LTC1077 [Linear]
Temperature Sensor with Alert Outputs Voltage Output Proportional to Temperature; 温度传感器与警报输出电压输出与温度成正比
| 型号： | LTC1077 |
| 厂家： | 
Linear |
| 描述： | Temperature Sensor with Alert Outputs Voltage Output Proportional to Temperature |
| 文件： | 总16页 (文件大小：236K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTC2996
Temperature Sensor with
Alert Outputs
FeaTures
DescripTion
The LTC®2996 is a high accuracy temperature sensor
with adjustable overtemperature and undertemperature
thresholds and open drain alert outputs. It converts the
temperature of an external diode sensor or its own die
temperature to an analog output voltage while rejecting
errors due to noise and series resistance. The measured
temperature is compared against upper and lower limits
set with resistive dividers. If a threshold is exceeded, the
device communicates an alert by pulling low the corre-
spondent open drain logic output.
n
Converts Remote or Internal Diode Temperature to
Analog Voltage
n
Adjustable Overtemperature and Undertemperature
Thresholds
n
Voltage Output Proportional to Temperature
n
1°C Remote Temperature Accuracy
n
2°C Internal Temperature Accuracy
n
Built-In Series Resistance Cancellation
n
Open Drain Alert Outputs
n
2.25V to 5.5V Supply Voltage
n
1.8V Reference Voltage Output
The LTC2996 gives 1°C accurate temperature results
using commonly available NPN or PNP transistors or
temperature diodes built into modern digital devices. A
1.8V reference output simplifies threshold programming
and can be used as an ADC reference input.
n
200μA Quiescent Current
n
10-Lead 3mm × 3mm DFN Package
applicaTions
The LTC2996 provides an accurate, low power solution
for temperature monitoring in a compact 3mm × 3mm
DFN package.
n
Temperature Monitoring and Measurement
n
System Thermal Control
n
Network Servers
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.
n
Desktop and Notebook Computers
n
Environmental Monitoring
Typical applicaTion
Remote Temperature Monitor with Overtemperature
and Undertemperature Thresholds
VPTAT vs Remote
Diode Temperature
2.25V TO 5.5V
0.1µF
1.8
V
1.8V
43k
OT T > 70°C
UT T < –20°C
CC
V
OT
REF
1.6
TEMPERATURE
CONTROL
SYSTEM
1.4
LTC2996
VTH
VTL
UT
36k
4mV/K
470pF
V
PTAT
1.2
+
102k
D
MMBT3904
1.0
–
D
GND
2996 TA01a
0.8
75 100
125 150
–50 –25
0
25 50
REMOTE DIODE TEMPERATURE (°C)
2996 TA01b
2996f
1
LTC2996
absoluTe MaxiMuM raTings
pin conFiguraTion
(Notes 1, 2)
V
.............................................................. –0.3V to 6V
CC
D , D , V
+
–
, V ............................. –0.3V to V + 0.3V
PTAT REF
CC
OT, UT, VTH, VTL ......................................... –0.3V to 6V
Operating Ambient Temperature Range
TOP VIEW
VTH
VTL
1
2
3
4
5
10 OT
LTC2996C ................................................ 0°C to 70°C
LTC2996I .............................................–40°C to 85°C
LTC2996H.......................................... –40°C to 125°C
Storage Temperature Range .................. –65°C to 150°C
9
8
7
6
UT
+
11
D
V
REF
–
D
GND
V
V
CC
PTAT
DD PACKAGE
10-LEAD (3mm × 3mm) PLASTIC DFN
T
= 150°C, θ = 43°C/W
JA
JMAX
EXPOSED PAD PCB GROUND CONNECTION OPTIONAL
orDer inForMaTion
LEAD FREE FINISH
LTC2996CDD#PBF
LTC2996IDD#PBF
LTC2996HDD#PBF
TAPE AND REEL
PART MARKING*
LFQX
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTC2996CDD#TRPBF
LTC2996IDD#TRPBF
LTC2996HDD#TRPBF
0°C to 70°C
10-Lead (3mm × 3mm) Plastic QFN
10-Lead (3mm × 3mm) Plastic QFN
10-Lead (3mm × 3mm) Plastic QFN
LFQX
–40°C to 85°C
–40°C to 125°C
LFQX
Consult LTC Marketing for parts specified with wider operating temperature ranges. *Temperature grades are identified by a label on the shipping container.
