the temperature falls below a temperature equal to TTRIP minus THYST. OVERTEMP is active-high with a push-pull structure. OVERTEMP, is active-low with an open-drain structure. The comparator hysteresis is fixed at 5°C.
Driving the TRIP-TEST high activates the digital outputs. A processor can check the logic level of the OVERTEMP or OVERTEMP, confirming that they changed to their active state. This allows for system production testing verification that the comparator and output circuitry are functional after system assembly. When the TRIP-TEST pin is high, the trip-level reference voltage appears at the VTEMP pin. Tying OVERTEMP to TRIP-TEST latches the output after it trips. It can be cleared by forcing TRIP-TEST low or powering off the LM26LV or LM26LV-Q1.
The LM26LV and LM26LV-Q1 have one out of four possible factory-set gains, Gain 1 through Gain 4, depending on the range of the Temperature Trip Point. The VTEMP temperature sensor voltage, in millivolts, at each discrete die temperature over the complete operating temperature range, and for each of the four Temperature Trip Point ranges, is shown in Table 1. This table is the reference from which the LM26LV and LM26LV-Q1 accuracy specifications (listed in Accuracy Characteristics) are determined. This table can be used, for example, in a host processor look-up table. See The Second-Order Equation (Parabolic) for the parabolic equation used in the Conversion Table.
DIE TEMPERATURE (°C) | ANALOG OUTPUT VOLTAGE, VTEMP (mV)(1) | |||
---|---|---|---|---|
GAIN 1 | GAIN 2 | GAIN 3 | GAIN 4 | |
–50 | 1312 | 1967 | 2623 | 3278 |
–49 | 1307 | 1960 | 2613 | 3266 |
–48 | 1302 | 1952 | 2603 | 3253 |
–47 | 1297 | 1945 | 2593 | 3241 |
–46 | 1292 | 1937 | 2583 | 3229 |
–45 | 1287 | 1930 | 2573 | 3216 |
–44 | 1282 | 1922 | 2563 | 3204 |
–43 | 1277 | 1915 | 2553 | 3191 |
–42 | 1272 | 1908 | 2543 | 3179 |
–41 | 1267 | 1900 | 2533 | 3166 |
–40 | 1262 | 1893 | 2523 | 3154 |
–39 | 1257 | 1885 | 2513 | 3141 |
–38 | 1252 | 1878 | 2503 | 3129 |
–37 | 1247 | 1870 | 2493 | 3116 |
–36 | 1242 | 1863 | 2483 | 3104 |
–35 | 1237 | 1855 | 2473 | 3091 |
–34 | 1232 | 1848 | 2463 | 3079 |
–33 | 1227 | 1840 | 2453 | 3066 |
–32 | 1222 | 1833 | 2443 | 3054 |
–31 | 1217 | 1825 | 2433 | 3041 |
–30 | 1212 | 1818 | 2423 | 3029 |
–29 | 1207 | 1810 | 2413 | 3016 |
–28 | 1202 | 1803 | 2403 | 3004 |
–27 | 1197 | 1795 | 2393 | 2991 |
–26 | 1192 | 1788 | 2383 | 2979 |
–25 | 1187 | 1780 | 2373 | 2966 |
–24 | 1182 | 1773 | 2363 | 2954 |
–23 | 1177 | 1765 | 2353 | 2941 |
–22 | 1172 | 1757 | 2343 | 2929 |
–21 | 1167 | 1750 | 2333 | 2916 |
–20 | 1162 | 1742 | 2323 | 2903 |
–19 | 1157 | 1735 | 2313 | 2891 |
–18 | 1152 | 1727 | 2303 | 2878 |
–17 | 1147 | 1720 | 2293 | 2866 |
