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NCT51, NCT52 Ultra Small Temperature Switch with Pin-Selectable Hysteresis
The NCT51 and NCT52 are SOT-23 temperature switches that require no external components and the design is facilitated with factory-programmed temperature thresholds. A choice of factory-trimmed temperature trip points are available. Pin selectable hysteresis of +2C or +10C allows flexibility to the design. These parts typically consume only 17 A of current and operate over the entire -55C to +125C temperature range while offering accuracies of "0.5C (typ) and "4C (max). The NCT51 has an open drain, active low output, meant for microprocessor reset control. The NCT52 has a CMOS, active high output designed to drive a logic level MOSFET to turn on a fan or heater element. The NCT51/NCT52 are aimed for hot-temperature monitoring (+45C to +115C). These devices assert a logic signal when the temperature goes above the threshold. The NCT51 and NCT52 are offered in three standard temperature thresholds. Available in 5-Pin SOT-23A packages, these parts are ideal for applications requiring high integration, small size, low power and low installed cost.
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5 4 1 2 SOT-23A SN SUFFIX CASE 1212
3
PIN CONNECTIONS
GND 1 GND 2 HYST 3 4 VCC *For NCT52 Note: 5-Pin SOT-23A is equivalent to EIAJ SC-74A 5 TOVER (TOVER)*
* 5-Pin SOT-23A * Factory-Programmed Thresholds from +45C to +115C in 10C * * * * * * * * * * *
Increments Pin-Selectable +2C or +10C Hysteresis "0.5C (Typ) Threshold Accuracy Over Full Temperature Range No External Components Required 17 A Supply Current Thermal Management in PCs and Servers Over Temperature Fail Safe Circuits Simple Fan Controller Temperature Alarms Projectors/Printers Notebook Computers Network Boxes
ORDERING INFORMATION
See detailed ordering and shipping information in the package dimensions section on page 9 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking section on page 9 of this data sheet.
Typical Applications
(c) Semiconductor Components Industries, LLC, 2000
1
September, 2000 - Rev. 0
Publication Order Number: NCT51/D
NCT51, NCT52
ABSOLUTE MAXIMUM RATINGS*
Rating Supply Voltage TOVER (NCT51) TOVER (NCT52) All Other Pins Input Current (All Pins) Output Current (All Pins) Operating Temperature Range Storage Temperature Range Lead Temperature (Soldering, 10 seconds) Power Dissipation (TA = +70C) (Derate 7.1 mW/C Above +70C) Symbol VCC - - -
-
Value -0.3 to +7.0 -0.3 to +7.0 -0.3 to (VCC +0.3) -0.3 to (VCC +0.3) 20 20 -55 to +125 -65 to +165 +300 571
Unit V V V V mA mA C C C mW
-
-
Tstg
- -
*Static-sensitive device. Unused devices must be stored in conductive material. Protect devices from static discharge and static fields. Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operational sections of the specifications is not implied. Exposure to Absolute Maximum Rating Conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS VCC = +2.7 V to +5.5 V, RPULL-UP = 100 K (NCT51 only), CCOUPLING = 100 pF from VCC to
GND, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C. Characteristics Supply Voltage Range Supply Current Temperature Threshold Accuracy (Note 1.) Temperature Threshold Hysteresis HYST Input Threshold HYST Input Threshold Output Voltage High Test Conditions - - +45C to +65C +75C to +115C HYST = GND HYST = VCC - - ISOURCE = 500 A, VCC u 2.7 V (NCT52 Only) ISOURCE = 800 A, VCC u 4.5 V (NCT52 Only) ISINK = 1.2 mA, VCC u 2.7 V ISINK = 3.2 mA, VCC u 4.5 V VCC = 2.7 V, VTOVER = 5.5 V (NCT51 Only) Symbol VCC ICC TTH THYST VIH VIL VOH Min 2.7 - -4.0 -6.0 - - 0.8 x VCC - 0.8 x VCC VCC -1.5 VOL
-
Typ - 17 "0.5 "0.5 2.0 10 - - - - - - 10
Max 5.5 40 4.0 6.0 - - - 0.2 x VCC - - 0.3 0.4 -
Unit V A C C V V V
Output Voltage Low Open-Drain Output Leakage Current
- - -
V nA
1. The NCT51 and NCT52 are available with internal, factory-programmed temperature trip thresholds from +45C to +115C in +10C increments.
