LM57 Resistor-Programmable Temperature Switch and Analog Temperature Sensor
- SNIS152E May 2009 – July 2015 LM57
  
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DATA SHEET

LM57 Resistor-Programmable Temperature Switch and Analog Temperature Sensor

1 Features

See LM57-Q1 Data Sheet for AEC-Q100 Grade 1/Grade 0/Grade 0 Extended (Qualified and Manufactured on an Automotive Grade Flow)
Trip Temperature Set by External Resistors with
Accuracy of ±1.7°C or ±2.3°C from −40°C to +150°C
Resistor Tolerance Contributes Zero Error
Push-Pull and Open-Drain Switch Outputs
Wide Operating Temperature Range of −50°C to 150°C
Very Linear Analog V_TEMP Temp Sensor Output
with ±0.8°C or ±1.3°C Accuracy from −50°C to +150°C
Short-Circuit Protected Analog and Digital Outputs
Latching Function for Digital Outputs
TRIP-TEST Pin Allows In-System Testing
Low Power Minimizes Self-Heating to Under 0.02°C

2 Applications

Factory Automation
Industrial
Automotive
Down Hole
Avionics
Telecom Infrastructure

3 Description

The LM57 device is a precision, dual-output, temperature switch with analog temperature sensor output for wide temperature industrial applications. The trip temperature (T_TRIP) is selected from 256 possible values in the range of –40°C to 150°C. The V_TEMP is a class AB analog voltage output that is proportional to temperature with a programmable negative temperature coefficient (NTC). Two external 1% resistors set the T_TRIP and V_TEMP slope. The digital and analog outputs enable protection and monitoring of system thermal events.

Built-in thermal hysteresis (T_HYST) prevents the digital outputs from oscillating. The T_OVER and T_OVER digital outputs will assert when the die temperature exceeds T_TRIP and will de-assert when the temperature falls below a temperature equal to T_TRIP minus T_HYST.

T_OVER is active-high with a push-pull structure. T_OVER is active-low with an open-drain structure. Tying T_OVER to TRIP-TEST will latch the output after it trips. The output can be cleared by forcing TRIP-TEST low. Driving the TRIP-TEST high will assert the digital outputs. A processor can check the state of T_OVER or T_OVER, confirming they changed to an active state. This allows for in situ verification that the comparator and output circuitry are functional after system assembly. When TRIP-TEST is high, the trip-level reference voltage appears at the V_TEMP pin. The system could then use this voltage to calculate the threshold of the LM57.

Device Information ⁽¹⁾⁽²⁾

PART NUMBER	PACKAGE	BODY SIZE (NOM)
LM57BISD	WSON (8)	2.50 mm × 2.50 mm
LM57FPW	TSSOP (8)	3.00 mm × 6.40 mm

For all available packages, see the orderable addendum at the end of the data sheet.
For device comparison see Device Comparison Table.

LM57 Overtemperature Alarm

Temperature Transfer Function

4 Revision History

Changes from D Revision (February 2013) to E Revision

Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section Go
Added TSSOP Package option throughout data sheetGo

Changes from C Revision (February 2010) to D Revision

Changed layout of National Data Sheet to TI formatGo

5 Device Comparison Table

ORDER NUMBER	PACKAGE	GRADE (TEMP RANGE)	V_TEMP ACCURACY	TRIP POINT ACCURACY	HYSTERESIS
LM57BISD-5, LM57BISDX-5	WSON/SD/NGR/DFN (8)	Commercial (-50°C to 150°C)	±0.8°C	±1.5°C	5°C
LM57BISD-10, LM57BISDX-10	WSON/SD/NGR/DFN (8)	Commercial (-50°C to 150°C)	±0.8°C	±1.5°C	10°C
LM57CISD-5, LM57CISD-5	WSON/SD/NGR/DFN (8)	Commercial (-50°C to 150°C)	±1.3°C	±2.3°C	5°C
LM57CISD-10, LM57CISDX-10	WSON/SD/NGR/DFN (8)	Commercial (-50°C to 150°C)	±1.3°C	±2.3°C	10°C
LM57FPW, LM57FPWR	PW/TSSOP (8)	Commercial (-50°C to 150°C)	±1.3°C	±2.3°C	5°C
LM57TPW, LM57TPWR	PW/TSSOP (8)	Commercial (-50°C to 150°C)	±1.3°C	±2.3°C	10°C
LM57FSPWQ1, LM57FSPWRQ1⁽¹⁾	PW/TSSOP (8)	Automotive Grade 0 Extended (-50°C to 160°C)	±1.3°C	±2.3°C	5°C
LM57TSPWQ1, LM57TSPWRQ1⁽¹⁾	PW/TSSOP (8)	Automotive Grade 0 Extended (-50°C to 160°C)	±1.3°C	±2.3°C	10°C
LM57FEPWQ1, LM57FEPWRQ1⁽¹⁾	PW/TSSOP (8)	Automotive Grade 0 Standard (-50°C to 150°C)	±1.3°C	±2.3°C	5°C
LM57TEPWQ1, LM57TEPWRQ1⁽¹⁾	PW/TSSOP (8)	Automotive Grade 0 Standard (-50°C to 150°C)	±1.3°C	±2.3°C	10°C
LM57FQPWQ1, LM57FQPWRQ1⁽¹⁾	PW/TSSOP (8)	Automotive Grade 1 Standard (-50°C to 125°C)	±1.3°C	±2.3°C	5°C
LM57TQPWQ1, LM57TQPWRQ1⁽¹⁾	PW/TSSOP (8)	Automotive Grade 1 Standard (-50°C to 125°C)	±1.3°C	±2.3°C	10°C

