LTC1392
Micropower Temperature,
Power Supply and
Differential Voltage Monitor
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DESCRIPTIO
FEATURES
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Complete Ambient Temperature Sensor Onboard
System Power Supply Monitor
10-Bit Resolution Rail-to-Rail Common-Mode
Differential Voltage Input
Available in 8-Pin SO and PDIP
0.2µA Supply Current When Idle
700µA Supply Current When Sampling at
Maximum Rate
Single Supply Voltage: 4.5V to 6V
3-Wire Half-Duplex Serial I/O
Communicates with Most MPU Serial Ports and All
MPU Parallel I/O Ports
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APPLICATI
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Temperature Measurement
Power Supply Measurement
Current Measurement
Remote Data Acquisition
Environment Monitoring
, LTC and LT are registered trademarks of Linear Technology Corporation.
The LTC®1392 is a micropower data acquisition system
designed to measure temperature, on-chip supply voltage
and a differential voltage. The differential inputs feature
rail-to-rail common mode input voltage range. The LTC1392
contains a temperature sensor, a 10-bit A/D converter with
sample-and-hold, a high accuracy bandgap reference and
a 3-wire half-duplex serial interface.
The LTC1392 can be programmed to measure ambient
temperature, power supply voltage and an external voltage at the differential input pins, that can also be used for
current measurement using an external sense resistor.
When measuring temperature, the output code of the A/D
converter is linearly proportional to the temperature in °C.
Production trimming achieves ±2°C initial accuracy at
room temperature and ±4°C over the full – 40°C to 85°C
temperature range.
The on-chip serial port allows efficient data transfer to a
wide range of MPUs over three or four wires. This,
coupled with low power consumption, makes remote
location sensing possible and facilitates transmitting
data through isolation barriers.
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TYPICAL APPLICATI
Output Temperature Error
Complete Temperature, Supply Voltage and
Supply Current Monitor
5
LTC1392C
GUARANTEED
LIMIT
4
+
5V
LTC1392
P1.4
MPU
(e.g., 68HC11)
P1.3
P1.2
1
2
3
4
DIN
DOUT
CLK
CS
VCC
–VIN
+VIN
GND
8
7
6
RSENSE
ILOAD
5
LTC1392 • TA01
TEMPERATURE ERROR (°C)
1µF
3
LTC1392I
GUARANTEED
LIMIT
2
1
TYPICAL
0
–1
–2
–3
–4
–5
–40 –20
40
20
0
60
TEMPERATURE (°C)
80
100
LTC1392 • TA02
1
LTC1392
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ABSOLUTE
PACKAGE/ORDER I FOR ATIO
(Note 1)
Supply Voltage (VCC) ................................................ 7V
Input Voltage ................................. – 0.3V to VCC + 0.3V
Output Voltage ............................... – 0.3V to VCC + 0.3V
Operating Temperature Range
LTC1392C............................................... 0°C to 70°C
LTC1392I........................................... – 40°C to 85°C
Junction Temperature.......................................... 125°C
Storage Temperature Range ................ – 65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART
NUMBER
TOP VIEW
DIN 1
8
VCC
DOUT 2
7
–VIN
CLK 3
6
+VIN
CS 4
5
GND
N8 PACKAGE
8-LEAD PDIP
LTC1392CN8
LTC1392CS8
LTC1392IN8
LTC1392IS8
S8 PACKAGE
8-LEAD PLASTIC SO
S8 PART MARKING
