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LTC1392 Micropower Temperature, Power Supply and Differential Voltage Monitor
FEATURES
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DESCRIPTIO
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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 0.2A Supply Current When Idle 700A 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
The LTC(R)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 2C initial accuracy at room temperature and 4C over the full - 40C to 85C 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.
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.
TYPICAL APPLICATI
Complete Temperature, Supply Voltage and Supply Current Monitor
1F
TEMPERATURE ERROR (C)
Output Temperature Error
5 4 LTC1392C GUARANTEED LIMIT LTC1392I GUARANTEED LIMIT TYPICAL
+
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 5
5V
3 2 1 0 -1 -2 -3 -4 -5 -40 -20 40 20 0 60 TEMPERATURE (C) 80 100
RSENSE ILOAD
LTC1392 * TA01
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LTC1392 * TA02
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1
LTC1392 ABSOLUTE
(Note 1)
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RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW DIN 1 DOUT 2 CLK 3 CS 4 N8 PACKAGE 8-LEAD PDIP 8 7 6 5 VCC -VIN +VIN GND
Supply Voltage (VCC) ................................................ 7V Input Voltage ................................. - 0.3V to VCC + 0.3V Output Voltage ............................... - 0.3V to VCC + 0.3V Operating Temperature Range LTC1392C............................................... 0C to 70C LTC1392I........................................... - 40C to 85C Junction Temperature.......................................... 125C Storage Temperature Range ................ - 65C to 150C Lead Temperature (Soldering, 10 sec)................. 300C
ORDER PART NUMBER LTC1392CN8 LTC1392CS8 LTC1392IN8 LTC1392IS8 S8 PART MARKING 1392 1392I
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125C, JA = 100C/ W (N8) TJMAX = 125C, JA = 130C/ W (S8)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER Power Supply To Digital Conversion Resolution Total Absolute Error Differential Voltage to Digital Conversion (Full-Scale Input = 1V) Resolution Integral Linearity Error (Note 5) Differential Linearity Error Offset Error Full-Scale Error Differential Voltage to Digital Conversion (Full-Scale Input = 0.5V) Resolution Integral Linearity Error (Note 5) Differential Linearity Error Offset Error Full-Scale Error Temperature to Digital Conversion Accuracy Nonlinearity CONDITIONS
(Note 2, 3)
MIN TYP MAX 10
q
UNITS Bit LSB
VCC = 4.5V to 6V VCC = 4.5V to 6V
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10
q q q q
0.5 0.5
1 1 4 15
10
q q q q
0.5 0.5
2 1 8 25 2 4
TA = 25C (Note 7) TA = TMAX or TMIN (Note 7) TMIN TA TMAX (Note 4)
q
1
2
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Bit LSB LSB LSB LSB Bit LSB LSB LSB LSB C C C
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LTC1392
ELECTRICAL CHARACTERISTICS
SYMBOL ION LEAKAGE IOFF LEAKAGE VIH VIL IIH IIL VOH VOL IOZ ISOURCE ISINK ICC tSMPL tCONV tdDO ten tdis thDO tf tr CIN PARAMETER On-Channel Leakage Current (Note 6) Off-Channel Leakage Current (Note 6) High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current High Level Output Voltage Low Level Output Voltage Hi-Z Output Current Output Source Current Output Sink Current Supply Current Analog Input Sample Time Conversion Time Delay Time, CLK to DOUT Data Valid Delay Time, CLK to DOUT Data Enabled Delay Time, CS to DOUT Hi-Z Time Output Data Remains Valid After CLK DOUT Fall Time DOUT Rise Time Input Capacitance
(Note 2, 3)
MIN
q q
CONDITIONS
TYP
MAX 1 1
UNITS A A V V A A V V
VCC = 5.25V VCC = 4.75V VIN = VCC VIN = 0V VCC = 4.75V, IOUT = 10A VCC = 4.75V, IOUT = 360A VCC = 4.75V, IOUT = 1.6mA CS = High VOUT = 0V VOUT = VCC CS = High CS = Low, VCC = 5V See Figure 1 See Figure 1 CLOAD = 100pF CLOAD = 100pF CLOAD = 100pF CLOAD = 100pF CLOAD = 100pF Analog Input On-Channel Analog Input Off-Channel Digital Input
q q q q q q q
2 0.8 5 -5 4.5 2.4 4.74 4.72 0.4 5 - 25 45
V A mA mA
q q
0.1 0.7 1.5 10
5 1
A mA CLK Cycles CLK Cycles
q q q
150 60 170 30 70 25 30 5 5
300 150 450 250 100
ns ns ns ns ns ns pF pF pF
q q
RECOM ENDED OPERATING CONDITIONS
SYMBOL VCC fCLK tCYC thDI tsuCS tWAKEUP tsuDI tWHCLK tWLCLK tWHCS tWLCS PARAMETER Supply Voltage Clock Frequency Total Cycle Time Hold Time, DIN After CLK Setup Time CS Before First CLK (See Figure 1) Wakeup Time CS Before Start Bit (See Figure 1) Setup Time, DIN Stable Before CLK Clock High Time Clock Low Time CS High Time Between Data Transfer Cycles CS Low Time During Data Transfer VCC = 5V fCLK = 250kHz Temperature Conversion Only VCC = 5V VCC = 5V VCC = 5V Temperature Conversion Only VCC = 5V VCC = 5V VCC = 5V VCC = 5V, fCLK = 250kHz VCC = 5V, fCLK = 250kHz Temperature Conversion Only CONDITIONS MIN 4.5 150 74 144 150 2 10 80 150 1.6 2 2 72 142 250 TYP MAX 6 350 UNITS V kHz s s ns s s s ns s s s s s
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LTC1392
RECOM ENDED OPERATING CONDITIONS
The q denotes specifications which apply over the operating temperature range (0C TA 70C for commercial grade and - 40C TA 85C 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 = 25C 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.
