LTC2997 - Remote/Internal Temperature Sensor

LTC2997
Remote/Internal
Temperature Sensor
FEATURES
DESCRIPTION
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The LTC®2997 is a high-accuracy analog output temperature
sensor. It converts the temperature of an external sensor or
its own temperature to an analog voltage output. A built-in
algorithm eliminates errors due to series resistance between the LTC2997 and the sensor diode.
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Converts Remote Sensor or Internal Diode
Temperature to Analog Voltage
±1°C Remote Temperature Accuracy
±1.5°C Internal Temperature Accuracy
Built-In Series Resistance Cancellation
2.5V to 5.5V Supply Voltage
1.8V Reference Voltage Output
3.5ms VPTAT Update Time
4mV/°K Output Gain
170μA Quiescent Current
Available in 6-Pin 2mm × 3mm DFN Package
The LTC2997 gives accurate results with low-cost diodeconnected NPN or PNP transistors or with integrated
temperature transistors on microprocessors or FPGAs.
Tying pin D+ to VCC configures the LTC2997 to measure
its internal temperature.
The LTC2997 provides an additional 1.8V reference voltage
output which can be used as an ADC reference input or
for generating temperature threshold voltages to compare
against the VPTAT output.
APPLICATIONS
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Temperature Measurement
Remote Temperature Measurement
Environmental Monitoring
System Thermal Control
Desktop and Notebook Computers
Network Servers
The LTC2997 provides a precise and versatile micropower
solution for accurate temperature sensing.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
Single Remote Temperature Sensor
VPTAT vs Remote Sensor Temperature
2.5V TO 5.5V
1.8
0.1μF
1.6
D+
VCC
VREF
1.8V
LTC2997
470pF
D–
GND
VPTAT
4mV/K
2997 TA01a
VPTAT (V)
MMBT 3904
1.4
1.2
1.0
0.8
25 50 75 100 125 150
–50 –25 0
REMOTE SENSOR TEMPERATURE (°C)
2997 TA01b
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LTC2997
ABSOLUTE MAXIMUM RATINGS
(Notes 1, 2)
Terminal Voltages
VCC........................................................... –0.3V to 6V
D+, D –, VPTAT, VREF ......................–0.3V to VCC + 0.3V
Operating Ambient Temperature Range
LTC2997C ................................................ 0°C to 70°C
LTC2997I .............................................–40°C to 85°C
LTC2997H .......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
PIN CONFIGURATION
TOP VIEW
D+ 1
D–
2
6 VREF
7
5 GND
4 VCC
VPTAT 3
DCB PACKAGE
6-LEAD (2mm w 3mm) PLASTIC DFN
TJMAX = 150°C, θJA = 64°C/W
EXPOSED PAD PCB GROUND CONNECTION OPTIONAL
ORDER INFORMATION
Lead Free Finish
TAPE AND REEL (MINI)
TAPE AND REEL
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2997CDCB#TRMPBF
LTC2997CDCB#TRPBF
LFQZ
6-Lead (2mm × 3mm) Plastic DFN
0°C to 70°C
LTC2997IDCB#TRMPBF
LTC2997IDCB#TRPBF
LFQZ
6-Lead (2mm × 3mm) Plastic DFN
–40°C to 85°C
LTC2997HDCB#TRMPBF
LTC2997HDCB#TRPBF
LFQZ
6-Lead (2mm × 3mm) Plastic DFN
TRM = 500 pieces. *Temperature grades are identified by a label on the shipping container.
Consult LTC Marketing for parts specified with wider operating temperature ranges.
Consult LTC Marketing for information on lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
–40°C to 125°C
2997fa
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LTC2997
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C, VCC = 3.3V, unless otherwise noted.
