LTC2991IMS#PBF

LTC2991 Octal I2C Voltage, Current, and Temperature Monitor FEATURES n n n n n n n n n n n n DESCRIPTION Measures Voltage, Current, Temperature Measures Four Remote Diode Temperatures 0.7°C (Typ) Accuracy, 0.06°C Resolution 1°C (Typ) Internal Temperature Sensor Series Resistance Cancellation 14-Bit ADC Measures Voltage/Current PWM Temperature Output 3V to 5.5V Supply Operating Voltage Eight Selectable Addresses Internal 10ppm/°C Voltage Reference V1 to V8 Inputs ESD Rated to 6kV HBM 16-Lead MSOP Package APPLICATIONS n n n n n The LTC®2991 is used to monitor system temperatures, voltages and currents. Through the I2C serial interface, the eight monitors can individually measure supply voltages and can be paired for differential measurements of current sense resistors or temperature sensing transistors. Additional measurements include internal temperature and internal VCC. The internal 10ppm reference minimizes the number of supporting components and area required. Selectable address and configurable functionality give the LTC2991 flexibility to be incorporated in various systems needing temperature, voltage or current data. The LTC2991 fits well in systems needing submillivolt 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 and Easy Drive is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Temperature Measurement Supply Voltage Monitoring Current Measurement Remote Data Acquisition Environmental Monitoring TYPICAL APPLICATION Temperature Total Unadjusted Error 5V 3.3V 3.3V I/O 2.5V 2.5V I/O RSENSE VCC V1 1.2V CORE V2 I 2-WIRE SCL ADR0 V3 V4 FPGA V5 SDA 2C INTERFACE 0.75 LTC2991 V6 FPGA TEMPERATURE ADR2 TAMBIENT TREMOTE 0.25 0 TINTERNAL –0.25 ADR1 V7 0.50 TERROR (°C) 1.2V 1.00 BOARD TEMPERATURE –0.50 –0.75 –1.00 –50 –25 0 25 50 75 TAMBIENT (°C) 100 125 150 2991 TA01b V8 GND PWM TO FAN 2991 TA01a 2991ff For more information www.linear.com/LTC2991 1 LTC2991 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) Supply Voltage (VCC)................................. –0.3V to 6.0V Input Voltages V1, V2, V3, V4, V5, V6, V7, V8, SCL, ADR0, ADR1, ADR2...............–0.3V to (VCC + 0.3V) Output Voltage PWM.....................–0.3V to (VCC + 0.3V) Output Voltage SDA...................................... –0.3V to 6V Operating Temperature Range LTC2991C................................................. 0°C to 70°C LTC2991I..............................................–40°C to 85°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) MS Package........................................................... 300°C TOP VIEW V1 V2 V3 V4 V5 V6 V7 V8 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 VCC ADR2 ADR1 ADR0 PWM SCL SDA GND MS PACKAGE 16-LEAD PLASTIC MSOP TJMAX = 125°C, θJA = 120°C/W ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC2991CMS#PBF LTC2991CMS#TRPBF 2991 16-Lead Plastic MSOP 0°C to 70°C LTC2991IMS#PBF LTC2991IMS#TRPBF 2991 16-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. 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/. Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix. 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 CONDITIONS MIN TYP MAX UNITS General VCC Input Supply Range l Input Supply Current During Conversion, I2C Inactive l ISD Input Supply Current Shutdown Mode, I2C Inactive l VCC(UVL) Input Supply Undervoltage Lockout ICC l 2.9 1.1 1.3 5.5 V 1.5 mA 1 6 µA 2.0 2.6 V ±1 ±3.5 °C Measurement Accuracy TINTERNAL(TUE) Internal Temperature Total Unadjusted Error TRMT(TUE) Remote Diode Temperature Total Unadjusted Error η = 1.004 l ±0.7 ±1.5 °C VCC(TUE) VCC Voltage Total Unadjusted Error 2.9V ≤ 5.5V l ±0.05 ±0.25 % VN(TUE) V1 Through V8 Total Unadjusted Error 0V ≤ 4.9V l ±0.05 ±0.25 % VDIFF(TUE) Differential Voltage Total Unadjusted Error V1 – V2, V3 – V4, V5 – V6, V7 – V8 –300mV≤ VD ≤300mV l ±0.1 ±0.75 % VDIFF(MAX) Full-Scale Differential Voltage l –312.5 312.5 mV VOFFSET_DIFF Differential Offset V1 through V8 = 0V l –12.5 0 12.5 LSB VOFFSET_SE Single-Ended Offset V1 through V8 = 0V l –6 0 6 LSB 2991ff 2 For more information www.linear.com/LTC2991 LTC2991 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 CONDITIONS MIN VDIFF(CMR) Differential Voltage Common Mode Range VLSB(DIFF) Differential Voltage LSB Weight 19.075 µV VLSB(SINGLE_ENDED) Single-Ended Voltage LSB Weight 305.18 µV VLSB(TEMP) Temperature LSB Weight Celsius or Kelvin 0.0625 Deg VLSB(DIODE_VOLTAGE) Diode Voltage LSB Weight Includes Series Resistance IR Drop 38.15 µV TNOISE Temperature Noise Celsius or Kelvin Filter Disengaged 0.2 °RMS TNOISE Temperature Noise Celsius or Kelvin Filter Engaged 0.07 °RMS RES Resolution (No Missing Codes) (Note 2) l 14 INL Integral Nonlinearity 2.9V ≤ VCC ≤ 5.5V, VIN(CM) = 1.5V (Note 2) Single-Ended Differential l l –2 –2 l TYP 0 MAX UNITS VCC V Bits 2 2 LSB LSB CIN V1 Through V8 Input Sampling Capacitance (Note 2) 0.35 pF IIN(AVG) V1 Through V8 Input Average Sampling Current (0 ≤ VN ≤ 4.9V) (Note 2) 0.6 µA IDC_LEAK(VIN) V1 Through V8 Input Leakage Current (0 ≤ VN ≤ VCC) l –10 10 nA 1.2 ms PWM FPWM PWM Period l 0.9 DCPWM Duty Cycle Range l 0 SCALEPWM 0% to 100% PWM Temperature Range 99.8 32 % Deg Measurement Delay TINTERNAL, TR1, TR2, TR3, TR4 Per Configured Temperature Measurement l 37 46 55 ms V1, V2, V3, V4, V5, V6, V7, V8 Single-Ended Voltage Measurement l 0.9 1.5 1.8 ms V1 – V2, V3 – V4, V5 – V6, V7 – V8 Differential Voltage Measurement l 0.9 1.5 1.8 ms VCC VCC Measurement l 0.9 1.5 1.8 ms Max Delay Mode[4:0] = 11101, TINTERNAL, TR1, TR2, TR3, TR4 VCC l 277 ms 350 µA VCC V 0.3•VCC V V1, V3, V5, V7 OUTPUT (Remote Diode Mode Only) IOUT Output Current VOUT Output Voltage Remote Diode Mode 260 l l 0 I2C Interface VADR(L) ADR Input Low Threshold Voltage Falling l VADR(H) ADR Input High Threshold Voltage Rising l VOL1 SDA Low Level Maximum Voltage IO = –3mA, VCC 2.9V to 5.5V l 0.4 V VIL Maximum Low Level Input Voltage SDA and SCL Pins l 0.3•VCC V VIH Minimum High Level Input Voltage SDA and SCL Pins l ISDAI, SCLI SDA, SCL Input Current 0 < VSDA, SCL < VCC l ±1 µA IADR(MAX) Maximum ADR0, ADR1, ADR2 Input Current ADR0, ADR1 or ADR2 Tied to VCC or GND l ±1 µA 0.7•VCC V 0.7•VCC V 2991ff For more information www.linear.com/LTC2991 3 LTC2991 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 CONDITIONS MIN TYP MAX UNITS I2C Timing (Note 2) fSCL(MAX) Maximum SCL Clock Frequency 400 tLOW Minimum SCL Low Period 1.3 µs tHIGH Minimum SCL High Period 600 ns tBUF(MIN) Minimum Bus Free Time Between Stop/Start Condition 1.3 µs tHD, STA(MIN) Minimum Hold Time After (Repeated) Start Condition 600 ns tSU, STA(MIN) Minimum Repeated Start Condition Set-Up Time 600 ns tSU, STO(MIN) Minimum Stop Condition Set-Up Time 600 ns tHD, DATI(MIN) Minimum Data Hold Time Input tHD, DATO(MIN) Minimum Data Hold Time Output tSU, DAT(MIN) Minimum Data Set-Up Time Input tSP(MAX) Maximum Suppressed Spike Pulse Width CX SCL, SDA Input Capacitance 300 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. 50 kHz 0 ns 900 ns 100 ns 250 ns 10 pF 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. 2991ff 4 For more information www.linear.com/LTC2991 LTC2991 TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Current vs Temperature 3.5 TA = 25°C, VCC = 3.3V, unless otherwise noted. 4 1200 VCC = 5V MEASUREMENT DELAY VARIATION (%) VCC = 5V 3.0 1150 2.5 1100 2.0 ICC (µA) ICC (µA) Measurement Delay Variation vs T Normalized to 3.3V, 25°C Supply Current vs Temperature 1.5 1050 VCC = 3.3V 1.0 VCC = 3.3V 1000 0.5 0 –50 –25 950 –50 –25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 3 VCC = 5V 2 1 –1 –50 –25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 2991 G01 VCC = 3.3V 0 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 2991 G03 2991 G02 VCC TUE Single-Ended VX TUE 0.25 Differential Voltage TUE 0.50 0.25 VDIFF TUE (%) VX TUE (%) VCC TUE (%) 0.25 0 0 –0.25 0 –0.25 –0.25 –0.50 –50 –25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) –0.50 –50 –25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 2991 G04 2991 G05 Remote Diode Error with LTC2991 at Same Temperature as Diode 1.5 0.4 1.0 0.5 0 –0.5 1.00 0.75 LTC2991 TRX ERROR (DEG) 0.6 LTC2991 TRX ERROR (°C) ERROR (°C) 2.0 0.2 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 2991 G07 0.50 0.25 0 –0.25 –0.2 –0.50 –0.4 0 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 2991 G06 Remote Diode Error with LTC2991 at 25°C TINTERNAL Error –1.0 –50 –25 –0.50 –50 –25 –0.6 –50 –25 –0.75 0 25 50 75 100 125 150 BATH TEMPERATURE (°C) 2991 G08 –1.00 –50 –25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE (°C) 2991 G09 2991ff For more information www.linear.com/LTC2991 5 LTC2991 TYPICAL PERFORMANCE CHARACTERISTICS Single-Ended Noise Single-Ended Transfer Function 4800 READINGS 3500 LTC2991 VALUE (V) COUNTS 1.0 5 3000 2500 2000 1500 1000 VCC = 5V 4 0.5 VCC = 3.3V 3 2 1 –3 –2 2 1 0 LSBs (305.18µV/LSB) –1 3 –1 VCC = 5V –1 –0 1 3 2 VX (V) 5 4 –1.0 6 0 1 2 3 VX (V) 4 2991 G11 LTC2991 Differential Noise Differential INL 2 0.4 800 READINGS 5 2991 G12 Differential Transfer Function 0.3 400 1 0.2 300 200 0.1 INL (LSBs) LTC2991 V1-V2 (V) COUNTS 0 –0.5 2991 G10 500 VCC = 3.3V 0 500 0 Single-Ended INL 6 INL (LSBs) 4000 TA = 25°C, VCC = 3.3V, unless otherwise noted. 