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/
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
CONDITIONS
MIN
2.25
1.7
TYP
MAX
5.5
UNITS
l
l
l
V
Supply Voltage
V
V
CC
UVLO
Supply Undervoltage Lockout Threshold
Average Supply Current
V
Falling
1.9
2.1
CC
I
CC
200
300
µA
Temperature Measurement
Reference Voltage
V
LTC2996
1.797
1.795
1.790
1.8
1.8
1.8
1.803
1.805
1.808
V
V
V
REF
l
l
LTC2996C
LTC2996I, LTC2996H
l
l
V
Load Regulation
I
=
200μA, V = 3.3V
1.5
mV
mV
µA
REF
LOAD
CC
Diode Select Threshold
(Note 3)
V
– 600
V
CC
– 300
V
– 100
CC
CC
Remote Diode Sense Current
–8
–192
2996f
2
LTC2996
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
CONDITIONS
MIN
TYP
3.5
4
MAX
UNITS
ms
T
Temperature Update Interval
5
CONV
K
V
PTAT
V
PTAT
Slope
mV/K
mV
Ideality Factor η = 1.004
T
Load Regulation
I
=
200μA
1.5
LOAD
T
T
Internal Temperature Accuracy
Remote Temperature Error, η = 1.004
Temperature Noise
0.5
0.5
0.5
1
2
3
°C
°C
°C
INT
l
l
LTC2996C, LTC2996I
LTC2996H
0°C to 85°C (Notes 4, 5)
–40°C to 0°C (Notes 4, 5)
85°C to 125°C (Notes 4, 5)
0.25
0.25
0.25
1
1.5
1.5
°C
°C
°C
RMT
0.15
0.01
°C
RMS
°C
RMS
/√Hz
°C/V
°C
l
l
T
T
Temperature Error vs Supply
0.5
1
VCC
RS
Series Resistance Cancellation Error
R
= 100Ω
0.25
SERIES
Temperature Monitoring
l
l
l
T
VTH, VTL Offset
–3
2
–1
5
1
°C
°C
nA
OFF
∆T
OT, UT Temperature Hysteresis
VTH, VTL, Input Current
10
20
HYST
I
IN
Digital Outputs
l
l
V
V
High Level Output Voltage, OT, UT
Low Level Output Voltage, OT, UT
I = –0.5μA
I = 3mA
V
CC
– 1.2
V
V
OH
OL
0.4
+
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 3: If voltage on pin D exceeds the diode select threshold the
LTC2996 uses the internal diode sensor.
Note 4: Remote diode temperature, not LTC2996 temperature.
Note 5: Guaranteed by design and test correlation.
Note 2: All currents into pins are positive; all voltages are referenced to
GND unless otherwise noted.
2996f
3
LTC2996
TA = 25°C, VCC = 3.3V unless otherwise noted.