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NCT51, NCT52
PIN DESCRIPTION
NCT51 1,2 3 4 5 NCT52 1,2 3 4 - Name GND HYST VCC TOVER Description Ground. Ground both pins together close to the chip. Pin 2 provides the lowest thermal resistance to the die. Hysteresis Input. Connect HYST to GND for +2C hysteresis, or connect to VCC for +10C hysteresis. Supply Input (+2.7 V to +5.5 V). Recommend 100 pF or greater Coupling capacitor from VCC to GND. Open-Drain, Active-Low Output. TOVER goes low when the die temperature exceeds the factory-programmed temperature threshold. Connect to a 100 K pull-up resistor. May be pulled up to a voltage higher than VCC. Push/Pull Active-High Output. TOVER goes high when the die temperature exceeds the factory-programmed temperature threshold. Open-Drain, Active-Low Output. TUNDER goes low when the die temperature goes below the factory-programmed temperature threshold. Connect to a 100 K pull-up resistor. May be pulled up to a voltage higher than VCC. Push/Pull Active-High Output. TUNDER goes high when the die temperature is below the factory-programmed temperature threshold.
- -
5 -
TOVER TUNDER
-
-
TUNDER
Typical Operating Circuit
+2.7 V to +5.5 V
The NCT51 is intended for applications with a microprocessor reset input. The NCT52 is intended for applications of turning on a fan or heater element.
Hysteresis Input
100 pF
VCC
VCC P INT GND
NCT52 TOVER GND GND HYST
To prevent the output from "chattering'' at or near the trip point temperature, a selectable HYST input pin is provided. Hysteresis can be externally selected at 2C (HYST = GND) or 10C (HYST = VDD) by means of the CMOS compatible HYST input pin. Do not let the HYST pin float as this could cause increase supply current. The hysteresis does not depend on the part's programmed trip threshold.
Table 1. Factory-Programmed Threshold Range
Part Number NCT51 NCT52 Threshold (TTH) Range +45C t TTH t +115C +45C t TTH t +115C
DETAILED DESCRIPTION The NCT51 and NCT52 integrate a temperature sensor with a factory-programmed threshold switch. A logic signal is asserted when the die temperature crosses the factory programmed threshold. An external hysteresis input pin allows the user to select either 2C or 10C hysteresis to give further flexibility to the design of the application. The NCT51 and NCT52 are intended for a temperature range from 45C to 115C in a 10C increment. The NCT51 has an open drain output and the NCT52 has a push/pull output stage.
With a very low 17 A supply current, the NCT51 and NCT52 dissipates very little power. Thus, the die temperature is basically the same as the package temperature. To minimize the error in temperature readings, the load current should be limited to a few milliamps. As an example, the typical thermal resistance of a 5-Pin SOT-23A package is 140C/W. If the NCT51 had to sink 1.0 mA, and the output voltage is guaranteed to be less than 0.3 V, then an additional 0.3 mW of power is dissipated within the IC. This corresponds to a 0.042C rise in die temperature in the 5-Pin SOT-23A.
Thermal Considerations
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NCT51, NCT52
Temperature monitoring accuracy depends on the thermal resistance between the device being monitored and the temperature switch die. Heat flows primarily through the leads onto the die. Pin 2 provides the lowest thermal resistance to the die. To achieve the best temperature monitoring results, the NCT51 and NCT52 should be placed closest to the device being monitored. In addition, a short and wide copper trace from Pin 2 to the device should be used. In some cases, the 5-Pin SOT-23A package can be placed directly under the socketed microprocessor for improved thermal contact. APPLICATIONS The NCT51 has an open drain output and is therefore intended to interface as a microprocessor reset input. Moreover, the combination of these two devices can be used to implement a temperature window alarm by wire-ORing the outputs and using an external pull up resistor. (See Figure 1)
+5 V RPULL-UP 100 k 100 pF VCC Temperature Out of Range 100 pF VCC
NCT51SN115
NCT51SN055
GND GND HYST
GND GND HYST
Figure 1. Over and Under Temperature Alarm
The NCT52 can be used to control a DC fan. The fan turns on when the sensed temperature rises above the factory set threshold and remains on until the temperature falls below threshold minus the hysteresis selected. An additional fail