–16 | 1142 | 1712 | 2283 | 2853 |
–15 | 1137 | 1705 | 2272 | 2841 |
–14 | 1132 | 1697 | 2262 | 2828 |
–13 | 1127 | 1690 | 2252 | 2815 |
–12 | 1122 | 1682 | 2242 | 2803 |
–11 | 1116 | 1674 | 2232 | 2790 |
–10 | 1111 | 1667 | 2222 | 2777 |
–9 | 1106 | 1659 | 2212 | 2765 |
–8 | 1101 | 1652 | 2202 | 2752 |
–7 | 1096 | 1644 | 2192 | 2740 |
–6 | 1091 | 1637 | 2182 | 2727 |
–5 | 1086 | 1629 | 2171 | 2714 |
–4 | 1081 | 1621 | 2161 | 2702 |
–3 | 1076 | 1614 | 2151 | 2689 |
–2 | 1071 | 1606 | 2141 | 2676 |
–1 | 1066 | 1599 | 2131 | 2664 |
0 | 1061 | 1591 | 2121 | 2651 |
1 | 1056 | 1583 | 2111 | 2638 |
2 | 1051 | 1576 | 2101 | 2626 |
3 | 1046 | 1568 | 2090 | 2613 |
4 | 1041 | 1561 | 2080 | 2600 |
5 | 1035 | 1553 | 2070 | 2587 |
6 | 1030 | 1545 | 2060 | 2575 |
7 | 1025 | 1538 | 2050 | 2562 |
8 | 1020 | 1530 | 2040 | 2549 |
9 | 1015 | 1522 | 2029 | 2537 |
10 | 1010 | 1515 | 2019 | 2524 |
11 | 1005 | 1507 | 2009 | 2511 |
12 | 1000 | 1499 | 1999 | 2498 |
13 | 995 | 1492 | 1989 | 2486 |
14 | 990 | 1484 | 1978 | 2473 |
15 | 985 | 1477 | 1968 | 2460 |
16 | 980 | 1469 | 1958 | 2447 |
17 | 974 | 1461 | 1948 | 2435 |
18 | 969 | 1454 | 1938 | 2422 |
19 | 964 | 1446 | 1927 | 2409 |
20 | 959 | 1438 | 1917 | 2396 |
21 | 954 | 1431 | 1907 | 2383 |
22 | 949 | 1423 | 1897 | 2371 |
23 | 944 | 1415 | 1886 | 2358 |
24 | 939 | 1407 | 1876 | 2345 |
25 | 934 | 1400 | 1866 | 2332 |
26 | 928 | 1392 | 1856 | 2319 |
27 | 923 | 1384 | 1845 | 2307 |
28 | 918 | 1377 | 1835 | 2294 |
29 | 913 | 1369 | 1825 | 2281 |
30 | 908 | 1361 | 1815 | 2268 |
31 | 903 | 1354 | 1804 | 2255 |
32 | 898 | 1346 | 1794 | 2242 |
33 | 892 | 1338 | 1784 | 2230 |
34 | 887 | 1331 | 1774 | 2217 |
35 | 882 | 1323 | 1763 | 2204 |
36 | 877 | 1315 | 1753 | 2191 |
37 | 872 | 1307 | 1743 | 2178 |
38 | 867 | 1300 | 1732 | 2165 |
39 | 862 | 1292 | 1722 | 2152 |
40 | 856 | 1284 | 1712 | 2139 |
41 | 851 | 1276 | 1701 | 2127 |
42 | 846 | 1269 | 1691 | 2114 |
43 | 841 | 1261 | 1681 | 2101 |
44 | 836 | 1253 | 1670 | 2088 |
45 | 831 | 1245 | 1660 | 2075 |
46 | 825 | 1238 | 1650 | 2062 |
47 | 820 | 1230 | 1639 | 2049 |
48 | 815 | 1222 | 1629 | 2036 |
49 | 810 | 1214 | 1619 | 2023 |
50 | 805 | 1207 | 1608 | 2010 |
51 | 800 | 1199 | 1598 | 1997 |
52 | 794 | 1191 | 1588 | 1984 |
53 | 789 | 1183 | 1577 | 1971 |
54 | 784 | 1176 | 1567 | 1958 |
55 | 779 | 1168 | 1557 | 1946 |
56 | 774 | 1160 | 1546 | 1933 |
57 | 769 | 1152 | 1536 | 1920 |
58 | 763 | 1144 | 1525 | 1907 |
59 | 758 | 1137 | 1515 | 1894 |
60 | 753 | 1129 | 1505 | 1881 |
61 | 748 | 1121 | 1494 | 1868 |
62 | 743 | 1113 | 1484 | 1855 |
63 | 737 | 1105 | 1473 | 1842 |
64 | 732 | 1098 | 1463 | 1829 |
65 | 727 | 1090 | 1453 | 1816 |
66 | 722 | 1082 | 1442 | 1803 |
67 | 717 | 1074 | 1432 | 1790 |
68 | 711 | 1066 | 1421 | 1776 |