SYMBOL
PARAMETER
VCC
Supply Voltage
UVLO
Supply Undervoltage Lockout Threshold
ICC
Average Supply Current
CONDITIONS
VCC Falling
MIN
TYP
l
MAX
UNITS
2.5
3.3
5.5
V
l
1.7
1.9
2.1
V
l
120
170
250
μA
1.797
1.793
1.790
1.787
1.8
1.8
1.8
1.8
1.803
1.804
1.807
1.808
V
V
V
V
±1.5
mV
Temperature Monitoring
VREF
Reference Voltage
LTC2997
LTC2997C
LTC2997I
LTC2997H
l
l
l
VREF Load Regulation Error
ILOAD = ±200μA; VCC = 3.3V
l
(Note 3)
l
Remote Sense Current
Diode Select Threshold
–8
TUPDATE
Temperature Update Interval
KT
VPTAT Slope
η = 1.004 (Note 4)
VPTAT Load Regulation
ILOAD = ±200μA; VCC = 3.3V (Note 7)
TINT
Internal Temperature Error
LTC2997C, LTC2997I
LTC2997H
TRMT
Remote Temperature Error, η = 1.004
0°C to 100°C (Notes 5, 7)
–40°C to 0°C (Notes 5, 7)
100°C to 125°C (Notes 5, 7)
TVCC
Temperature Error vs Supply
2.5V ≤ VCC ≤ 5.5V
TRS
Series Resistance Cancellation Error
RSERIES = 100Ω
Temperature Noise
(Note 6)
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
–192
μA
VCC – 600 VCC – 300 VCC – 100
mV
3.5
ms
5
4
mV/°K
±1.5
mV
±0.5
±1.5
±2
°C
°C
±0.25
±0.25
±1
±1.5
±1.5
°C
°C
°C
l
±0.1
±1
°C/V
l
±0.25
±1
°C
l
l
0.25
0.015
°C RMS
°C/√Hz
Note 3: If voltage on pin D+ exceeds the diode select threshold the
LTC2997 uses the internal diode sensor.
Note 4: η = ideality factor of remote diode
Note 5: Remote diode temperature.
Note 6: Guaranteed by design and not subject to test.
Note 7: Guaranteed by design and test correlation.
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LTC2997
TYPICAL PERFORMANCE CHARACTERISTICS
Remote Temperature Error vs
TA with Remote Diode at 25°C
3
2
2
2
1
1
1
0
–1
TINT ERROR (°C)
3
0
–1
–2
–2
–3
–50 –25
0
25
50 75
TA (°C)
–3
–50 –25
100 125 150
–1
0
25
50 75
TA (°C)
–3
–50 –25
100 125 150
0
25
50 75
TA (°C)
100 125 150
2997 G02
Temperature Error vs
VCC - Remote/Internal, T VCC
2997 G03
Remote Temperature Error vs
CDECOUPLE (Between D+ and D –)
Remote Temperature Error vs
Series Resistance, TRS
0.4
1.5
0.2
1.0
0.8
0.4
0
–0.2
–0.4
ERROR (°C)
0.5
ERROR (°C)
ERROR (°C)
0
–2
2997 G01
0
0
–0.5
–0.6
–0.4
–1.0
–0.8
–1.0
1
2
4
3
6
5
–1.5
0
200
VCC (V)
400
600
800
SERIES RESISTOR (Ω)
2997 G04
2.4
0.25
2.2
1.810
VCC RISING
VCC FALLING
1.805
1.8
1.800
1.6
1.4
0.05
5
VRFE (V)
UVLO (V)
0.10
3
4
1
2
DECOUPLE CAPACITOR (nF)
Buffered Reference Voltage
vs Temperature, VREF
2.0
0.20
0.15
0
2997 G06
UVLO vs Temperature
VCC Rising, Falling
0.30
0
0.01
–0.8
1000
2997 G05
VPTAT Noise vs Averaging Time
VPTAT NOISE (°C RMS)
Internal Temperature Error vs
TA, TINT
3
TRMT ERROR (°C)
TRMT ERROR (°C)
Temperature Error with LTC2997
at Same Temperature as Remote
Diode
TA = 25°C, VCC = 3.3V unless otherwise noted.