0 –0.1 –1 –0.2 100 0 –0.3 0 –4 –3 0 1 –2 –1 LSBs (19.075µV/LSB) 2 –0.4 –0.4 –0.3 –0.2 –0.1 0 0.1 V1-V2 (V) 3 0.2 0.4 –2 –0.4 0 –0.2 0.2 0.4 VIN (V) 2991 G13 2991 G15 2991 G14 TINTERNAL Noise 500 0.3 Remote Diode Noise 600 1000 READINGS 1000 READINGS 500 400 COUNTS COUNTS 400 300 200 200 100 0 300 100 –0.75 –0.5 –0.25 0 0.25 (°C) 0.5 0.75 0 –0.75 –0.5 –0.25 2991 G16 0 0.25 (°C) 0.5 0.75 2991 G17 2991ff 6 For more information www.linear.com/LTC2991 LTC2991 TYPICAL PERFORMANCE CHARACTERISTICS Digital Filter Step Response TA = 25°C, VCC = 3.3V, unless otherwise noted. TERROR vs CPARALLEL TERROR vs RSERIES 100 1.2 100 90 1.0 70 0.8 TERROR (°C) 10 TERROR (°C) % FULL-SCALE 80 60 50 40 0.4 1 30 0.6 20 0.2 10 0 0 50 100 150 200 ITERATION 2991 G18 0.1 0 1000 2000 3000 RSERIES (Ω) 4000 5000 2991 G19 0 1 10 100 1k 10k CPARALLEL (pF) 100k 1000k 2991 G20 2991ff For more information www.linear.com/LTC2991 7 LTC2991 PIN FUNCTIONS V1 (Pin 1): First Monitor Input. This pin can be configured as a single-ended input (0V to 4.9V) or the positive input for a differential or remote diode temperature measurement (in combination with V2). Differential common mode range is 0V to VCC, ±300mV differential. 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 (0V to 4.9V) or the negative input for a differential or remote diode temperature measurement (in combination with V1). Differential common mode range is 0V to VCC, ±300mV differential. 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 (0V to 4.9V) or the positive input for a differential or remote diode temperature measurement (in combination with V4). Differential common mode range is 0V to VCC, ±300mV differential. 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 (0V to 4.9V) or the negative input for a differential or remote diode temperature measurement (in combination with V3). Differential common mode range is 0V to VCC, ±300mV differential. When configured for remote diode temperature, this pin will have an internal termination, while the measurement is active. V5 (Pin 5): Fifth Monitor Input. This pin can be configured as a single-ended input (0V to 4.9V) or the positive input for a differential or remote diode temperature measurement (in combination with V6). Differential common mode range is 0V to VCC, ±300mV differential. When configured for remote diode temperature, this pin will source a current. V6 (Pin 6): Sixth Monitor Input. This pin can be configured as a single-ended input (0V to 4.9V) or the negative input for a differential or remote diode temperature measurement (in combination with V5). Differential common mode range is 0V to VCC, ±300mV differential. When configured for remote diode temperature, this pin will have an internal termination, while the measurement is active. V7 (Pin 7): Seventh Monitor Input. This pin can be configured as a single-ended input (0V to 4.9V) or the positive input for a differential or remote diode temperature measurement (in combination with V8). Differential common mode range is 0V to VCC, ±300mV differential. When configured for remote diode temperature, this pin will source a current. V8 (Pin 8): Eighth Monitor Input. This pin can be configured as a single-ended input (0V to 4.9V) or the negative input for a differential or remote diode temperature measurement (in combination with V7). Differential common mode range is 0V to VCC, ±300mV differential. When configured for remote diode temperature, this pin will have an internal termination, while the measurement is active. GND (Pin 9): Device Ground. Connect this pin through a low impedance connection to system ground. SDA (Pin 10): 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 11): Serial Bus Clock Input of the I2C Interface. The LTC2991 can only act as a slave and the SCL pin only accepts external serial clock. The LTC2991 does not implement clock stretching. PWM (Pin 12): PWM Output. The PWM pin provides a CMOS output level with a duty cycle proportional to the remote diode temperature of the sensor connected to pins V7 and V8. ADR0, ADR1, ADR2 (Pins 13, 14, 15): Serial Bus Address Control Input. The ADR pins are address control bits for the device I2C address. See Table 1. VCC (Pin 16): Chip Power. Connect to 2.9V to 5.5V low noise supply. A 0.1µF decoupling capacitor to GND is required for this pin. 2991ff 8 For more information www.linear.com/LTC2991 LTC2991 FUNCTIONAL DIAGRAM VCC –+ VOLTAGE MONITORING –+ + – POWER MONITORING 1 3 4 5 RL 6 7 REMOTE DIODE SENSORS VCC VCC VCC VCC 16 MODE 2 RSENSE VCC 8 GND 9 V1 ADR2 V2 CONTROL LOGIC V3 ADR1 I2C ADC V4 ADR0 SCL V5 MUX V6 SDA V7 15 14 13 11 10 UV REFERENCE V8 INTERNAL SENSOR UNDERVOLTAGE DETECTOR VCC PWM PULSE WIDTH DETECTOR 12 2991 FD TIMING DIAGRAM SDAI/SDAO tSU, DAT tHD, DATO, tHD, DATI tSU, STA tSP tHD, STA tSP tBUF tSU, STO 2991 TD SCL tHD, STA START CONDITION REPEATED START CONDITION STOP CONDITION START CONDITION 2991ff For more information