(1) For Automotive grade device complete datasheet see LM57-Q1.

6 Pin Configuration and Functions

TSSOP/PW and WSON/SD/NGR/DFN Packages

8-Pin

Top View

Pin Functions

PIN		TYPE	EQUIVALENT CIRCUIT	DESCRIPTION
NAME	NO.	TYPE	EQUIVALENT CIRCUIT	DESCRIPTION
GND	1	Ground	—	Power supply ground
SENSE1	2	—		Trip-point resistor sense. One of two sense pins which selects the temperature at which T_OVER and T_OVER will assert.
SENSE2	3	—		Trip-point resistor sense. One of two sense pins which selects the temperature at which T_OVER and T_OVER will assert.
V_DD	4	Power		Supply voltage
TRIP TEST	5	Digital Input		TRIP TEST pin. Active High input. If TRIP TEST = 0 (default), then the V_TEMPoutput has the analog temperature sensor output voltage. If TRIP TEST = 1, then T_OVER and T_OVER outputs are asserted and V_TEMP = V_TRIP, the temperature trip voltage. Tie this pin to ground if not used.
T_OVER	6	Digital Output		Overtemperature switch output Active low, open-drain (see LM57 VTEMP Voltage-to-Temperature Equations regarding required pullup resistor.) Asserted when the measured temperature exceeds the Trip Point Temperature or if TRIP TEST = 1 This pin may be left open if not used.
T_OVER	7	Digital Output		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.
V_TEMP	8	Analog Output		V_TEMP analog voltage output If TRIP TEST = 0, then V_TEMP = V_TS, temperature sensor output voltage If TRIP TEST = 1, then V_TEMP = V_TRIP, temperature trip voltage This pin may be left open if not used.
Thermal Pad (WSON package only)	—	—	—	Connected to GND

7 Specifications

7.1 Absolute Maximum Ratings

over operating free-air temperature range (unless otherwise noted) ⁽¹⁾⁽²⁾

	MIN	MAX	UNIT
Supply voltage	−0.3	6	V
Voltage at T_OVER	−0.3	6	V
Voltage at T_OVER , V_TEMP, TRIP-TEST, SENSE1, and SENSE2	−0.3	(V_DD + 0.3 V)	V
Current at any pin		5	mA
Storage temperature	−65	150	°C

(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) Soldering process must comply with Reflow Temperature Profile specifications. Refer to www.ti.com/packaging.

7.2 ESD Ratings

			VALUE	UNIT
LM57BISD and LM57CISD in WSON package
V_(ESD)	Electrostatic discharge ⁽¹⁾	Human body model (HBM)	±5500	V
		Charged-device model (CDM)	±1250
		Machine Model (MM)	±450
LM57FPW and LM57TPW in TSSOP package
V_(ESD)	Electrostatic discharge	Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 ⁽²⁾	±2000	V
V_(ESD)	Electrostatic discharge	Charged-device model (CDM), per JEDEC specification JESD22-C101 ⁽³⁾	±750	V

(1) The Human Body Model (HBM) is a 100-pF capacitor charged to the specified voltage then discharged through a 1.5-kΩ resistor into each pin. The Machine Model (MM) is a 200 pF capacitor charged to the specified voltage then discharged directly into each pin. The Charged Device Model (CDM) is a specified circuit characterizing an ESD event that occurs when a device acquires charge through some triboelectric (frictional) or electrostatic induction processes and then abruptly touches a grounded object or surface.

