Datenblatt für AD22105 von Analog Devices Inc.

ANALOG Resistor-Programmable, DEVICES Thermostatic Switch A022105 M_ WWI—HT |_l|_||_H_l
Low Voltage, Resistor-Programmable,
Thermostatic Switch
Data Sheet
AD22105
Rev. A Document Feedback
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FEATURES
User-programmable temperature setpoint
±2.0°C maximum ambient setpoint accuracy
4.1°C typical hysteresis
Wide supply range: 2.7 V to 7.0 V
Wide temperature range: −40°C to +150°C
Low power dissipation
APPLICATIONS
Industrial process control
Thermal control systems
CPU monitoring
Computer thermal management circuits
Fan control
Handheld/portable electronic equipment
GENERAL DESCRIPTION
The AD22105 is a solid state thermostatic switch. Requiring
only one external programming resistor, the AD22105 can be
set to switch accurately at any temperature in the −40°C to +150°C
wide operating range. Using a novel circuit architecture, the
AD22105 asserts an open-collector output when the ambient
temperature exceeds the user-programmed setpoint temperature.
The AD22105 has approximately 4°C of hysteresis, which prevents
rapid thermal on and off cycling.
The AD22105 operates on a single power supply voltage from
2.7 V to 7.0 V, facilitating operation in battery-powered
applications as well as in industrial control systems. Because of
low power dissipation (230 µW at 3.3 V), self heating errors are
minimized, and battery life is maximized.
An optional internal 200 kΩ pull-up resistor is included to facilitate
driving light loads such as complementary metal–oxide
semiconductor (CMOS) inputs.
Alternatively, a low power light emitting diode (LED) indicator
can be driven directly.
FUNCTIONAL BLOCK DIAGRAM
1
2
3
4
8
7
6
5
NC
V
S
RSET
NC
R
PULL–UP
OUT
GND
NC TEMPERATURE
SENSOR
200kΩ
SET-
POINT
AD22105
02099-001
Figure 1.
AD22105 Data Sheet
Rev. A | Page 2 of 11
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications ....................................................................................... 1
General Description ......................................................................... 1
Functional Block Diagram .............................................................. 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 4
Thermal Resistance ...................................................................... 4
ESD Caution .................................................................................. 4
Pin Configuration and Function Descriptions ............................. 5
Typical Performance Characteristics ............................................. 6
Theory of Operation ........................................................................ 8
The Setpoint Resistor ................................................................... 8
Effect of Resistor Tolerance and Thermal Drift on Setpoint
Accuracy .........................................................................................8
Hysteresis and Self Heating ..........................................................9
Output Section ...............................................................................9
Mounting Considerations ............................................................9
Thermal Environment Effects .....................................................9
Using the AD22105 as a Cooling Setpoint Detector ................9
Applications Information .............................................................. 10
Electromagnetic Interference (EMI) Suppression ................. 10
Leakage at the RSET Pin ............................................................... 10
Outline Dimensions ....................................................................... 11
Ordering Guide .......................................................................... 11
REVISION HISTORY
10/2018—Rev. 0 to Rev. A
Update Format .................................................................... Universal
Changes to Features Section............................................................ 1
Changed Product Description Section to Theory of Operation
Section ................................................................................................ 8
Changed Application Hint Section to Applications Information
Section .............................................................................................. 10
Updated Outline Dimensions ....................................................... 11
Changes to Ordering Guide .......................................................... 11
1/1996—Revision 0: Initial Version
Table L awn-c (m)
Data Sheet AD22105
Rev. A | Page 3 of 11
SPECIFICATIONS
Supply voltage (VS) = 3.3 V, TA = 25°C, and load resistor (RLOAD) = internal 200 kΩ, unless otherwise noted.
Table 1.
