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TC623
3V, DUAL TRIP POINT TEMPERATURE SENSOR
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FEATURES
GENERAL DESCRIPTION
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The TC623 is a 3V solid-state, programmable temperature sensor designed for use in thermal management applications. It features dual thermal interrupt outputs (LOW
LIMIT and HIGH LIMIT) each of which program with a single
external resistor. The HIGH LIMIT and LOW LIMIT outputs
are driven active (high) when measured temperature equals
the user-programmed limits. The CONTROL output is driven
active (high) when temperature equals the HIGH LIMIT
setpoint, and turned off when temperature falls below the
LOW LIMIT setpoint. The CONTROL output can be used to
provide simple ON/OFF control to a cooling fan if so desired.
Low voltage operation, easy setpoint programming,
small size and low cost make the TC623 an ideal choice for
many thermal management applications.
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Integrated Temp Sensor and Detector Operate
from a Supply Voltage as Low as 2.7V
Replaces Mechanical Thermostats and Switches
On-Chip Temperature Sense
8-Pin DIP or SOIC for Direct PCB Mounting
2 User-Programmable Temperature Set Points
2 Independent Temperature Limit Outputs
Heat/Cool Regulate Output
APPLICATIONS
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CPU Thermal Management
System Over-or Under-Temperature Shutdown
Advanced Thermal Warning
Fan Speed Control Circuits
Accurate Appliance Temperature Sensing
Environmental Control
FUNCTIONAL BLOCK DIAGRAM
NC
1
8
VCC
TEMP
TO
VOLTAGE
CONVERTER
+
LOW SET
2
VREF
GEN.
7
HIGH SET
VREF
GEN.
TC623CCOA
TC623CCPA
TC623CEOA
TC623CEPA
TC623CVOA
8-Pin SOIC
8-Pin Plastic DIP
8-Pin SOIC
8-Pin Plastic DIP
8-Pin SOIC
0°C to +70°C
0°C to +70°C
– 40°C to +85°C
– 40°C to +85°C
– 40°C to +125°C
6
4
S
LATCH
5
Q
6
NC
1
LOW SET
2
HIGH SET
3
GND
4
TC623CCOA
TC623CEOA
TC623CVOA
8
VCC
7
LOW LIMIT
6
HIGH LIMIT
5
CONTROL
HIGH LIMIT
CONTROL
7
NC
1
LOW SET
2
RLOW < RHIGH
HIGH SET
3
GND
4
TC623CCPA
TC623CEPA
8
VCC
7
LOW LIMIT
6
HIGH LIMIT
5
CONTROL
8
TC623-5 9/18/96
TELCOM SEMICONDUCTOR, INC.
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NOTE: Latch Q Output, ("C" Option), is a Standard Device. Contact
Factory for Latch Q Output, ("H" Option).
–
R
GND
Package
–
+
3
Temperature
Range
Part No.
LOW LIMIT
VREF
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ORDERING INFORMATION
PIN CONFIGURATION (DIP and SOIC)
TC623
3
2-25
3V, DUAL TRIP POINT
TEMPERATURE SENSOR
TC623
ABSOLUTE MAXIMUM RATINGS*
Package Power Dissipation (TA ≤ 70°C)
Plastic DIP ......................................................730mW
SOIC ............................................................... 470mW
Derating Factors
Plastic DIP .................................................... 8mW/°C
SOIC ............................................................. 6mW/°C
Supply Voltage ...........................................................5.5V
Input Voltage Any Input ....... (GND – 0.3V) to (VDD +0.3V)
Operating Temperature
V Version ........................................ – 40°C to +125°C
E Version .......................................... – 40°C to +85°C
C Version ............................................... 0°C to +70°C
ELECTRICAL CHARACTERISTICS
Parameter
2.7V ≤ VDD ≤ 4.5V
T = Programmed Temperature
IOH = 250µA
IOH = 500µA
IOL = 500µA
IOL = 1mA
Falling Temperature
VOL
Hysteresis
*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 operation sections of the specifications is not implied.