1.795
1.2
10
1
0.1
AVERAGING TIME (ms)
100
2997 G07
1.0
–50 –25
0
25
50 75 100 125 150 175
TA (°C)
2997 G08
1.790
–50 –25
0
25
50 75
TA (°C)
100 125 150
2997 G09
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LTC2997
TYPICAL PERFORMANCE CHARACTERISTICS
Load Regulation of VPTAT –
Voltage vs Current
1.28
VCC = 2.5V
VCC = 3.5V
VCC = 4.5V
VCC = 5.5V
1.810
Supply Current vs Temperature
200
VCC = 2.5V
VCC = 3.5V
VCC = 4.5V
VCC = 5.5V
1.27
190
SUPPLY CURRENT (μA)
Load Regulation of VREF –
Voltage vs Current
1.820
TA = 25°C, VCC = 3.3V unless otherwise noted.
VPTAT (V)
VREF (V)
1.26
1.800
1.25
1.24
1.790
0
–2
2
LOAD CURRENT (mA)
–4
4
1.22
–4
2
–2
0
LOAD CURRENT (mA)
2997 G10
4
TRMT ERROR (°C)
VPTAT (°C)
10
ABSOLUTE TEMPERATURE ERROR (°C)
100
50
25
0
AIR
0
1
BOILING
WATER
3
2
TIME (s)
LTC2997 CONNECTED VIA 5 INCH
30AWG WRAPPING WIRES
4
2
0
–2
–4
5
–6
–200
–100
0
100
200
ILEAKAGE (nA)
2997 G13
25
50 75
TA (°C)
100 125 150
Single Wire Remote Temperature
Error vs Potential Difference Between
Remote and Local Ground (VAC)
6
75
0
2997 G12
Remote Temperature Error vs
Leakage Current at D+ with
Remote Diode at 25°C, T RMT
125
–50
150
–50 –25
4
2997 G11
LTC2997 Internal Sensor
Thermal Step Response
ICE
–25 WATER
170
160
1.23
1.780
180
2997 G14
VAC = 50mVP-P
1
0.1
0.01
0.1
1
100
10
FREQUENCY (kHz)
1000
2997 G15
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LTC2997
PIN FUNCTIONS
D+: Diode Sense Current Source. D+ sources the remote
diode sensing current. Connect D+ to the anode of the remote sensor device. It is recommended to connect a 470pF
bypass capacitor between D+ and D–. Larger capacitors
may cause settling time errors (see Typical Performance
Characteristics). If D+ is tied to VCC, the LTC2997 measures
the internal sensor temperature. Tie D+ to VCC if unused.
VPTAT : VPTAT Voltage Output. The voltage on this pin is
proportional to the sensor’s absolute temperature. VPTAT
can drive a capacitive load of up to 1000pF. For larger
load capacitance, insert 1kΩ between VPTAT and load to
guarantee stability. VPTAT can drive up to ±200μA of load
current. VPTAT is pulled low when the supply voltage goes
below the under voltage lockout threshold.
D–: Diode Sense Current Sink. Connect D– to the cathode
of the remote sensor device. Tie D– to GND for single
wire remote sensing (see Typical Applications) or internal
temperature sensing.
VREF : Voltage Reference Output. VREF provides a 1.8V
reference voltage. VREF can drive a capacitive load of up
to 1000pF. For larger load capacitance, insert 1kΩ between
VREF and load to guarantee stability. VREF can drive up to
±200μA of load current. Leave VREF open if unused.
GND: Device Ground.
VCC : Supply Voltage. Bypass this pin to GND with a 0.1μF
(or greater) capacitor. VCC operating range is 2.5V to 5.5V.
Exposed Pad: Exposed pad may be left open or soldered
to GND for better thermal coupling.
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LTC2997
BLOCK DIAGRAM
VSUPPLY
4
VCC
+
–
UVLO
TEMPERATURE TO
VOLTAGE
CONVERTER
+
–
1
2
3
1.2V
EXT/INT MUX
+
D+
1.8V VREF
–
6
600k
INTERNAL
SENSOR
EXTERNAL
SENSOR
VPTAT
MUX
300mV
D–
1200k
GND
5
2997 BD
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LTC2997
OPERATION
The Block Diagram shows the main components of the
LTC2997.