TYPICAL PERFORMANCE CHARACTERISTICS
Differential Nonlinearity Power Supply Voltage Mode
DIFFERENTIAL NONLINEARITY ERROR (LSB)
Integral Nonlinearity Power Supply Voltage Mode
INTEGRAL NONLINEARITY ERROR (LSB)
fCLK = 250kHz TA = 25C 0.5
DIFFERENTIAL NONLINEARITY ERROR (LSB)
1.0 fCLK = 250kHz TA = 25C 0.5
1.0
0
0
-0.5
-0.5
-1.0 256 320 384 448 512 576 640 704 768 832 CODE
1392 G01
-1.0 256 320 384 448 512 576 640 704 768 832 CODE
1392 G02
Integral Nonlinearity
DIFFERENTIAL NONLINEARITY ERROR (LSB)
1.0
INTEGRAL NONLINEARITY ERROR (LSB)
1.0
Differential Nonlinearity
1.0
INTEGRAL NONLINEARITY ERROR (LSB)
0.5
Full Scale = 1V fCLK = 250kHz TA = 25C VCC = 5V
0.5
Full Scale = 0.5V fCLK = 250kHz TA = 25C VCC = 5V
0
0
-0.5
-0.5
-1.0 0 128 256 384 512 640 768 896 1024 CODE
1392 G04
-1.0 0 128 256 384 512 640 768 896 1024 CODE
1392 G05
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Differential Nonlinearity
1.0 Full Scale = 1V fCLK = 250kHz TA = 25C VCC = 5V
0.5
0
-0.5
-1.0 0 128 256 384 512 640 768 896 1024 CODE
1392 G03
Integral Nonlinearity
Full Scale = 0.5V fCLK = 250kHz TA = 25C VCC = 5V
0.5
0
-0.5
-1.0 0 128 256 384 512 640 768 896 1024 CODE
1392 G06
LTC1392 TYPICAL PERFORMANCE CHARACTERISTICS
Thermal Response in Stirred Oil Bath
70 65 60 TEMPERATURE (C) VCC = 5V 70 65 60 VCC = 5V
TEMPERATURE (C)
55 50 45 40 35 30 25 20 0 5 10 15 20 TIME (SEC) 25 30
1392 G07
55 50 45 40 35 30 25 20 0 50 100 150 200 TIME (SEC) 250 300 S8 N8
SUPPLY CURRENT (A)
N8 S8
PIN FUNCTIONS
DIN (Pin 1): Digital Input. The A/D configuration word is shifted into this input. DOUT (Pin 2): Digital Output. The A/D result is shifted out of this output. CLK (Pin 3): Shift Clock. This clock synchronizes the serial data. CS (Pin 4): Chip Select Input. A logic low on this input enables the LTC1392. GND (Pin 5): Ground Pin. GND should be tied directly to an analog ground plane. +VIN (Pin 6): Positive Analog Differential Input. The pin can be used as a single-ended input by grounding - VIN. - VIN (Pin 7): Negative Analog Differential Input. The input must be free from noise. VCC (Pin8): Positive Supply. This supply must be kept free from noise and ripple by bypassing directly to the ground plane.
