SNIS191A July   2015  – July 2015 LM57-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Device Comparison Table
  5. 5 Pin Configuration and Functions
  6. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 LM57-Q1 VTEMP Temperature-to-Voltage Transfer Function
        1. 7.3.1.1 LM57-Q1 VTEMP Voltage-to-Temperature Equations
      2. 7.3.2 RSENSE
      3. 7.3.3 Resistor Selection
      4. 7.3.4 TOVER and TOVER Digital Outputs
        1. 7.3.4.1 TOVER and TOVER Noise Immunity
      5. 7.3.5 Trip Test Digital Input
      6. 7.3.6 VTEMP Analog Temperature Sensor Output
        1. 7.3.6.1 VTEMP Noise Considerations
        2. 7.3.6.2 VTEMP Capacitive Loads
        3. 7.3.6.3 VTEMP Voltage Shift
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 ADC Input Considerations
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Selection of RSENSE Resistors
      3. 8.2.3 Application Curves
      4. 8.2.4 Grounding of the TRIP TEST Pin
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Temperature Considerations
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Community Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

7 Detailed Description

7.1 Overview

The LM57-Q1 is a precision, dual-output, temperature switch with analog temperature sensor output. The trip temperature (TTRIP) is selected from 256 possible values by using two external 1% resistors. The VTEMP class AB analog output provides a voltage that is proportional to temperature. The LM57-Q1 includes an internal reference DAC, analog temperature sensor and analog comparator. The reference DAC is connected to one of the comparator inputs. The reference DAC output voltage (VTRIP) is controlled by the value of resistance applied to the SENSE pins. The resistance value sets one of 16 "logic" levels at the SENSE pins. These "logic" levels are then decoded and applied to the DAC input, thus the actual resistance tolerance does not directly affect the threshold level accuracy. The result of the reference DAC voltage and the temperature sensor output comparison is provided on two output pins TOVER and TOVER.

The VTEMP output has a programmable gain. The output gain has 4 possible settings as described in Figure 12. The gain setting is dependent on the trip point selected by resistance applied to the SENSE pins.

Built-in temperature hysteresis (THYST) prevents the digital outputs from oscillating. The TOVER and TOVER will activate when the die temperature exceeds TTRIP and will release when the temperature falls below a temperature equal to TTRIP minus THYST. TOVER is active-high with a push-pull structure. TOVER, is active-low with an open-drain structure. There are two different hysteresis options available that are factory preset. The preset hysteresis can be selected by purchasing the proper order number as described in Device Comparison Table.

Driving the TRIP-TEST high will activate the digital outputs. A processor can check the logic level of the TOVER or TOVER, 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 TOVER to TRIP-TEST will latch the output after it trips. It can be cleared by forcing TRIP-TEST low or powering off the LM57-Q1.

7.2 Functional Block Diagram

LM57-Q1 30080503.gif

7.3 Feature Description

7.3.1 LM57-Q1 VTEMP Temperature-to-Voltage Transfer Function

The value of the RSENSE resistors select a trip point and a corresponding VTEMP gain (J2, J3, J4, or J5).The trip point range associated with a given gain is shown in bold green or bold red italics in Table 1. Temperatures above 150°C apply to the LM57FSPWQ1 and LM57TSPWQ1 only and are highlighted in red and italics in Table 1. The VTEMP gain is selected by the RSENSE resistors. VTEMP is valid over the entire temperature range. The VTEMP gain is selected by the RSENSE resistors. VTEMP is valid over the entire temperature range.

LM57-Q1 C101_SNIS191.pngFigure 12. Temperature Transfer Characteristics

Table 1. LM57-Q1 VTEMP Temperature to Voltage (1)

