LTC2990 I2C Temperature, Voltage and Current Monitor Features n n n n n n n n n Description Measures Voltage, Current and Temperature Measures Two Remote Diode Temperatures ±1°C Accuracy, 0.06°C Resolution ±2°C Internal Temperature Sensor 14-Bit ADC Measures Voltage/Current 3V to 5.5V Supply Operating Voltage Four Selectable Addresses Internal 10ppm/°C Voltage Reference 10-Lead MSOP Package Applications n n n n n Temperature Measurement Supply Voltage Monitoring Current Measurement Remote Data Acquisition Environmental Monitoring The LTC®2990 is used to monitor system temperatures, voltages and currents. Through the I2C serial interface, the device can be configured to measure many combinations of internal temperature, remote temperature, remote voltage, remote current and internal VCC. The internal 10ppm/°C reference minimizes the number of supporting components and area required. Selectable address and configurable functionality give the LTC2990 flexibility to be incorporated in various systems needing temperature, voltage or current data. The LTC2990 fits well in systems needing sub-millivolt voltage resolution, 1% current measurement and 1°C temperature accuracy or any combination of the three. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Typical Application Voltage, Current, Temperature Monitor Temperature Total Unadjusted Error RSENSE 2.5V 1.0 ILOAD 5V SDA SCL ADR0 ADR1 V1 0.5 V2 V3 LTC2990 TREMOTE TUE (°C) VCC TREMOTE 0 V4 2990 TA01a GND –0.5 TINTERNAL MEASURES: TWO SUPPLY VOLTAGES, SUPPLY CURRENT, INTERNAL AND REMOTE TEMPERATURES –1.0 –50 –25 0 50 25 TAMB (°C) 75 100 125 2990 TA01b 2990f LTC2990 Absolute Maximum Ratings (Note 1) Pin Configuration Supply Voltage VCC.................................... –0.3V to 6.0V Input Voltages V1, V2, V3, V4, SDA, SCL, ADR1, ADR2...................................–0.3V to (VCC + 0.3V) Operating Temperature Range LTC2990C................................................. 0°C to 70°C LTC2990I..............................................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec)................... 300°C TOP VIEW V1 V2 V3 V4 GND 10 9 8 7 6 1 2 3 4 5 VCC ADR1 ADR0 SCL SDA MS PACKAGE 10-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 150°C/W Order Information LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2990CMS#PBF LTC2990CMS#TRPBF LTDSQ 10-Lead Plastic MSOP 0°C to 70°C LTC2990IMS#PBF LTC2990IMS#TRPBF LTDSQ 10-Lead Plastic MSOP –40°C to 85°C LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2990CMS LTC2990CMS#TR LTDSQ 10-Lead Plastic MSOP 0°C to 70°C LTC2990IMS LTC2990IMS#TR LTDSQ 10-Lead Plastic MSOP –40°C to 85°C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. Contact LTC Marketing for parts trimmed to ideality factors other than 1.004. 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 General Input Supply Range VCC Input Supply Current ICC Input Supply Current ISD Input Supply Undervoltage Lockout VCC(UVL) Measurement Accuracy Internal Temperature Total Unadjusted TINT(TUE) Error Remote Diode Temperature Total Unadjusted Error VCC Voltage Total Unadjusted Error VCC(TUE) V1 Through V4 Total Unadjusted Error Vn(TUE) Differential Voltage Total Unadjusted Error VDIFF(TUE) V1 – V2 or V3 – V4 Maximum Differential Voltage VDIFF(MAX) Differential Voltage Common Mode Range VDIFF(CMR) Differential Voltage LSB Weight VLSB(DIFF) VLSB(SINGLE-ENDED) Single-Ended Voltage LSB Weight Temperature LSB Weight VLSB(TEMP) Temperature Noise TNOISE TRMT(TUE) CONDITIONS MIN l During Conversion, I2C Inactive Shutdown Mode, I2C Inactive l l 1.3 LTC2990C LTC2990I TAMB = –40°C to 25°C TAMB = 25°C to 85°C η = 1.004 (Note 4) l l l l –3 –2 –3 2.9V ≤ VCC ≤ 5.5V 0V ≤ VN ≤ VCC, Vn ≤ 4.9V –300mV ≤ VD ≤ 300mV l l l l l Celsius or Kelvin Celsius or Kelvin TMEAS = 46ms (Note 2) MAX 1.1 1 2.1 5.5 1.8 5 2.7 V mA µA V ±1 ±0.5 ±2.5 5 5 1 ±1.5 °C °C °C °C °C ±0.1 ±0.1 ±0.2 ±0.25 ±0.25 ±0.75 % % % 2.9 l l TYP ±1 1 –300 0 19.42 305.18 0.0625 0.2 0.05 300 VCC UNITS mV V µV µV Deg °RMS °/√Hz 2990f LTC2990 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 Res INL CIN IIN(AVG) PARAMETER Resolution (No Missing Codes) Integral Nonlinearity V1 Through V4 Input Sampling Capacitance V1 Through V4 Input Average Sampling Current V1 Through V4 Input Leakage Current IDC_LEAK(VIN) Measurement Delay Per Configured Temperature Measurement TINT , TR1, TR2 V1, V2, V3, V4 Single-Ended Voltage Measurement V1 – V2, V3 – V4 Differential Voltage Measurement VCC Measurement VCC Max Delay Mode[4:0] = 11101, TINT , TR1, TR2, VCC V1, V3 Output (Remote Diode Mode Only) Output Current IOUT Output Voltage VOUT I2C Interface ADR0, ADR1 Input Low Threshold Voltage VADR(L) ADR0, ADR1 Input High Threshold Voltage VADR(H) SDA Low Level Maximum Voltage VOL1 Maximum Low Level Input Voltage VIL Minimum High Level Input Voltage VIH SDA, SCL Input Current ISDAI,SCLI Maximum ADR0, ADR1 Input Current IADR(MAX) I2C Timing (Note 2) Maximum SCL Clock Frequency fSCL(MAX) Minimum SCL Low Period tLOW Minimum SCL High Period tHIGH Minimum Bus Free Time Between Stop/ tBUF(MIN) Start Condition Minimum Hold Time After (Repeated) tHD,STA(MIN) Start Condition Minimum Repeated Start Condition Set-Up tSU,STA(MIN) Time Minimum Stop Condition Set-Up Time tSU,STO(MIN) Minimum Data Hold Time Input tHD,DATI(MIN) Minimum Data Hold Time Output tHD,DATO(MIN) Minimum Data Set-Up Time Input tSU,DAT(MIN) Maximum Suppressed Spike Pulse Width tSP(MAX) SCL, SDA Input Capacitance CX CONDITIONS (Note 2) 2.9V ≤ VCC ≤ 5.5V, VIN(CM) = 1.5V (Note 2) Single-Ended Differential (Note 2) l MIN 14 –2 –2 0V ≤ VN ≤ VCC l –10 (Note 2) (Note 2) Per Voltage, Two Minimum (Note 2) (Note 2) (Note 2) l 37 1.2 1.2 1.2 Remote Diode Mode l l l l 2 2 UNITS Bits 0.35 LSB LSB pF 0.6 µA 10 nA 46 1.5 1.5 1.5 55 1.8 