LTC1392 Micropower Temperature, Power Supply and Differential Voltage Monitor U DESCRIPTIO FEATURES ■ ■ ■ ■ ■ ■ ■ ■ ■ 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 UO APPLICATI ■ ■ ■ ■ ■ S 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. UO 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 U U RATI GS W W W W AXI U U 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 U U U U WW 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 U U U U WW 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. U W 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 U W 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 U U U 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. W 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 5 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 U W U U 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 6 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 U U W U 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. 7 LTC1392 U W U U 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 U U W U 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 9 LTC1392 U 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