Temperature (°C) VTEMP VOLTAGE (mV)
J2 (-5.166 mV/°C) J3 (–7.752 mV/°C) J4 (–10.339 mV/°C) J5 (–12.924 mV/°C)
–50 1352.56 2028.80 2705.20 3381.40
–49 1347.60 2021.35 2695.26 3368.98
–48 1342.64 2013.90 2685.32 3356.55
–47 1337.67 2006.44 2675.38 3344.12
–46 1332.70 1998.98 2665.43 3331.68
–45 1327.73 1991.52 2655.47 3319.23
–44 1322.76 1984.05 2645.51 3306.78
–43 1317.78 1976.58 2635.54 3294.32
–42 1312.81 1969.11 2625.57 3281.85
–41 1307.82 1961.63 2615.60 3269.38
–40 1302.84 1954.15 2605.62 3256.90
–39 1297.86 1946.66 2595.63 3244.41
–38 1292.87 1939.17 2585.64 3231.92
–37 1287.88 1931.68 2575.64 3219.42
–36 1282.88 1924.18 2565.64 3206.92
–35 1277.89 1916.68 2555.63 3194.41
–34 1272.89 1909.17 2545.62 3181.89
–33 1267.88 1901.66 2535.60 3169.37
–32 1262.88 1894.15 2525.58 3156.84
–31 1257.87 1886.63 2515.56 3144.30
–30 1252.86 1879.11 2505.52 3131.76
–29 1247.85 1871.59 2495.49 3119.21
–28 1242.84 1864.06 2485.44 3106.66
–27 1237.82 1856.53 2475.40 3094.10
–26 1232.80 1848.99 2465.34 3081.53
–25 1227.78 1841.45 2455.29 3068.96
–24 1222.75 1833.91 2445.23 3056.38
–23 1217.73 1826.36 2435.16 3043.79
–22 1212.70 1818.81 2425.09 3031.20
–21 1207.67 1811.26 2415.01 3018.60
–20 1202.63 1803.70 2404.93 3006.00
–19 1197.59 1796.13 2394.84 2993.38
–18 1192.55 1788.57 2384.74 2980.77
–17 1187.51 1781.00 2374.65 2968.14
–16 1182.46 1773.42 2364.54 2955.51
–15 1177.42 1765.85 2354.44 2942.87
–14 1172.37 1758.26 2344.32 2930.23
–13 1167.31 1750.68 2334.20 2917.58
–12 1162.26 1743.09 2324.08 2904.93
–11 1157.20 1735.50 2313.95 2892.26
–10 1152.14 1727.90 2303.82 2879.60
–9 1147.07 1720.30 2293.68 2866.92
–8 1142.01 1712.69 2283.54 2854.24
–7 1136.94 1705.09 2273.39 2841.55
–6 1131.87 1697.47 2263.24 2828.86
–5 1126.79 1689.86 2253.08 2816.16
–4 1121.72 1682.24 2242.91 2803.45
–3 1116.64 1674.61 2232.74 2790.74
–2 1111.56 1666.99 2222.57 2778.02
–1 1106.47 1659.35 2212.39 2765.30
0 1101.39 1651.72 2202.21 2752.57
1 1096.30 1644.08 2192.02 2739.83
2 1091.20 1636.44 2181.82 2727.08
3 1086.11 1628.79 2171.62 2714.33
4 1081.01 1621.14 2161.42 2701.58
5 1075.91 1613.48 2151.21 2688.82
6 1070.81 1605.83 2141.00 2676.05
7 1065.71 1598.16 2130.78 2663.27
8 1060.60 1590.50 2120.55 2650.49
9 1055.49 1582.83 2110.32 2637.70
10 1050.38 1575.15 2100.09 2624.91
11 1045.26 1567.48 2089.85 2612.10
12 1040.14 1559.80 2079.60 2599.30
13 1035.02 1552.11 2069.35 2586.48
14 1029.90 1544.42 2059.10 2573.66
15 1024.77 1536.73 2048.84 2560.84
16 1019.65 1529.03 2038.57 2548.01
17 1014.51 1521.33 2028.30 2535.17
18 1009.38 1513.63 2018.03 2522.32
19 1004.25 1505.92 2007.75 2509.47
20 999.11 1498.21 1997.46 2496.61
21 993.97 1490.49 1987.17 2483.75
22 988.82 1482.77 1976.88 2470.88
23 983.68 1475.05 1966.58 2458.00