Parameter Symbol Test Conditions/Comments Min Typ Max Unit
TEMPERATURE ACCURACY
Ambient Setpoint Accuracy ACC ±0.5 ±2.0 °C
Temperature Setpoint Accuracy ACCT −40°C ≤ TA ≤ +125°C ±3.0 °C
Power Supply Rejection PSR 2.7 V1 < VS < 7.0 V ±0.05 ±0.15 °C/V
HYSTERESIS HYS 4.1 °C
OPEN-COLLECTOR OUTPUT
Output Low Voltage VOL Sink current (ISINK) = 5 mA 250 400 mV
POWER SUPPLY
Supply Voltage Range VS 2.7 7.0 V
Supply Current
Output Low ISON 120 µA
Output High ISOFF 90 µA
INTERNAL PULL-UP RESISTOR RPULL-UP 140 200 260 kΩ
TURN-ON SETTLING TIME tON 5 µs
1 The AD22105 operates at voltages as low as 2.2 V.
SETPOINT TEMPERATURE (°C)
80
0
70
40
30
20
10
60
50
5
15
25
35
45
55
65
75
–50 150–25
R
SET
(kΩ)
025 50 75 100 125
R
SET
= –90.3kΩ
39MΩ °C
T
SET
(°C) + 281.6°C
02099-003
Figure 2. Setpoint Resistor Values
Table 2‘ Table 3‘ Thermal Resistance ESD CAUTION ESD (eledroslali: dis¢harg:) sensifive device‘ Charged demes and (1mm boavds (an aismavge wlmum daemon Ahhougn m: mam fame; paxemed or pvopvelavy pmecnon (Hcmvy, damage may occuv on devlces Subjeded w hlgh enevgy ESD Theveme, pvcpev ESD pvezaunons should be mken m avowd pelfovmance degvadanon m ‘05: of funcnonalwy
AD22105 Data Sheet
Rev. A | Page 4 of 11
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Ratings
Maximum Supply Voltage 11 V
Maximum Output Voltage (R
PULL-UP
)
11 V
Maximum Output Current (OUT) 10 mA
Operating Temperature Range −40°C to +150°C
Dice Junction Temperature 160°C
Storage Temperature Range −65°C to +160°C
Lead Temperature (Soldering, 10 sec) 300°C
Stresses at or above those listed under Absolute Maximum Ratings
may cause permanent damage to the product. This is a stress
rating only; functional operation of the product at these or any
other conditions above those indicated in the operational section of
this specification is not implied. Operation beyond the maximum
operating conditions for extended periods may affect product
reliability.
THERMAL RESISTANCE
Thermal performance is directly linked to PCB design and
operating environment. Careful attention to PCB thermal
design is required.
Table 3. Thermal Resistance
Package
θ
JA
(°C/W)
τ (sec)
1
SOIC_N (R-8)
Moving Air Without Heat Sink
2
100
3.5
Still Air Without Heat Sink 190 15
1 The time constant is defined as the time to reach 63.2% of the final temperature
change.
2 1200 cubic feet per minute (CFM)
ESD CAUTION
Table 4‘ Pin Function Descripfions flflflfl UUUU
Data Sheet AD22105
Rev. A | Page 5 of 11
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
R
PULL-UP1
OUT
2
GND
3
NC
4
NC
8
V
S
7
R
SET
6
NC
5
NC = NO CONNECT
AD22105
TOP VIEW
(Not to Scale)
02099-004
Figure 3. Pin Configuration
Table 4. Pin Function Descriptions
Pin No. Mnemonic Description
1 RPULL-UP Internal 200 kΩ Pull-Up Resistor (Optional).
2 OUT Device Output.
3 GND Ground.
4, 5, 8
NC
No Connect.