www.linear.com/LTC2991 9 LTC2991 OPERATION The LTC2991 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 can be configured. Remote temperature measurements use transistors as temperature sensors, 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 functional components of the device. The input signals are selected with an input mux, controlled by the control logic block. The control logic block uses the mode bits in the control registers to manage the sequence and types of data acquisition. The control logic block also controls the current sources during remote temperature acquisition. The order of acquisitions is fixed: V1, V2, V3, V4, V5, V6, V7, V8, TINTERNAL then VCC. The ADC performs the necessary conversion(s) and supplies the data to the control logic for routing to the appropriate data register. The I2C interface supplies access to control, status and data registers. The ADR2, ADR1 and ADR0 pins select one of eight possible I2C addresses (see Table 1). The UVLO 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. The V2, V4, V6 or V8 terminals of the LTC2991 are terminated with a diode if that channel is configured for temperature measurements. It is acceptable to ground these pins, but increased noise may result on the temperature measurements. The LTC2991 is calibrated to yield the correct temperature for a remote diode with an ideality factor of 1.004. See the Applications Information section for compensation of sensor ideality factors other than the factory calibrated value of 1.004. The LTC2991 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 LTC2991 supports 100kbit/s in the standard mode and up to 400kbit/s in fast mode. The eight 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 registers contents have been previously read. This bit is set when the register is updated with new data, and cleared when read. 2991ff 10 For more information www.linear.com/LTC2991 LTC2991 APPLICATIONS INFORMATION The basic LTC2991 application circuit is shown in Figure 1. The diode equation: 5V 3.3V 3.3V I/O 2.5V 1.8V VCC V1 V2 SCL ADR0 V3 FPGA V4 V5 LTC2991 T= FPGA TEMPERATURE V6 ADR1 ADR2 V7 BOARD TEMPERATURE TAMBIENT V8 PWM GND TO FAN Figure 1. Power Up The VCC pin must exceed the undervoltage (UV) threshold of 2.5V to keep the LTC2991 out of power-on reset. Power-on reset will clear all of the data registers and the control registers. Temperature Measurements The LTC2991 can measure internal temperature and up to four external diode or transistor sensors. During temperature conversion, current is sourced through the V1, V3, V5 or the V7 pin to forward bias the remote sensing diode. The change in sensor voltage per degree temperature change is hundreds of µV/°C, so environmental noise must be kept to a minimum. Recommended shielding and PCB trace considerations are illustrated in Figure 2. LTC2991 470pF NPN SENSOR V1 V2 V3 V4 V5 V6 V7 V8 (1) VBE • q I  η • k • In  C   IS  (2) The LTC2991 makes differential measurements of diode voltage to calculate temperature. Proprietary techniques allow for cancellation of error due to series resistance. Ideality Factor Scaling 2991 F01 GND SHIELD TRACE I  k•T • ln  C  q  IS  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. 1.8V CORE SDA 2-WIRE I2C INTERFACE 2.5V I/O RSENSE VBE = η • The LTC2991 is calibrated to yield the correct temperature for a remote diode with an ideality factor of 1.004. While this value is typical of target sensors, small deviations can yield significant temperature errors. The ideality factor of the diode 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 298K, a +1% accurate ideality factor error yields a +2.98 degree error. At 85°C, or 358K, a +1% error yields a 3.6 degree error. It is possible to scale the measured Kelvin or Celsius temperature measured using the LTC2991 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: hCAL = 1.004 Actual sensor ideality value: VCC ADR2 ADR1 ADR0 PWM SCL SDA GND 0.1µF hACT 2991 F01 Figure 2. Recommended PCB Layout 2991ff For more information www.linear.com/LTC2991 11 LTC2991 APPLICATIONS INFORMATION Sampling Currents Compensated Kelvin temperature: TK _ COMP = ηCAL • TK _ MEAS η ACT (3) Compensated Celsius temperature: TC _ COMP = ηCAL ηACT (T C _ MEAS ISAMPLE = (VIN – 1.49V) • 0.17[µA/V] ) + 273.15 – 273.15 (4) A 16-bit unsigned number is capable of representing the ratio ηCAL/ηACT 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. Similarly, Celsius coded temperature values can be scaled using 16-bit fixed-point arithmetic, using Equation (4). In both cases, the scaled result will have a 9-bit integer (d[12:4]) and the four LSB’s (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 target application, it