24 978.53 1467.32 1956.27 2445.12
25 973.38 1459.59 1945.96 2432.23
26 968.22 1451.86 1935.64 2419.34
27 963.07 1444.12 1925.32 2406.43
28 957.91 1436.38 1915.00 2393.53
29 952.74 1428.63 1904.67 2380.61
30 947.58 1420.88 1894.33 2367.69
31 942.41 1413.13 1883.99 2354.76
32 937.24 1405.37 1873.64 2341.83
33 932.07 1397.61 1863.29 2328.89
34 926.90 1389.84 1852.94 2315.94
35 921.72 1382.07 1842.57 2302.99
36 916.54 1374.30 1832.21 2290.03
37 911.36 1366.52 1821.84 2277.07
38 906.17 1358.74 1811.46 2264.10
39 900.98 1350.96 1801.08 2251.12
40 895.79 1343.17 1790.69 2238.14
41 890.60 1335.38 1780.30 2225.15
42 885.41 1327.58 1769.90 2212.15
43 880.21 1319.78 1759.50 2199.15
44 875.01 1311.98 1749.09 2186.14
45 869.81 1304.17 1738.68 2173.12
46 864.60 1296.36 1728.26 2160.10
47 859.39 1288.54 1717.84 2147.07
48 854.18 1280.72 1707.41 2134.04
49 848.97 1272.90 1696.98 2121.00
50 843.75 1265.07 1686.54 2107.95
51 838.53 1257.24 1676.10 2094.90
52 833.31 1249.41 1665.65 2081.84
53 828.09 1241.57 1655.20 2068.77
54 822.86 1233.73 1644.74 2055.70
55 817.63 1225.88 1634.28 2042.62
56 812.40 1218.03 1623.81 2029.54
57 807.17 1210.18 1613.34 2016.44
58 801.93 1202.32 1602.86 2003.35
59 796.69 1194.46 1592.38 1990.24
60 791.45 1186.60 1581.89 1977.13
61 786.20 1178.73 1571.40 1964.02
62 780.96 1170.86 1560.90 1950.89
63 775.71 1162.98 1550.40 1937.76
64 770.46 1155.10 1539.89 1924.63
65 765.20 1147.22 1529.37 1911.49
66 759.94 1139.33 1518.86 1898.34
67 754.68 1131.44 1508.33 1885.19
68 749.42 1123.54 1497.80 1872.02
69 744.16 1115.64 1487.27 1858.86
70 738.89 1107.74 1476.73 1845.68
71 733.62 1099.83 1466.19 1832.50
72 728.35 1091.92 1455.64 1819.32
73 723.07 1084.01 1445.08 1806.13
74 717.79 1076.09 1434.53 1792.93
75 712.51 1068.17 1423.96 1779.72
76 707.23 1060.24 1413.39 1766.51
77 701.94 1052.31 1402.82 1753.30
78 696.65 1044.38 1392.24 1740.07
79 691.36 1036.44 1381.65 1726.84
80 686.07 1028.50 1371.07 1713.61
81 680.77 1020.55 1360.47 1700.36
82 675.48 1012.60 1349.87 1687.11
83 670.17 1004.65 1339.27 1673.86
84 664.87 996.69 1328.66 1660.60
85 659.56 988.73 1318.04 1647.33
86 654.25 980.77 1307.42 1634.05
87 648.94 972.80 1296.80 1620.77
88 643.63 964.83 1286.17 1607.49
89 638.31 956.85 1275.53 1594.19
90 632.99 948.87 1264.89 1580.89
91 627.67 940.89 1254.25 1567.59
92 622.35 932.90 1243.60 1554.28
93 617.02 924.91 1232.94 1540.96
94 611.69 916.92 1222.28 1527.63
95 606.36 908.92 1211.61 1514.30
96 601.02 900.91 1200.94 1500.97
97 595.69 892.91 1190.27 1487.62
98 590.34 884.90 1179.59 1474.27
99 585.00 876.88 1168.90 1460.92
100 579.66 868.87 1158.21 1447.55
101 574.31 860.84 1147.52 1434.18
102 568.96 852.82 1136.81 1420.81
103 563.61 844.79 1126.11 1407.43
104 558.25 836.76 1115.40 1394.04