BLOCK DIAGRAM
DIN 1
TEMPERATURE SENSOR
GND VCC
+VIN
6
VREF
-VIN 7
UW
+ - + - + -
Thermal Response in Still Air
1000
Supply Current vs Sample Rate
CS LOW BETWEEN SAMPLES 100 CS HIGH BETWEEN SAMPLES 10
1 VCC = 5V fCLK = 250kHz TA = 25C 0.1 0.1 1 10 100 1k 10k SAMPLE FREQUENCY (Hz) 100k
1392 G09
1392 G08
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3 VREF = 2.42V INPUT SHIFT REGISTER BANDGAP VREF = 1V VREF = 0.5V 2 10-BIT CAPACITIVE DAC SERIAL PORT 10 BITS 10-BIT SAR
CLK
DOUT
ANALOG INPUT MUX CSAMPLE
COMP
8 VCC
5 GND
CONTROL AND TIMING
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LTC1392 * BD
CS
5
LTC1392
TEST CIRCUITS
Load Circuit for tdDO, tr and tf
1.4V
CLK VIL tdDO
Voltage Waveforms for DOUT Delay Time, tdDO
3k DOUT 100pF
LTC1392 * TC02
TEST POINT
DOUT
LTC1392 * TC03
VOH VOL
Voltage Waveforms for DOUT Rise and Fall Times, tr and tf
DOUT VOH VOL
CS 2.0V
Voltage Waveforms for tdis
tr
tf
1392 TC04
Load Circuit for tdis and ten
TEST POINT
DOUT WAVEFORM 1 (SEE NOTE 1) tdis DOUT WAVEFORM 2 (SEE NOTE 2)
90%
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.
LTC1392 * TC06
3k DOUT 100pF
5V tdis WAVEFORM 2, ten tdis WAVEFORM 1
LTC1392 * TC05
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 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 80s delay is needed for
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LTC1392
APPLICATIONS INFORMATION
MSB-First Data (MSBF = 1)
tCYC CS tsuCS CLK tWAKEUP SEL1 SEL0 DIN START DOUT Hi-Z tSMPL tCONV MSBF B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Hi-Z FILLED WITH ZEROS
CS tsuCS CLK tWAKEUP SEL1 SEL0 DIN START DOUT Hi-Z MSBF B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 Hi-Z FILLED WITH ZEROS
tSMPL
tCONV
LTC1392 * F01
temperature measurement or a 10s 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
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tCYC
Figure 1
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 Start BIT 2 Select 1 BIT 1 Select 0 BIT 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.
7
LTC1392
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
SELECT 1 0 0 1 1 SELECT 0 0 1 0 1 MEASUREMENT MODE Temperature Power Supply Voltage Differential Input, 1V Full Scale Differential Input, 0.5V Full Scale
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 0C to 70C temperature range and the LTC1392I over the - 40C to 85C range. Performance at tempera-
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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 1111111111 1111111110 ... 1001101101 1001101100 1001101011 ... 0000000001 0000000000 TEMPERATURE (C) 125.75 125.50 ... 25.25 25.00 24.75 ... - 129.75 - 130.00
Voltage Supply (VCC) Monitor 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 1011110110 1011110101 ... 1000100010 ... 0110111001 0110111000 Supply Voltage (VCC) 6.003V 5.998V ... 5.001V ... 4.504V 4.500V
LTC1392
APPLICATIONS INFORMATION
Differential Voltage Conversion 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. Differential Voltage = 1V * (10-bit code)/1024 Differential Voltage = 0.5V * (10-bit code)/1024
Table 4a. Codes for 1V Differential Voltage Range
OUTPUT CODE 1111111111 1111111110 ... 0000000001 0000000000 INPUT VOLTAGE 1V - 1LSB 1V - 2LSB ... 1LSB 0LSB INPUT RANGE = 1V 999.0mV 998.0mV ... 0.977mV 0.00mV 1LSB = 1/1024 REMARKS (3) (4)
Table 4b. Codes for 0.5V Differential Voltage Range
OUTPUT CODE 1111111111 1111111110 ... 0000000001 0000000000 INPUT VOLTAGE 0.5V - 1LSB 0.5V - 2LSB ... 1LSB 0LSB INPUT RANGE = 0.5V 499.5mV 499.0mV ... 0.488mV 0.00mV 1LSB = 0.5/1024 REMARKS
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Thermal Coupling/Airflow The supply current of the LTC1392 is 700A typically when running at the maximum conversion rate. The equivalent power dissipation of 3.5mW causes a temperature rise of 0.455C in the SO8 and 0.35C in PDIP packages due to self-heating effects. At sampling rates less than 400 samples per second, less than 20A 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.