TJMAX = 125°C, θJA = 100°C/ W (N8)
TJMAX = 125°C, θJA = 130°C/ W (S8)
1392
1392I
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER
(Note 2, 3)
CONDITIONS
MIN
TYP
MAX
UNITS
Power Supply To Digital Conversion
Resolution
VCC = 4.5V to 6V
Total Absolute Error
VCC = 4.5V to 6V
●
10
Bit
±8
LSB
10
Bit
Differential Voltage to Digital
Conversion (Full-Scale Input = 1V)
Resolution
Integral Linearity Error (Note 5)
●
±0.5
±1
LSB
Differential Linearity Error
●
±0.5
±1
LSB
Offset Error
●
±4
LSB
Full-Scale Error
●
±15
LSB
Differential Voltage to Digital
Conversion (Full-Scale Input = 0.5V)
Resolution
10
Bit
Integral Linearity Error (Note 5)
●
±0.5
±2
LSB
Differential Linearity Error
●
±0.5
±1
LSB
Offset Error
●
±8
LSB
Full-Scale Error
●
±25
LSB
●
±2
±4
°C
°C
Temperature to Digital Conversion
Accuracy
Nonlinearity
2
TA = 25°C (Note 7)
TA = TMAX or TMIN (Note 7)
TMIN ≤ TA ≤ TMAX (Note 4)
±1
°C
LTC1392
ELECTRICAL CHARACTERISTICS
(Note 2, 3)
SYMBOL
PARAMETER
ION LEAKAGE
On-Channel Leakage Current (Note 6)
CONDITIONS
●
MIN
TYP
MAX
±1
µA
IOFF LEAKAGE
Off-Channel Leakage Current (Note 6)
●
±1
µA
VIH
High Level Input Voltage
VCC = 5.25V
●
VIL
Low Level Input Voltage
VCC = 4.75V
●
0.8
V
IIH
High Level Input Current
VIN = VCC
●
5
µA
IIL
Low Level Input Current
VIN = 0V
●
–5
µA
VOH
High Level Output Voltage
VCC = 4.75V, IOUT = 10µA
VCC = 4.75V, IOUT = 360µA
●
VOL
Low Level Output Voltage
VCC = 4.75V, IOUT = 1.6mA
●
0.4
V
IOZ
Hi-Z Output Current
CS = High
●
±5
µA
ISOURCE
Output Source Current
VOUT = 0V
ISINK
Output Sink Current
VOUT = VCC
ICC
Supply Current
CS = High
CS = Low, VCC = 5V
tSMPL
Analog Input Sample Time
See Figure 1
tCONV
Conversion Time
See Figure 1
tdDO
Delay Time, CLK↓ to DOUT Data Valid
CLOAD = 100pF
●
150
300
ns
ten
Delay Time, CLK↓ to DOUT Data Enabled
CLOAD = 100pF
●
60
150
ns
tdis
Delay Time, CS ↑ to DOUT Hi-Z
●
170
450
thDO
Time Output Data Remains Valid After CLK↓
CLOAD = 100pF
tf
DOUT Fall Time
CLOAD = 100pF
●
tr
DOUT Rise Time
CLOAD = 100pF
●
CIN
Input Capacitance
Analog Input On-Channel
Analog Input Off-Channel
30
5
pF
pF
Digital Input
5
pF
2
4.5
2.4
V
4.74
4.72
V
V
– 25
mA
45
0.1
0.7
●
●
UNITS
mA
5
1
1.5
µA
mA
CLK Cycles
10
CLK Cycles
30
ns
ns
70
250
25
100
ns
ns
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RECOM ENDED OPERATING CONDITIONS
SYMBOL
PARAMETER
VCC
Supply Voltage
CONDITIONS
MIN
TYP
fCLK
Clock Frequency
VCC = 5V
150
tCYC
Total Cycle Time
fCLK = 250kHz
Temperature Conversion Only
74
144
µs
µs
thDI
Hold Time, DIN After CLK↑
VCC = 5V
150
ns
tsuCS
Setup Time CS↓ Before First CLK↑ (See Figure 1)
VCC = 5V
2
µs
tWAKEUP
Wakeup Time CS↓ Before Start Bit↑ (See Figure 1)
VCC = 5V
Temperature Conversion Only
10
80
µs
µs
tsuDI
Setup Time, DIN Stable Before CLK↑
VCC = 5V
150
ns
tWHCLK
Clock High Time
VCC = 5V
1.6
µs
tWLCLK
Clock Low Time
VCC = 5V
2
µs
tWHCS
CS High Time Between Data Transfer Cycles
VCC = 5V, fCLK = 250kHz
2
µs
tWLCS
CS Low Time During Data Transfer
VCC = 5V, fCLK = 250kHz
Temperature Conversion Only
72
142
µs
µs
4.5
MAX
6
250
350
UNITS
V
kHz
3
LTC1392
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RECOM ENDED OPERATING CONDITIONS
The ● denotes specifications which apply over the operating temperature
range (0°C ≤ TA ≤ 70°C for commercial grade and – 40°C ≤ TA ≤ 85°C for
industrial grade).