is beneficial to configure the LTC2991 for Kelvin coded results to limit the number of math operations required in the target processor. TK _ COMP = TC _ COMP = η  (UNSIGNED)  CAL 215  TK _ MEAS  ηACT  215 ( Inputs with source resistance less than 500Ω will yield full-scale gain errors due to source impedance of < ½ LSB for 14-bit conversions. The nominal conversion time is 1.5ms for single-ended conversions. Current Measurements The LTC2991 has the ability to perform 14-bit current measurements with the addition of a current sense resistor (see Figure 3). RSENSE 0V – VCC ILOAD V1 V2 LTC2991 2991 F03 Figure 3. Simplified Current Sense Schematic In order to achieve 13-bit 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: ISAMPLE = (VIN – 1.49V) • 0.34[µA/V] (5) ) η  (UNSIGNED)  CAL 215 TC _ MEAS + 273.15 • 24 ηACT  215 –  273.15 • 24 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: (6) The maximum source impedance to yield 14-bit results with ½ LSB full-scale error is ~50Ω. In order to achieve 14-bit 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 LTC2991. The full-scale differential voltage is 0.300V. The external sense resistance, is then a function of the maximum measurable current, or REXT_MAX = 0.300V/IMAX. For example, if you wanted to measure a 2991ff 12 For more information www.linear.com/LTC2991 LTC2991 APPLICATIONS INFORMATION current range of ±5A, the external shunt resistance would equal 0.300V/5A = 60mΩ. There exists a way to improve the sense resistor’s precision using the LTC2991. The LTC2991 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 LTC2991 would measure both the differential voltage across this resistor and the resistor temperature. From this measurement, RO and TO in the following equation 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 = 3930ppm/°C for copper trace α = ±2 to ~200ppm/°C for discrete R I = (V1 – V2)/RT (7) (8) Device Configuration The LTC2991 is configured by writing the channel control registers through the serial interface. Refer to Tables 5, 6 and 7 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 the internal tempera- ture sensor and V1 through V8 as single-ended voltages, if triggered. The eight input pins V1 through V8 will be in a high impedance state, until configured otherwise, and a measurement triggered. Please note that when the device is configured for remote temperature measurements (using the control registers 0x06 and/or 0x07), the temperature data (Trx T) is stored in V1, V3, V5 and V7 respectively depending on the channel being used. Similarly, during this configuration the diode voltage (Trx Voltage) is stored in V2, V4, V6 and V8 registers. Data Format The data registers are broken into 8-bit upper and lower bytes. Voltage and temperature conversions are 13-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 11 and 12, each with 0.0625 degree weighted LSBs. The format is controlled by the control registers. 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. The LTC2991 internal bias circuitry maintains this voltage above this level during normal operating conditions. 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 16 for conversion value examples. Remote diode voltage is digitized at ~50µA of bias current. The ADC LSB value during these conversions is typically 38.15µV. Voltages are only available for the remote diodes, not the internal sensor. This code repeats at a diode voltage of approximately 0.3125V (see Tables 13 and 14). The absolute temperature of the diode can be used to detect whether the diode is operating (≤0.3125V or ≥ 0.3125V). This mode is useful for testing small relative 2991ff For more information www.linear.com/LTC2991 13 LTC2991 APPLICATIONS INFORMATION changes in temperature using the approximate relationship of –2.1mV/°C of voltage dependence on temperature. With an LSB weight of 38.15µV and a diode temperature relationship of –2.1mV/°C this yields ~0.018 degree resolution. For sensor applications involving heaters, the ability to sense small changes in temperature with low noise can yield significant power savings, allowing the heater power to be reduced. Table 16 has some conversion result examples for various diode voltages. 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 V8, and differential (current measurements) V1 – V2 , V3 – V4, V5 – V6 and V7 – V8. Single-ended voltages are limited to positive values in the range 0V to 4.9V or VCC + 0.2V, whichever is smaller. 