Typical perForMance characTerisTics
Remote Temperature Error
vs Ambient Temperature
Internal Temperature Error
vs Ambient Temperature
Temperature Error with LTC2996 at
Same Temperature as Remote Diode
3
2
3
2
3
2
T
= 35°C
T
= T
REMOTE
REMOTE
INTERNAL
1
1
1
0
0
0
–1
–2
–3
–1
–2
–3
–1
–2
–3
–50 –25
0
25
T
50
(°C)
75 100 125
–50 –25
0
25
T
50
(°C)
75 100 125
–50 –25
0
25
50
(°C)
75 100 125
T
A
A
A
2996 G02
2996 G03
2996 G01
Temperature Error vs Supply
Voltage
Remote Temperature Error
Remote Temperature Error
vs Series Resistance
vs CDECOUPLE (Between D+ and D–)
6
4
0.4
0.3
6
4
0.2
0.1
2
0
2
0.0
0
–0.1
–0.2
–0.3
–0.4
–2
–4
–6
–2
–4
–6
6
1
2
3
4
5
0
200
400
600
800 1000 1200
0
2
4
6
8
10
V
(V)
SERIES RESISTANCE (Ω)
DECOUPLE CAPACITOR (nF)
CC
2996 G04
2996 G05
2996 G06
UVLO vs Temperature
VCC Rising, Falling
Buffered Reference Voltage
vs Temperature
VPTAT Noise vs Averaging Time
1.810
1.805
1.800
1.795
1.790
0.20
0.15
0.10
0.05
0
2.2
2.1
2.0
1.9
1.8
V
CC
RISING
CC
V
FALLING
80 100 140 160
–60 –40 –20
0
20 40 60
(°C)
10
AVERAGING TIME (ms)
100
1000
100 125 150
0.01
0.1
1
–50 –25
0
25 50 75
(°C)
T
T
A
A
2996 G09
2996 G07
2996 G08
2996f
4
LTC2996
Typical perForMance characTerisTics TA = 25°C, VCC = 3.3V unless otherwise noted.
Load Regulation of VREF
Voltage vs Current
Single Wire Remote Temperature
Error vs Ground Noise
Load Regulation of VPTAT
Voltage vs Current
10
1
1.820
1.810
1.800
1.790
1.780
1.22
1.21
1.20
1.19
1.18
V
= 2.5V
= 3.5V
= 4.5V
= 5.5V
V
= 2.5V
= 3.5V
= 4.5V
= 5.5V
CC
CC
VAC = 50mV
P-P
V
V
CC
CC
V
V
CC
CC
V
V
CC
CC
0.1
0.01
1.17
1.16
100
1000
–4
–2
0
2
4
0.1
1
10
FREQUENCY (kHz)
2
4
–4
–2
0
LOAD CURRENT (mA)
LOAD CURRENT (mA)
2996 G10
2996 G12
2996 G11
Remote Temperature Error vs
Leakage Current at D+ with
Remote Diode at 25°C, TRMT
UT, OT, vs Output Sink Current
Supply Current vs Temperature
1
0.8
0.6
0.4
0.2
0
220
210
200
190
180
6
4
2
0
–2
–4
–6
40
0
10
20
30
75 100
–100
100
200
–50 –25
0
25 50
(°C)
125 150
–200
0
I (mA)
T
I
(nA)
A
LEAKAGE
2996 G17
2996 G14
2996 G16
2996f
5
LTC2996
pin FuncTions
+
+
D : Diode Sense Current Source. D sources the remote
OT:OvertemperatureLogicOutput.Opendrainlogicoutput
thatpullstoGNDwhenV isabovethethresholdvoltage
+
diode sensing current. Connect D to the anode of the re-
PTAT
motesensordevice.Itisrecommendedtoconnecta470pF
on pin VTH. When V
falls below the threshold voltage
PTAT
+
–
bypass capacitor between D and D . Larger capacitors
on pin VTH, an additional hysteresis of 20mV is required
may cause settling time errors (see Typical Performance
to release OT high. OT has a weak 400kΩ pull-up to V
CC
+
Characteristics).IfD istiedtoV ,theLTC2996measures
and may be pulled above V using an external pull-up.
CC
CC
+
the internal sensor temperature. Tie D to V if unused.
Leave OT open if unused.