Note 1: Absolute maximum ratings are those values beyond which the life
of the device may be impaired.
Note 2: All voltage values are with respect to GND.
Note 3: Testing done at VCC = 5V, CLK = 250kHz and TA = 25°C unless
otherwise specified.
Note 4: Temperature integral nonlinearity is defined as the deviation of the
A/D code versus temperature curve from the best-fit straight line over the
device’s rated temperature range.
Note 5: Voltage integral nonlinearity is defined as the deviation of a code
from a straight line passing through the actual end points of the transfer
curve.
Note 6: Channel leakage current is measured after the channel selection.
Note 7: See guaranteed temperature limit curves vs temperature range on
the first page of this data sheet.
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TYPICAL PERFORMANCE CHARACTERISTICS
Integral Nonlinearity
Power Supply Voltage Mode
fCLK = 250kHz
TA = 25°C
0.5
0
–0.5
fCLK = 250kHz
TA = 25°C
0.5
0
–0.5
–1.0
256 320 384 448 512 576 640 704 768 832
CODE
–1.0
256 320 384 448 512 576 640 704 768 832
CODE
Integral Nonlinearity
0
–0.5
–1.0
0
0
–0.5
Integral Nonlinearity
1.0
1.0
Full Scale = 0.5V
fCLK = 250kHz
TA = 25°C
VCC = 5V
0.5
0
–0.5
128 256 384 512 640 768 896 1024
CODE
1392 G04
Full Scale = 0.5V
fCLK = 250kHz
TA = 25°C
VCC = 5V
0.5
0
–0.5
–1.0
–1.0
–1.0
128 256 384 512 640 768 896 1024
CODE
1392 G03
INTEGRAL NONLINEARITY ERROR (LSB)
DIFFERENTIAL NONLINEARITY ERROR (LSB)
INTEGRAL NONLINEARITY ERROR (LSB)
Full Scale = 1V
fCLK = 250kHz
TA = 25°C
VCC = 5V
Full Scale = 1V
fCLK = 250kHz
TA = 25°C
VCC = 5V
0.5
Differential Nonlinearity
1.0
0
1.0
1392 G02
1392 G01
0.5
DIFFERENTIAL NONLINEARITY ERROR (LSB)
1.0
4
Differential Nonlinearity
1.0
INTEGRAL NONLINEARITY ERROR (LSB)
DIFFERENTIAL NONLINEARITY ERROR (LSB)
Differential Nonlinearity
Power Supply Voltage Mode
0
128 256 384 512 640 768 896 1024
CODE
1392 G05
0
128 256 384 512 640 768 896 1024
CODE
1392 G06
LTC1392
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TYPICAL PERFORMANCE CHARACTERISTICS
Thermal Response in Stirred
Oil Bath
1000
70
VCC = 5V
60
55
55
TEMPERATURE (°C)
60
50
45
40
N8
35
S8
30
VCC = 5V
65
50
45
40
35
N8
30
25
CS LOW BETWEEN SAMPLES
SUPPLY CURRENT (µA)
65
TEMPERATURE (°C)
Supply Current vs Sample Rate
Thermal Response in Still Air
70
100
CS HIGH BETWEEN
SAMPLES
10
1
VCC = 5V
fCLK = 250kHz
TA = 25°C
S8
25
20
20
0
5
10
15
20
TIME (SEC)
25
30
50
0
100
150
200
TIME (SEC)
250
1392 G07
300
0.1
0.1
1
10
100
1k
10k
SAMPLE FREQUENCY (Hz)
100k
1392 G09
1392 G08
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PIN FUNCTIONS
DIN (Pin 1): Digital Input. The A/D configuration word is
shifted into this input.
GND (Pin 5): Ground Pin. GND should be tied directly to
an analog ground plane.
DOUT (Pin 2): Digital Output. The A/D result is shifted out
of this output.
+VIN (Pin 6): Positive Analog Differential Input. The pin
can be used as a single-ended input by grounding – VIN.
CLK (Pin 3): Shift Clock. This clock synchronizes the serial
data.
– VIN (Pin 7): Negative Analog Differential Input. The input
must be free from noise.