6 RSET Temperature Setpoint Resistor.
7 VS Supply Voltage. VS must be between 2.7 V and 7.0 V.
GHARANTEED LIMIT m GUARANYEED LIMIT 1-1 _// //// // // / / /// // ‘ /// // / / / \ / // /// / / /
AD22105 Data Sheet
Rev. A | Page 6 of 11
TYPICAL PERFORMANCE CHARACTERISTICS
ERROR (°C)
TEMPERATURE (°C)
4
–4
–50 150–25 025 50 75 100 125
3
0
–1
–2
–3
2
1
GUARANTEED LIMIT (+)
GUARANTEED LIMIT (–)
02099-005
Figure 4. Error vs. Temperature, Setpoint
±0.1
±0.3
±1.1
±0.5
±0.7
±0.9
SETPOINT ERROR (°C/%)
TEMPERATURE (°C)
–50 150–25 025 50 75 100 125
02099-006
Figure 5. Setpoint Error vs. Temperature Due to RSET Tolerance
90
80
40
70
60
50
SUPPLY CURRENT (µA)
TEMPERATURE (°C)
–50 150–25 025 50 75 100 125
02099-007
V
S
= 7V
V
S
= 5V
V
S
= 3V
Figure 6. Supply Current (VS) vs. Temperature, Output Voltage (VOUT) = High
HYSTERESIS (°C)
TEMPERATURE (°C)
–50 150–25
4.4
4.2
4.0
3.8
3.6
3.4
3.2
025 50 75 100 125
02099-008
Figure 7. Hysteresis vs. Temperature, Setpoint
SETPOINT ERROR (°C)
2.0
1.5
–2.0 345
SUPPLY VOLTAGE (V)
6 7
0
–0.5
–1.0
–1.5
1.0
0.5
+125°C
+25°C
–40°C
02099-009
Figure 8. Setpoint Error vs. Supply Voltage for Various Temperatures
120
110
60
100
90
70
80
SUPPLY CURRENT (µA)
TEMPERATURE (°C)
–50 150–25 025 50 75 100 125
02099-010
V
S
= 7V
V
S
= 5V
V
S
= 3V
Figure 9. Supply Current vs. Temperature, VOUT = Low
15 \\
Data Sheet AD22105
Rev. A | Page 7 of 11
0.4
0.3
010µ 10m1m100µ1µ
0.2
0.1
IOUT (A)
VOUT (V)
02099-011
TA = –40°C
TA = +25°C
TA = +125°C
Figure 10. VOUT vs. Output Current (IOUT), VOUT = Low
TIME (Seconds)
FLOW RATE (CFM)
16
14
2
01200400 800
10
8
6
4
12
02099-012
Figure 11. Time vs. Flow Rate, Thermal Response
THERMAL RESISTANCE (°C/W)
FLOW RATE (CFM)
200
200
50
01200400 800
100
150
02099-013
Figure 12. Thermal Resistance (θJA) vs. Flow Rate
PERCENTAGE OF FINAL VALUE (%)
TIME (Seconds)
100
80
006010 20 30 40 50
60
40
20
90
70
50
30
10
STILL AIR
MOVING AIR
(1200cfm)
02099-014
Figure 13. Percentage of Final Value vs. Time, Thermal Response Time
AD22105 Data Sheet
Rev. A | Page 8 of 11
THEORY OF OPERATION
The AD22105 is a single-supply semiconductor thermostat
switch that uses a circuit architecture to realize the combined
functions of a temperature sensor, setpoint comparator, and output
stage all in one IC. By using one external resistor, the AD22105
can be programmed to switch at any temperature selected by
the system designer in the −40°C to +150°C range. The internal
comparator is designed to switch accurately as the ambient
temperature rises past the setpoint temperature. When the ambient
temperature falls, the comparator relaxes its output at a somewhat
lower temperature than that at which the comparator originally
switched. The difference between the switch and unswitched
temperatures, known as the hysteresis, is nominally 4°C.
THE SETPOINT RESISTOR
Determine the setpoint resistor by the following equation:
( )
Ω−
°+°
°Ω
=k
CCT
CM
R
SET
SET
3.90
6.281
39
(1)
Connect the setpoint resistor directly between the RSET pin and
the GND pin. If a ground plane is used, connect the resistor
directly to this plane at the closest available point.
The setpoint resistor, RSET, can be almost any resistor type.
