Datasheet

LTC2990
23
Rev. F
For more information www.analog.com
TYPICAL APPLICATIONS
Liquid-Level Indicator
V
CC
LTC2990
3.3V
µC
GND
SDA
SCL
ADR0
ADR1
V1
V4
V3
V2
470pF
3.3V
470pF
T
INTERNAL
CONTROL REGISTER: 0x5D
T
AMB
REG 4, 5 0.0625°C/LSB
T
HI
REG 6, 7 0.0625°C/LSB
T
LO
REG A, B 0.0625°C/LSB
V
CC
REG E, F 2.5V + 305.18µV/LSB
NDS351AN
2290 TA09
HEATER: 75Ω 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
V
CC
V1
LTC2990
HEATER
PWR
= I •V
0.1Ω
HEATER
VOLTAGE
2-WIRE
I
2
C
INTERFACE
5V
GND
470pF
FEED
FORWARD
FEED
BACK
HEATER
HEATER CONSTRUCTION:
5FT COIL OF #34 ENAMEL WIRE
~1.6Ω AT 70°C
P
HEATER
= ~0.4W WITH T
A
= 20°C
HEATER POWER = α • (T
SET
– T
AMB
) + β • ∫(T
OVEN
– T
SET
) dt
20°C
AMBIENT
STYROFOAM
INSULATION
70°C
OVEN
T
OVEN
α = 0.004W, β = 0.00005W/DEG-s
MMBT3904
SDA
SCL
ADR0
ADR1
V3
V4
V2
2990 TA10
T
INTERNAL
CURRENT AND TEMPERATURE CONFIGURATION:
CONTROL REGISTER: 0x59
T
AMB
REG 4, 5 0.0625°C/LSB
I
HEATER
REG 6, 7 269µVLSB
T
HEATER
REG A, B 0.0625°C/LSB
V
CC
REG E, F 2.5V + 305.18µV/LSB
VOLTAGE AND TEMPERATURE CONFIGURATION:
CONTROL REGISTER: 0x58
T
AMB
REG 4, 5 0.0625°C/LSB
V1, V2 REG 8, 9 305.18µVLSB
T
OVEN
REG A, B 0.0625°C/LSB
V
CC
REG E, F 2.5V + 305.18µV/LSB
0.1µF
Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.Downloaded from Arrow.com.