69 | 706 | 1059 | 1411 | 1763 |
70 | 701 | 1051 | 1400 | 1750 |
71 | 696 | 1043 | 1390 | 1737 |
72 | 690 | 1035 | 1380 | 1724 |
73 | 685 | 1027 | 1369 | 1711 |
74 | 680 | 1019 | 1359 | 1698 |
75 | 675 | 1012 | 1348 | 1685 |
76 | 670 | 1004 | 1338 | 1672 |
77 | 664 | 996 | 1327 | 1659 |
78 | 659 | 988 | 1317 | 1646 |
79 | 654 | 980 | 1306 | 1633 |
80 | 649 | 972 | 1296 | 1620 |
81 | 643 | 964 | 1285 | 1607 |
82 | 638 | 957 | 1275 | 1593 |
83 | 633 | 949 | 1264 | 1580 |
84 | 628 | 941 | 1254 | 1567 |
85 | 622 | 933 | 1243 | 1554 |
86 | 617 | 925 | 1233 | 1541 |
87 | 612 | 917 | 1222 | 1528 |
88 | 607 | 909 | 1212 | 1515 |
89 | 601 | 901 | 1201 | 1501 |
90 | 596 | 894 | 1191 | 1488 |
91 | 591 | 886 | 1180 | 1475 |
92 | 586 | 878 | 1170 | 1462 |
93 | 580 | 870 | 1159 | 1449 |
94 | 575 | 862 | 1149 | 1436 |
95 | 570 | 854 | 1138 | 1422 |
96 | 564 | 846 | 1128 | 1409 |
97 | 559 | 838 | 1117 | 1396 |
98 | 554 | 830 | 1106 | 1383 |
99 | 549 | 822 | 1096 | 1370 |
100 | 543 | 814 | 1085 | 1357 |
101 | 538 | 807 | 1075 | 1343 |
102 | 533 | 799 | 1064 | 1330 |
103 | 527 | 791 | 1054 | 1317 |
104 | 522 | 783 | 1043 | 1304 |
105 | 517 | 775 | 1032 | 1290 |
106 | 512 | 767 | 1022 | 1277 |
107 | 506 | 759 | 1011 | 1264 |
108 | 501 | 751 | 1001 | 1251 |
109 | 496 | 743 | 990 | 1237 |
110 | 490 | 735 | 979 | 1224 |
111 | 485 | 727 | 969 | 1211 |
112 | 480 | 719 | 958 | 1198 |
113 | 474 | 711 | 948 | 1184 |
114 | 469 | 703 | 937 | 1171 |
115 | 464 | 695 | 926 | 1158 |
116 | 459 | 687 | 916 | 1145 |
117 | 453 | 679 | 905 | 1131 |
118 | 448 | 671 | 894 | 1118 |
119 | 443 | 663 | 884 | 1105 |
120 | 437 | 655 | 873 | 1091 |
121 | 432 | 647 | 862 | 1078 |
122 | 427 | 639 | 852 | 1065 |
123 | 421 | 631 | 841 | 1051 |
124 | 416 | 623 | 831 | 1038 |
125 | 411 | 615 | 820 | 1025 |
126 | 405 | 607 | 809 | 1011 |
127 | 400 | 599 | 798 | 998 |
128 | 395 | 591 | 788 | 985 |
129 | 389 | 583 | 777 | 971 |
130 | 384 | 575 | 766 | 958 |
131 | 379 | 567 | 756 | 945 |
132 | 373 | 559 | 745 | 931 |
133 | 368 | 551 | 734 | 918 |
134 | 362 | 543 | 724 | 904 |
135 | 357 | 535 | 713 | 891 |
136 | 352 | 527 | 702 | 878 |
137 | 346 | 519 | 691 | 864 |
138 | 341 | 511 | 681 | 851 |
139 | 336 | 503 | 670 | 837 |
140 | 330 | 495 | 659 | 824 |
141 | 325 | 487 | 649 | 811 |
142 | 320 | 479 | 638 | 797 |
143 | 314 | 471 | 627 | 784 |
144 | 309 | 463 | 616 | 770 |
145 | 303 | 455 | 606 | 757 |
146 | 298 | 447 | 595 | 743 |
147 | 293 | 438 | 584 | 730 |
148 | 287 | 430 | 573 | 716 |
149 | 282 | 422 | 562 | 703 |
150 | 277 | 414 | 552 | 690 |
The LM26LV's and LM26LV-Q1's VTEMP analog temperature output is very linear. Table 1 and the equation in The Second-Order Equation (Parabolic) represent the most accurate typical performance of the VTEMP voltage output versus temperature.