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 16 for examples): VSINGLE_ENDED = D[13:0] • 305.18µV VDIFFERENTIAL = D[13:0] • 19.075µV, if sign = 0 PWM Output A 9-bit, 1kHz PWM output proportional to temperature V7 is available for controlling fans or heaters. PWM_Threshold is a 9-bit value with an LSB weighting of one degree Kelvin. PWM_Threshold is subtracted from V7 and a pulse width proportional to the difference is produced. Note that the PWM threshold is split among two registers, with PWM_Threshold[8:1] in register 09h[7:0] and PWM_Threshold[0] in register 08h[7]. Equation 9 shows the registers involved. The PWM frequency is ~1kHz. The PWM output can be disabled or inverted with the PWM enable and PWM invert bits is register 08h, respectively. Figure 9 illustrates the PWM transfer function. The equation for the duty cycle is: 100 • (REG7 – PWM • 16) (9) PWM_DUTY_CYCLE( %) = 512 Where REG7 is bits [12:0] and PWM is PWM Threshold bits [8:0] A 50% duty cycle PWM signal would occur, for example, if the PWM threshold was set to 10h (16°C) and register 7 contained 200h (32°C). If channel 7 is configured for Kelvin temperatures, the PWM threshold must also be a Kelvin temperature. The registers are two’s compliment numbers. When calculating the duty cycle above for Celsius temperatures care should be taken to sign extend the register 7 and PWM threshold values. For temperatures below the PWM Threshold, the PWM output pin will be a constant logic level 0. For temperatures 32 degrees above 99.8% Current = D[13:0] • 19.075µV/RSENSE, if sign = 0 Current = (D[13:0] +1) • –19.075µV/RSENSE, if sign = 1, Where RSENSE is the current sensing resistor, typically < 1Ω. PWM DC (%) VDIFFERENTIAL = (D[13:0] +1) • –19.075µV, if sign = 1 50% PWM INVERT = LOGIC 0 0% VCC The LTC2991 measures VCC. To convert the contents of the VCC register to voltage, use the following equation: VCC = 2.5 + (D[13:0] • 305.18µV). 0 16 32 REG7[12:4]-PWM_THRESHOLD[8:0] 2991 F09 Figure 9. PWM Transfer Function 2991ff 14 For more information www.linear.com/LTC2991 LTC2991 APPLICATIONS INFORMATION the PWM Threshold, the PWM output pin will be a constant logic level 1. This relationship is opposite if the PWM invert bit is set. If the filter is enabled for the V7/V8 pair, the filtered result is routed to the PWM block; otherwise, the unfiltered version is used. The PWM CMOS output drive is intended to be buffered to drive large (>100pF) external capacitances or resistors 5 0 10110011001101 3.5000 0 01111111111111 2.5000 0 00000000000000 0.0000 1 11110000101001 –0.3000 0 11110101101111 0.300 0 10000010001111 0.159 0 00000000000000 0.0000 1 01111101110001 –0.159 1 00001010010001 –0.300 0 10110011001101 VCC = 6.0 0 10000000000000 VCC = 5.0 0 00001010001111 VCC = 2.7 2991ff For more information www.linear.com/LTC2991 21 LTC2991 APPLICATIONS INFORMATION Table 16. Conversion Formats TEMPERATURE FORMATS FORMAT BINARY VALUE D[12:0] TEMPERATURE Temperature Internal, TR1 Through TR4 LSB = 0.0625 Degrees Celsius 0011111010000 125.0000 Celsius 0000110010001 25.0625 Celsius 0000110010000 25.0000 Celsius 1110110000000 –40.0000 Kelvin 1100011100010 398.1250 Kelvin 1000100010010 273.1250 Kelvin 0111010010010 233.1250 Kelvin 0010011010000 77.0000 Sign Binary Value D[12:0] Voltage 0 0000000000000 0.0000 0 1111111111111 0.31249 0 0000000000000 0.31252 0 1111111111111 0.62501 0 0000000000000 0.62505 0 1001100110010 0.99999 DIODE VOLTAGE FORMATS Diode Voltage TR1 Through TR4 LSB = 38.15µV Table 17. Recommended Transistors to Be Used as Temperature Sensors MANUFACTURER PART NUMBER PACKAGE Fairchild Semiconductor MMBT3904 SOT-23 Fairchild Semiconductor FMMT3904 SOT-23 Fairchild Semiconductor 2N3904 TO-92 Central Semiconductor CMPT3904 SOT-23 Central Semiconductor CET3904E SOT-883L Diodes, Inc. MMBT3904 SOT-23 MMBT3904LT1 SOT-23 NXP MMBT3904 SOT-23 Infineon MMBT3904 SC-70 UMT3904 SOT-23 On Semiconductor Rohm 2991ff 22 For more information www.linear.com/LTC2991 LTC2991 TYPICAL APPLICATIONS High Voltage/Current and Temperature Monitoring RSENSE = 1mΩ 1% ILOAD 0A TO 10A VIN 5V TO 105V RIN 20Ω 1% –INF +IN 0.1µF –INS – + V– V+ VREG OUT 200k 1% 4.75k 1% LTC6102HV ROUT 4.99k 1% 0.1µF 0.1µF 5V VCC 2C 2-WIRE I INTERFACE V1 V2 SDA SCL LTC2991 ADR0 ADR1 ADR2 GND MMBT3904 V3 V4 2991 TA02 V5 TO V8 4 OTHER APPS ALL CAPACITORS ±20% VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x06 0xA0 REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 13.2mV/LSB VLOAD REG 0C, 0D: 1.223mA/LSB V2(ILOAD) REG 0E, 0F: 0.0625°C/LSB TPROCESSOR REG 1C, 1D: 2.5V + 305.18µV/LSB VCC 2991ff For more information www.linear.com/LTC2991 23 LTC2991 TYPICAL APPLICATIONS Computer Voltage and Temperature Monitoring 12V 5V 3.3V 0.1µF 10k 1% 30.1k 1% 10k 1% 10k 1% VCC V1 2C 2-WIRE I INTERFACE SDA SCL ADR0 ADR1 ADR2 V2 LTC2991 MICROPROCESSOR V3 V4 GND V5 TO V8 2991 TA03 4 OTHER APPS VOLTAGE AND TEMPERATURE CONFIGURATION CONTROL REGISTER: 0x06 0x0A REG 1A, 1B: 