105 552.89 828.72 1104.68 1380.65
106 547.53 820.68 1093.96 1367.24
107 542.17 812.63 1083.23 1353.84
108 536.80 804.59 1072.50 1340.42
109 531.43 796.53 1061.77 1327.01
110 526.06 788.48 1051.02 1313.58
111 520.69 780.42 1040.28 1300.15
112 515.31 772.35 1029.53 1286.71
113 509.93 764.29 1018.77 1273.26
114 504.55 756.21 1008.01 1259.81
115 499.17 748.14 997.24 1246.36
116 493.78 740.06 986.47 1232.89
117 488.39 731.98 975.69 1219.42
118 483.00 723.89 964.91 1205.95
119 477.61 715.80 954.12 1192.46
120 472.21 707.70 943.33 1178.98
121 466.81 699.61 932.53 1165.48
122 461.41 691.50 921.73 1151.98
123 456.00 683.40 910.92 1138.47
124 450.60 675.29 900.11 1124.96
125 445.19 667.18 889.29 1111.44
126 439.78 659.06 878.47 1097.91
127 434.36 650.94 867.64 1084.38
128 428.94 642.81 856.81 1070.84
129 423.52 634.68 845.97 1057.29
130 418.10 626.55 835.13 1043.74
131 412.67 618.41 824.28 1030.18
132 407.25 610.27 813.43 1016.62
133 401.82 602.13 802.57 1003.05
134 396.38 593.98 791.71 989.47
135 390.95 585.83 780.84 975.89
136 385.51 577.67 769.97 962.30
137 380.07 569.51 759.09 948.70
138 374.63 561.35 748.20 935.10
139 369.18 553.18 737.32 921.49
140 363.73 545.01 726.42 907.87
141 358.28 536.84 715.52 894.25
142 352.83 528.66 704.62 880.62
143 347.37 520.48 693.71 866.99
144 341.91 512.29 682.80 853.35
145 336.45 504.10 671.88 839.70
146 330.99 495.91 660.95 826.05
147 325.52 487.71 650.03 812.39
148 320.05 479.51 639.09 798.73
149 314.58 471.30 628.15 785.05
150 309.10 463.09 617.21 771.38
151 303.63 454.88 606.26 757.69
152 298.15 446.66 595.30 744.00
153 292.66 438.44 584.35 730.30
154 287.18 430.22 573.38 716.60
155 281.69 421.99 562.41 702.89
156 276.20 413.76 551.44 689.17
157 270.71 405.52 540.46 675.45
158 265.22 397.28 529.47 661.72
159 259.72 389.04 518.48 647.99
160 254.22 380.79 507.49 634.25
161 248.71 372.54 496.49 620.50
162 243.21 364.28 485.48 606.75
163 237.70 356.02 474.47 592.98
164 232.19 347.76 463.46 579.22
165 226.68 339.50 452.44 565.45
166 221.16 331.23 441.41 551.67
167 215.64 322.95 430.38 537.88
168 210.12 314.67 419.35 524.09
169 204.60 306.39 408.31 510.29
170 199.07 298.11 397.26 494.59
171 193.54 289.82 386.21 480.52
172 188.01 281.52 375.15 466.44
173 182.48 273.23 364.09 452.36
174 176.94 264.92 353.03 438.27
175 171.40 256.62 341.96 424.17
(1) The RSENSE resistors select a trip point and a corresponding VTEMP gain (J2, J3, J4, or J5). The trip point range associated with a given gain is shown in bold green or red on this table. Temperatures above 150°C apply to the LM57FSPWQ1 and LM57TSPWQ1 only and are italicized and highlighted in red. The VTEMP gain is selected by the RSENSE resistors. VTEMP is valid over the entire temperature range.