The LTC2997 measures temperature using either a remote
or internal diode and provides a buffered voltage proportional to absolute temperature (VPTAT) and a buffered 1.8V
reference voltage. Remote temperature measurements
usually use a diode connected transistor as a temperature sensor, allowing the remote sensor to be a discrete
NPN (ex. MMBT3904) or an embedded PNP device in a
microprocessor or FPGA.
Temperature measurements are conducted by measuring the diode voltage at multiple test currents. The diode
equation can be solved for T, where T is degrees Kelvin,
IS is a process dependent factor on the order of 10–13A,
η is the diode ideality factor, k is the Boltzmann constant
and q is the electron charge:
T=
V
q
• DIODE
⎛I ⎞
η•k
ln ⎜ D ⎟
⎝IS ⎠
This equation has a relationship between temperature and
voltage, dependent on the process-dependent variable IS.
Measuring the same diode (with the same value IS) at two
different currents yields an expression which is independent
I1, I2
of IS. The value in the natural logarithm term becomes the
ratio of the two currents, which is process independent.
T=
– V DIODE1
V
• DIODE2
⎛I ⎞
η•k
ln ⎜ D2 ⎟
⎝ I D1 ⎠
q
Series Resistance Cancellation
Resistance in series with the remote diode causes a positive
temperature error by increasing the measured voltage at
each test current. The composite voltage equals:
VDIODE + VERROR = η
⎛I ⎞
kT
• ln ⎜ D ⎟ +R S • I D
q
⎝IS ⎠
where RS is the series resistance.
The LTC2997 removes this error term from the sensor
signal by subtracting a cancellation voltage (see Figure 1).
A resistance extraction circuit uses one additional current
(I3) to determine the series resistance in the measurement
path. Once the correct value of the resistor is determined
VCANCEL equals VERROR. Now the temperature to voltage
converter's input signal is free from errors due to series
resistance and the sensor temperature can be determined
using currents I1 and I2.
I3
D+
RSERIES
RESISTANCE
EXTRACTION
CIRCUIT
VERROR
VBE
D–
+
–
VCANCEL = VERROR
VBE
TEMPERATURE
TO VOLT
CONVERTER
VPTAT
2997 F01
Figure 1. Series Resistance Cancellation
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LTC2997
APPLICATIONS INFORMATION
Power Up and UVLO
The basic LTC2997 application using an external NPN
transistor is shown in Figure 2.
2.5V TO 5.5V
Input Noise Filtering
0.1μF
D+
MMBT3904
VCC
VREF
1.8V
LTC2997
470pF
D–
GND
VPTAT
4mV/K
2997 F02
Figure 2. Basic Application Circuit
The VCC pin must exceed the undervoltage threshold of
1.9V (typical) for normal operation. For VCC below UVLO
the LTC2997 enters power-on reset and VPTAT is pulled low.
Temperature Measurements
Before each conversion a voltage comparator connected
to D+ automatically sets the LTC2997 into external or internal mode. Tying D+ to VCC enables internal mode and
VPTAT represents the die temperature. The VPTAT gain, KT,
is 4mV/K. The temperature in Kelvin is easily calculated:
TKELVIN =
of up to 100Ω to an error smaller than 1°C (see Typical
Performance Characteristics). The LTC2997 continuously
measures the sensor diode at different test currents and
updates VPTAT every 3.5ms (typical).
VPTAT
KT
For VD+ more than 300mV below VCC (typical) the LTC2997
assumes that an external sensor is connected and will start
sending sensing currents to the remote sensor diode. The
anode of the external sensor must be connected to pin D+.
The cathode should be connected to D– for best external
noise immunity. For single wire measurements the sensor cathode is connected to remote GND and D– must be
connected to local GND (see Figure 7). Small ground DC
voltages (<±200mV) between the two cathode potentials
do not impact the measurement accuracy. AC voltages at
odd multiples of 6kHz (±20%) cause temperature measurement errors (see Typical Performance Characteristics).
The LTC2997 is calibrated to yield a VPTAT gain of 4mV/K
for a remote diode with an ideality factor of 1.004. A
built-in algorithm cancels errors due to series resistance
The change in sensor voltage per °C is hundreds of microvolts, so electrical noise must be kept to a minimum.