However, the resistor initial tolerance and thermal drift affects
the accuracy of the programmed switching temperature. For most
applications, a 1% metal film resistor provides the best tradeoff
between cost and accuracy. Calculations for computing an error
budget are found in the Effect of Resistor Tolerance and Thermal
Drift on Setpoint Accuracy section.
After RSET is calculated, the calculated value does not agree with
readily available standard resistors of the chosen tolerance. To
achieve an RSET value as close as possible to the calculated value,
a compound resistor can be constructed by connecting two
resistors in series or in parallel. To conserve cost, one moderately
precise resistor and one lower precision resistor can be combined.
If the moderately precise resistor provides most of the necessary
resistance, the lower precision resistor can provide a fine
adjustment. Consider an example where the closest standard
1% resistor has only 90% of the value required for RSET. If a
5% series resistor is used for the remainder, the tolerance of
the resistor only adds 5% of 10% or 0.5% additional error to
the combination. Likewise, the 1% resistor only contributes
90% of 1% or 0.9% error to the combination. These two
contributions are additive, resulting in a total compound
resistor tolerance of 1.4%.
EFFECT OF RESISTOR TOLERANCE AND THERMAL
DRIFT ON SETPOINT ACCURACY
Figure 4 shows the typical accuracy error in setpoint
temperature as a function of the programmed setpoint
temperature. This curve assumes an ideal resistor for RSET.
Figure 5 can be used to calculate additional setpoint error as a
function of resistor tolerance. Figure 5 shows additional error
beyond the initial accuracy error of the device and must be
added to the value found in Table 1. For example, consider
using the AD22105 programmed to switch at 125°C. Figure 5
indicates that at +125°C, the additional error is approximately
−0.2°C/% of RSET. If a 1% resistor (of exactly correct value) is
chosen, the additional error is −0.2°C/% × 1% or −0.2°C. If the
closest standard resistor value is 0.6% away from the calculated
value, the total error is 0.6% for the nominal value and 1% for
the tolerance or 1.006 × 1. 01 or 1.01606 (about 1.6%). The
closest resistor value differing slightly from the calculated value
can lead to an additional setpoint error as high as 0.32°C.
For additional accuracy considerations, take the thermal drift of
the setpoint resistor into account. For example, consider that
the drift of the metal film resistor is 100 ppm/°C. Because this
drift is usually referred to 25°C, the setpoint resistor can be in
error by an additional 100 ppm/°C × (125°C − 25°C) or 1%.
Using a setpoint temperature of 125°C, this error source adds an
additional −0.2°C (for positive drift) making the overall
setpoint error potentially −0.52°C higher than the original
accuracy error.
To combine and calculate the initial tolerance and thermal drift
effects of the setpoint resistor use the following equation:
RMAX = RNOM × (1 + ε) × (1 + TC × (TSET − 25°C))
where:
RMAX is the worst case value that the setpoint resistor can be at TSET.
RNOM is the standard resistor with a value closest to the desired RSET.
ε is the 25°C tolerance of the chosen resistor (usually 1%, 5%, or
10%).
TC is the temperature coefficient of the available resistor.
TSET is the desired setpoint temperature.
After calculation, compare RMAX to the desired RSET from
Equation 1. The required value of RSET at a TSET of 125°C is
5.566 kΩ. If the nearest standard resistor value is 5.600 kΩ, its worst
case maximum value at +125°C is 5.713 kΩ, which is +2.6%
higher than RSET, leading to a total additional error of −0.52°C
beyond that given in Table 1.
Data Sheet AD22105
Rev. A | Page 9 of 11
HYSTERESIS AND SELF HEATING
The actual value of hysteresis generally has a minor dependence on
the programmed setpoint temperature, as shown in Figure 7.