7.3.1.1 LM57-Q1 VTEMP Voltage-to-Temperature Equations

Equation 1. VTEMP= a (T-30)2+ b (T-30) + c

where

  • VTEMP is in mV and T is in °C
Equation 2. LM57-Q1 EqQuad_01_SNIS188.gif

where

  • T is in °C and VTEMP is in mV

Table 2. LM57-Q1 VTEMP Voltage-to-Temperature Equations Coefficients

Trip-Point Region LM57-Q1 Trip Point Range a b c
J2 −41°C to 52°C – 0.00129 − 5.166  947.6
J3  52°C to 97°C – 0.00191 − 7.752 1420.9
J4  97°C to 119°C – 0.00253 − 10.339 1894.3
J5 119°C to 160°C – 0.00316 − 12.924 2367.7

7.3.2 RSENSE

The LM57-Q1 uses the voltage at the two SENSE pins to set the trip point for the temperature switch. It is possible to drive the two SENSE pins with a voltage equal to the value generated by the resistor and the internal current-source and have the same switch point. Thus one can use an external DAC to drive each SENSE pin, allowing for the temperature trip point to be set dynamically by the system processor. Table 3 shows the RSENSE value and its corresponding generated SENSE pin voltage (the center value).

Table 3. RSENSE Values (kΩ) vs SENSE Pin Voltage (mV)

RSENSE (kΩ) SENSE Pin Voltage (mV)
Center Value
976 1875
825 1585
698 1341
590 1134
499 959
412 792
340 653
280 538
226 434
178 342
140 269
105 202
75 146
46.4 87
22.6 43
0.01 0

7.3.3 Resistor Selection

Table 4. Trip Point (°C) vs Sense Resistor (RSENSE) Values (Ω) (1)

RSENSE2
J2 (2) J3 (2) J4 (2) J5
976 kΩ 825 kΩ 698 kΩ 590 kΩ 499 kΩ 412 kΩ 340 kΩ 280 kΩ 226 kΩ 178 kΩ 140 kΩ 105 kΩ 75 kΩ 46.4 kΩ
RSENSE1 976 kΩ –40.68 –16.26 7.33 30.38 52.73 67.77 82.74 97.47 108.61 119.62 128.46 137.28 146.08 154.77
825 kΩ –39.13 –14.76 8.79 31.81 53.68 68.71 83.67 98.17 109.30 120.18 129.01 137.83 146.62 155.31
698 kΩ –37.57 –13.27 10.24 33.24 54.62 69.65 84.60 98.86 110.00 120.73 129.56 138.38 147.16 155.85
590 kΩ –36.03 –11.78 11.70 34.67 55.56 70.59 85.53 99.56 110.70 121.28 130.12 138.93 147.71 156.39
499 kΩ –34.49 –10.29 13.15 36.10 56.50 71.52 86.46 100.25 111.39 121.84 130.67 139.49 148.25 156.93
412 kΩ –32.95 –8.81 14.60 37.53 57.44 72.46 87.40 100.95 112.09 122.39 131.22 140.04 148.80 157.46
340 kΩ –31.41 –7.32 16.05 38.95 58.39 73.40 88.33 101.64 112.79 122.94 131.77 140.59 149.34 158.00
280 kΩ –29.88 –5.83 17.49 40.38 59.33 74.33 89.26 102.34 113.48 123.50 132.32 141.14 149.88 158.54
226 kΩ –28.34 –4.35 18.93 41.81 60.27 75.27 90.19 103.03 114.18 124.05 132.87 141.69 150.43 159.08
178 kΩ –26.83 –2.88 20.36 43.23 61.21 76.20 91.12 103.73 114.87 124.60 133.43 142.24 150.97 159.62
140 kΩ –25.32 –1.42 21.79 44.65 62.15 77.14 92.05 104.42 115.57 125.15 133.98 142.79 151.51 160.16
105 kΩ –23.80 0.04 23.22 46.07 63.08 78.07 92.99 105.11 116.26 125.71 134.53 143.34 152.06
75 kΩ –22.29 1.50 24.65 47.50 64.02 79.01 93.92 105.81 116.95 126.26 135.08 143.89 152.60
46.4 kΩ –20.77 2.96 26.08 48.92 64.96 79.94 94.84 106.50 117.65 126.81 135.63 144.44 153.14
22.6 kΩ –19.26 4.42 27.51 50.33 65.90 80.87 95.77 107.19 118.34 127.36 136.18 144.99 153.68
0.01 kΩ –17.75 5.88 28.94 51.75 66.84 81.81 96.70 107.89 119.04 127.91 136.73 145.54 154.23
(1) Temperatures above 150°C apply to the LM57FSPWQ1 and LM57TSPWQ1 only and are italicized.
(2) There are four gains corresponding to each of the four Temperature Trip Point Ranges:
 J2 (-5.166 mV/°C) is the temperature sensor output gain used for Temperature Trip Points −40.68°C to 51.8°C.
 J3 (-7.752 mV/°C) is for Trip Points 52°C to 97°C.
 J4 (-10.339 mV/°C) for 97°C to 119°C.
 J5 (-12.924 mV/°C) for 119°C to 160°C.