0.0625°C/LSB TAMBIENT V1(+5) REG 0A, 0B: 610µV/LSB V2(+12) REG 0C, 0D: 1.22mV/LSB REG 0E, 0F: 0.0625°C/LSB TPROCESSOR REG 1C, 1D: 2.5V + 305.18µV/LSB VCC Motor Protection/Regulation LOADPWR = I • V 0.1Ω 1% MOTOR CONTROL VOLTAGE 0VDC TO 5VDC 0A TO ±2.2A 5V 2-WIRE I2C INTERFACE VCC V1 V2 SDA SCL LTC2991 ADR0 ADR1 ADR2 V3 V4 MMBT3904 TMOTOR MOTOR GND V5 TO V8 TAMBIENT 2991 TA04 4 OTHER APPS VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0x06: 0xA1 REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 305.18µV/LSB VMOTOR REG 0C, 0D: 190.75µA/LSB IMOTOR REG 1A, 1B: 0.0625°C/LSB TMOTOR REG 1C, 1D: 2.5V + 305.18µV/LSB VCC 2991ff 24 For more information www.linear.com/LTC2991 LTC2991 TYPICAL APPLICATIONS Large Motor Protection/Regulation MOTOR CONTROL VOLTAGE 0V TO 40V 0A TO 10A 5V LOADPWR = I • V 0.01Ω 1W, 1% 71.5k 1% 71.5k 1% 10.2k 1% 10.2k 1% TAMBIENT 2-WIRE I2C INTERFACE VCC V1 V2 SDA SCL LTC2991 ADR0 ADR1 ADR2 MMBT3904 V3 V4 MOTOR TMOTOR GND V5 TO V8 2991 TA05 4 OTHER APPS VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION: CONTROL REGISTER 06: 0xA1 REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 2.44mV/LSB VMOTOR REG 0C, 0D: 15.54mA/LSB IMOTOR REG 0E, 0F: 0.0625°C/LSB TMOTOR REG 1C, 1D: 2.5V + 305.18µV/LSB VCC Fan/Air Filter/Temperature Alarm MMBT3904 3.3V 22Ω 0.125W 3.3V 2C 2-WIRE I INTERFACE VCC V1 V3 HEATER ENABLE 22Ω 0.125W V4 FAN GOOD FAN BAD FAN HEATER GND V5 TO V8 TAMBIENT TEMPERATURE FOR: MMBT3904 V2 SDA SCL LTC2991 ADR0 ADR1 FAN NDS351AN 4 OTHER APPS HEATER ENABLE 2 SECOND PULSE 2991 TA06 CONTROL REGISTER 0x06 = 0xAA REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 0.0625°C/LSB TFAN1 REG 0C, 0D: 0.0625°C/LSB TFAN2 REG 1C, 1D: 2.5V + 305.18µV/LSB VCC 2991ff For more information www.linear.com/LTC2991 25 LTC2991 TYPICAL APPLICATIONS Battery Monitoring CHARGING CURRENT BATTERY I AND V MONITOR 0.1Ω* 5V 2-WIRE I2C INTERFACE VCC V1 V2 MMBT3904 SDA V3 SCL LTC2991 ADR0 ADR1 V4 ADR2 GND V5 TO V8 ••• T(t) V(t) NiMH BATTERY 100% TBATT I(t) 100% 100% 2991 TA07 *IRC LRF3W01R015F 4 TAMBIENT + OTHER APPS VOLTAGE AND TEMPERATURE CONFIGURATION: CONTROL REGISTER: 0xA1 REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 305.18µV/LSB VBAT REG 0C, 0D: 190.75µA/LSB IBAT REG 0E, 0F: 0.0625°C/LSB TBAT REG 1C, 1D: 2.5V + 305.18µV/LSB VCC Wet Bulb Psychrometer 5V VCC µC V1 V2 MMBT3904 SDA V3 SCL LTC2991 ADR0 ADR1 V4 ADR2 GND V5 TO V8 TAMBIENT 4 OTHER APPS CONTROL REGISTER 0x06 = 0xAA REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 0.0625°C/LSB TWET REG 0C, 0D: 0.0625°C/LSB TDRY REG 1C, 1D: 2.5V + 305.18µV/LSB VCC MMBT3904 ∆T 470pF 2991 TA08 TDRY TWET FAN: SUNON KDE0504PFB2 DAMP MUSLIN FAN 5V FAN ENABLE NDS351AN WATER RESERVOIR REFERENCES http://en.wikipedia.org/wiki/Hygrometer http://en.wikipedia.org/wiki/Psychrometrics 2991ff 26 For more information www.linear.com/LTC2991 LTC2991 TYPICAL APPLICATIONS Liquid Level Indicator 3.3V SENSOR HI* TAMBIENT 3.3V HEATER ENABLE VCC µC V1 SDA V2 SCL LTC2991 V3 ADR0 ADR1 V4 ADR2 GND V5 TO V8 4 SENSOR LO* SENSOR HI SENSOR LO ∆T = ~2.0°C pp, SENSOR HI ~0.2°C pp, SENSOR LO HEATER ENABLE 2 SECOND PULSE NDS351AN *HEATER: 75Ω 0.125W *SENSOR MMBT3904, DIODE CONNECTED OTHER APPS 2991 TA09 CONTROL REGISTER 0x06 = 0xAA REG 1A, 1B: 0.0625°C/LSB TAMBIENT REG 0A, 0B: 0.0625°C/LSB TDRY REG 0C, 0D: 0.0625°C/LSB TWET REG 1C, 1D: 2.5V + 305.18µV/LSB VCC Wind Direction/Instrumentation 3.3V VCC µC V1 V2 MMBT3904 3.3V SDA V3 SCL LTC2991 ADR0 ADR1 V4 ADR2 GND V5 TO V8 TAMBIENT 2991 TA10 HEATER 75Ω 0.125W 4 OTHER APPS MMBT3904 HEATER ENABLE 2 SECOND PULSE 2N7002 CONTROL REGISTER 0x06 0xAA REG 1A, 1B 0.0625°C/LSB TAMBIENT REG 0A, 0B 0.0625°C/LSB TR1 REG 0E, 0F 0.0625°C/LSB TR2 REG 1C, 1D 2.5V + 305.18µV/LSB VCC 2991ff For more information www.linear.com/LTC2991 27 LTC2991 TYPICAL APPLICATIONS Oven Control with Power Monitor VOLTAGE AND CURRENT (POWER) MONITOR 5V VCC V1 V2 SDA I SCL 2-WIRE ADR0 2C INTERFACE OTHER APPLICATIONS V3 LTC2991 ADR1 V4 VCC V5 OVEN TSET 70°C V6 ADR2 V7 TAMBIENT HEATER V8 GND TEMPERATURE SENSOR PWM VCC 5V 100k + VOLTAGE, CURRENT, TEMPERATURE AND PWM CONFIGURATION: CONTROL REGISTER 0x06: 0x01 0x07: 0xA0 PWM, TINTERNAL, VCC REG: 0x08: 0x50 PWM REGISTER 0x09: 0x1B TAMBIENT VHEATER IHEATER TOVEN VCC REG 1A, 1B REG 0A, 0B REG 0C, 0D REG 16, 17 REG 1C, 1D 100k – 1µF 1M 0.0625°C/LSB 305µV/LSB 19.075µV/RHEATERA/LSB 0.0625°C/LSB 2.5V + 305.18µV/LSB LT6240 2991 TA11 Remote Temperature Sensing with Extended ESD Performance 3.3V VCC SDA SCL LTC2991 GND V1 V2 500Ω MMBT3904 MMBT3904 PROTECTION DEVICE REMOTE TEMPERATURE SENSOR > 8kV ESD 500Ω CONTROL REGISTER 0x06 = 0xAA REMOTE TEMPERATURE SENSOR REG OB, OB: 0.0625 °C/LSB 2991 TA13 2991ff 28 For more information www.linear.com/LTC2991 