CS (Pin 4): Chip Select Input. A logic low on this input
enables the LTC1392.
VCC (Pin8): Positive Supply. This supply must be kept free
from noise and ripple by bypassing directly to the ground
plane.
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BLOCK DIAGRAM
3
CLK
VREF = 2.42V
DIN
1
INPUT
SHIFT
REGISTER
BANDGAP
VREF = 1V
VREF = 0.5V
2
10-BIT
CAPACITIVE DAC
TEMPERATURE
SENSOR
GND
VCC
+VIN
6
–VIN 7
VREF
+
–
+
–
+
–
COMP
ANALOG
INPUT
MUX
DOUT
SERIAL
PORT
10
BITS
10-BIT
SAR
CSAMPLE
8
VCC
5
GND
CONTROL
AND TIMING
4
CS
LTC1392 • BD
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LTC1392
TEST CIRCUITS
Voltage Waveforms for DOUT Delay Time, tdDO
Load Circuit for tdDO, tr and tf
1.4V
CLK
VIL
3k
tdDO
DOUT
TEST POINT
100pF
VOH
DOUT
VOL
LTC1392 • TC02
LTC1392 • TC03
Voltage Waveforms for DOUT Rise and Fall Times, tr and tf
Voltage Waveforms for tdis
VOH
DOUT
VOL
2.0V
CS
tr
tf
1392 TC04
DOUT
WAVEFORM 1
(SEE NOTE 1)
Load Circuit for tdis and ten
90%
tdis
DOUT
WAVEFORM 2
(SEE NOTE 2)
TEST POINT
5V tdis WAVEFORM 2, ten
3k
DOUT
10%
NOTE 1: WAVEFORM 1 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH
THAT THE OUTPUT IS HIGH UNTIL DISABLED BY THE OUTPUT CONTROL.
NOTE 2: WAVEFORM 2 IS FOR AN OUTPUT WITH INTERNAL CONDITIONS SUCH
THAT THE OUTPUT IS LOW UNTIL DISABLED BY THE OUTPUT CONTROL.
tdis WAVEFORM 1
100pF
LTC1392 • TC06
LTC1392 • TC05
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APPLICATIONS INFORMATION
The LTC1392 is a micropower data acquisition system
designed to measure temperature, an on-chip power
supply voltage and a differential input voltage. The LTC1392
contains the following functional blocks:
1. On-chip temperature sensor
2. 10-bit successive approximation capacitive ADC
3. Bandgap reference
4. Analog multiplexer (MUX)
5. Sample-and-hold (S/H)
6. Synchronous, half-duplex serial interface
7. Control and timing logic
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DIGITAL CONSIDERATIONS
Serial Interface
The LTC1392 communicates with microprocessors and
other external circuitry via a synchronous, half-duplex,
3-wire serial interface (see Figure 1). The clock (CLK)
synchronizes the data transfer with each bit being transmitted on the falling CLK edge and captured on the rising
CLK edge in both transmitting and receiving systems. The
input data is first received and then the A/D conversion
result is transmitted (half-duplex). Half-duplex operation
allows DIN and DOUT to be tied together allowing transmission over three wires: CS, CLK and DATA (DIN/DOUT). Data
transfer is initiated by a falling chip select (CS) signal. After
the falling CS is recognized, an 80µs delay is needed for
LTC1392
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APPLICATIONS INFORMATION
MSB-First Data (MSBF = 1)
tCYC
CS
tsuCS
CLK
tWAKEUP
SEL1 SEL0
DIN
START
DOUT
MSBF
Hi-Z
B9
B8
B7
B6
B5
B4
B3
B2
B1
Hi-Z
B0
FILLED WITH ZEROS
tSMPL
tCONV
tCYC
CS
tsuCS
CLK
tWAKEUP
SEL1 SEL0
DIN
START
DOUT
MSBF
Hi-Z
B9
tSMPL
B8
B7
B6
B5
B4
B3
B2
B1
B0
B1
B2
B3
B4
B5
B6
B7
B8
B9
Hi-Z
FILLED WITH ZEROS
tCONV
LTC1392 • F01
Figure 1
temperature measurement or a 10µs delay for other measurements, followed by a 4-bit input word which configures the LTC1392 for the current conversion. This data
word is shifted into the DIN input. DIN is then disabled from
shifting in any data and the DOUT pin is configured from
three-state to an output pin. A null bit and the result of the
current conversion are serially transmitted on the falling
CLK edge onto the DOUT line. The format of the A/D result
can be either MSB-first sequence or MSB-first sequence
followed by an LSB-first sequence. This provides easy
interface to MSB- or LSB-first serial ports. Bringing CS
high resets the LTC1392 for the next data exchange.