9
LTC1392
TYPICAL APPLICATIONS
System Monitor for Two Supply Voltages and Ambient Temperature
5V 1N4148 22 10F 16V 0.1F 0.1F VCC FB LTC1430 COMP SHDN C1 220pF RC 7.5k CC 4700pF GND - VIN 100pF 10k 12k 10k TRIMMED TO VOUT = 3.3V M1, M2, M3: MOTOROLA MTD20N03HL SHDN PVCC G1 G2 M3 +VIN M2 M1
+
System Monitor for Relative Humidity, Supply Voltage and Ambient Temperature
0.01F
- 5V 470 1k 1% 1/4 LTC1043 500 90% RH TRIM 13 1F 3 LT1004-1.2 12 1F SENSOR 22M - 5V 14 2 11 17 100pF 5V 0.1F -5V
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220F 10V x4 2.5H 15A CO 330F 6.3V x6 VOUT 3.3V
+
10F 0.1F 100k
LTC1392 8 7 6 VCC -VIN +VIN GND DIN DOUT CLK CS 1 2 3 4 P1.4 MPU (e.g., 8051) P1.3 P1.2
LTC1392 * TA03
+
33k
0.1F
5
1/4 LTC1043 8 7 16 0.1F 5V 0.1F 5V 0.1F 8 10k 3 OUTPUT 0.1F 0V TO 1V = 0% TO 100% 6 8 100pF 7 6 5 LTC1392 VCC -VIN +VIN GND DIN DOUT CLK CS 1 2 3 4 P1.4 MPU (e.g., 8051) P1.3 P1.2 5V
- +
7 LT (R)1056 4 0.1F 6
+
LM301A
2
-
1
10k 5% RH TRIM
0.1F 33k -5V
SENSOR: PANAMETRICS #RHS 500pF AT RH = 76% 1.7pF/%RH 9k* * 1% FILM RESISTOR
1392 TA04
1k*
LTC1392
PACKAGE DESCRIPTION
0.300 - 0.325 (7.620 - 8.255)
0.009 - 0.015 (0.229 - 0.381)
(
+0.025 0.325 -0.015 +0.635 8.255 -0.381
)
*THESE DIMENSIONS DO NOT INCLUDE MOLD FLASH OR PROTRUSIONS. MOLD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.010 INCH (0.254mm)
0.010 - 0.020 x 45 (0.254 - 0.508) 0.008 - 0.010 (0.203 - 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
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.
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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
0.255 0.015* (6.477 0.381)
1
2
3
4 0.130 0.005 (3.302 0.127)
0.045 - 0.065 (1.143 - 1.651)
0.065 (1.651) TYP 0.005 (0.127) MIN 0.100 0.010 (2.540 0.254) 0.125 (3.175) MIN 0.018 0.003 (0.457 0.076) 0.015 (0.380) MIN
N8 0695
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
0.228 - 0.244 (5.791 - 6.197)
0.150 - 0.157** (3.810 - 3.988)
1
2
3
4
0.053 - 0.069 (1.346 - 1.752)
0.004 - 0.010 (0.101 - 0.254)
0.014 - 0.019 (0.355 - 0.483)
0.050 (1.270) BSC
SO8 0695
11
LTC1392
TYPICAL APPLICATI
Measuring a Secondary Temperature with an External Thermistor
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 20 5V R1* 6.8k
DIVIDER OUTPUT VOLTAGE (V)
LT1004-1.2
RELATED PARTS
PART NUMBER LT1025 DESCRIPTION Micropower Thermocouple Cold Junction Compensator COMMENT Compatible with Standard Thermocouples (E, J, K, R, S, T) Differential or 2-Channel Multiplexed, Single Supply Differential or 2-Channel Multiplexed, Single Supply SPI, QSPI Compatible, Single 5V or 3V, Low RON, Low Charge Injection 3 Pins, Current Out Pin LTC1285/LTC1288 3V Micropower 12-Bit ADCs with Auto Shutdown LTC1286/LTC1298 Micropower 12-Bit ADCs with Auto Shutdown LTC1391 LM334 Low Power, Precision 8-to-1 Analog Multiplexer Constant Current Source and Temperature Sensor
12
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417q (408)432-1900 FAX: (408) 434-0507q TELEX: 499-3977 q www.linear-tech.com
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IDEAL OUTPUT (V) = -11.15mV/C * TEMPERATURE + 1.371 ACTUAL DIVIDER OUTPUT 30 60 50 40 TEMPERATURE (C) 5V 8 R2* 1.8k IDEAL OUTPUT (V) = -11.15mV/C * TEMPERATURE + 1.371 TEMPERATURE RANGE: 38C TO 80C 4C RT = ERT - D2FHL103S ASSUMING 3% AND 10% RTO TOLERANCES 7 6 5 70 80 LTC1392 VCC -VIN +VIN GND DIN DOUT CLK CS 1 2 3 4 P1.4 MPU (e.g., 8051) P1.3 P1.2 * 1% FILM RESISTOR
1392 TA05
1392f LT/TP 0497 7K * PRINTED IN USA
(c) LINEAR TECHNOLOGY CORPORATION 1995

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