Datasheet

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LTC2990

Rev. F

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TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Quad I

C Voltage, Current

and Temperature Monitor

The LTC

2990 is used to monitor system temperatures,

voltages and currents. Through the I

C serial interface,

the device can be configured to measure many combi-

nations of internal temperature, remote temperature,

remote voltage, remote current and internal V

. 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.

Temperature Total Unadjusted Error

Temperature Measurement

Supply Voltage Monitoring

Current Measurement

Remote Data Acquisition

Environmental Monitoring

Measures Voltage, Current and Temperature

Measures Two Remote Diode Temperatures

±0.5°C Accuracy, 0.06°C Resolution (Typ)

±1°C Internal Temperature Sensor (Typ)

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

LTC2990

INTERNAL

SENSE

2.5V

GND

SDA

SCL

ADR0

ADR1

MEASURES: TWO SUPPLY VOLTAGES,

SUPPLY CURRENT, INTERNAL AND

REMOTE TEMPERATURES

LOAD

REMOTE

2990 TA01a

Voltage, Current, Temperature Monitor

All registered trademarks and trademarks are the property of their respective owners.

AMB

(°C)

–50

TUE (°C)

2990 TA01b

1.0

–25 0 50

–0.5

–1.0

0.5

75 100 125

REMOTE

Downloaded from Arrow.com.

Summary of content (26 pages)

