LTC2990IMS

LTC2990 I2C Temperature, Voltage and Current Monitor FeaTures n n n n n n n n n DescripTion 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. 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 Typical applicaTion Voltage, Current, Temperature Monitor 2.5V 5V VCC SDA SCL ADR0 ADR1 V1 V2 TUE (°C) V3 LTC2990 V4 GND TINTERNAL MEASURES: TWO SUPPLY VOLTAGES, SUPPLY CURRENT, INTERNAL AND REMOTE TEMPERATURES –1.0 –50 –25 0 50 25 TAMB (°C) 75 100 125 2990 TA01a Temperature Total Unadjusted Error 1.0 ILOAD 0.5 TREMOTE RSENSE TREMOTE 0 –0.5 2990 TA01b 2990f  LTC2990 absoluTe MaxiMuM raTings 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 (Note 1) pin conFiguraTion TOP VIEW V1 V2 V3 V4 GND 1 2 3 4 5 10 9 8 7 6 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 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 TRMT(TUE) 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 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. CONDITIONS l MIN 2.9 TYP MAX 5.5 1.8 5 2.7 ±2.5 5 5 1 ±1.5 ±0.25 ±0.25 ±0.75 300 VCC UNITS V mA µA V °C °C °C °C °C % % % mV V µV µV Deg °RMS °/√Hz 2990f During Conversion, I2C Inactive Shutdown Mode, I2C Inactive l l l 1.3 1.1 1 2.1 ±1 1 ±1 ±0.5 ±0.1 ±0.1 ±0.2 LTC2990C LTC2990I TAMB = –40°C to 25°C TAMB = 25°C to 85°C η = 1.004 (Note 4) 2.9V ≤ VCC ≤ 5.5V 0V ≤ VN ≤ VCC, Vn ≤ 4.9V –300mV ≤ VD ≤ 300mV l l l l l l l l l l –3 –2 –3 –300 0 19.42 305.18 0.0625 0.2 0.05 Celsius or Kelvin Celsius or Kelvin TMEAS = 46ms (Note 2)  LTC2990 elecTrical characTerisTics SYMBOL Res INL PARAMETER Resolution (No Missing Codes) Integral Nonlinearity 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. CONDITIONS (Note 2) 2.9V ≤ VCC ≤ 5.5V, VIN(CM) = 1.5V (Note 2) Single-Ended Differential (Note 2) 0V ≤ VN ≤ 3V (Note 2) 0V ≤ VN ≤ VCC (Note 2) (Note 2) Per Voltage, Two Minimum (Note 2) (Note 2) (Note 2) Remote Diode Mode l l l l l l l l l l MIN 14 –2 –2 TYP MAX UNITS Bits LSB LSB pF µA 2 2 0.35 0.6 CIN IIN(AVG) 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 V1 Through V4 Input Sampling Capacitance V1 Through V4 Input Average Sampling Current V1 Through V4 Input Leakage Current –10 37 1.2 1.2 1.2 46 1.5 1.5 1.5 10 55 1.8 1.8 1.8 167 350 VCC 0.3 • VCC 0.4 0.3 • VCC ±1 ±1 nA ms ms ms ms ms µA V V V V V V µA µA kHz µs ns µs ns ns ns ns ns ns ns pF 260 0 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 l l l l l l l 0.7 • VCC 0.7 • VCC 400 1.3 600 1.3 600 600 600 0 900 100 250 10 300 50 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. 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 Shutdown Current vs Temperature 3.5 3.0 2.5 ICC (µA) ICC (µA) 2.0 1.5 1.0 0.5 0 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G01 TA = 25°C, VCC = 3.3V unless otherwise noted Measurement Delay Variation vs T Normalized to 3.3V, 25°C 4 MEASUREMENT DELAY VARIATION (%) Supply Current vs Temperature 1200 VCC = 5V VCC = 5V 1150 3 VCC = 5V 2 1100 VCC = 3.3V 1050 VCC = 3.3V 1 VCC = 3.3V 1000 0 950 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G02 –1 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G03 VCC TUE 0.10 0.10 Single-Ended VX TUE 1.0 Differential