Exposure to absolute maximum rating conditions for extended periods may
affect device reliability.
Over Operating Temperature Range) VDD = 2.7V to 4.5V, unless otherwise specified.
Conditions
Supply Voltage Range
Supply Current
Absolute Accuracy
VOH
Maximum Chip Temperature ................................. +150°C
Storage Temperature ............................ – 65°C to +150°C
Lead Temperature (Soldering, 10 sec) ................. +300°C
Min
Typ*
Max
2.7
—
T–3
0.9 x VDD
0.8 x VDD
—
—
—
—
150
T ±1
—
—
—
—
—
4.5
250
T +3
—
—
0.1 x VDD
0.2 x VDD
–2
Unit
V
µA
°C
V
V
V
V
°C
* Measured at 25°C
creases, the LOW LIMIT is driven high when temperature
equals the LOW LIMIT setpoint (±3°C). If temperature
continues to climb, the HIGH LIMIT output is driven high
when temperature equals the HIGH LIMIT setpoint (±3°C).
Figure 1 shows the relationship between the sense resistance values and trip point temperature.
The CONTROL output is driven high when the HIGH
LIMIT output goes high, and is reset low when the LOW
LIMIT output goes low. This output provides the logic for
simple ON/OFF fan control. Figure 2 shows overall TC623
operation.
RESISTANCE (kΩ)
250
200
150
100
50
-55
-35
-15
5
25
45
65
85
105
125
TEMPERATURE (°C)
Figure 1. TC623 Sense Resistors vs. Trip Temperature
HIGH SET POINT
DETAILED DESCRIPTION
TC623 Operation
TEMPERATURE
LOW SET POINT
LOW LIMIT OUTPUT
The TC623 consists of a positive temperature coefficient (PTC) temperature sensor and dual threshold detector. Temperature set point programming is easily accomplished with external programming resistors from the HIGH
SET and LOW SET inputs to VCC. The HIGH LIMIT and LOW
LIMIT outputs remain inactive (low) as long as the measured
temperature is below setpoint values. As temperature in2-26
HIGH LIMIT OUTPUT
CONTROL OUTPUT (COOL OPTION)
Figure 2. TC623 Temperature vs. Output
TELCOM SEMICONDUCTOR, INC.
3V, DUAL TRIP POINT
TEMPERATURE SENSOR
1
TC623
To prevent output "chattering" when measured temperature is at (or near) the programmed trip point values, the
LOW SET and HIGH SET inputs each have a built-in
hysteresis of – 2°C max. As a result, the HIGH LIMIT and
LOW LIMIT outputs remain active until the measured temperature falls a maximum of 2°C below the programmed
HIGH SET and LOW SET thresholds as shown in Figure 3.
The programmed setting threshold of Figure 3 is userprogrammed temperature trip points of either the LOW SET
or HIGH SET inputs. The LOW LIMIT or HIGH LIMIT output
is driven active when temperature equals the programmed
setpoint value (to within 3°C). The output remains active
until the temperature falls an additional 2°C below the
setpoint due to hysteresis.
PROGRAMMED SETPOINT
APPLICATIONS
Mounting
If the TC623 is used to measure the temperature
of another device, it is important that the top surface
of the TC623 package be in intimate contact with the
measured device. Good thermal conductivity and no air
space is critical to accurate temperature measurement in
applications of this type.
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Trip Point Programming
The resistance values required for the HIGH SET and
LOW SET inputs are calculated using the formula below:
RTRIP = 0.5997 x T 2.1312
Where Rtrip = Programming resistor value in Ohms
T = Desired trip temperature in degrees Kelvin.
–2°C HYSTERESIS
HIGH LIMIT OR LOW LIMIT OUTPUT
Figure 3. High Set and Low Set Thresholds
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For example, to program a trip point of 50°C, the
programming resistor is:
RTRIP = 0.5997 x (50 + 273.15)2.1312) = 133,652 Ω
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TELCOM SEMICONDUCTOR, INC.
2-27