Bypass D+ and D– with a 470pF capacitor close to the
LTC2997 to suppress external noise. Bypass capacitors
greater 1nF cause settling time errors of the different
measurement currents. See Typical Performance Characteristics. Long wires connecting external sensors add
series resistance, mutual capacitance between D+ and
D–, and cause leakage currents. A 10m CAT6 cable has
~500pF of mutual capacitance and adds negligible series
resistance and leakage currents. Recommended shielding
and PCB trace considerations for best noise immunity are
illustrated in Figure 3.
GND SHIELD TRACE
470pF
D+
D–
LTC2997
GND
NPN SENSOR
2997 F03
Figure 3. Recommended PCB Layout
Output Noise Filtering
The VPTAT output typically exhibits 1mV RMS (0.25°C RMS)
noise. For applications which require lower noise digital
or analog averaging can be applied to the output. Choose
the averaging time according to the following equation:
⎛ 0.015 [°C / Hz ] ⎞ 2
t AVG = ⎜
⎟
TNOISE
⎠
⎝
where tAVG is the averaging time and TNOISE the desired
temperature noise in °C RMS. For example, if the desired
noise performance is 0.015°C RMS, set the averaging time
to one second. See Typical Performance Characteristics.
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LTC2997
APPLICATIONS INFORMATION
Choosing a Sensor
10Ω
The LTC2997 is factory calibrated for an ideality factor of
1.004, which is typical of the popular MMBT3904 NPN
transistor. Semiconductor purity and wafer-level processing
intrinsically limit device-to-device variation, making these
devices interchangeable between most manufacturers with
a temperature error of typically less than 0.5°C. Some
recommended sources are listed in Table 1:
Table 1. Recommended Transistors for Use as Temperature
Sensors.
MANUFACTURER
PART NUMBER
PACKAGE
Fairchild
Semiconductor
MMBT3904
SOT-23
Central Semiconductor
CMPT3904
SOT-23
Diodes, Inc.
MMBT3904
SOT-23
On Semiconductor
MMBT3904LT1
SOT-23
NXP
MMBT3904
SOT-23
Infineon
MMBT3904
SOT-23
UMT3904
SC-70
Rohm
Discrete two terminal diodes usually have ideality factors
significantly higher than 1.004 and are therefor not recommended as remote sensing devices.
Protection
The LTC2997 can withstand up to ±4kV of electrostatic
discharge (ESD, human body). ESD beyond this voltage
can damage or degrade the device including lowering the
remote sensor measurement accuracy due to increased
leakage currents on D+ and D–.
To protect the sensing inputs against larger ESD strikes,
external protection can be added using TVS diodes to
ground (Figure 4). Care must be taken to choose diodes
with low capacitance and low leakage currents in order
not to degrade the external sensor measurement accuracy
(see Typical Performance Characteristics).
MMBT3904
D+
LTC2997
220pF
10Ω
D–
GND
PESD5Z6.0
2997 F04
Figure 4. Increasing ESD Robustness with TVS Diodes
Ideality Factor Scaling
While an ideality factor value of 1.004 is typical of many
sensor devices, small deviations can yield significant temperature errors. The ideality factor acts as a temperature
scaling factor. The temperature error for a 1% deviation
is 1% of the Kelvin temperature. Thus, at 25°C (298K) a
+1% accurate ideality factor error yields a +2.98 degree
error. At 85°C (358K) a +1% error yields a 3.58 degree
error. It is possible to scale the PTAT voltage if an external
sensor with an ideality factor other than 1.004 is used.
The scaling equation for the compensated PTAT voltage
is listed below.