Voltage TUE 0.05 VCC TUE (%) VX TUE (%) 0.05 VDIFF TUE (%) 0.5 VCC = 5V 0 VCC = 3.3V –0.5 0 0 –0.05 –0.05 –0.10 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G04 –0.10 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G05 –1.0 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G06 TINTERNAL Error 4 3 2 1 0 –1 –2 –3 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G07 Remote Diode Error with LTC2990 at 25°C, 90°C 0.6 0.4 LTC2990 TRX ERROR (°C) 0.2 0 –0.2 –0.4 –0.6 –50 –25 LTC2990 AT 90°C LTC2990 AT 25°C 1.00 0.75 LTC2990 TRX ERROR (DEG) 0.50 0.25 Remote Diode Error with LTC2990 at Same Temperature as Diode TINTERNAL ERROR (DEG) –0.25 0 –0.50 –0.75 25 50 75 100 125 150 BATH TEMPERATURE (°C) 2990 G08 0 –1.00 –50 –25 0 25 50 75 TAMB (°C) 100 125 150 2990 G09 2990f  LTC2990 Typical perForMance characTerisTics Single-Ended Noise 4000 3500 3000 LTC2990 VALUE (V) COUNTS 2500 2000 1500 1000 500 0 –3 –2 2 1 0 LSBs (305.18µV/LSB) –1 3 2990 G10 TA = 25°C, VCC = 3.3V unless otherwise noted Single-Ended INL 1.0 Single-Ended Transfer Function 6 5 4 3 2 1 0 –1 –1 3 2 VX (V) 4 5 6 2990 G11 4800 READINGS VCC = 5V VCC = 3.3V 0.5 INL (LSBs) VCC = 3.3V 0 VCC = 5V –0.5 –0 1 –1.0 0 1 2 3 VX (V) 4 5 2990 G12 LTC2990 Differential Noise 500 800 READINGS 0.4 0.3 400 LTC2990 V1-V2 (V) 0.2 Differential Transfer Function 2 Differential INL 1 INL (LSBs) COUNTS 300 0.1 0 –0.1 –0.2 –0.3 0 200 100 –1 0 –4 –3 0 1 –2 –1 LSBs (19.42µV/LSB) 2 3 2990 G13 –0.4 –0.4 –0.3 –0.2 –0.1 0 0.1 V1-V2 (V) 0.2 0.3 0.4 –2 –0.4 –0.2 0 VIN (V) 0.2 0.4 2990 G15 2990 G14 TINT Noise 500 1000 READINGS 600 500 Remote Diode Noise 1000 READINGS 2.6 2.4 2.2 THRESHOLD (V) 400 COUNTS 2.0 1.8 1.6 1.4 100 0 1.2 –0.75 –0.5 –0.25 0 0.25 (°C) 0.5 0.75 2990 G17 POR Thresholds vs Temperature 400 VCC RISING COUNTS 300 300 200 VCC FALLING 200 100 0 –0.75 –0.5 –0.25 0 0.25 (°C) 0.5 0.75 2990 G16 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. GND (Pin 5): Device Circuit Ground. Connect this pin to a ground plane through a low impedance connection. 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. 2990f  LTC2990 FuncTional DiagraM REMOTE DIODE SENSORS MODE 1 2 3 4 V1 V2 V3 V4 CONTROL LOGIC MUX ADC I2C VCC 10 GND 5 SCL SDA 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 tSU, STO tBUF 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 15m 0.1µF VCC V1 V2 V3 470pF V4 2990 F01 Power Up 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. Temperature Measurements 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 ILOAD MMBT3904 2-WIRE I2C INTERFACE SDA SCL LTC2990 ADR0 ADR1 GND Figure 1  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) 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: TK _ COMP = ηACT •T ηCAL K _ MEAS (3) 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) The LTC2990 makes differential measurements of diode voltage to calculate temperature. Proprietary techniques allow for cancellation of error due to series resistance. 0.1µF Compensated Celsius Temperature GND SHIELD TRACE LTC2990 V1 V2 V3 V4 VCC ADR1 ADR0 SCL GND SDA 2990 F02 470pF NPN SENSOR 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