Table 5. VTEMP (mV) at the Trip Point vs Sense Resistor (RSENSE) Value (Ω) (1)

RSENSE2
J2 (2) J3 (2) J4 (2) J5 (2)
976 kΩ 825 kΩ 698 kΩ 590 kΩ 499 kΩ 412 kΩ 340 kΩ 280 kΩ 226 kΩ 178 kΩ 140 kΩ 105 kΩ 75 kΩ 46.4 kΩ
RSENSE1 976 kΩ 1306.23 1183.77 1064.00 945.63 1243.67 1125.34 1006.75 1185.27 1066.00 1184.05 1064.59 944.83 824.96 705.99
825 kΩ 1298.50 1176.23 1056.56 938.23 1236.27 1117.93 999.34 1177.83 1058.52 1176.57 1057.10 937.33 817.53 698.60
698 kΩ 1290.72 1168.70 1049.13 930.83 1228.88 1110.52 991.92 1170.40 1051.03 1169.10 1049.62 929.83 810.09 691.20
590 kΩ 1283.03 1161.16 1041.69 923.43 1221.48 1103.10 984.51 1162.96 1043.55 1161.63 1042.13 922.33 802.66 683.81
499 kΩ 1275.33 1153.62 1034.26 916.02 1214.09 1095.69 977.09 1155.52 1036.07 1154.16 1034.65 914.83 795.22 676.41
412 kΩ 1267.64 1146.09 1026.82 908.62 1206.69 1088.28 969.66 1148.09 1028.59 1146.68 1027.16 907.33 787.78 669.02
340 kΩ 1259.94 1138.55 1019.38 901.22 1199.30 1080.87 962.22 1140.65 1021.10 1139.21 1019.67 899.83 780.35 661.62
280 kΩ 1252.25 1131.02 1011.99 893.82 1191.90 1073.45 954.78 1133.22 1013.62 1131.74 1012.19 892.33 772.91 654.22
226 kΩ 1244.55 1123.48 1004.62 886.42 1184.50 1066.04 947.35 1125.78 1006.14 1124.27 1004.70 884.83 765.48 646.83
178 kΩ 1236.99 1116.05 997.26 879.02 1177.11 1058.63 939.91 1118.35 998.66 1116.79 997.22 877.33 758.04 639.43
140 kΩ 1229.38 1108.61 989.89 871.61 1169.71 1051.22 932.48 1110.91 991.17 1109.32 989.73 869.82 750.61 632.04
105 kΩ 1221.76 1101.18 982.53 864.21 1162.32 1043.80 925.04 1103.48 983.69 1101.85 982.25 862.32 743.17
75 kΩ 1214.15 1093.74 975.16 856.81 1154.92 1036.39 917.61 1096.04 976.21 1094.38 974.76 854.82 735.74
46.4 kΩ 1206.53 1086.30 967.80 849.41 1147.53 1028.98 910.17 1088.60 968.73 1086.90 967.28 847.32 728.30
22.6 kΩ 1198.92 1078.87 960.43 842.01 1140.13 1021.57 902.74 1081.17 961.24 1079.43 959.79 839.82 720.86
0.01 kΩ 1191.30 1071.43 953.07 834.62 1132.74 1014.15 895.30 1073.73 953.76 1072.04 952.31 832.32 713.43
(1) Items italicized and highlighted in red apply to the LM57FSPWQ1 and LM57TSPWQ1 only.
(2) There are four gains corresponding to each of the four Temperature Trip Point Ranges:
 J2 (-5.166 mV/°C) is the temperature sensor output gain used for Temperature Trip Points −40.68°C to 51.8°C.
 J3 (-7.752 mV/°C) is for Trip Points 52°C to 97°C.
 J4 (-10.339 mV/°C) for 97°C to 119°C.
 J5 (-12.924 mV/°C) for 119°C to 160°C.