CC
–
–
D : Diode Sense Current Sink. Connect D to the cathode
V
:ProportionaltoAbsoluteTemperatureVoltageOut-
PTAT
–
of the remote sensor device. Tie D to GND for single
wire remote temperature measurement (see Applications
Information) or internal temperature sensing.
put. The voltage on this pin is proportional to the sensor’s
absolute temperature. V can drive up to 200μA of
PTAT
loadcurrentandupto1000pFofcapacitiveload.Forlarger
load capacitances insert 1kΩ between V and the load
to ensure stability. V
voltage goes below the under voltage lockout threshold.
PTAT
Exposed Pad: Exposed pad may be left open or soldered
to GND for better thermal coupling.
is pulled low when the supply
PTAT
GND: Device Ground
V
: Voltage Reference Output. V provides a 1.8V
REF
REF
UT: Undertemperature Logic Output. Open drain logic
reference voltage. V
can drive up to 200μA of load
REF
outputthatpullstoGNDwhenV
voltage on pin VTL. When V
isbelowthethreshold
rises above the threshold
current and up to 1000pF of capacitive load. For larger
PTAT
PTAT
load capacitances, insert 1kΩ between V and the load
REF
voltage on pin VTL, an additional hysteresis of 20mV is
to ensure stability. Leave V
open if unused.
REF
required to release UT high. UT has a weak 400kΩ pull-
VTL: Temperature Threshold Low. When V
is below
PTAT
up to V and may be pulled above V using an external
CC
CC
the voltage on VTL, UT is pulled low. Tie VTL to GND if
pull-up. Leave UT open if unused.
unused.
VTH: Temperature Threshold High. When V
is above
PTAT
the voltage on VTH, OT is pulled low. Tie VTH to V if
CC
unused.
2996f
6
LTC2996
block DiagraM
6
V
CC
+
–
1.2V
V
REF
1.8V
200k
8
V
CC
400k
400k
OT
–
VTH
CT2
10
1
+
OT/UT
PULSE
GENERATOR
UVLO
V
CC
400k
UT
–
CT1
9
VTL
+
2
T TO V
CONVERTER
V
PTAT
5
1
–
+
D
D
GND
4
3
7
2996 BD
2996f
7
LTC2996
operaTion
Overview
diode (with the same value I ) at two different currents
S
(I and I ) yields an expression independent of I :
D1
D2
S
The LTC2996 provides a buffered voltage proportional to
the absolute temperature of either an internal or a remote
q
η • k
V
– V
D2
D1
T =
•
diode(V
)andcomparesthisvoltagetothresholdsthat
PTAT
I
D2
can be set by external resistor dividers from the on-board
ln
I
D1
reference (V ).
REF
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 device in a microprocessor or FPGA.
Series Resistance Cancellation
Resistanceinserieswiththeremotediodecausesapositive
temperature error by increasing the measured voltage at
each test current. The composite voltage equals:
Diode Temperature Sensor
I
kT
= η • ln
q
D
Temperature measurements are conducted by measuring
the voltage of either an internal or an external diode with
multiple test currents. The relationship between diode
voltage V and diode current I can be solved for absolute
V + V
+ R •I
S D
D
ERROR
I
S
The LTC2996 removes this error term from the sensor
signal by subtracting a cancellation voltage V . A
D
D
Temperature in degrees Kelvin T:
CANCEL
resistance extraction circuit uses one additional current
measurement to determine the series resistance in the
measurementpath.Oncethecorrectvalueoftheresistoris
q
η • k
V
D
T =
•
I
D
ln
I
determined,V
equalsV
.Nowthetemperature
CANCEL
ERROR
S
to voltage converter input signal is free from errors due
to series resistance.
where I is a process dependent factor on the order of
S
–13
10 A, η is the diode ideality factor, k is the Boltzmann
LTC2996cancelsseriesresistancesuptoseveralhundred
ohms (see Typical Performance Characteristics curves).