INPUT DATA WORD
Data transfer is initiated by a falling chip select (CS) signal.
After CS falls, the LTC1392 looks for a start bit. Once the
start bit is received, the next three bits are shifted into the
DIN input which configures the LTC1392 and starts the
conversion. Further inputs on the DIN input are then
ignored until the next CS cycle. The four bits of the input
word are defined as follows:
BIT 3
BIT 2
BIT 1
BIT 0
Start
Select 1
Select 0
MSBF
Start Bit
The first “logic one” clocked into the DIN input after CS
goes low is the Start Bit. The Start Bit initiates the data
transfer and all leading zeros which precede this logical
one will be ignored. After the Start Bit is received the
remaining bits of the input word will be clocked in. Further
input on the DIN pin are then ignored until the next CS
cycle.
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LTC1392
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APPLICATIONS INFORMATION
Measurement Mode Selections
The two bits of the input word following the Start Bit assign
the measurement mode for the requested conversion.
Table 1 shows the mode selections. Whenever there is a
mode change from another mode to temperature measurement, a temperature mode initializing cycle is needed.
The first temperature data measurement after a mode
change should be ignored.
Table 1. Measurement Mode Selections
tures outside these specified temperature ranges is not
guaranteed and errors may be greater than those shown in
the Electrical Characteristics table.
Table 2. Codes for Temperature Conversion
OUTPUT CODE
TEMPERATURE (°C)
1111111111
125.75
1111111110
125.50
...
...
1001101101
25.25
1001101100
25.00
1001101011
24.75
SELECT
1
SELECT
0
0
0
Temperature
...
...
0
1
Power Supply Voltage
0000000001
– 129.75
1
0
Differential Input, 1V Full Scale
0000000000
– 130.00
1
1
Differential Input, 0.5V Full Scale
MEASUREMENT MODE
Voltage Supply (VCC) Monitor
MSB-First/LSB-First (MSBF)
The output data of the LTC1392 is programmed for
MSB-first or LSB-first sequence using the MSBF bit. When
the MSBF bit is a logical one, data will appear on the DOUT
line in MSB-first format. Logical zeros will be filled in
indefinitely following the last data bit to accommodate
longer word lengths required by some microprocessors.
When the MSBF bit is a logical zero, LSB-first data will
follow the normal MSB-first data on the DOUT line.
CONVERSIONS
Temperature Conversion
The LTC1392 measures temperature through the use of an
on-chip, proprietary temperature measurement technique.
The temperature reading is provided in a 10-bit, unipolar
format. Table 2 describes the exact relationship of output
data to measured temperature or equation 1 can be used
to calculate the temperature.
Temperature (°C) = Output Code/4 – 130
(1)
Note that the LTC1392C is only specified for operation
over the 0°C to 70°C temperature range and the LTC1392I
over the – 40°C to 85°C range. Performance at tempera-
8
The LTC1392 measures supply voltage through the onchip VCC supply line. The VCC reading is provided in a
10-bit, unipolar format. Table 3 describes the exact relationship of output data to measured VCC or equation (2)
can be used to calculate the measured VCC.
Measured VCC =
[(Output Code) • 4.84/1024] + 2.42
(2)
The guaranteed supply voltage monitor range is from 4.5V
to 6V. Typical parts are able to maintain measurement
accuracy with VCC as low as 3.25V. The typical INL and
DNL error plots shown on page 4 are measured with VCC
from 3.63V to 6.353V.
Table 3. Codes for Voltage Supply Conversion
OUTPUT CODE
Supply Voltage (VCC)
1011110110
6.003V
1011110101
5.998V
...
...
1000100010
5.001V
...
...