(2) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

(3) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.

7.3 Recommended Operating Conditions

		MIN	NOM	MAX	UNIT
Supply voltage		2.4		5.5	V
Free air temperature range (T_MIN ≤ T_A ≤ T_MAX)		−50		150	°C

7.4 Thermal Information

THERMAL METRIC ⁽¹⁾		LM57		UNIT
		NGR (WSON/SD)	PW (TSSOP)
		8 PINS	8 PINS
R_θJA	Junction-to-ambient thermal resistance	71.3	183	°C/W
R_θJC(top)	Junction-to-case (top) thermal resistance	82.8	66	°C/W
R_θJB	Junction-to-board thermal resistance	43.4	111	°C/W
ψ_JT	Junction-to-top characterization parameter	2.2	8	°C/W
ψ_JB	Junction-to-board characterization parameter	43.7	110	°C/W
R_θJC(bot)	Junction-to-case (bottom) thermal resistance	11.9	—	°C/W

(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953.

7.5 Electrical Characteristics - Accuracy Characteristics – Trip Point Accuracy

PARAMETER	TEST CONDITIONS			LM57B			LM57C, LM57F or LM57T			UNIT
PARAMETER	TEST CONDITIONS			MIN	TYP	MAX	MIN	TYP	MAX	UNIT
Trip Point Accuracy (Includes 1% set-resistor tolerance) ⁽¹⁾	J2	T_A = −41°C to 52°C	V_DD = 2.4 V to 5.5 V			±1.5			±2.3	°C
	J3	T_A = 52°C to 97°C	V_DD = 2.4 V to 5.5 V			±1.5			±2.3	°C
	J4	T_A = 97°C to 119°C	V_DD = 2.4 V to 5.5 V			±1.5			±2.3	°C
	J5	T_A = 119°C to free air temperature max	V_DD = 2.4 V to 5.5 V			±1.5			±2.3	°C

(1) Accuracy is defined as the error between the measured and reference output voltages, tabulated in the Conversion 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.

7.6 Electrical Characteristics - Accuracy Characteristics – V_TEMP Analog Temperature Sensor Output Accuracy

These limits do not include DC load regulation. These stated accuracy limits are with reference to the values in Table 1.

PARAMETER	TEST CONDITIONS			LM57B			LM57C, LM57F or LM57T			UNIT
PARAMETER	TEST CONDITIONS			MIN	TYP	MAX	MIN	TYP	MAX	UNIT
V_TEMP Accuracy (These stated accuracy limits are with reference to the values in Table 1, LM57 V_TEMP Temperature-to-Voltage.) ⁽¹⁾	J2	T_A = −50°C to free air temperature max	V_DD = 2.4 V to 5.5 V			±0.95			±1.3	°C
	J3	T_A= −50°C to free air temperature max	V_DD = 2.4 V to 5.5 V			±0.8			±1.3	°C
	J4	T_A = 20°C to 50°C	V_DD = 2.4 V to 5.5 V			±0.7			±1.3	°C
		T_A = 0°C to free air temperature max	V_DD = 2.7 V to 5.5 V			±0.7			±1.3
		T_A = −50°C to 0°C	V_DD = 3.1 V to 5.5 V			±0.8			±1.3
	J5	T_A = 60°C to free air temperature max	V_DD = 2.4 V to 5.5 V			±0.7			±1.3	°C
		T_A = 20°C to 50°C	V_DD = 2.9 V to 5.5 V			±0.7			±1.3
		T_A = 0°C to free air temperature max	V_DD = 3.2 V to 5.5 V			±0.7			±1.3
		T_A = −50°C to 0°C	V_DD = 4 V to 5.5 V			±0.8			±1.3

7.7 Electrical Characteristics

Unless otherwise noted, these specifications apply for V_DD = 2.4 to 5.5 V. Limits apply over free air temperature range.