LTC2997 Ideality Calibration Value:
ηCAL = 1.004
Actual Remote Sensor Ideality Value:
ηACT
Compensated PTAT Voltage:
VPTAT _ COMP =
η CAL
• VPTAT _ MEAS
η ACT
Compensated Kelvin Temperature:
TKELVIN _ COMP =
η CAL
• TKELVIN _ MEAS
η ACT
Compensated Celsius Temperature:
TCELSIUS _ COMP =
η CAL
•(TKELVIN _ MEAS ) – 273.15
η ACT
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LTC2997
TYPICAL APPLICATIONS
2.5V TO 5.5V
0.1μF
MMBT3904
VCC
D+
VREF
1.8V
LTC2997
470pF
D–
GND
VPTAT
4mV/K
2997 F05
Figure 5. Single Remote Temperature Sensor
2.5V TO 5.5V
0.1μF
D+
VCC
VREF
μC
1.8V
LTC2997
D–
GND
VPTAT
4mV/K
A/D
2997 F06
Figure 6. Internal Temperature Sensor
2.5V TO 5.5V
0.1μF
D+
CPU/
FPGA/
ASIC
VCC
VREF
1.8V
LTC2997
470pF
D–
GND
VPTAT
4mV/K
2997 F07
Figure 7. Remote CPU Temperature Sensor
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LTC2997
TYPICAL APPLICATIONS
2.5V TO 5.5V
0.1μF
D+
2N3904
VCC
1.8V
VREF
LTC2997
470pF
D–
GND
4mV/K
VPTAT
2997 F08
Figure 8. Single Wire Remote Temperature Sensor
0.30
2.5V TO 5.5V
D+
VCC
>1k
VPTAT
LTC2997
VPTAT(FILTER)
CFILTER
D–
GND
2997 F09
VPTAT NOISE (°C RMS)
0.25
0.1μF
0.20
0.15
0.10
0.05
0
0.005
5
0.5
0.05
RC TIME CONSTANT (ms)
50
Figure 9. Output Noise Filter
2.5V TO 5.5V
CAT6 STP CABLE
10m MAXIMUM
0.1μF
D+
MMBT
3904
VCC
VREF
1.8V
LTC2997
470pF
D–
GND
VPTAT
4mV/K
2997 F10
Figure 10. Long Distance Remote Temperature Sensor
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LTC2997
TYPICAL APPLICATIONS
MEASURE TEMPERATURE AND SET
TARGET TEMPERATURE WITH
RESISTIVE DIVIDER
INTEGRATE
TEMPERATURE
ERROR
PWM
OSCILLATOR
5V
100μF
10M
0.1μF
100pF
10M
200k
ZXM64PO35
D
+
VCC
1k
–
VPTAT
100k
LTC2997
470pF
5V
LTC6079
–
+
D–
GND
VREF
+
LTC6079
CET 3904
22k
VTARGET
75k
VREF
100k
1M
10Ω
RHEATER
2997 F11
Figure 11. Analog PWM Heater Controller
CET 3904
5V
10Ω
RHEATER
0.1μF
D+
VCC
VPTAT
–
4mV/K
LTC2997
470pF
D–
GND
VREF
+
1.8V
LTC6079
IRF3708
22k
VTARGET = 1.3917V
75k
2997 F12
Figure 12. 75°C Analog Heater Controller
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LTC2997
TYPICAL APPLICATIONS
2.5V TO 5.5V
0.1μF
VCC
D+
VREF
LTC2997
470pF
MMBT3904
1.8V
D–
GND
VPTAT
4mV/K
2997 F13
Figure 13. Remote Diode Sensor Insensitive to Cable Connection Polarity
12V
5V
0.1μF
39k
B6015L12F
68k
FAN
MMBT 3904
D+
VCC
10k
VREF
–
LTC2997
470pF
VPTAT
D–
GND
VCC
+
IRF3708
OUT
MOD
LTC6078
LTC6692
DIV
SET
390k
GND
2997 F14
Figure 14. Temperature Proportional PWM Fan Speed Controller
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LTC2997
TYPICAL APPLICATIONS
0.1μF
150k
2.5V TO 5.5V
1.8k
0.1μF
5V
D+
VCC
VREF
1.8V
LTC2997
D–
VPTAT
4mV/K
100k
1k
–
62k
GND
143k
7
LTC1150
1
+ 4
10mV/°C
0V AT 0°C
1μF
–5V
2997 F15
Figure 15. Celsius Thermometer
0.1μF
255k
2.5V TO 5.5V
0.1μF
D+
VREF
1.8V
LTC2997
D–
5V
270k
VCC