0110111001
4.504V
0110111000
4.500V
LTC1392
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APPLICATIONS INFORMATION
Differential Voltage Conversion
Thermal Coupling/Airflow
The LTC1392 measures the differential input voltage
through pins + VIN and – VIN. Input ranges of 0.5V or 1V
full scale are available for differential voltage measurement with resolutions of 10 bits. Tables 4a and 4b describe
the exact relationship of output data to measured differential input voltage in the 1V and 0.5V input range. Equations
(3) and (4) can be used to calculate the differential voltage
in the 1V and 0.5V input voltage range respectively. The
output code is in unipolar format.
The supply current of the LTC1392 is 700µA typically
when running at the maximum conversion rate. The equivalent power dissipation of 3.5mW causes a temperature
rise of 0.455°C in the SO8 and 0.35°C in PDIP packages
due to self-heating effects. At sampling rates less than 400
samples per second, less than 20µA current is drawn from
the supply (see Typical Performance Characteristics) and
the die self-heating effect is negligible. This LTC1392 can
be attached to a surface (such as microprocessor chip or
a heat sink) for precision temperature monitoring. The
package leads are the principal path to carry the heat into
the device; thus any wiring leaving the device should be
held at the same temperature as the surface. The easiest
way to do this is to cover up the wires with a bead of epoxy
which will ensure that the leads and wires are at the same
temperature as the surface. The thermal time constant of
the LTC1392 in still air is about 22 seconds (see the graph
in the Typical Performance Charateristics section). Attaching an LTC1392 to a small metal fin (which also
provides a small thermal mass) will help reduce thermal
time constant, speed up the response and give the steadiest reading in slow moving air.
Differential Voltage = 1V • (10-bit code)/1024
Differential Voltage = 0.5V • (10-bit code)/1024
(3)
(4)
Table 4a. Codes for 1V Differential Voltage Range
OUTPUT
CODE
INPUT
VOLTAGE
INPUT
RANGE = 1V
1111111111
1V – 1LSB
999.0mV
1111111110
1V – 2LSB
998.0mV
...
...
...
0000000001
1LSB
0.977mV
0000000000
0LSB
0.00mV
REMARKS
1LSB = 1/1024
Table 4b. Codes for 0.5V Differential Voltage Range
OUTPUT
CODE
INPUT
VOLTAGE
INPUT
RANGE = 0.5V
1111111111
0.5V – 1LSB
499.5mV
1111111110
0.5V – 2LSB
499.0mV
...
...
...
0000000001
1LSB
0.488mV
0000000000
0LSB
0.00mV
REMARKS
1LSB = 0.5/1024
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LTC1392
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TYPICAL APPLICATIONS
System Monitor for Two Supply Voltages and Ambient Temperature
5V
1N4148
22Ω
10µF
16V
+
0.1µF
+
220µF
10V
×4
+VIN
0.1µF
PVCC
VCC
M2
G1
G2
FB
COMP SHDN
RC
7.5k
CC
4700pF
C1
220pF
SHDN
LTC1392
+
8
10µF
CO
330µF
6.3V
×6
M3
LTC1430
VOUT
3.3V
2.5µH
15A
M1
0.1µF
+
7
100k
6
GND
33k
– VIN
5
0.1µF
VCC
1
DIN
–VIN
DOUT
+VIN
CLK
GND
P1.4
MPU
(e.g., 8051)
2
3
P1.3
4
CS
P1.2
100pF
LTC1392 • TA03
M1, M2, M3:
MOTOROLA MTD20N03HL
10k
10k
TRIMMED TO
VOUT = 3.3V
12k
System Monitor for Relative Humidity, Supply Voltage and Ambient Temperature
0.01µF
1/4 LTC1043
7
8
16
5V
0.1µF
– 5V
11
470Ω
1k
1%
100pF
5V
0.1µF
0.1µF
5V
1/4 LTC1043
500Ω
90%
RH TRIM
5V
–5V
17
13
14
2
–
1µF
7
LT ®1056
3
LT1004-1.2
+
22M
+
OUTPUT
0.1µF
0V TO 1V =
0% TO 100%
6
8
–
7
6
5
100pF
VCC
–VIN
DIN
DOUT
+VIN
CLK
GND
CS
1
2
3
4
P1.4
MPU
(e.g., 8051)
P1.3
P1.2
1
– 5V
10k
5%
RH TRIM
3
2
0.1µF
1µF
10k
LM301A
4
12
SENSOR
6
LTC1392
8
0.1µF
0.1µF
33k
SENSOR: PANAMETRICS #RHS
500pF AT RH = 76%
1.7pF/%RH
9k*
–5V
* 1% FILM RESISTOR
1392 TA04
1k*
10
LTC1392
U
PACKAGE DESCRIPTION
Dimemsions in inches (millimeters) unless otherwise noted.