The data from Table 1, or Equation 1, when plotted, has an umbrella-shaped parabolic curve. VTEMP is in mV.
For a quicker approximation, although less accurate than the second-order, over the full operating temperature range the linear formula below can be used. Using Equation 2, with the constant and slope in the following set of equations, the best-fit VTEMP versus die temperature performance can be calculated with an approximation error less than 18 mV. VTEMP is in mV.
For a linear approximation, a line can easily be calculated over the desired temperature range from Table 1 using the two-point equation:
where
For example, to determine the equation of a line with GAIN4, with a temperature from 20°C to 50°C, proceed using Equation 4, Equation 5, and Equation 6:
Using this method of linear approximation, the transfer function can be approximated for one or more temperature ranges of interest.
The OVERTEMP active high, push-pull output and the OVERTEMP active low, open-drain output both assert at the same time whenever the die temperature reaches the factory preset temperature trip point. They also assert simultaneously whenever the TRIP_TEST pin is set high. Both outputs deassert when the die temperature goes below the temperature trip point hysteresis. These two types of digital outputs enable the user the flexibility to choose the type of output that is most suitable for his design.
Either the OVERTEMP or the OVERTEMP digital output pins can be left open if not used.
The OVERTEMP active low, open-drain digital output, if used, requires a pullup resistor between this pin and VDD. The following section shows how to determine the pullup resistor value.
The pullup resistor value is calculated at the condition of maximum total current, IT, through the resistor. The total current is:
where
The pullup resistor maximum value can be found by using Equation 8.
where
Suppose, for this example, a VDD of 3.3 V ± 0.3 V, a CMOS digital input as a load, a VOL of 0.2 V.
In this example, if 5% resistor values are used, then the next closest value is 100 kΩ.
The TRIP_TEST pin simply provides a means to test the OVERTEMP and OVERTEMP digital outputs electronically by causing them to assert, at any operating temperature, as a result of forcing the TRIP_TEST pin high.
When the TRIP_TEST pin is pulled high the VTEMP pin is at the VTRIP voltage.
If not used, the TRIP_TEST pin may either be left open or grounded.
The VTEMP push-pull output provides 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 Application and Implementation for more discussion of this topic. The LM26LV and LM26LV-Q1 are ideal for applications which require strong source or sink current.