1.8 1.8 167 ms ms ms ms ms 260 350 VCC µA V 0.3 • VCC ±1 ±1 V V V V V µA µA 1.3 600 1.3 kHz µs ns µs 600 ns 600 ns 600 0 900 100 250 10 ns ns ns ns ns pF l l Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: Guaranteed by design and not subject to test. Note 3: Integral nonlinearity is defined as the deviation of a code from a straight line passing through the actual endpoints of the transfer curve. The deviation is measured from the center of the quantization band. MAX l 0V ≤ VN ≤ 3V (Note 2) Falling Rising IO = –3mA, VCC = 2.9V to 5.5V SDA and SCL Pins SDA and SCL Pins 0 < VSDA,SCL < VCC ADR0 or ADR1 Tied to VCC or GND TYP 0 l l 0.7 • VCC l l l 0.7 • VCC l l 0.4 0.3 • VCC 400 300 50 Note 4: Trimmed to an ideality factor of 1.004 at 25°C. Remote diode temperature drift (TUE) verified at diode voltages corresponding to the temperature extremes with the LTC2990 at 25°C. Remote diode temperature drift (TUE) guaranteed by characterization over the LTC2990 operating temperature range. 2990f LTC2990 Typical Performance Characteristics TA = 25°C, VCC = 3.3V unless otherwise noted 1200 3.5 4 MEASUREMENT DELAY VARIATION (%) VCC = 5V 3.0 1150 VCC = 5V 1100 2.0 ICC (µA) 1.5 1050 VCC = 3.3V 1.0 VCC = 3.3V 1000 0.5 0 –50 –25 0 25 50 75 TAMB (°C) 950 –50 –25 100 125 150 0 25 50 75 TAMB (°C) 3 VCC = 5V 2 1 VCC TUE Single-Ended VX TUE 0.5 VDIFF TUE (%) 0.05 VX TUE (%) 0.05 VCC TUE (%) 1.0 0 –0.05 0 25 50 75 TAMB (°C) 100 125 150 0 25 50 75 TAMB (°C) –1.0 –50 –25 100 125 150 3 LTC2990 TRX ERROR (°C) 0 –1 0.75 LTC2990 AT 25°C 0.2 LTC2990 AT 90°C 0 25 50 75 TAMB (°C) 100 125 150 2990 G07 0.50 0.25 –0.25 –0.2 0 –0.50 –0.4 –2 100 125 150 1.00 0.4 1 25 50 75 TAMB (°C) Remote Diode Error with LTC2990 at Same Temperature as Diode 0.6 2 0 2990 G06 Remote Diode Error with LTC2990 at 25°C, 90°C 4 0 VCC = 3.3V 2990 G05 2990 G04 –3 –50 –25 VCC = 5V 0 –0.5 –0.10 –50 –25 TINTERNAL Error 100 125 150 Differential Voltage TUE 0.10 –0.10 –50 –25 25 50 75 TAMB (°C) 2990 G03 0.10 –0.05 0 2990 G02 2990 G01 0 VCC = 3.3V 0 –1 –50 –25 100 125 150 LTC2990 TRX ERROR (DEG) ICC (µA) 2.5 TINTERNAL ERROR (DEG) Measurement Delay Variation vs T Normalized to 3.3V, 25°C Supply Current vs Temperature Shutdown Current vs Temperature –0.6 –50 –25 –0.75 0 25 50 75 100 125 150 BATH TEMPERATURE (°C) 2990 G08 –1.00 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G09 2990f LTC2990 Typical Performance Characteristics Single-Ended Noise Single-Ended Transfer Function 4800 READINGS 3500 LTC2990 VALUE (V) COUNTS 1.0 5 3000 2500 2000 1500 1000 VCC = 5V 4 0.5 VCC = 3.3V 3 2 1 0 VCC = 5V –0.5 –3 –2 2 1 0 LSBs (305.18µV/LSB) –1 –1 3 –1 –0 1 3 2 VX (V) 5 4 2990 G10 –1.0 6 0 1 2 3 VX (V) 4 Differential Transfer Function Differential INL 2 0.4 800 READINGS 5 2990 G12 2990 G11 LTC2990 Differential Noise 500 VCC = 3.3V 0 500 0 Single-Ended INL 6 INL (LSBs) 4000 TA = 25°C, VCC = 3.3V unless otherwise noted 0.3 1 0.2 300 200 0.1 INL (LSBs) LTC2990 V1-V2 (V) COUNTS 400 0 –0.1 –1 –0.2 100 0 –0.3 0 –4 –3 0 1 –2 –1 LSBs (19.42µV/LSB) 2 –0.4 –0.4 –0.3 –0.2 –0.1 0 0.1 V1-V2 (V) 3 0.2 1000 READINGS POR Thresholds vs Temperature 1000 READINGS 2.4 COUNTS THRESHOLD (V) 400 COUNTS VCC RISING 2.2 200 0.4 2.6 500 400 0.2 2990 G15 Remote Diode Noise 600 300 0 –0.2 2990 G14 TINT Noise 300 200 2.0 1.8 VCC FALLING 1.6 1.4 100 0 –2 –0.4 0.4 VIN (V) 2990 G13 500 0.3 100 –0.75 –0.5 –0.25 0 0.25 (°C) 0.5 0.75 2990 G16 0 1.2 –0.75 –0.5 –0.25 0 0.25 (°C) 0.5 0.75 2990 G17 1.0 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G18 2990f LTC2990 Pin Functions V1 (Pin 1): First Monitor Input. This pin can be configured as a single-ended input or the positive input for a differential or remote diode temperature measurement (in combination with V2). When configured for remote diode temperature, this pin will source a current. V2 (Pin 2): Second Monitor Input. This pin can be configured as a single-ended input or the negative input for a differential or remote diode temperature measurement (in combination with V1). When configured for remote diode temperature, this pin will have an internal termination, while the measurement is active. V3 (Pin 3): Third Monitor Input. This pin can be configured as a single-ended input or the positive input for a differential or remote diode temperature measurement (in combination with V4). When configured for remote diode temperature, this pin will source a current. V4 (Pin 4): Fourth Monitor Input. This pin can be configured as a single-ended input or the negative input for a differential or remote diode temperature measurement (in combination with V3). When configured for remote diode temperature, this pin will have an internal termination, while the measurement is active. SDA (Pin 6): Serial Bus Data Input and Output. In the transmitter mode (Read), the conversion result is output through the SDA pin, while in the receiver mode (Write), the device configuration bits are input through the SDA pin. At data input mode, the pin is high impedance; while at data output mode, it is an open-drain N-channel driver and therefore an external pull-up resistor or current source to VCC is needed. SCL (Pin 7): Serial Bus Clock Input. The LTC2990 can only act as a slave and the SCL pin only accepts external serial clock. The LTC2990 does not implement clock stretching. ADR0 (Pin 8): Serial Bus Address Control Input. The ADR0 pin is an address control bit for the device I2C address. ADR1 (Pin 9): Serial Bus Address Control Input. The ADR1 pin is an address control bit for the device I2C address. See Table 1. VCC (Pin 10): Supply Voltage Input. GND (Pin 5): Device Circuit Ground. Connect this pin to a ground plane through a low impedance connection. 