7.3.4 TOVER and TOVER Digital Outputs

The TOVER active high, push-pull output and the TOVER Active Low, Open-Drain Output both assert at the same time whenever the Die Temperature reaches the Trip Point. They also assert simultaneously whenever the TRIP TEST pin is set high. Both outputs de-assert 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 TOVER or the TOVER Digital Output pins can be left open if not used.

The TOVER Active Low, Open-Drain Digital Output, if used, requires a pullup resistor between this pin and VDD.

7.3.4.1 TOVER and TOVER Noise Immunity

The LM57-Q1 has some noise immunity to a premature trigger due to noise on the power supply. With the die temperature at 1°C below the trip point, there are no premature triggers for a square wave injected into the power supply with a magnitude of 100 mVPP over a frequency range of 100 Hz to 2 MHz. Above the frequency a premature trigger may occur.

With the die temperature at 2°C below the trip point, and a magnitude of 200 mVPP, there are no premature triggers from 100 Hz to 300 kHz. Above that frequency a premature trigger may occur.

Therefore if the supply line is noisy, it is recommended that a local supply decoupling capacitor be used to reduce that noise.

7.3.5 Trip Test Digital Input

The TRIP TEST pin provides a means to test the digital outputs by causing them to assert, regardless of temperature.

In addition, when the TRIP TEST pin is pulled high the VTEMP pin will be at the VTRIP voltage.

7.3.6 VTEMP Analog Temperature Sensor Output

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 the Typical Application section for more discussion of this topic. The LM57-Q1 is ideal for this and other applications which require strong source or sink current.

7.3.6.1 VTEMP Noise Considerations

A load capacitor on VTEMP can help to filter noise.

For noisy environments, TI recommends a 100 nF supply decoupling capacitor placed closed across VDD and GND pins of LM57-Q1.

7.3.6.2 VTEMP Capacitive Loads

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 13. For capacitive loads greater than 1100 pF, a series resistor is required on the output, as shown in Figure 14, to maintain stable conditions.

LM57-Q1 30080516.gifFigure 13. LM57-Q1 With No Isolation Resistor Required
LM57-Q1 30080517.gifFigure 14. LM57-Q1 With Series Resistor for Capacitive Loading Greater than 1100 pF

Table 6. CLOAD and RS Values of Figure 14

CLOAD Minimum RS
1.1 to 99 nF 3 kΩ
100 to 999 nF 1.5 kΩ
1 μF 750 Ω

7.3.6.3 VTEMP Voltage Shift

The LM57-Q1 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 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. Since the shift takes place over a wide temperature change of 5°C to 20°C, VTEMP is always monotonic. The accuracy specifications in the Electrical Characteristics table already includes this possible shift.

7.4 Device Functional Modes

The LM57-Q1 has several modes of operation as detailed in the following drawings.

LM57-Q1 LM57_T_OVER_PushPull.gifFigure 15. Temperature Switch Using Push-Pull Output
LM57-Q1 LM57_T_OVER_BAR_OpenDrain.gifFigure 16. Temperature Switch Using Open-Drain Output

As shown in Figure 17 the LM57-Q1 has a TRIP Test input simplifying in situ board conductivity testing. Forcing TRIP TEST pin "HIGH" will drive the TOVER pin "LOW" and the TOVER pin "HIGH".

LM57-Q1 30080560.gifFigure 17. Trip Test Digital Output Test Circuit

In the circuit shown in Figure 18 when TOVER goes active high, it drives trip test high. Trip test high causes TOVER to stay high. It is therefore latched. To release the latch, power down, then power up. The LM57-Q1 always comes up in a released condition.

LM57-Q1 30080573.gifFigure 18. Simple Latch Circuit

The TRIP TEST pin, normally used to check the operation of the TOVER and TOVER 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 19, when TOVER goes high, the TRIP TEST input is also pulled high and causes TOVER output to latch high and the TOVER output to latch low. Momentarily switching the TRIP TEST input low will reset the LM57-Q1 to normal operation. The resistor limits the current out of the TOVER output pin.

LM57-Q1 30080565.gifFigure 19. Latch Circuit Using TOVER Output