N8 Package
8-Lead PDIP (Narrow 0.300)
(LTC DWG # 05-08-1510)
0.400*
(10.160)
MAX
8
7
6
5
1
2
3
4
0.255 ± 0.015*
(6.477 ± 0.381)
0.300 – 0.325
(7.620 – 8.255)
0.065
(1.651)
TYP
0.009 – 0.015
(0.229 – 0.381)
(
0.130 ± 0.005
(3.302 ± 0.127)
0.045 – 0.065
(1.143 – 1.651)
0.125
(3.175)
MIN
0.005
(0.127)
MIN
+0.025
0.325 –0.015
+0.635
8.255
–0.381
)
0.015
(0.380)
MIN
0.018 ± 0.003
(0.457 ± 0.076)
0.100 ± 0.010
(2.540 ± 0.254)
N8 0695
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS.
MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
S8 Package
8-Lead Plastic Small Outline (Narrow 0.150)
(LTC DWG # 05-08-1610)
0.189 – 0.197*
(4.801 – 5.004)
8
7
6
5
0.150 – 0.157**
(3.810 – 3.988)
0.228 – 0.244
(5.791 – 6.197)
1
0.010 – 0.020
× 45°
(0.254 – 0.508)
0.008 – 0.010
(0.203 – 0.254)
2
3
4
0.053 – 0.069
(1.346 – 1.752)
0.004 – 0.010
(0.101 – 0.254)
0°– 8° TYP
0.016 – 0.050
0.406 – 1.270
*DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH
SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE
**DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD
FLASH SHALL NOT EXCEED 0.010" (0.254mm) PER SIDE
0.014 – 0.019
(0.355 – 0.483)
0.050
(1.270)
BSC
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.
SO8 0695
11
LTC1392
UO
TYPICAL APPLICATI
Measuring a Secondary Temperature with an External Thermistor
DIVIDER OUTPUT VOLTAGE (V)
ERT-D2FHL103S DIVIDER OUTPUT VOLTAGE
VS TEMPERATURE
1.5
1.4
1.3
1.2
1.1
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
IDEAL OUTPUT (V) =
–11.15mV/°C • TEMPERATURE + 1.371
ACTUAL
DIVIDER
OUTPUT
20
30
5V
60
50
40
TEMPERATURE (°C)
R1*
6.8k
70
5V
LTC1392
8
R2*
1.8k
7
6
LT1004-1.2
IDEAL OUTPUT (V) =
–11.15mV/°C • TEMPERATURE + 1.371
TEMPERATURE RANGE: 38°C TO 80°C ±4°C
RT = ERT – D2FHL103S
ASSUMING 3% β AND
10% RTO TOLERANCES
80
5
VCC
–VIN
DIN
DOUT
+VIN
CLK
GND
CS
* 1% FILM RESISTOR
1
2
3
4
P1.4
MPU
(e.g., 8051)
P1.3
P1.2
1392 TA05
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENT
LT1025
Micropower Thermocouple Cold Junction Compensator
Compatible with Standard Thermocouples (E, J, K, R, S, T)
LTC1285/LTC1288 3V Micropower 12-Bit ADCs with Auto Shutdown
Differential or 2-Channel Multiplexed, Single Supply
LTC1286/LTC1298 Micropower 12-Bit ADCs with Auto Shutdown
Differential or 2-Channel Multiplexed, Single Supply
LTC1391
Low Power, Precision 8-to-1 Analog Multiplexer
SPI, QSPI Compatible, Single 5V or 3V, Low RON, Low Charge Injection
LM334
Constant Current Source and Temperature Sensor
3 Pins, Current Out Pin
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417● (408)432-1900
FAX: (408) 434-0507● TELEX: 499-3977 ● www.linear-tech.com
1392f LT/TP 0497 7K • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 1995