safe measure could be designed by using a second NCT52 with a higher temperature threshold to alert the user of an impending thermal shutdown, should the temperature continue to rise. (See Figure 2)
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NCT51, NCT52
+5 V
VCC 100 pF HEAT
NCT52SN095 GND GND TOVER HYST
TEMPERATURE FAULT
P
FAN CONTROL HEAT 100 pF VCC HYST NCT52SN055 TOVER
GND GND
Figure 2. Fan Control Circuit with Over Temperature Alert
TOVER + Positive Tempco Reference Negative Tempco Reference HYST Network NCT51 COLD + TOVER Positive Tempco Reference Negative Tempco Reference HYST Network NCT52 TEMP COLD +25C TTH HOT V TOVER NCT52 +25C TTH HOT V TOVER NCT51 With 100 k Pull-Up
HYST
TEMP
HYST
Figure 3. Functional Block Diagrams
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NCT51, NCT52
TYPICAL CHARACTERISTICS
60 50 FREQUENCY 40 30 20 10 0 -5 40 35 SUPPLY CURRENT (A) -4 -3 -2 -1 0 1 2 4 5 30 25 20 15 10 5 3 0 -60 -40 -20 0 20 40 60 80 100 120 140
ACCURACY (C)
TEMPERATURE (C)
Figure 4. Trip Threshold Accuracy
Figure 5. Supply Current vs. Temperature
OUTPUT SOURCE RESISTANCE ()
180 160 140 120 100 80 60 180 40 20 0 20 40 60 80 100 120 140 VCC = 5.0 V OUTPUT SINK RESISTANCE () VCC = 2.7 V VCC = 4.0 V
80 70 60 50 40 30 20 10 0 0 10 20 30 40 50 60 70 80 90 100 TEMPERATURE (C) VCC = 5.0 V VCC = 4.0 V VCC = 2.7 V
TEMPERATURE (C)
Figure 6. NCT52 Output Source Resistance vs. Temperature
12 HYS = VCC 10 HYSTERESIS (C)
Figure 7. Output Sink Resistance vs. Temperature
NCT51/52 8 6 4 HYS = GND 2 NCT51/52 0 -45 -25 -5 15 35 55 75 95 115
TRIP TEMPERATURE (C)
Figure 8. Hysteresis vs. Trip Temperature
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NCT51, NCT52
TYPICAL CHARACTERISTICS
+100C +15C/div Mounted On 0.75 in2 of 2 oz. Copper
+25C 5 sec/div
Figure 9. SOT-23 Thermal Step Response in Perfluorinated Fluid
+100C
+12.5C/div Mounted On 0.75 in2 of 2 oz. Copper
+25C 20 sec/div
Figure 10. SOT-23 Thermal Step Response in Still Air
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NCT51, NCT52
Component Taping Orientation for 5-Pin SOT-23A (EIAJ SC-74A) Devices
USER DIRECTION OF FEED
DEVICE MARKING
PIN 1
Standard Reel Component Orientation TR Suffix Device (Mark Right Side Up) PIN 1
USER DIRECTION OF FEED
DEVICE MARKING W = Width of Carrier Tape P = Pitch Reverse Reel Component Orientation RT Suffix Device (Mark Upside Down) Carrier Tape, Reel Size, and Number of Components Per Reel Package SOT-23A Carrier Width (W) 8 mm Pitch (P) 4 mm Part Per Full Reel 3000 Reel Size 7 inches
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NCT51, NCT52
MARKING DIAGRAM
1
2
3
4
1 and 2 3 4
= Two Letter Part Number Codes = Year and Two-Month Period Code = Lot ID Number
ORDERING INFORMATION
Standard Temperature Threshold 55C 95C 115C 5 Pin SOT 23A 5-Pin SOT-23A 55C 95C 115C Marking Output Stage Open Drain Open Drain Open Drain Push/Pull Push/Pull Push/Pull
1 and 2
Device NCT51SN055T1 NCT51SN095T1 NCT51SN115T1 NCT52SN055T1 NCT52SN095T1 NCT52SN115T1
Package
Shipping
HB HF HH JB JF JH 3000 Units Tape and Reel
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NCT51, NCT52
Notes
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PACKAGE DIMENSIONS
SOT-23 SN SUFFIX CASE 1212-01 ISSUE O
A
5 1
D
4 2 3
B
A2 0.05 S
A1 L
NOTES: 1. DIMENSIONS ARE IN MILLIMETERS. 2. INTERPRET DIMENSIONS AND TOLERANCES PER ASME Y14.5M, 1994. 3. DATUM C IS A SEATING PLANE. DIM A1 A2 B C D E E1 e e1 L L1 MILLIMETERS MIN MAX 0.00 0.10 1.00 1.30 0.30 0.50 0.10 0.25 2.80 3.00 2.50 3.10 1.50 1.80 0.95 BSC 1.90 BSC 0.20 --0.45 0.75
E
E1 L1 e e1 B
5X
C
M
0.10
CB
S
A
S
C
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ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. "Typical" parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. SCILLC does not convey any license under its patent rights nor the rights of others. SCILLC products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the SCILLC product could create a situation where personal injury or death may occur. Should Buyer purchase or use SCILLC products for any such unintended or unauthorized application, Buyer shall indemnify and hold SCILLC and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that SCILLC was negligent regarding the design or manufacture of the part. SCILLC is an Equal Opportunity/Affirmative Action Employer.
PUBLICATION ORDERING INFORMATION
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For additional information, please contact your local Sales Representative.
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NCT51/D

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