Higher series resistances cause the cancelation voltage
to saturate.
constantandqistheelectroncharge.Thisequationshows
arelationshipbetweentemperatureandvoltagedependent
on the process depended variable I . Measuring the same
S
2996f
8
LTC2996
applicaTions inForMaTion
Temperature Measurements
Table 2. Recommended Transistors for Use as Temperature
Sensors
Before each conversion, a voltage comparator connected
MANUFACTURER
PART NUMBER
PACKAGE
+
to D automatically sets the LTC2996 into external or
Fairchild
Semiconductor
MMBT3904
SOT-23
+
internal mode. Tying D to V enables internal mode,
CC
+
whereV
representsthedietemperature.ForV more
PTAT
D
Central
Semiconductor
CMBT3904
SOT-23
than 300mV below V (typical), the LTC2996 assumes
CC
that an external sensor is connected.
Diodes Inc.
On Semiconductor
NXP
MMBT3904
MMBT3904LT1
MMBT3904
MMBT3904
UMT3904
SOT-23
SOT-23
SOT-23
SOT-23
SC-70
The LTC2996 continuously measures the sensor diode at
differenttestcurrentsandgeneratesavoltageproportional
Infineon
to the absolute temperature of the sensor at the V
pin.
PTAT
Rohm
The voltage at V
is updated every 3.5ms.
PTAT
Discrete two terminal diodes are not recommended as
remote sensing devices as their ideality factor is typically
much higher than 1.004. Also, MOS transistors are not
suitable as they don’t exhibit the required current to tem-
peraturerelationship. Furthermore,golddopedtransistors
(low beta), high frequency and high voltage transistors
should be avoided as remote sensing devices.
The gain of V
is calibrated to 4mV/K for the measure-
PTAT
ment of the internal diode as well as for remote diodes
with an ideality factor of 1.004.
V
PTAT
4mV/K
TKELVIN
=
(η = 1.004)
If an external sensor with an ideality factor different from
Connecting an External Sensor
1.004 is used, the gain of V
will be scaled by the ratio
PTAT
of the actual ideality factor (η ) to 1.004. In these cases
ACT
The anode of the external sensor must be connected to
the temperature of the external sensor can be calculated
+
–
pin D . The cathode should be connected to D for best
external noise immunity.
from V
by:
PTAT
V
1.004
η
ACT
The change in sensor voltage per °C is hundreds of
microvolts, so electrical noise must be kept to a mini-
mum. Bypass D and D with a 470pF capacitor close to
the LTC2996 to suppress external noise. Recommended
shielding and PCB trace considerations for best noise
immunity are illustrated in Figure 1.
PTAT
TKELVIN
=
•
4mV/K
+
–
Temperature in degrees Celsius can be deduced from
degrees Kelvin by:
T
= T
– 273.15
KELVIN
CELSIUS
GND SHIELD TRACE
Choosing an External Sensor
LTC2996
+
The LTC2996 is factory calibrated for an ideality factor of
1.004, which is typical of the popular MMBT3904 NPN
transistor. Semiconductor purity and wafer level process-
ing intrinsically limit device-to-device variation, making
these devices interchangeable between manufacturers
withatemperatureerroroftypicallylessthan0.5°C.Some
recommended sources are listed in Table 2:
D
D
470pF
–
GND
2996 F01
NPN SENSOR
Figure 1. Recommended PCB Layout
+
Leakage currents at D affect the precision of the remote
temperature measurements. 100nA leakage current leads
to an additional error of 2°C (see Typical Performance
Characteristics).
2996f
9
LTC2996
applicaTions inForMaTion
Note that bypass capacitors greater than 1nF will cause
settling time errors of the different measurement cur-
rents and therefore introduce an error in the temperature
measurement (see Typical Performance Characteristics).
The LTC2996 can withstand up to 4kV of electrostatic
discharge (ESD, human body model). ESD beyond this
voltage can damage or degrade the device including
lowering the remote sensor measurement accuracy due
+
–
to increased leakage currents on D or D .