2990f LTC2990 Functional Diagram REMOTE DIODE SENSORS VCC 10 MODE 1 2 3 4 V1 GND 5 V2 SCL CONTROL LOGIC V3 MUX ADC SDA I2C V4 ADR0 ADR1 7 6 8 9 UV INTERNAL SENSOR VCC REFERENCE UNDERVOLTAGE DETECTOR 2990 FD Timing Diagram SDAI/SDAO tSU, DAT tHD, DATO, tHD, DATI tSU, STA tSP tHD, STA tSP tBUF tSU, STO 2990 TD SCL tHD, STA START CONDITION REPEATED START CONDITION STOP CONDITION START CONDITION 2990f LTC2990 Operation The LTC2990 monitors voltage, current, internal and remote temperatures. It can be configured through an I2C interface to measure many combinations of these parameters. Single or repeated measurements are possible. Remote temperature measurements use a transistor as a temperature sensor, allowing the remote sensor to be a discrete NPN (ex. MMBT3904) or an embedded PNP device in a microprocessor or FPGA. The internal ADC reference minimizes the number of support components required. The Functional Diagram displays the main components of the device. The input signals are selected with an input MUX, controlled by the control logic block. The control logic uses the mode bits in the control register to manage the sequence and types of data acquisition. The control logic also controls the variable current sources during remote temperature acquisition. The order of acquisitions is fixed: TINTERNAL, V1, V2, V3, V4 then VCC. The ADC performs the necessary conversion(s) and supplies the data to the control logic for further processing in the case of temperature measurements, or routing to the appropriate data register for voltage and current measurements. Current and temperature measurements, V1 – V2 or V3 – V4, are sampled differentially by the internal ADC. The I2C interface supplies access to control, status and data registers. The ADR1 and ADR0 pins select one of four possible I2C addresses (see Table 1). The undervoltage detector inhibits I2C communication below the specified threshold. During an undervoltage condition, the part is in a reset state, and the data and control registers are placed in the default state of 00h. Remote diode measurements are conducted using multiple ADC conversions and source currents to compensate for sensor series resistance. During temperature measurements, the V2 or V4 terminal of the LTC2990 is terminated with a diode. The LTC2990 is calibrated to yield the correct temperature for a remote diode with an ideality factor of 1.004. See the applications section for compensation of sensor ideality factors other than the factory calibrated value of 1.004. The LTC2990 communicates through an I2C serial interface. The serial interface provides access to control, status and data registers. I2C defines a 2-wire open-drain interface supporting multiple slave devices and masters on a single bus. The LTC2990 supports 100kbits/s in the standard mode and up to 400kbit/s in fast mode. The four physical addresses supported are listed in Table 1. The I2C interface is used to trigger single conversions, or start repeated conversions by writing to a dedicated trigger register. The data registers contain a destructive-read status bit (data valid), which is used in repeated mode to determine if the register ’s contents have been previously read. This bit is set when the register is updated with new data, and cleared when read. Applications Information Figure 1 is the basic LTC2990 application circuit. 2.5V 5V RSENSE 15mΩ ILOAD 0.1µF 2-WIRE I2C INTERFACE VCC V1 MMBT3904 V2 SDA SCL LTC2990 ADR0 ADR1 GND The VCC pin must exceed the undervoltage (UV) threshold of 2.5V to keep the LTC2990 out of power-on reset. Power-on reset will clear all of the data registers and the control register. V3 Temperature Measurements 470pF V4 2990 F01 Figure 1 Power Up The LTC2990 can measure internal temperature and up to two external diode or transistor sensors. During temperature conversion, current is sourced through either the V1 or the V3 pin to forward bias the sensing diode. 2990f LTC2990 Applications Information The change in sensor voltage per degree temperature change is 275µV/°C, so environmental noise must be kept to a minimum. Recommended shielding and PCB trace considerations are illustrated in Figure 2. The diode equation: VBE = η • I k•T • ln C q IS (1) can be solved for T, where T is Kelvin degrees, IS is a process dependent factor on the order of 1E-13, η is the diode ideality factor, k is Boltzmann’s constant and q is the electron charge. VBE • q T= I η • k • In C IS (2) sensor can be considered a temperature scaling factor. The temperature error for a 1% accurate ideality factor error is 1% of the Kelvin temperature. Thus, at 25°C, or 298°K, a +1% accurate ideality factor error yields a +2.98 degree error. At 85°C or 358°K, a +1% error yields a 3.6 degree error. It is possible to scale the measured Kelvin or Celsius temperature measured using the LTC2990 with a sensor ideality factor other than 1.004, to the correct value. The scaling Equations (3) and (4) are simple, and can be implemented with sufficient precision using 16-bit fixed-point math in a microprocessor or microcontroller. Factory Ideality Calibration Value: ηCAL = 1.004 Actual Sensor Ideality Value: ηACT Compensated Kelvin Temperature: The LTC2990 makes differential measurements of diode voltage to calculate temperature. Proprietary techniques allow for cancellation of error due to series resistance. TK _ COMP = ηACT •T ηCAL K _ MEAS (3) Compensated Celsius Temperature 0.1µF GND SHIELD TRACE LTC2990 470pF NPN SENSOR V1 V2 V3 V4 VCC ADR1 ADR0 SCL GND SDA 2990 F02 Figure 2. Recommended PCB Layout Ideality Factor Scaling The LTC2990 is factory calibrated for an ideality factor of 1.004, which is typical of the popular MMBT3904 NPN transistor. The semiconductor purity and wafer-level processing limits device-to-device variation, making these devices interchangeable (typically <0.5C) for