PARAMETER		TEST CONDITIONS	MIN ⁽²⁾	TYP ⁽¹⁾	MAX ⁽²⁾	UNIT
TEMPERATURE SENSOR
	V_TEMP sensor gain	J2: −50°C to 52°C		−5.166		mV/°C
		J3: 52°C to 97°C		−7.752
		J4: 97°C to 119°C		−10.339
		J5: 119°C to 150°C		−12.924
	Line regulation DC: supply-to-V_TEMP⁽³⁾	V_DD = 2.4 V to 5.5 V Temp = 90°C		0.18		mV
				58		μV/V
				−84		dB
	Load regulation: V_TEMP output ⁽⁶⁾	Source ≤ 240 µA, (V_DD – V_TEMP) ≥ 200 mV; T_A = −50°C to 150°C			−1	mV
		Sink ≤ 300 µA, V_TEMP ≥ 360 mV; T_A = −50°C to 150°C			1	mV
		Source or sink = 100 µA; T_A = −50°C to 150°C		1		Ω
	Maximum Load capacitance: V_TEMP output	No output series resistor required; (See VTEMP Capacitive Loads)			1100	pF
I_S	Supply current: quiescent ⁽⁴⁾			24	28	µA
TRIP-TEST INPUT
V_IH	Logic 1 threshold voltage		V_DD – 0.5			V
V_IL	Logic 0 threshold voltage				0.5	V
I_IH	Logic 1 input current			1.4	3	µA
I_IL	Logic 0 input leakage current ⁽⁵⁾	T_A = −50°C to 150°C		0.001	1	µA
T_OVER (PUSH-PULL, ACTIVE-HIGH) OUTPUT
V_OH	Logic 1 push-pull output voltage	Source ≤ 600 µA	V_DD – 0.2			V
V_OH	Logic 1 push-pull output voltage	Source ≤ 1.2 mA	V_DD – 0.45			V
V_OL	Logic 0 output voltage	Sink ≤ 600 µA			0.2	V
V_OL	Logic 0 output voltage	Sink ≤ 1.2 mA			0.45	V
T_OVER (OPEN-DRAIN, ACTIVE-LOW) OUTPUT
V_OL	Logic 0 output voltage	Sink ≤ 600 µA			0.2	V
V_OL	Logic 0 output voltage	Sink ≤1.2 mA			0.45	V
I_OH	Logic 1 output leakage current ⁽⁵⁾	Temperature = 30°C;		0.001	1	µA
HYSTERESIS
T_HYST	Hysteresis temperature	5°C hysteresis option (for all LM57F or LM57-5)	4.7	5	5.4	°C
T_HYST	Hysteresis temperature	10°C hysteresis option (for all LM57T or LM57-10)	9.6	10	10.6	°C

(1) Typicals are at T_J = T_A = 25°C and represent most likely parametric norm.

(2) Limits are specified to TI's average outgoing quality level (AOQL).

(3) 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 VTEMP Voltage Shift.

(4) Supply current refers to the quiescent current of the LM57 only and does not include any load current

(5) This current is leakage current only and is therefore highest at high temperatures. Prototype test indicate that the leakage is well below 1 μA over the full temperature range. This 1 μA specification reflects the limitations of measuring leakage at room temperature. For this reason only, the leakage current is not specified at a lower value.

(6) Source currents are flowing out of the LM57. Sink currents are flowing into the LM57. Load Regulation is calculated by measuring V_TEMP at 0 μA and subtracting the value with the conditions specified.

7.8 Switching Characteristics

Unless otherwise noted, these specifications apply for V_DD = 2.4 to 5.5 V over the free air temperature range.

PARAMETER		TEST CONDITIONS		MIN	TYP	MAX	UNIT
t_EN	Maximum time from power on to digital output enabled				1.5	2.9	ms
t_VTEMP	Maximum time from power on to analog temperature (V_TEMP) valid				1.5	2.9	ms

Figure 1. Definition of t_EN

Figure 2. Definition of t_VTEMP

7.9 Typical Characteristics

Figure 3. Supply Current vs Supply Voltage

Figure 5. Load Regulation: Change In V_TEMP vs Source Current Overhead Is Vdd-Vtemp

Figure 7. Line Regulation: V_TEMP vs Supply Voltage

Figure 9. Start-Up Response

Conditions: J2, V_DD=5V

Figure 11. J2 Accuracy Specification Over Temperature

Figure 4. Supply Current vs Temperature

Figure 6. Load Regulation: Change In V_TEMP vs Sink Current

Figure 8. Line Regulation: Hysteresis vs Supply Voltage 30°C

Figure 10. Hysteresis vs Temperature

8 Detailed Description

8.1 Overview

The LM57 is a precision, dual-output, temperature switch with analog temperature sensor output. The trip temperature (T_TRIP) is selected from 256 possible values by using two external 1% resistors. The V_TEMP class AB analog output provides a voltage that is proportional to temperature. The LM57 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 (V_TRIP) 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 T_OVER and T_OVER.