The LTC2996 compensates series resistance in the
measurement path and thereby allows accurate remote
temperature measurements even with several meters of
distance between the sensor and the device. The cable
lengthbetweenthesensorandtheLTC2996isonlylimited
To protect the sensing inputs against larger ESD strikes,
external protection can be added using TVS diodes to
ground (Figure 3). Care must be taken to choose diodes
with low capacitance and low leakage currents in order
nottodegradetheexternalsensormeasurementaccuracy
(see Typical Performance Characteristics curves).
+
by the mutual capacitance introduced between D and
–
D which degrades measurement accuracy (see Typical
Performance Characteristics).
LTC2996
10Ω
10Ω
+
–
For example, a CAT6 cable with 50pF/m should be kept
shorter than ~20m to keep the capacitance less than 1nF.
D
D
MMBT3904
220pF
GND
To save wiring, the cathode of the remote sensor can
2996 F03
PESD5Z6.0
–
also be connected to remote GND and D to local GND
as shown below.
Figure 3. Increasing ESD Robustness with TVS Diodes
LTC2996
+
D
470pF
2N3904
–
D
GND
To make the connection of the cable to the IC polarity
insensitive during installation, two sensor transistors
with opposite polarity at the end of a two wire cable can
be used as shown on Figure 4.
2996 F02
Figure 2. Single Wire Remote Temperature Sensing
LTC2996
+
The temperature measurement of LTC2996 relies only
on differences between the diode voltage at multiple test
circuits.ThereforeDCoffsetssmallerthan300mVbetween
remote and local GND do not impact the precision of the
temperature measurement. The cathode of the sensor
can accommodate modest ground shifts across a system
which is beneficial in applications where a good thermal
connectivity of the sensor to a device whose temperature
is to be monitored (shunt resistor, coil, etc.) is required.
Care must be taken if the potential difference between
D
MMBT3904
470pF
–
D
GND
2995 F04
Figure 4. Polarity Insensitive Remote Diode Sensor
Again, care must be taken that the leakage current of the
second transistor does not degrade the measurement
accuracy.
–
the cathode and D does not only contain DC but also AC
components. Noise around odd multiples of 6kHz ( 20%)
is amplified by the measurement algorithm and converted
toaDCoffsetinthetemperaturemeasurement(seeTypical
Performance Characteristics).
2996f
10
LTC2996
applicaTions inForMaTion
Output Noise Filtering
When V
falls below 1.093V, UT is pulled low. Once the
PTAT
temperature rises again and V
reaches 1.093V plus
PTAT
The V
output typically exhibits 0.6mV RMS (0.25°C
PTAT
a hysteresis of 20mV, UT is released high again. Accord-
ingly, OT is pulled low if temperature increases to 90°C as
RMS) noise. For applications which require lower noise,
digital or analog averaging can be applied to the output.
Choose the averaging time according to:
V
reaches 1.453V and is released high if V
drops
PTAT
PTAT
again below 1.433V.
2
[
]
°
0.01 C Hz
Temperature Thresholds
tAVG
=
T
NOISE
The threshold voltages at VTL and VTH can be set with
the 1.8V reference voltage (V ) and a resistive divider
REF
as shown in Figure 5.
where t
is the averaging time and T
the desired
NOISE
AVG
temperature noise in °C RMS. For example, if the desired
noise performance is 0.01°C RMS, set the averaging time
to one second. See Typical Performance Characteristics.
η
mV
K
V
= 1.8V
V
ACT
REF
PTAT
SLOPE =
• 4
1.004
1.8V
VT2
R
TC
Temperature Monitoring
R
TB
VT1
The LTC2996 continuously compares the voltage at V
PTAT
to the voltages at the pins VTH and VTL to detect either an
overtemperature(OT)orundertemperature(UT)condition.