no additional cost. Several manufacturers supply suitable transistors, some recommended sources are listed in Table 10. While an ideality factor value of 1.004 is typical of target sensors, small deviations can yield significant temperature errors. Contact LTC Marketing for parts trimmed to ideality factors other than 1.004. The ideality factor of the diode η (4) TC _ COMP = ACT • TC _ MEAS + 273 – 273 η CAL A 16-bit unsigned number is capable of representing the ratio ηACT/ηCAL in a range of 0.00003 to 1.99997, by multiplying the fractional ratio by 215. The range of scaling encompasses every conceivable target sensor value. The ideality factor scaling granularity yields a worst-case temperature error of 0.01° at 125°C. Multiplying this 16‑bit unsigned number and the measured Kelvin (unsigned) temperature represented as a 16-bit number, yields a 32‑bit unsigned result. To scale this number back to a 13‑bit temperature (9-bit integer part, and a 4-bit fractional part), divide the number by 215 per Equation (5). Similarly, Celsius coded temperature values can be scaled using 16-bit fixed-point arithmetic, using Equation (6). In both cases, the scaled result will have a 9-bit integer (d[12:4]) and the 4LSBs (d[3:0]) representing the 4-bit fractional part. To convert the corrected result to decimal, divide the final result by 24 or 16, as you would the register contents. If ideality factor scaling is implemented in the ( ) 2990f LTC2990 Applications Information target application, it is beneficial to configure the LTC2990 for Kelvin coded results to limit the number of math operations required in the target processor. TK _ COMP = TC _ COMP = η (Unsigned) ηACT 215 TK _ MEAS CAL 15 (5) 2 (Unsigned) ηACT 215 ( TC _ MEAS + 273.15 • 24 ) η CAL (6) 215 – 273.15 • 24 Sampling Currents Single-ended voltage measurements are directly sampled by the internal ADC. The average ADC input current is a function of the input applied voltage as follows: IIN(AVG) = (VIN – 1.49) • 0.17µA Inputs with source resistance less than 200Ω will yield full-scale gain errors due to source impedance of <1/2LSB for 14-bit conversions. The nominal conversion time is 1.5ms for single-ended conversions. Current Measurements The LTC2990 has the ability to perform 14-bit current measurements with the addition of a current sense resistor (see Figure 3). In order to achieve accurate current sensing a few details must be considered. Differential voltage or current measurements are directly sampled by the internal ADC. The average ADC input current for each leg of the differential input signal during a conversion is (VIN – 1.49) • 0.34µA. The maximum source impedance to yield 14-bit results with, 1/2LSB full-scale error is ~50Ω. In order to achieve high accuracy, 4-point, or Kelvin connected measurements of the sense resistor differential voltage are necessary. In the case of current measurements, the external sense resistor is typically small, and determined by the full-scale input voltage of the LTC2990. The full-scale differential voltage is 0.300V. The external sense resistance is then a function of the maximum measurable current, or REXT_MAX = 0.300/IMAX. For example, if you wanted to measure a current range of ±5A, the external shunt resistance would equal 0.300/5 = 60mΩ. There exists a way to improve the sense resistor’s precision using the LTC2990. The LTC2990 measures both differential voltage and remote temperature. It is therefore, possible to compensate for the absolute resistance tolerance of the sense resistor and the temperature coefficient of the sense resistor in software. The resistance would be measured by running a calibrated test current through the discrete resistor. The LTC2990 would measure both the differential voltage across this resistor and the resistor temperature. From this measurement, RO and TO in the equation below would be known. Using the two equations, the host microprocessor could compensate for both the absolute tolerance and the TCR. RT = RO • [1 + α(T – TO)] where: α = +3930 ppm/°C for copper trace α = ±2 to ~+200ppm/°C for discrete R (7) I = (V1 – V2)/RT (8) RSENSE 0V – VCC ILOAD V1 V2 LTC2990 2990 F03 Figure 3. Simplified Current Sense Schematic 2990f 10 LTC2990 Applications Information Device Configuration The LTC2990 is configured by writing the control register through the serial interface. Refer to Table 4 for control register bit definition. The device is capable of many application configurations including voltage, temperature and current measurements. It is possible to configure the device for single or repeated acquisitions. For repeated acquisitions, only the initial trigger is required and new data is written over the old data. Acquisitions are frozen during serial read data transfers to prevent the upper and lower data bytes for a particular measurement from becoming out of sync. Internally, both the upper and lower bytes are written at the same instant. Since serial data transfer timeout is not implemented, failure to terminate a read operation will yield an indefinitely frozen wait state. The device can also make single measurements, or with one trigger, all of the measurements for the configuration. When the device is configured for multiple measurements, the order of measurements is fixed. As each new data result is ready, the MSB of the corresponding data register is set, and the corresponding status register bit is set. These bits are cleared when the corresponding data register is addressed. The configuration register value at power-up yields the measurement of only the internal temperature sensor, if triggered. The four input pins V1 through V4 will be in a high impedance state, until configured otherwise, and a measurement triggered. Data Format