Furthermore, the hysteresis can be affected by self heating if the
device is driving a heavy load. For example, if the device is driving a
load of 5 mA at an output voltage (given by Figure 10) of 250 m V,
the additional power dissipation is approximately 1.25 m W. With a
θJA of 190°C/W in still air, the internal die temperature is 0.24°C
higher than ambient, leading to an increase of 0.24°C in
hysteresis. In the presence of a heat sink or a turbulent
environment, the additional hysteresis is less.
OUTPUT SECTION
The output of the AD22105 is the collector of the negative positive
negative (NPN) transistor. When the ambient temperature of the
device exceeds the programmed setpoint temperature, this
transistor is activated, causing its collector to become a low
impedance. A pull-up resistor, such as the internal 200 kΩ
provided, is needed to observe a change in the output voltage. For
versatility, the optional pull-up resistor is not permanently
connected to the output pin. Instead, this resistor is undedicated
and connects from the VS pin to the RPULL-UP pin. To use RPULL-UP,
a single connection must be made from the RPULL-UP pin to the
OUT pin.
The 200 kΩ pull-up resistor can drive CMOS loads because
essentially no static current is required at these inputs. When
driving low power Schottky (LS) and other bipolar family logic
inputs, a parallel resistor may be necessary to supply the 20 µA
to 50 µA high level input current (IIH) specified for such devices.
To determine the current required, consult the appropriate
manufacturer data sheet. When the output is switched, indicating
an over temperature condition, the output is capable of pulling
down with 10 mA at a voltage of about 375 mV, which allows a
fanout of 2 with standard bipolar logic and 20 with LS family
logic.
Low power indicator LEDs (up to 10 mA) can be driven directly
from the output pin of the AD22105. In most cases, a small series
resistor (usually of several hundred ohms) is required to limit
the current to the LED and the output transistor of the AD22105.
MOUNTING CONSIDERATIONS
If the AD22105 is thermally attached and properly protected, it
can be used in any measuring situation where the maximum
range of temperatures encountered is between −40°C and
+150°C. Because plastic IC packaging technology is employed,
excessive mechanical stress must be avoided when fastening the
device with a clamp or screw on the heat tab. Thermally conductive
epoxy or glue is recommended for typical mounting conditions.
In wet or corrosive environments, use an electrically isolated
metal or ceramic well to protect the AD22105.
THERMAL ENVIRONMENT EFFECTS
The thermal environment in which the AD22105 is used
determines two performance traits: the effect of self heating on
accuracy and the response time of the sensor to rapid changes in
temperature. In the first case, a rise in the IC junction temperature
above the ambient temperature is a function of two variables:
the power consumption of the AD22105 and the thermal
resistance between the chip and the ambient environment, θJA.
Self heating error can be derived by multiplying the power
dissipation by θJA. Because errors of this type can vary widely
for surroundings with different heat sinking capacities, it is
necessary to specify θJA under several conditions.
Table 3 shows how the magnitude of self heating error varies
relative to the environment. A typical device dissipates about
230 µW at room temperature with a 3.3 V supply and negligible
output loading. In still air, without a heat sink, Table 3 indicates a
θJA of 190°C/W, which yields a temperature rise of 0.04°C.
Thermal rise of the die is considerably less in an environment of
turbulent or constant moving air or if the device is in direct
physical contact with a solid (or liquid) body.
Response of the AD22105 internal die temperature to abrupt
changes in ambient temperatures can be modeled by a single time
constant exponential function. Figure 12 shows the typical
response for moving and still air. The time constant, τ (time to
reach 63.2% of the final value), is dependent on θJA and the
thermal capacities of the chip and the package.
Table 3 lists the effective τ for moving and still air. Copper PCB
connections were neglected in the analysis. However, these
connections sink or conduct heat directly through the AD22105
solder plated copper leads. When faster response is required, use a
thermally conductive grease or glue between the AD22105 and
the surface temperature being measured.