The VTH comparator output drives the open-drain logic
output pin OT and the VTL comparator output drives the
O.8V
R
TA
T
2996 F05
O
200K
T
T
450K
1
2
open-drain logic output pin UT. The voltage at V
must
PTAT
Figure 5. Temperature Thresholds
exceedathresholdforfiveconsecutivetemperatureupdate
intervals (3.5ms each) before the respective output pin is
pulled low. Once the V
voltage crosses the threshold
PTAT
The following design procedure can be used to size the
resistive divider.
withanadditional20mVofhysteresis,therespectiveoutput
pin is released after a single update interval.
1. Calculate Threshold Voltages:
Temperature Monitor Design Example
mV η
ACT
VTL = T1• 4
•
The LTC2996 can be configured to give an alert if the
K
1.004
temperature of the internal sensor falls below 0°C or rises
+
above 90°C. Tie the D pin to V to select the internal
CC
mV η
ACT
VTH = T2 • 4
•
sensor. The voltages at VTL and VTH are set to:
K
1.004
mV
K
VTL =(0K + 273.15K) • 4
VTH =(90K + 273.15K) • 4
= 1.093V
= 1.453V
mV
K
2996f
11
LTC2996
applicaTions inForMaTion
where η denotes the actual ideality factor if an external
IntheTemperatureMonitorexamplediscussedearlierwith
thresholds at VTL = 0°C and VTH = 90°C and a desired
ACT
sensor is used and T1 and T2 are the desired threshold
temperatures in degrees Kelvin.
reference current of 10μA, the required values for R ,
TA
R
TB
and R can be calculated as :
TC
2. Choose R to obtain the desired VTL threshold for
TA
a desired current through the resistive divider
1.093V
10µA
R
=
=
=
= 109.3K
(I ):
REF
TA
TB
TC
VTL
R
=
TA
1.453V – 1.093V
10µA
I
REF
R
R
= 36K
3. Choose R to obtain the desired VTH threshold:
TB
VTH– VTL
1.8V – 1.453V
R
=
= 34.7K
TB
I
10µA
REF
4. Finally R is determined by:
TC
1.8V – VTH
R
=
TC
I
REF
3.3V
+
D
V
LTC2996
CC
V
CC
V
CC
400k
OT
+
–
1.2V
1.8V
V
REF
200k
400k
R
TC
V
CC
VTH
VTL
–
+
400k
OT/UT
PULSE
GENERATOR
UT
UVLO
R
R
TB
–
+
V
PTAT
T/V
TA
–
D
GND
2996 F06
Figure 6. Monitoring Internal Temperature
2996f
12
LTC2996
applicaTions inForMaTion
Remote Temperature Monitor with Overtemperature and Undertemperature Thresholds
2.25V TO 5.5V
0.1µF
V
1.8V
43k
OT T > 70°C
CC
V
OT
REF
TEMPERATURE
CONTROL
SYSTEM
LTC2996
UT T < –20°C
VTH
VTL
UT
36k
4mV/K
V
PTAT
+
102k
D
470pF
MMBT3904
–
D
GND
2996 TA02
ASIC/FPGA/Processor Temperature Monitor
2.25V TO 5.5V
0.1µF
V
1.8V
20.5k
OT T > 125°C
UT T < 30°C
CC
V
OT
INT1
INT2
REF
LTC2996
VTH
VTL
UT
CPU/
FPGA/
ASIC
38.3k
121k
V
PTAT
+
D
470pF
INTERNAL
DIODE
–
D
GND
2996 TA03
Analog Heater Controller
5V
0.1µF
V
1.8V
30.9k
CC
10Ω
HEATER
V
V
REF
PTAT
MMBT3904
B6015L12F
R
LTC2996
HIGH IF T < 0°C
1.09V
1.49V
IRF3708
VTH
VTL
OT
40.2k
110k
+
D
470pF
–
D
HIGH IF T < 100°C
2N7000
UT
GND
2996 TA04
2996f
13
LTC2996
Typical applicaTions
Battery Stack Temperature Supervisor
2.25V TO 5.5V
0.1µF
V
CC
+
D
BATTERY
10k