The data registers are broken into 8-bit upper and lower bytes. Voltage and current conversions are 14-bits. The upper bits in the MSB registers provide status on the resulting conversions. These status bits are different for temperature and voltage conversions: Temperature: Temperature conversions are reported as Celsius or Kelvin results described in Tables 7 and 8, each with 0.0625 degree-weighted LSBs. The format is controlled by the control register, Bit 7. All temperature formats, TINT , TR1 and TR2 are controlled by this bit. The Temperature MSB result register most significant bit (Bit 7) is the DATA_VALID bit, which indicates whether the current register contents have been accessed since the result was written to the register. This bit will be set when new data is written to the register, and cleared when accessed. Bit 6 of the register is a sensor-shorted alarm. This bit of the corresponding register will be high if the remote sensor diode differential voltage is below 0.14 VDC. The LTC2990 internal bias circuitry maintains this voltage above this level during normal operating conditions. Bit 5 of the register is a sensor open alarm. This bit of the corresponding register will be high if the remote sensor diode differential voltage is above 1.0VDC. The LTC2990 internal bias circuitry maintains this voltage below this level during normal operating conditions. The two sensor alarms are only valid after a completed conversion indicated by the data_valid bit being high. Bit 4 through Bit 0 of the MSB register are the conversion result bits D[12:8], in two’s compliment format. Note in Kelvin results, the result will always be positive. The LSB register contains temperature result bits D[7:0]. To convert the register contents to temperature, use the following equation: T = D[12:0]/16. See Table 9 for conversion value examples. Voltage/Current: Voltage results are reported in two respective registers, an MSB and LSB register. The Voltage MSB result register most significant bit (Bit 7) is the data_valid bit, which indicates whether the current register contents have been accessed since the result was written to the register. This bit will be set when the register contents are new, and cleared when accessed. Bit 6 of the MSB register is the sign bit, Bits 5 though 0 represent bits D[13:8] of the two’s complement conversion result. The LSB register holds conversion bits D[7:0]. The LSB value is different for single-ended voltage measurements V1 through V4, and differential (current measurements) V1 – V2 and V3 – V4. Single-ended voltages are limited to positive values in the range 0V to 3.5V. Differential voltages can have input values in the range of –0.300V to 0.300V. Use the following equations to convert the register values (see Table 9 for examples): VSINGLE-ENDED = D[13:0] • 305.18µV VDIFFERENTIAL = D[13:0] • 19.42µV, if Sign = 0 VDIFFERENTIAL = (D[13:0] +1) • –19.42µV, if Sign = 1 Current = D[13:0] • 19.42µV/RSENSE, if Sign = 0 Current = (D[13:0] +1) • –19.42µV/RSENSE, if Sign = 1, 2990f 11 LTC2990 Applications Information where RSENSE is the current sensing resistor, typically <1Ω. VCC: The LTC2990 measures VCC. To convert the contents of the VCC register to voltage, use the following equation: VCC = 2.5 + D[13:0] • 305.18µV Digital Interface The LTC2990 communicates with a bus master using a two-wire interface compatible with the I2C Bus and the SMBus, an I2C extension for low power devices. The LTC2990 is a read-write slave device and supports SMBus bus Read Byte Data and Write Byte Data, Read Word Data and Write Word Data commands. The data formats for these commands are shown in Tables 2 though 9. The connected devices can only pull the bus wires LOW and can never drive the bus HIGH. The bus wires are externally connected to a positive supply voltage via a current source or pull-up resistor. When the bus is free, both lines are HIGH. Data on the I2C bus can be transferred at rates of up to 100kbit/s in the standard mode and up to 400kbit/s in the fast mode. Each device on the I2C bus is recognized by a unique address stored in that device and can operate as either a transmitter or receiver, depending on the function of the device. In addition to transmitters and receivers, devices can also be considered as masters or slaves when performing data transfers. A master is the device which initiates a data transfer on the bus and generates the clock signals to permit that transfer. At the same time any device addressed is considered a slave. The LTC2990 can only be addressed as a slave. Once addressed, it can receive configuration bits or transmit the last conversion result. Therefore the serial clock line SCL is an input only and the data line SDA is bidirectional. The device supports the standard mode and the fast mode for data transfer speeds up to 400kbit/s. The Timing Diagram shows the definition of timing for fast/standard mode devices on the I2C bus. The internal state machine cannot update internal data registers during an I2C read operation. The state machine pauses until the I2C read is complete. It is therefore, important not to leave the LTC2990 in this state for long durations, or increased conversion latency will be experienced. START and STOP Conditions When the bus is idle, both SCL and SDA must be high. A bus master signals the beginning of a transmission with a START condition by transitioning SDA from high to low while SCL is high. When the bus is in use, it stays busy if a repeated START (SR) is generated instead of a STOP condition. The repeated START (SR) conditions are functionally identical to the START (S). When the master has finished communicating with the slave, it issues a STOP condition by transitioning SDA from low to high while SCL