SEMICONDUCTOR
AS273
Over-Temperature Detector
Description
The AS273 is a series of programmable over-temperature
detectors. Each is internally composed of a precision 2.5 V
shunt reference, a proportional-to-absolute temperature
thermal sensor, a comparator with controlled hysteresis, and
an open collector output that indicates an over-temp condi-
tion. The threshold for the over-temp signal can be set to any
of three values on a given part by controlling the magnitude
of the reference shunt current.
The AS273 has an excellent absolute temperature accuracy
of ±3¡C for each of the three over-temp thresholds. The low
power dissipation minimizes any temperature sensing errors
due to self-heating. There is either 5¡C or 10¡C of tempera-
ture hysteresis to prevent bouncing when an over-temp con-
dition is removed.
The packaging options available with the AS273 make it
appealing to a wide variety of temperature-sensing applica-
tions. The TO-92 package can be mechanically clamped to a
heat sink to monitor the temperature of power devices. The
8L-SOIC and SOT-223 surface mount packages allow for
temperature sensing in high component density applications.
Features
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Programmable to three different
over-temperature thresholds
2.5 V temperature compensated
bandgap reference trimmed to 1%
Open collector output goes low
on over-temp condition
±3¡C temperature accuracy
Reference shunt current serves to
program over-temp threshold
Available with 5¡C or 10¡C of
temperature hysteresis
Available in a wide range of over-
temp thresholds to fit most
temperature monitoring
applications
Now available in the SOT-223 for
improved substrate temperature
sensing
¥
Pin Configuration Ñ
SOIC (D)
OUT
N/C
N/C
N/C
1
2
3
4
8
7
6
5
Top view
TO-92 (LP)
VREF
OUT
DO NOT USE
DO NOT USE
GROUND
GROUND
V
REF
SOT-223 (G)
OUT
GROUND
V
REF
ASTEC Semiconductor
1
AS273
Ordering Information
AS273 D 1 D A
Circuit Type:
Over-Temperature Detector
Temperature Option:
(Refer to Table A)
Table A – Temperature Options
Code
T
OT1
D
40
F
75
G
90
H
105
Over-Temperature Detector
Packaging Option:
A = Ammo Pack
B = Bulk
T = Tube
13 = Tape and Reel (13" Reel Dia)
Package Style:
D = SOIC
G = SOT-223
LP = TO-92
Hysteresis Option:
1 = 10°C
5 = 5°C
T
OT2
45
80
95
110
T
OT3
50
85
100
115
Functional Block Diagram
V
REF
1
CURRENT
PROGRAMMING
OUT
3
2.5 V
+
Ð
4 mV/K
+
Ð
2
GND
Pin Function Description
Pin Number
1
2
3
Function
V
REF
GND
OUT
Description
2.5 V shunt reference; current into V
REF
pin also programs
over-temperature trip point to one of three T
OT
values
Circuit ground and silicon substrate
Open collector output. Output low when die temperature exceeds
programmed trip point
ASTEC Semiconductor
2
Over-Temperature Detector
Absolute Maximum Ratings
Parameter
Reference Current
Output Current
Output Voltage
Continuous Power Dissipation at 25¡C
TO-92
8-SOIC
SOT-223
Junction Temperature
Storage Temperature
Lead Temp, Soldering 10 Seconds
P
D
P
D
P
D
T
J
T
STG
T
L
775
750
1000
150
Ð65 to 150
300
mW
mW
mW
¡C
¡C
¡C
Symbol
V
REF
I
OUT
V
OUT
Rating
±10
±10
18
Unit
mA
mA
V
AS273
Stresses greater than those listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a
stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational sec-
tions of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect reliability.
Typical Thermal Resistances
Package
SOT-223
TO-92
8L SOIC
θ
JA
115¡C/W
160¡C/W
175¡C/W
θ
JC
8¡C/W
80¡C/W
45¡C/W
Typical Derating
8.7 mW/¡C
6.3 mW/¡C
5.7 mW/¡C
ASTEC Semiconductor
3
AS273
Electrical Characteristics
Over-Temperature Detector
Electrical Characteristics are guaranteed over the full junction temperature range (0 to 125¡C). Ambient temperature must be derated
based upon power dissipation and package thermal characteristics.
Parameter
Reference
Reference Voltage
Load Regulation
Average Temperature Coefficient
Output
Saturation Voltage
Breakdown Voltage
Leakage Current
Over-Temp Sensing
Temperature Accuracy
T
OT(1)
T
OT(2)
T
OT(3)
Hysteresis
H
OT
0.7 mA
≤
I
REF
≤
1.3 mA
1.55 mA
≤
I
REF
≤
2.6 mA
3.0 mA
≤
I
REF
≤
5.0 mA
Percentage Error in Nominal Hysteresis
Ð3
Ð3
Ð3
Ð30
+3
+3
+3
+30
¡C
¡C
¡C
%
V
OL
BV
I
OH
I
OUT
= 4 mA; T
J
> T
OT
I
OUT
= 100
µA;
T
J
< T
OT
V
OUT
= 18 V; T
J
< T
OT
18
200
30
1
1000
400
mV
V
nA
V
REF
V
Id
∆V
REG
/∆T
I
REF
= 2 mA, T
J
= 25¡C
0.65 mA
≤
I
REF
≤
5.5 mA
0.65 mA
≤
I
REF
≤
5.5 mA
2.500
2.525
5
75
2.550
10
V
mV
ppm/¡C
Symbol
Test Condition
Min.
Typ.
Max.
Unit
Test Circuit
+5V
R
LOAD
2 kΩ
V
REF
AS273
I
REF
GND
OUT
Figure 1. Test Circuit for Output Hysteresis Curve
ASTEC Semiconductor
4
Over-Temperature Detector
Typical Performance Curves
AS273
Minimum Reference Current for Regulation
300
275
250
Turn-on Current, I
REF
(µA)
Reference Voltage, V
REF
(V)
2
225
200
175
150
125
100
0
25
50
75
100
125
150
Junction Temperature, T
J
(°C)
0
0
3
Turn-on Characteristic of Reference
1
200
400
600
800
1000
Reference Current, I
REF
(µA)
Figure 2
Figure 3
Temperature Regulation of Reference
2.55
10
9
2.54
Reference Voltage, V
REF
(V)
Load Regulation (mV)
8
7
6
5
4
3
2.51
2
1
2.50
0
25
50
75
100
125
150
Junction Temperature, T
J
(°C)
0
0
Load Regulation of Reference Over-temperature
2.53
2.52
25
50
75
100
125
150
Junction Temperature, T
J
(°C)
Figure 4
Figure 5
ASTEC Semiconductor
5
PCB Design
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