The LM26LV's and LM26LV-Q1's supply-noise rejection (the ratio of the AC signal on VTEMP to the AC signal on VDD) was measured during bench tests. The device's typical attenuation is shown in Typical Characteristics. A load capacitor on the output can help to filter noise.
For operation in very noisy environments, some bypass capacitance must be present on the supply within approximately 2 inches of the LM26LV or LM26LV-Q1.
The VTEMP Output 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 VTEMP can drive a capacitive load less than or equal to 1100 pF as shown in Figure 20. For capacitive loads greater than 1100 pF, a series resistor is required on the output, as shown in Figure 21, to maintain stable conditions.
CLOAD | MINIMUM RS |
---|---|
1.1 nF to 99 nF | 3 kΩ |
100 nF to 999 nF | 1.5 kΩ |
1 µF | 800 Ω |
The LM26LV and LM26LV-Q1 are 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 VTEMP. The shift typically occurs when VDD – VTEMP = 1 V.
This slight shift (a few millivolts) takes place over a wide change (approximately 200 mV) in VDD or VTEMP. Because the shift takes place over a wide temperature change of 5°C to 20°C, VTEMP is always monotonic. The accuracy specifications Accuracy Characteristics already includes this possible shift.
The LM26LV and LM26LV-Q1 have several modes of operation as detailed in the following drawings.
The TRIP_TEST pin, normally used to check the operation of the OVERTEMP and OVERTEMP pins, may be used to latch the outputs whenever the temperature exceeds the programmed limit and causes the digital outputs to assert. As shown in Figure 25, when OVERTEMP goes high the TRIP_TEST input is also pulled high and causes OVERTEMP output to latch high and the OVERTEMP output to latch low. The latch can be released by either momentarily pulling the TRIP_TEST pin low (GND), or by toggling the power supply to the device. The resistor limits the current out of the OVERTEMP output pin.
Alternately, the circuit in Figure 25 the 100 kΩ can be replaced with a short and the momentary reset switch may be removed. In this configuration, when OVERTEMP goes active high, it drives TRIP_TEST high. THRIP TEST high causes OVERTEMP to stay high. It is therefore latched. To release the latch, power down, then power up the LM26LV or LM26LV-Q1. The LM26LV and LM26LV-Q1 always come up in a released condition.
NOTE
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
The LM26LV and LM26LV-Q1 have an analog temperature sensor output VTEMP that can be directly connected to an ADC (Analog-to-Digital Converter) input. Most CMOS ADCs found in microcontrollers and ASICs have a sampled data comparator input structure. When the ADC charges the sampling cap, it requires instantaneous charge from the output of the analog source such as the LM26LV or LM26LV-Q1 temperature sensor. 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. Because not all ADCs have identical input stages, the charge requirements vary. This general ADC application is shown as an example only.
For this design example, use the parameters listed in Table 3 as the input parameters.
PARAMETER | EXAMPLE VALUE |
---|---|
Temperature | 0°C to 150°C (LM26LV), –40°C to 85°C for microcontroller |
Accuracy | ±2.3°C (Gain1, TA = 0°C to 150°C) |
VDD | 3.3 V |
IDD | 8 µA |
The LM26LV and LM26LV-Q1 come with a factory preset trip point. See Mechanical, Packaging, and Orderable Information for available trip point options. Figure 27 shows the device's OVERTEMP output driving a microcontroller interrupt input to indicate an overtemperature event. In addition to the OVERTEMP output, a OVERTEMP output is available for use depending on the interrupt polarity of the microcontroller's interrupt pin. A VTEMP analog output is available to drive the microcontroller ADC input allowing the microcontroller to determine the sensing temperature of the LM26LV or LM26LV-Q1. The TRIP_TEST input is connected to a microcontroller output pin allowing the microcontroller to run on the fly electrical conductivity testing. For normal operation TRIP_TEST must be driven low by the microcontroller output. If no testing is required, the TRIP_TEST pin may be continuously grounded.