The V_TEMP 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 (T_HYST) prevents the digital outputs from oscillating. The T_OVER and T_OVER will activate when the die temperature exceeds T_TRIP and will release when the temperature falls below a temperature equal to T_TRIP minus T_HYST. T_OVER is active-high with a push-pull structure. T_OVER, 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 T_OVER or T_OVER, 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 V_TEMP pin. Tying T_OVER to TRIP-TEST will latch the output after it trips. It can be cleared by forcing TRIP-TEST low or powering off the LM57.

8.2 Functional Block Diagram

8.3 Feature Description

8.3.1 LM57 V_TEMP Temperature-to-Voltage Transfer Function

The value of the R_SENSE resistors select a trip point and a corresponding V_TEMP gain (J2, J3, J4, or J5).The trip point range associated with a given gain is shown in bold green in Table 1. The V_TEMP gain is selected by the R_SENSE resistors. V_TEMP is valid over the entire temperature range. The V_TEMP gain is selected by the R_SENSE resistors. V_TEMP is valid over the entire temperature range.

Figure 12. Temperature Transfer Characteristics

Table 1. LM57 V_TEMP Temperature to Voltage ⁽¹⁾

Temperature (°C)	V_TEMP VOLTAGE (mV)
Temperature (°C)	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

(1) The R_SENSE resistors select a trip point and a corresponding V_TEMP gain (J2, J3, J4, or J5). The trip point range associated with a given gain is shown in bold green on this table. V_TEMP is valid over the entire temperature range.

8.3.1.1 LM57 V_TEMP Voltage-to-Temperature Equations

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

where

V_TEMP is in mV and T is in °C

Equation 2. LM57 EqQuad_01_SNIS188.gif

where

T is in °C and V_TEMP is in mV

Table 2. LM57 V_TEMP Voltage-to-Temperature Equations Coefficients

Trip-Point Region	LM57 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 150°C	– 0.00316	− 12.924	2367.7

8.3.2 R_SENSE

The LM57 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 R_SENSE value and its corresponding generated SENSE pin voltage (the center value).

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

R_SENSE (kΩ)	SENSE Pin Voltage (mV)
R_SENSE (kΩ)	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

8.3.3 Resistor Selection

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

		R_SENSE2
		J2 ⁽¹⁾				J3 ⁽¹⁾			J4 ⁽¹⁾		J5 ⁽¹⁾
		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
R_SENSE1	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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

(1) 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 150°C.

Table 5. V_TEMP (mV) at the Trip Point vs Sense Resistor (R_SENSE) Value (Ω)

		R_SENSE2
		J2 ⁽¹⁾				J3 ⁽¹⁾			J4 ⁽¹⁾		J5 ⁽¹⁾
		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
R_SENSE1	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
	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 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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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
	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

8.3.4 T_OVER and T_OVER Digital Outputs

The T_OVER active high, push-pull output and the T_OVER 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 T_OVER or the T_OVER Digital Output pins can be left open if not used.

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

8.3.4.1 T_OVER and T_OVER Noise Immunity

The LM57 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 mV_PP 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 mV_PP, 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.

8.3.5 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 V_TEMP pin will be at the V_TRIP voltage.

8.3.6 V_TEMP Analog Temperature Sensor Output

The V_TEMP 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 is ideal for this and other applications which require strong source or sink current.

8.3.6.1 V_TEMP Noise Considerations

A load capacitor on V_TEMP can help to filter noise.

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

8.3.6.2 V_TEMP Capacitive Loads

The V_TEMP 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 V_TEMP 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.

Figure 13. LM57 With No Isolation Resistor Required

Figure 14. LM57 With Series Resistor for Capacitive Loading Greater than 1100 pF

Table 6. C_LOAD and R_S Values of Figure 14

C_LOAD	Minimum R_S
1.1 to 99 nF	3 kΩ
100 to 999 nF	1.5 kΩ
1 μF	750 Ω

8.3.6.3 V_TEMP Voltage Shift

The LM57 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 V_DD and V_TEMP. The shift typically occurs when V_DD − V_TEMP = 1 V.

This slight shift (a few millivolts) takes place over a wide change (approximately 200 mV) in V_DD or V_TEMP. Since the shift takes place over a wide temperature change of 5°C to 20°C, V_TEMP is always monotonic. The accuracy specifications in the table already includes this possible shift.

8.4 Device Functional Modes

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

Figure 15. Temperature Switch Using Push-Pull Output

Figure 16. Temperature Switch Using Open-Drain Output

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

Figure 17. Trip Test Digital Output Test Circuit

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

Figure 18. Simple Latch Circuit

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

Figure 19. Latch Circuit Using T_OVER Output