is high. The bus is then free for another transmission. I2C Device Addressing Four distinct bus addresses are configurable using the ADR0-ADR1 pins. Table 1 shows the correspondence between ADR0 and ADR1 pin states and addresses. Acknowledge The acknowledge signal is used for handshaking between the transmitter and the receiver to indicate that the last byte of data was received. The transmitter always releases the SDA line during the acknowledge clock pulse. When the slave is the receiver, it must pull down the SDA line so that it remains LOW during this pulse to acknowledge receipt of the data. If the slave fails to acknowledge by leaving SDA HIGH, then the master can abort the transmission by generating a STOP condition. When the master is receiving data from the slave, the master must pull down the SDA line during the clock pulse to indicate receipt of the data. After the last byte has been received the master will leave the SDA line HIGH (not acknowledge) and issue a STOP condition to terminate the transmission. Write Protocol The master begins communication with a START condition followed by the seven bit slave address and the R/W# bit set to zero. The addressed LTC2990 acknowledges the address and then the master sends a command byte which indicates which internal register the master wishes to write. The LTC2990 acknowledges the command byte and then latches the lower four bits of the command byte into its internal Register Address pointer. The master then 2990f 12 LTC2990 Applications Information delivers the data byte and the LTC2990 acknowledges once more and latches the data into its internal register. The transmission is ended when the master sends a STOP condition. If the master continues sending a second data byte, as in a Write Word command, the second data byte will be acknowledged by the LTC2990 and written to the next register in sequence, if this register has write access. Read Protocol The master begins a read operation with a START condition followed by the seven bit slave address and the R/W# bit set to zero. The addressed LTC2990 acknowledges this and then the master sends a command byte which indicates which internal register the master wishes to read. The LTC2990 acknowledges this and then latches the lower four bits of the command byte into its internal Register Address pointer. The master then sends a repeated START condition followed by the same seven bit address with the R/W# bit now set to one. The LTC2990 acknowledges and sends the contents of the requested register. The transmission is ended when the master sends a STOP condition. The register pointer is automatically incremented after each byte is read. If the master acknowledges the transmitted data byte, as in a Read Word command, the LTC2990 will send the contents of the next sequential register as the second data byte. The byte following register 0x0F is register 0x00, or the status register. a6-a0 S START 1-7 ADDRESS Control Register The control register (Table 3) determines the selected measurement mode of the device. The LTC2990 can be configured to measure voltages, currents and temperatures. These measurements can be single-shot or repeated measurements. Temperatures can be set to report in Celsius or Kelvin temperature scales. The LTC2990 can be configured to run particular measurements, or all possible measurements per the configuration specified by the mode bits. The power-on default configuration of the control register is set to 0x00, which translates to a repeated measurement of the internal temperature sensor, when triggered. This mode prevents the application of remote diode test currents on pins V1 and V3, and remote diode terminations on pins V2 and V4 at power-up. Status Register The status register (Table 3) reports the status of a particular conversion result. When new data is written into a particular result register, the corresponding DATA_VALID bit is set. When the register is addressed by the I2C interface, the status bit (as well as the DATA_VALID bit in the respective register) is cleared. The host can then determine if the current available register data is new or stale. The busy bit, when high, indicates a single-shot conversion is in progress. The busy bit is always high during repeated mode, after the initial conversion is triggered. b7-b0 8 9 R/W ACK 1-7 b7-b0 8 DATA 9 1-7 ACK 8 DATA 9 ACK P STOP 2990 F04 Figure 4. Data Transfer Over I2C or SMBus S ADDRESS W# A COMMAND A DATA A 10011a1:a0 0 0 XXXXXb3:b0 0 b7:b0 0 FROM MASTER TO SLAVE FROM SLAVE TO MASTER A: ACKNOWLEDGE (LOW) A#: NOT ACKNOWLEDGE (HIGH) P R: READ BIT (HIGH) W#: WRITE BIT (LOW) S: START CONDITION P: STOP CONDITION 2990 F05 Figure 5. LTC2990 Serial Bus Write Byte Protocol 2990f 13 LTC2990 Applications Information S ADDRESS W# A COMMAND A DATA A DATA A 10011a1:a0 0 0 XXXXXb3:b0 0 b7:b0 0 b7:b0 0 P 2990 F06 Figure 6. LTC2990 Serial Bus Repeated Write Byte Protocol S ADDRESS W# A COMMAND A 10011a1:a0 0 0 XXXXXb3:b0 0 S R A DATA A# 10011a1:a0 1 ADDRESS 0 b7:b0 1 P 2990 F07 Figure 7. LTC2990 Serial Bus Read Byte Protocol S ADDRESS W# A COMMAND A 10011a1:a0 0 0 XXXXXb3:b0 0 S R A DATA A DATA A# 10011a1:a0 1 0 b7:b0 0 b7:b0 1 ADDRESS P 2990 F08 Figure 8. LTC2990 Serial Bus Repeated Read Byte Protocol Table 1. I2C Base Address HEX I2C BASE ADDRESS BINARY I2C BASE ADDRESS ADR1 ADR0 98h 1001 100X* 0 0 9Ah 1001 101X* 0 1 9Ch 1001 110X* 1 0 9Eh 1001 111X* 1 1 *X = R/W Bit Table 2. LTC2990 Register Address and Contents REGISTER ADDRESS*† REGISTER NAME READ/WRITE 00h STATUS R 01h CONTROL R/W Controls Mode, Single/Repeat, Celsius/Kelvin 02h TRIGGER** R/W Triggers an Conversion DESCRIPTION Indicates BUSY State, Conversion Status 03h N/A 04h TINT (MSB) R Unused Address Internal Temperature MSB 05h TINT (LSB) R Internal Temperature LSB 06h V1 (MSB) R V1, V1 – V2 or TR1 MSB 07h V1 (LSB) R V1, V1 – V2 or TR1 LSB 08h V2 (MSB) R V2, V1 – V2 or TR1 MSB 09h V2 (LSB) R V2, V1 – V2 or TR1 LSB 0Ah V3 (MSB) R V3, V3 – V4 or TR2 MSB 0Bh V3 (LSB) R V3, V3 – V4 or TR2 LSB 0Ch V4 (MSB) R V4, V3 – V4 or TR2 MSB 0Dh V4 (LSB) R V4, V3 – V4 or TR2 LSB 0Eh VCC (MSB) R VCC MSB 0Fh VCC (LSB) R VCC LSB *Register Address MSBs b7-b4 are ignored. **Writing any value triggers a conversion. Data Returned reading this register address is the Status register. †Power-on reset sets all registers to 00h. 2990f 14 LTC2990 Applications Information Table 3. STATUS Register BIT NAME OPERATION b7 0 Always Zero b6 VCC Ready 1 = VCC Register Contains New Data, 0 = VCC Register Read b5 V4 Ready 1 = V4 Register Contains New Data, 0 = V4 Register Read b4 V3, T2, V3 – V4 Ready 1 = V3 Register Contains New Data, 0 = V3 Register Data Old b3 V2 Ready 1 = V2 Register Contains New Data, 0 = V2 Register Data Old b2 V1, T1, V1 – V2 Ready 1 = V1 Register Contains New Data, 0 = V1 Register Data Old b1 TINT Ready 1 = TINT Register Contains New Data, 0 = TINT Register Data Old b0 Busy* 1= Conversion In Process, 0 = Acquisition Cycle Complete *In Repeat mode, Busy = 1 always Table 4. CONTROL Register BIT NAME OPERATION b7 Temperature Format Temperature Reported In; Celsius = 0, Kelvin = 1 b6 Repeat/Single Repeated Acquisition = 0, Single Acquisition = 1 b5 Reserved Reserved Mode [4:3] Mode Description b[4:3] b[2:0] 0 0 Internal Temperature Only (Reset Value) 0 1 T1, V1 or V1 – V2 Only per Mode [2:0] 1 0 T2, V3 or V3 – V4 Only per Mode [2:0] 1 1 All Measurements per Mode [2:0] Mode [2:0] Mode Description 0 0 0 V1, V2, TR2 (Reset Value) 0 0 1 V1 – V2, TR2 0 1 0 V1 – V2, V3, V4 0 1 1 TR1, V3, V4 1 0 0 TR1, V3 – V4 1 0 1 TR1. TR2 1 1 0 V1 – V2, V3 – V4 1 1 1 V1, V2, V3, V4 2990f 15 LTC2990 Applications Information Table 5. Voltage/Current Measurement MSB Data Register Format BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 DV* Sign D13 D12 D11 D10 D9 D8 *Data Valid is set when a new result is written into the register. Data Valid is cleared when this register is addressed (read) by the I2C inteface. Table 6. Voltage/Current Measurement LSB Data Register Format BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 D7 D6 D5 D4 D3 D2 D1 D0 Table 7. Temperature Measurement MSB Data Register Format BIT 7 DV* BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 SS** SO† D12 D11 D10 D9 D8 *DATA_VALID is set when a new result is written into the register. DATA_VALID is cleared when this register is addressed (read) by the I2C interface. **Sensor Short is high if the voltage measured on V1 is too low during temperature measurements. This signal is always low for TINT measurements. †Sensor Open is high if the voltage measured on V1 is excessive during temperature measurements. This signal is always low for TINT measurements. Table 8. Temperature Measurement LSB Data Register Format BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 D7 D6 D5 D4 D3 D2 D1 D0 2990f 16 LTC2990 Applications Information Table 9. Conversion Formats VOLTAGE FORMATS SIGN BINARY VALUE D[13:0] VOLTAGE Single-Ended 0 11111111111111 >5 LSB = 305.18µV 0 10110011001101 3.500 0 01111111111111 2.500 0 00000000000000 0.000 1 11110000101001 –0.300 Differential 0 11111111111111 >0.318 LSB = 19.42µV 0 10110011001101 +0.300 0 10000000000000 +0.159 0 00000000000000 0.000 1 10000000000000 –0.159 1 00001110101000 –0.300 1 10000000000000 <–0.318 VCC = Result + 2.5V 0 10110011001101 VCC = 6V LSB = 305.18µV 0 10000000000000 VCC = 5V 0 00001010001111 VCC = 2.7V TEMPERATURE FORMATS FORMAT BINARY VALUE D[12:0] TEMPERATURE Temperature Internal, TR1 or TR2 Celsius 0011111010000 +125.0000 LSB = 0.0625 Degrees Celsius 0000110010001 +25.0625 Celsius 0000110010000 +25.0000 Celsius 1110110000000 –40.0000 Kelvin 1100011100010 398.1250 Kelvin 1000100010010 273.1250 Kelvin 0111010010010 233.1250 Table 10. Recommended Transistors to Be Used as Temperature Sensors MANUFACTURER PART NUMBER PACKAGE Fairchild Semiconductor MMBT3904 SOT-23 Central Semiconductor CMPT3904 SOT-23 Diodes, Inc. MMBT3904 SOT-23 MMBT3904LT1 SOT-23 NXP MMBT3904 SOT-23 Infineon MMBT3904 SOT-23 UMT3904 SC-70 On Semiconductor Rohm 2990f 17 LTC2990 Typical Applications High Voltage/Current and Temperature Monitoring RSENSE 1mΩ 1% 12V 5V ILOAD 0A TO 10A VIN 5V TO 105V RIN 20Ω 1% +IN – 0.1µF –INF V+ VREG V– 3.3V 0.1µF –INS + Computer Voltage and Temperature Monitoring 2-WIRE I2C INTERFACE 10.0k 1% 30.1k 1% 10.0k 1% 10.0k 1% VCC V1 SDA SCL ADR0 ADR1 V2 LTC2990 GND MICROPROCESSOR V3 470pF V4 OUT LTC6102HV 200k 1% 4.75k 1% 5V 2-WIRE I2C INTERFACE ROUT 4.99k 1% 2990 TA03 0.1µF 0.1µF VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB V1 (+5) REG 6, 7 0.61mVLSB V2(+12) REG 8, 9 1.22mV/LSB REG A, B 0.0625°C/LSB TPROCESSOR REG E, F 2.5V + 305.18µV/LSB VCC 0.1µF VCC V1 V2 SDA SCL LTC2990 ADR0 ADR1 GND MMBT3904 V3 470pF V4 2990 TA02 ALL CAPACITORS ±20% VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 13.2mVLSB VLOAD REG 8, 9 1.223mA/LSB V2(ILOAD) REG A, B 0.0625°C/LSB TREMOTE REG E, F 2.5V + 305.18µV/LSB VCC 2990f 18 LTC2990 Typical ApplicationS Motor Protection/Regulation LOADPWR = I • V 0.1Ω 1% MOTOR CONTROL VOLTAGE 0VDC TO 5VDC 0A TO ±2.2A 5V 0.1µF 2-WIRE I2C INTERFACE VCC V1 V2 SDA SCL LTC2990 ADR0 ADR1 GND MMBT3904 V3 470pF V4 TMOTOR 2990 TA04 TINTERNAL CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x59 REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 194µA/LSB IMOTOR REG A, B 0.0625°C/LSB TMOTOR REG E, F 2.5V + 305.18µV/LSB VCC MOTOR VOLTAGE AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB REG 8, 9 305.18µVLSB VMOTOR REG A, B 0.0625°C/LSB TMOTOR REG E, F 2.5V + 305.18µV/LSB VCC Large Motor