LTC2991 TYPICAL APPLICATIONS QUAD Remote Temperature Sensing with Two Wire Pairs Using One LTC2991 Channel 3.3V VCC SDA SCL LTC2991 GND V1 V2 9 1, 4 10 2, 3 S0, S1 LTC1393 SDA SCL MMBT3904 REMOTE TEMPERATURE SENSOR A MMBT3904 MMBT3904 6, 7 S2, S3 LTC2991 CONTROL REGISTER 0x06 0xAA LTC1393 CONTROL BYTE SENSOR A = 0x0B LTC1393 CONTROL BYTE SENSOR B = 0x0A LTC1393 CONTROL BYTE SENSOR C = 0x0C LTC1393 CONTROL BYTE SENSOR D = 0x0E MMBT3904 REMOTE TEMPERATURE SENSOR B 5, 8 LTC1393 WIRED AS A DUAL CROSS-POINT SWITCH WIRE PAIR 1 WIRE PAIR 2 REMOTE TEMPERATURE SENSOR D REMOTE TEMPERATURE SENSOR C 2991 TA14 LTC2291 REMOTE TEMPERATURE SENSOR REG OB, OB: 0.0625 °C/LSB 2991ff For more information www.linear.com/LTC2991 29 LTC2991 PACKAGE DESCRIPTION Please refer to http://www.linear.com/product/ltc2991#packaging for the most recent package drawings. MS Package 16-Lead Plastic MSOP (Reference LTC DWG # 05-08-1669 Rev A) 0.889 ±0.127 (.035 ±.005) 5.10 (.201) MIN 3.20 – 3.45 (.126 – .136) 4.039 ±0.102 (.159 ±.004) (NOTE 3) 0.50 (.0197) BSC 0.305 ±0.038 (.0120 ±.0015) TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) DETAIL “A” 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) 0° – 6° TYP 0.280 ±0.076 (.011 ±.003) REF 16151413121110 9 GAUGE PLANE 0.53 ±0.152 (.021 ±.006) DETAIL “A” 0.18 (.007) SEATING PLANE 1.10 (.043) MAX 0.17 – 0.27 (.007 – .011) TYP 1234567 8 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 0.86 (.034) REF 0.1016 ±0.0508 (.004 ±.002) MSOP (MS16) 0213 REV A 2991ff 30 For more information www.linear.com/LTC2991 LTC2991 REVISION HISTORY REV DATE DESCRIPTION A 10/11 Corrected axis label on Figure 9. PAGE NUMBER 14 Inserted new text in I2C Device Addressing section. 15 Inserted new row in Table 1. 17 Revised component values in Typical Application drawing TA05. 25 Corrected diode voltage value. 13 Corrected VDIFFERENTIAL and current equations. 14 Corrected slave address in Figures 5, 6, 7 and 8. 17 B 07/13 C 10/13 D 03/14 Corrected LSB size to 19.075µV/LSB and 190.75µA/LSB. E 08/15 Added Single-Ended and Differential VOFFSET. 2 Inserted new text in Device Configuration. 13 Updated MSOP Package Description to Rev A. 30 Correct serial bus protocol. 16 Correct Table 16. 22 F 10/15 6, 24, 26, 28, 32 2991ff 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 information circuits as described herein will not infringe on existing patent rights. For more www.linear.com/LTC2991 31 LTC2991 TYPICAL APPLICATION Parasitic Resistance Voltage and Current Monitoring with Temperature Compensation SWITCHING WAVEFORM INDUCTOR WITH RPARASITIC QUIET NODE ILOAD 5V 1µF BUCK REGULATOR 2.1k 2.1k 1µF 1µF THERMAL COUPLING 5V 1µF VCC 2-WIRE I2C INTERFACE V1 VOLTAGE, CURRENT AND TEMPERATURE CONFIGURATION CONTROL REGISTER 0x06: 0xA1: TAMBIENT REG 1A, 1B: 0.0625°C/LSB REG 0A, 0B: 305µV/LSB VLOAD REG 0C, 0D: 190.75µA/LSB ILOAD REG 1A, 1B: 0.0625°C/LSB TRPARASITIC REG 1C, 1D: 2.5V + 305.18µV/LSB VCC V2 SDA SCL LTC2991 ADR0 ADR1 ADR2 V3 MMBT3904 V4 GND V5 TO V8 RPARASITIC ~ 4000ppm/°C 2991 TA12 4 TAMBIENT OTHER APPS RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LTC2990 Quad I2C Temperature, Voltage and Remote and Internal Temperatures, 14-Bit Voltages and Current, Internal 10ppm/°C Reference LTC2997 Remote/Internal Temperature Sensor Current Monitor LTC6102/LTC6102HV Precision Zero Drift Current Sense Amplifier Temperature to Voltage with Integrated 1.8V Voltage Reference, ±1°C Accuracy 5V to 100V, 105V Absolute Maximum (LTC6102HV) LTC1392 Micropower Temperature, Power Supply Complete Ambient Temperature Sensor Onboard and Differential Voltage Monitor LTC2970 Dual I2C Power Supply Monitor and Margining Controller Integrated Reference and On-Chip Temperature Sensor Sequence, Trim, Margin and Supervise Eight Power Supplies LTC2977 Octal PMBus Power Supply Manager with EEPROM Integrated Reference and On-Chip Temperature Sensor and Fault Logging LTC2945 High Voltage I2C Power Monitor 0V to 80V Range, 12-Bit Voltage and Current. Measurement with 0.75% TUE I2C Interface Calculates 24-Bit Power Value, Stores Minimum and Maximum Values LTC2487 Internal Temperature Sensor 16-Bit 2-, 4-Channel Delta Sigma ADC with PGA, Easy Drive™ and I2C Interface LM134 Constant Current Source and Temperature Sensor Can Be Used as Linear Temperature Sensor LTC2983 Multi-Sensor High Accuracy Digital Temperature Measurement System 0.1°C Accuracy, Directly Digitize RTDs, Thermocouples, Thermistors and Diodes, 20 Flexible Inputs 2991ff 32 Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 For more information www.linear.com/LTC2991 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com/LTC2991 LT 1015 REV F • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2011