SUPERVISOR
LTC2996
V
OT
REF
T
ALERT
INT
43.2k
28k
VTH
VTL
UT
V
PTAT
–
D
110k
GND
LOW IF TEMPERATURE
OF ANY CELL
T
> 70°C
< 0°C
CELL
OR
T
CELL
0.1µF
V
CC
+
D
LTC2996
V
OT
REF
43.2k
28k
VTH
VTL
UT
V
PTAT
–
D
110k
GND
2996 TA05
2996f
14
LTC2996
package DescripTion
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
DD Package
10-Lead Plastic DFN (3mm × 3mm)
(Reference LTC DWG # 05-08-1699 Rev C)
0.70 ±0.05
3.55 ±0.05
2.15 ±0.05 (2 SIDES)
1.65 ±0.05
PACKAGE
OUTLINE
0.25 ±0.05
0.50
BSC
2.38 ±0.05
(2 SIDES)
RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS
R = 0.125
0.40 ±0.10
TYP
6
10
3.00 ±0.10
(4 SIDES)
1.65 ±0.10
(2 SIDES)
PIN 1 NOTCH
R = 0.20 OR
PIN 1
TOP MARK
(SEE NOTE 6)
0.35 × 45°
CHAMFER
(DD) DFN REV C 0310
5
1
0.25 ±0.05
0.50 BSC
0.75 ±0.05
0.200 REF
2.38 ±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 (WEED-2).
CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT
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
2996f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However,noresponsibilityisassumedforitsuse.LinearTechnologyCorporationmakesnorepresenta-
tionthattheinterconnectionofitscircuitsasdescribedhereinwillnotinfringeonexistingpatentrights.
15
LTC2996
Typical applicaTion
Celsius Thermometer and 20°C to 25°C Thermostat
5V
220V AC
5LPCV24110
0.1µF
5V
0.1µF
V
CC
OT
UT
HEATER
150k
1.8k
+
D
LTC2996
VOLTMETER
100k
1k
–
1.8V
MMBT3904
470pF
10mV/°C
0V AT 0°C
215mV
CORRESPONDS TO
21.5°C
–
D
LTC1077
62k
+
4mV/K
V
PTAT
2996 TA06
143k
1µF
GND
VTL VTH
63.4k
V
REF
118k
relaTeD parTs
PART NUMBER DESCRIPTION
COMMENTS
2
LTC2990
LTC2991
LTC2995
Quad I C Voltage, Current and Temperature Monitor
Measures Voltage, Current, Internal Temperature and/or Two Remote Diode
2
Temperatures, 0.5°C (Typ) Accuracy, 0.06°C Resolution, I C Interface
2
Octal I C Voltage, Current and Temperature Monitor
Measures Voltage, Current, Internal Temperature and/or Four Remote Diode
2
Temperatures, 0.7°C (Typ), 0.06°C Resolution, I C Interface, PWM Output
Temperature Sensor and Voltage Monitor with Alert
Outputs
Monitors Temperature and Two Voltages, Adjustable Thresholds, Open Drain
Alert Outputs, Temperature to Voltage Output with Integrated 1.8V Reference,
1°C (Max) Accuracy
LTC2997
LTC1077
Remote/Internal Temperature Sensor
Converts Remote Sensor or Int. Diode Temperature to Analog Voltage,
Integrated 1.8V Reference, 1°C (Max) Accuracy
Micropower, Single Supply, Precision Op Amp
60µA Supply Current, 40µV Offset, Low Noise
2996f
LT 0712 • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
16
●
●
LINEAR TECHNOLOGY CORPORATION 2012
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
相关型号：
LTC1090ACN#PBF
LTC1090 - Single Chip 10-Bit Data Acquisition System; Package: PDIP; Pins: 20; Temperature Range: 0°C to 70°C
Linear
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