LTC2997 datasheet(23/26 Pages) AD

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LTC2990

Rev. F

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TYPICAL APPLICATIONS

Liquid-Level Indicator

VCC

LTC2990

3.3V

µC

GND

SDA

SCL

ADR0

ADR1

470pF

3.3V

470pF

TINTERNAL

CONTROL REGISTER: 0x5D

TAMB

REG 4, 5

0.0625°C/LSB

THI

REG 6, 7

0.0625°C/LSB

TLO

REG A, B

0.0625°C/LSB

VCC

REG E, F

2.5V + 305.18µV/LSB

NDS351AN

2290 TA09

HEATER: 75 0.125W

*SENSOR MMBT3904, DIODE CONNECTED

SENSOR LO*

∆T = ~2.0°C pp, SENSOR HI

~0.2°C pp, SENSOR LO

SENSOR HI*

HEATER ENABLE

2 SECOND PULSE

HEATER ENABLE

SENSOR HI

SENSOR LO

0.1µF

Oscillator/Reference Oven Temperature Regulation

VCC

LTC2990

HEATERPWR = I •V

0.1

HEATER

VOLTAGE

2-WIRE

I2C

INTERFACE

GND

470pF

FEED

FORWARD

FEED

BACK

HEATER

HEATER CONSTRUCTION:

5FT COIL OF #34 ENAMEL WIRE

~1.6 AT 70°C

PHEATER = ~0.4W WITH TA = 20°C

HEATER POWER =

α • (TSET – TAMB) + β • ∫(TOVEN – TSET) dt

20°C

AMBIENT

STYROFOAM

INSULATION

70°C

OVEN

TOVEN

α = 0.004W, β = 0.00005W/DEG-s

MMBT3904

SDA

SCL

ADR0

ADR1

2990 TA10

TINTERNAL

CURRENT AND TEMPERATURE CONFIGURATION:

CONTROL REGISTER: 0x59

TAMB

REG 4, 5

0.0625°C/LSB

IHEATER

REG 6, 7

269µVLSB

THEATER

REG A, B

0.0625°C/LSB

VCC

REG E, F

2.5V + 305.18µV/LSB

VOLTAGE AND TEMPERATURE CONFIGURATION:

CONTROL REGISTER: 0x58

TAMB

REG 4, 5

0.0625°C/LSB

V1, V2

REG 8, 9

305.18µVLSB

TOVEN

REG A, B

0.0625°C/LSB

VCC

REG E, F

2.5V + 305.18µV/LSB

0.1µF

LTC2997 Datasheet(PDF) 23 Page - Analog Devices

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