PAGE 1
LTC2990 Quad I2C Voltage, Current and Temperature Monitor FEATURES DESCRIPTION Measures Voltage, Current and Temperature nn Measures Two Remote Diode Temperatures nn ±0.5°C Accuracy, 0.06°C Resolution (Typ) nn ±1°C Internal Temperature Sensor (Typ) nn 14-Bit ADC Measures Voltage/Current nn 3V to 5.5V Supply Operating Voltage nn Four Selectable Addresses nn Internal 10ppm/°C Voltage Reference nn 10-Lead MSOP Package nn The LTC®2990 is used to monitor system temperatures, voltages and currents.
PAGE 2
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)...........
PAGE 3
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 PARAMETER CONDITIONS MIN TYP MAX VOFFSET_DIFF Differential Offset V1 = V2 = VCC, V3 = V4 = 0V –12.5 0 12.
PAGE 4
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.
PAGE 5
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 2.5 1100 2.0 ICC (µA) ICC (µA) Measurement Delay Variation vs T Normalized to 3.3V, 25°C Supply Current vs Temperature Shutdown Current vs Temperature 1.5 1050 VCC = 3.3V 1.0 VCC = 3.3V 1000 0.
PAGE 6
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.
PAGE 7
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).
PAGE 8
LTC2990 FUNCTIONAL DIAGRAM REMOTE DIODE SENSORS VCC 10 MODE 1 2 3 4 V1 GND 5 V2 SCL CONTROL LOGIC V3 MUX SDA ADC I2C V4 ADR0 ADR1 7 6 8 9 UV INTERNAL SENSOR VCC UNDERVOLTAGE DETECTOR REFERENCE 2990 FD TIMING DIAGRAM SDA tSU, DAT tHD, DATO, tHD, DATI tSU, STA tSP tHD, STA tSP tBUF tSU, STO 2990 TD SCL tHD, STA START CONDITION 8 Downloaded from Arrow.com. REPEATED START CONDITION STOP CONDITION START CONDITION Rev. F For more information www.analog.
PAGE 9
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.
PAGE 10
LTC2990 APPLICATIONS INFORMATION 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 ⎞ • ln ⎜ C ⎟ q ⎝ IS ⎠ k•T (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.
PAGE 11
LTC2990 APPLICATIONS INFORMATION 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).
PAGE 12
LTC2990 APPLICATIONS INFORMATION Device Configuration The LTC2990 is configured by writing the control register through the serial interface. Refer to Table 5 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. The device can make single measurements, or in continuous mode, repeated acquisitions.
PAGE 13
LTC2990 APPLICATIONS INFORMATION Current = D[14:0] • 19.42µV/RSENSE, if Sign = 0 Current = (D[14:0] +1) • –19.42µV/RSENSE, if Sign = 1 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.
PAGE 14
LTC2990 APPLICATIONS INFORMATION 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 delivers the data byte and the LTC2990 acknowledges once more and latches the data into its internal register.
PAGE 15
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.
PAGE 16
LTC2990 APPLICATIONS INFORMATION Table 4.
PAGE 17
LTC2990 APPLICATIONS INFORMATION Table 6. 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 interface. Table 7. 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 8.
PAGE 18
LTC2990 APPLICATIONS INFORMATION Table 10. 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 11110001011000 +0.300 0 10000000000000 +0.159 0 00000000000000 0.000 1 10000000000000 –0.159 1 00001110101000 –0.300 1 00000000000000 <–0.318 VCC = Result + 2.
PAGE 19
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 10.0k 1% 30.1k 1% 10.0k 1% 10.0k 1% VCC V1 2-WIRE I2C INTERFACE 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.
PAGE 20
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.
PAGE 21
LTC2990 TYPICAL APPLICATIONS Fan/Air Filter/Temperature Alarm 3.3V MMBT3904 3.3V 22Ω 0.125W 470pF FAN 0.1µF VCC 2-WIRE I2C INTERFACE HEATER ENABLE V1 MMBT3904 V2 SDA SCL LTC2990 ADR0 ADR1 GND TEMPERATURE FOR: V3 22Ω 0.125W 470pF V4 FAN 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 2990 TA06 0.0625°C/LSB 0.0625°C/LSB 0.0625°C/LSB 2.5V + 305.
PAGE 22
LTC2990 TYPICAL APPLICATIONS Wet-Bulb Psychrometer 5V 0.1µF VCC µC V1 MMBT3904 V2 SDA SCL LTC2990 ADR0 ADR1 GND ∆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 V3 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 FAN ENABLE NDS351AN REFERENCES: http://en.wikipedia.org/wiki/Hygrometer http://en.wikipedia.
PAGE 23
LTC2990 TYPICAL APPLICATIONS Liquid-Level Indicator 3.3V 3.3V SENSOR HI* 0.1µF HEATER ENABLE VCC µC V1 SDA SCL LTC2990 ADR0 ADR1 GND 470pF V2 SENSOR HI SENSOR LO* V3 SENSOR LO 470pF V4 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 ∆T = ~2.0°C pp, SENSOR HI ~0.2°C pp, SENSOR LO NDS351AN HEATER: 75Ω 0.
PAGE 24
LTC2990 PACKAGE DESCRIPTION MS Package MS Package 10-Lead Plastic MSOP 10-Lead Plastic MSOP (Reference LTC DWG # 05-08-1661 Rev F) (Reference LTC DWG # 05-08-1661 Rev F) 0.889 ±0.127 (.035 ±.005) 5.10 (.201) MIN 3.20 – 3.45 (.126 – .136) 3.00 ±0.102 (.118 ±.004) (NOTE 3) 0.50 0.305 ±0.038 (.0197) (.0120 ±.0015) BSC TYP RECOMMENDED SOLDER PAD LAYOUT 0.254 (.010) 10 9 8 7 6 3.00 ±0.102 (.118 ±.004) (NOTE 4) 4.90 ±0.152 (.193 ±.006) DETAIL “A” 0.497 ±0.076 (.0196 ±.
PAGE 25
LTC2990 REVISION HISTORY REV A DATE DESCRIPTION 6/11 Revised title of data sheet from “I2C Temperature, Voltage and Current Monitor” 1 Revised Conditions and Values under Measurement Accuracy in Electrical Characteristics section 2 Revised curve G05 labels in Typical Performance Characteristics section Revised Applications Information section and renumbered tables and table references B C 8/11 12/11 1 Updated Current Measurements section 10 Updated Related Parts 24 Removed conditions for VC
PAGE 26
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 MMBT3904 V2 SDA SCL LTC2990 ADR0 ADR1 GND 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.