USING THE AD22105 AS A COOLING SETPOINT
DETECTOR
The AD22105 detects transitions from higher temperatures to
lower temperatures by programming the setpoint temperature
4°C greater than the desired trip point temperature. The 4°C is
necessary to compensate for the nominal hysteresis value designed
into the device. A more precise value of the hysteresis can be
obtained from Figure 7. In this mode, the logic state of the output
indicates a high for under temperature conditions. The total device
error is slightly greater than the specification value due to the
uncertainty in hysteresis.
AD22105 Data Sheet
Rev. A | Page 10 of 11
APPLICATIONS INFORMATION
Figure 14 shows the typical application circuit.
3 41 2
6 58 7
OUT
+2.7V TO +7.0V
R
SET
AD22105
02099-002
Figure 14. Typical Application Circuit
ELECTROMAGNETIC INTERFERENCE (EMI)
SUPPRESSION
Noisy environments may couple electromagnetic energy into
the RSET node causing the AD22105 to falsely trip or untrip.
Noise sources, which typically come from fast rising edges, can
be coupled into the device capacitively. Furthermore, if the
output signal is close to the RSET pin, energy can couple from the
OUT pin to the RSET pin, potentially causing oscillation. Stray
capacitance can come from several places such as IC sockets,
multiconductor cables, and PCB traces. In some cases,
constructing a Faraday shield around the RSET pin can correct
this; for example, by using a shielded cable with the shield
grounded. However, for best performance, avoid cables and
directly solder the AD22105 to a PCB whenever possible. Figure 15
shows a sample PCB layout with low inter pin capacitance and
Faraday shielding. If stray capacitance is unavoidable, and
interference or oscillation occurs, connect a low impedance
capacitor from the RSET pin to the GND pin. This capacitor
must be considerably larger than the estimated stray capacitance.
Typically, several hundred picofarads corrects the problem.
LEAKAGE AT THE RSET PIN
Leakage currents at the RSET pin, such as those generated from a
moist environment or PCB contamination, can have an adverse
effect on the programmed setpoint temperature of the AD22105.
Depending on the leakage source, leakage current can flow
into or out of the RSET pin. Consequently, the actual setpoint
temperature may be higher or lower than the intended setpoint
temperature by about 1°C for each 75 nA of leakage. With a 5 V
power supply, an isolation resistance of 100 MΩ creates 50 nA
of leakage current, resulting in a setpoint temperature error of
about 0.7°C (the RSET pin is near ground potential). Place a
guard ring around the RSET node to protect against leakage
from the power supply pin (as shown in Figure 15).
C1
PIN 1
OUT
GND
V
S
R
SET
02099-015
Figure 15. Suggested PCB Layout
5.nn(n.1§68? . HHHH’ f ' HHHHA 94H If ’ ‘ iafii fl ORDERING GUIDE magmmunauug Daimlnnnu.igmmumxnaemamand SEGIEOEE w w w . a n a | n g . c 0 n1
Data Sheet AD22105
Rev. A | Page 11 of 11
OUTLINE DIMENSIONS
CONTROLLING DIMENSIONSAREINMILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATEFOR USE IN DESIGN.
COMPLIANT TO JEDEC STANDARDSMS-012-AA
012407-A
0.25 (0.0098)
0.17 (0.0067)
1.27 (0.0500)
0.40(0.0157)
0.50 (0.0196)
0.25 (0.0099) 45°
8°
0°
1.75(0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
4
1
8 5
5.00 (0.1968)
4.80(0.1890)
4.00 (0.1574)
3.80 (0.1497)
1.27(0.0500)
BSC
6.20(0.2441)
5.80(0.2284)
0.51(0.0201)
0.31 (0.0122)
COPLANARITY
0.10
Figure 16. 8-Lead Standard Small Outline Package [SOIC_N]
Narrow Body
(R-8)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
AD22105ARZ −40°C to +150°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
AD22105ARZ-REEL −40°C to +150°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
AD22105ARZ-REEL7 −40°C to +150°C 8-Lead Standard Small Outline Package [SOIC_N] R-8
1 Z = RoHS Compliant Part.
©1996–2018 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D02099-0-10/18(A)