VPTAT
4mV/K
100k
–
7
LTC1150
1
+ 4
62k
10mV/°F
0V AT 0°F
1μF
GND
2997 F16
–5V
Figure 16. Fahrenheit Thermometer
2997fa
15
LTC2997
PACKAGE DESCRIPTION
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DCB Package
6-Lead Plastic DFN (2mm × 3mm)
(Reference LTC DWG # 05-08-1715 Rev A)
0.70 ±0.05
3.55 ±0.05
1.65 ±0.05
(2 SIDES)
2.15 ±0.05
PACKAGE
OUTLINE
0.25 ± 0.05
0.50 BSC
1.35 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.115
TYP
2.00 ±0.10
(2 SIDES)
R = 0.05
TYP
3.00 ±0.10
(2 SIDES)
0.40 ± 0.10
4
6
1.65 ± 0.10
(2 SIDES)
PIN 1 NOTCH
R0.20 OR 0.25
× 45° CHAMFER
PIN 1 BAR
TOP MARK
(SEE NOTE 6)
3
0.200 REF
0.75 ±0.05
1
(DCB6) DFN 0405
0.25 ± 0.05
0.50 BSC
1.35 ±0.10
(2 SIDES)
0.00 – 0.05
BOTTOM VIEW—EXPOSED PAD
NOTE:
1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (TBD)
2. DRAWING NOT TO SCALE
3. ALL DIMENSIONS ARE IN MILLIMETERS
4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE
MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE
5. EXPOSED PAD SHALL BE SOLDER PLATED
6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE
TOP AND BOTTOM OF PACKAGE
2997fa
16
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
LTC2997
REVISION HISTORY
REV
DATE
DESCRIPTION
A
9/11
Changed 4mV/°C to 4mV/°K in Features
1
Updated Description
1
Updated Electrical Characteristics
3
Added Graph G15
5
Updated Pin Functions
PAGE NUMBER
6
Updated Applications Information
9, 10
Updated Figures 9, 10, 13, 15, 16
12, 14, 15
Updated Related Parts
18
2997fa
17
LTC2997
TYPICAL APPLICATION
5V
+
OUT = 4mV/K
LTC6078
TYPE K
THERMOCOUPLE
–
1.3k
5V
127k
10k
5.6pF
0.1μF
D+
VCC
VPTAT
LTC2997
D–
GND
VREF
2997 F17
Figure 17. Thermocouple Thermometer with Cold Junction Compensation
RELATED PARTS
PART NUMBER DESCRIPTION
COMMENTS
LTC2990
Remote/Internal Temperature, Voltage and Current
Monitor
Measures Two Remote Diode Temperatures, ±1°C Accuracy, 0.06°C Resolution,
±2°C Internal Temperature Sensor, I2C Interface,
LTC2909
Precision Triple/Dual Input UV, OV and Negative Voltage
Monitor
Two Adjustable Inputs, ±1.5% Accuracy, 6.5V Shunt Regulator
LTC2919
Precision Triple/Dual Input UV, OV and Negative Voltage
Monitor
Two Adjustable Inputs, ±1.5% Accuracy, 6.5V Shunt Regulator, Open-Drain/RST,
OUT1 and OUT2 Outputs
LTC6078
LTC6078 Micropower Precision, Dual/Quad CMOS
Rail-to-Rail Input/Output Amplifiers
Maximum Offset Voltage of 25μV (25°C), Maximum Offset Drift of 0.7μV/°C,
Maximum Input Bias of 1pA (25°C) to 50pA (≤85°C)
LTC6079
Micropower Precision, Dual/Quad CMOS Rail-to-Rail
Input/Output Amplifiers
Maximum Offset Voltage of 25μV (25°C), Maximum Offset Drift of 0.7μV/°C,
Maximum Input Bias of 1pA (25°C) to 50pA (≤85°C)
2997fa
18 Linear Technology Corporation
LT 0911 REV A • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011