Protection/Regulation LOADPWR = I • V 0.1Ω 1W, 1% MOTOR CONTROL VOLTAGE 0V TO 40V 0A TO 10A 5V 2-WIRE I2C INTERFACE 71.5k 1% 71.5k 1% 10.2k 1% 10.2k 1% 0.1µF VCC V1 V2 SDA SCL LTC2990 ADR0 ADR1 GND MMBT3904 V3 470pF V4 TINTERNAL VOLTAGE AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB REG 8, 9 2.44mVLSB VMOTOR REG A, B 0.0625°C/LSB TMOTOR REG E, F 2.5V + 305.18µV/LSB VCC TMOTOR MOTOR 2990 TA05 CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x59 REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 1.56mA/LSB IMOTOR REG A, B 0.0625°C/LSB TMOTOR REG E, F 2.5V + 305.18µV/LSB VCC 2990f 19 LTC2990 Typical ApplicationS Fan/Air Filter/Temperature Alarm 3.3V MMBT3904 3.3V 2-WIRE I2C INTERFACE 22Ω 0.125W 470pF FAN 0.1µF VCC HEATER ENABLE V1 MMBT3904 V2 SDA SCL LTC2990 ADR0 ADR1 GND TEMPERATURE FOR: V3 22Ω 0.125W 470pF V4 GOOD FAN BAD FAN HEATER TINTERNAL NDS351AN HEATER ENABLE 2 SECOND PULSE CONTROL REGISTER: 0x5D REG 4, 5 TAMB REG 6, 7 TR1 REG A, B TR2 REG E, F VCC FAN 2990 TA06 0.0625°C/LSB 0.0625°C/LSB 0.0625°C/LSB 2.5V + 305.18µV/LSB Battery Monitoring CHARGING CURRENT 5V 2-WIRE I2C INTERFACE BATTERY I AND V MONITOR 15mΩ* 0.1µF VCC V1 SDA SCL LTC2990 ADR0 ADR1 GND V2 MMBT3904 V3 ••• 470pF V4 TINTERNAL + NiMH BATTERY TBATT T(t) V(t) 100% 100% I(t) 100% 2990 TA07 *IRC LRF3W01R015F VOLTAGE AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB REG 8, 9 305.18µVLSB VBAT REG A, B 0.0625°C/LSB TBAT REG E, F 2.5V + 305.18µV/LSB VCC CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x59 REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 1.295mA/LSB IBAT REG A, B 0.0625°C/LSB TBAT REG E, F 2.5V + 305.18µV/LSB VCC 2990f 20 LTC2990 Typical ApplicationS Wet-Bulb Psychrometer 5V 0.1µF VCC µC V1 MMBT3904 V3 $T 470pF 470pF V4 2990 TA08 TWET TDRY TINTERNAL CONTROL REGISTER: 0x5D REG 4, 5 TAMB REG 6, 7 TWET REG A, B TDRY REG E, F VCC MMBT3904 V2 SDA SCL LTC2990 ADR0 ADR1 GND FAN: SUNON KDE0504PFB2 0.0625°C/LSB 0.0625°C/LSB 0.0625°C/LSB 2.5V + 305.18µV/LSB DAMP MUSLIN FAN WATER RESERVOIR 5V NDS351AN FAN ENABLE REFERENCES: http://en.wikipedia.org/wiki/Hygrometer http://en.wikipedia.org/wiki/Psychrometrics Liquid-Level Indicator 3.3V 3.3V VCC µC SENSOR HI* 0.1µF SDA SCL LTC2990 ADR0 ADR1 GND HEATER ENABLE V1 V2 V3 V4 470pF SENSOR LO* SENSOR LO 470pF TINTERNAL HEATER ENABLE 2 SECOND PULSE CONTROL REGISTER: 0x5D REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 0.0625°C/LSB THI REG A, B 0.0625°C/LSB TLO REG E, F 2.5V + 305.18µV/LSB VCC SENSOR HI $T = ~2.0°C pp, SENSOR HI ~0.2°C pp, SENSOR LO NDS351AN HEATER: 75Ω 0.125W *SENSOR MMBT3904, DIODE CONNECTED 2290 TA09 2990f 21 LTC2990 Typical ApplicationS Oscillator/Reference Oven Temperature Regulation HEATER VOLTAGE 5V 2-WIRE I2C INTERFACE HEATERPWR = I •V 0.1Ω STYROFOAM INSULATION 0.1µF VCC V1 V2 SDA SCL LTC2990 ADR0 ADR1 GND 20°C AMBIENT MMBT3904 V3 HEATER 470pF V4 TOVEN 70°C OVEN TINTERNAL 2990 TA10 HEATER CONSTRUCTION: HEATER POWER = A • (TSET – TAMB) + B • ∫(TOVEN – TSET) dt 5FT COIL OF #34 ENAMEL WIRE FEED FEED ~1.6Ω AT 70°C FORWARD BACK PHEATER = ~0.4W WITH TA = 20°C A = 0.004W, B = 0.00005W/DEG-s VOLTAGE AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB V1, V2 REG 8, 9 305.18µVLSB REG A, B 0.0625°C/LSB TOVEN REG E, F 2.5V + 305.18µV/LSB VCC CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x59 REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 269µVLSB IHEATER REG A, B 0.0625°C/LSB THEATER REG E, F 2.5V + 305.18µV/LSB VCC Wind Direction/Instrumentation 3.3V 0.1µF VCC µC V1 MMBT3904 3.3V V2 SDA SCL LTC2990 ADR0 ADR1 GND 470pF 470pF V4 2990 TA11 TINTERNAL CONTROL REGISTER: 0x5D REG 4, 5 TAMB REG 8, 9 TR1 REG A, B TR2 REG E, F VCC MMBT3904 V3 FAN ENABLE 2 SECOND PULSE HEATER 75Ω 0.125W 2N7002 0.0625°C/LSB 0.0625°C/LSB 0.0625°C/LSB 2.5V + 305.18µV/LSB 2990f 22 LTC2990 Package Description MS Package 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661 Rev E) 0.889 p 0.127 (.035 p .005) 5.23 (.206) MIN 3.20 – 3.45 (.126 – .136) 3.00 p 0.102 (.118 p .004) (NOTE 3) 0.50 0.305 p 0.038 (.0197) (.0120 p .0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 10 9 8 7 6 3.00 p 0.102 (.118 p .004) (NOTE 4) 4.90 p 0.152 (.193 p .006) DETAIL “A” 0.497 p 0.076 (.0196 p .003) REF 0o – 6o TYP GAUGE PLANE 1 2 3 4 5 0.53 p 0.152 (.021 p .006) DETAIL “A” 0.18 (.007) SEATING PLANE 0.86 (.034) REF 1.10 (.043) MAX 0.17 – 0.27 (.007 – .011) TYP 0.50 (.0197) BSC NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 0.1016 p 0.0508 (.004 p .002) MSOP (MS) 0307 REV E 2990f 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. 23 LTC2990 Typical Application High Voltage/Current and Temperature Monitoring RSENSE 1mΩ 1% ILOAD 0A TO 10A VIN 5V TO 105V RIN 20Ω 1% +IN 0.1µF –INS – + –INF V+ VREG V– OUT LTC6102HV 200k 1% 4.75k 1% 5V ROUT 4.99k 1% 0.1µF 0.1µF 0.1µF VCC 2-WIRE I2C INTERFACE V1 V2 SDA SCL LTC2990 ADR0 ADR1 GND MMBT3904 V3 470pF V4 2990 TA02 ALL CAPACITORS ±20% VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x58 REG 4, 5 0.0625°C/LSB TAMB REG 6, 7 13.2mVLSB VLOAD REG 8, 9 1.223mA/LSB V2(ILOAD) REG A, B 0.0625°C/LSB TREMOTE REG E, F 2.5V + 305.18µV/LSB VCC Related Parts PART NUMBER DESCRIPTION COMMENTS LM134 Constant Current Source and Temperature Sensor Can Be Used as Linear Temperature Sensor LTC1392 Micropower Temperature, Power Supply and Differential Voltage Monitor Complete Ambient Temperature Sensor Onboard LTC2487 16-Bit, 2-/4-Channel Delta Sigma ADC with PGA, Easy Drive and I2C Interface Internal Temperature Sensor LTC6102/LTC6102HV Precision Zero Drift Current Sense Amplifier 5V to 100V, 105V Absolute Maximum (LTC6102HV) Easy Drive is a trademark of Linear Technology Corporation. 2990f 24 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LT 0910 • PRINTED IN USA LINEAR TECHNOLOGY CORPORATION 2010