Document
LTC1392 Micropower Temperature, Power Supply and Differential Voltage Monitor
FEATURES
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DESCRIPTIO
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Complete Ambient Temperature Sensor Onboard System Power Supply Monitor 10-Bit Resolution Rail-to-Rail Common-Mode Differential Voltage Input Available in 8-Pin SO and PDIP 0.2µA Supply Current When Idle 700µA Supply Current When Sampling at Maximum Rate Single Supply Voltage: 4.5V to 6V 3-Wire Half-Duplex Serial I/O Communicates with Most MPU Serial Ports and All MPU Parallel I/O Ports
The LTC®1392 is a micropower data acquisition system designed to measure temperature, on-chip supply voltage and a differential voltage. The differential inputs feature rail-to-rail common mode input voltage range. The LTC1392 contains a temperature sensor, a 10-bit A/D converter with sample-and-hold, a high accuracy bandgap reference and a 3-wire half-duplex serial interface. The LTC1392 can be programmed to measure ambient temperature, power supply voltage and an external voltage at the differential input pins, that can also be used for current measurement using an external sense resistor. When measuring temperature, the output code of the A/D converter is linearly proportional to the temperature in °C. Production trimming achieves ±2°C initial accuracy at room temperature and ± 4°C over the full – 40°C to 85°C temperature range. The on-chip serial port allows efficient data transfer to a wide range of MPUs over three or four wires. This, coupled with low power consumption, makes remote location sensing possible and facilitates transmitting data through isolation barriers.
APPLICATI
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Temperature Measurement Power Supply Measurement Current Measurement Remote Data Acquisition Environment Monitoring
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATI
Complete Temperature, Supply Voltage and Supply Current Monitor
1µF
TEMPERATURE ERROR (°C)
Output Temperature Error
5 4 LTC1392C GUARANTEED LIMIT LTC1392I GUARANTEED LIMIT TYPICAL
+
5V
3 2 1 0 –1 –2 –3 –4 –5 –40 –20 40 20 0 60 TEMPERATURE (°C) 80 100
LTC1392 P1.4 MPU (e.g., 68HC11) P1.3 P1.2 1 2 3 4 DIN DOUT CLK CS VCC –VIN +VIN GND 8 7 6 5
LTC1392 • TA01
RSENSE ILOAD
U
LTC1392 • TA02
UO
UO
1
LTC1392 ABSOLUTE
(Note 1)
AXI U
RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW DIN 1 DOUT 2 CLK 3 CS 4 N8 PACKAGE 8-LEAD PDIP 8 7 6 5 VCC –VIN +VIN GND
Supply Voltage (VCC) ................................................ 7V Input Voltage ................................. – 0.3V to VCC + 0.3V Output Voltage ............................... – 0.3V to VCC + 0.3V Operating Temperature Range LTC1392C............................................... 0°C to 70°C LTC1392I........................................... – 40°C to 85°C Junction Temperature.......................................... 125°C Storage Temperature Range ................ – 65°C to 150°C Lead Temperature (Soldering, 10 sec)................. 300°C
ORDER PART NUMBER LTC1392CN8 LTC1392CS8 LTC1392IN8 LTC1392IS8 S8 PART MARKING 1392 1392I
S8 PACKAGE 8-LEAD PLASTIC SO
TJMAX = 125°C, θJA = 100°C/ W (N8) TJMAX = 125° C, θJA = 130°C/ W (S8)
Consult factory for Military grade parts.
ELECTRICAL CHARACTERISTICS
PARAMETER Power Supply To Digital Conversion Resolution Total Absolute Error Differential Voltage to Digital Conversion (Full-Scale Input = 1V) Resolution Integral Linearity Error (Note 5) Differential Linearity Error Offset Error Full-Scale Error Differential Voltage to Digital Conversion (Full-Scale Input = 0.5V) Resolution Integral Linearity Error (Note 5) Differential Linearity Error Offset Error Full-Scale Error Temperature to Digital Conversion Accuracy Nonlinearity CONDITIONS
(Note 2, 3)
MIN TYP MAX 10
q
UNITS Bit LSB
VCC = 4.5V to 6V VCC = 4.5V to 6V
±8
10
q q q q
± 0.5 ± 0.5
±1 ±1 ±4 ± 15
10
q q q q
± 0.5 ± 0.5
±2 ±1 ±8 ± 25 ±2 ±4
TA = 25°C (Note 7) TA = TMAX or TMIN (Note 7) TMIN ≤ TA ≤ TMAX (Note 4)
q
±1
2
U
Bit LSB LSB LSB LSB Bit LSB LSB LSB LSB °C °C °C
W
U
U
W W
W
LTC1392
ELECTRICAL CHARACTERISTICS
SYMBOL ION LEAKAGE IOFF LEAKAGE VIH VIL IIH IIL VOH VOL IOZ ISOURCE ISINK ICC tSMPL tCONV tdDO ten tdis thDO tf tr CIN PARAMETER On-Channel Leakage Current (Note 6) Off-Channel Leakage Current (Note 6) High Level Input Voltage Low Level Input Voltage High Level Input Current Low Level Input Current High Level Output Voltage Low Level Output Voltage Hi-Z Output Current Output Source Current Output Sink Current Supply Current Analog Input Sample Time Conversion Time Delay Time, CLK↓ to DOUT Data Valid Delay Time, CLK↓ to DOUT Data Enabled Delay Time, CS ↑ to DOUT Hi-Z Time Output Data Remains Valid After CLK↓ DOUT Fall Time DOUT Rise Time Input Capacitance
(Note 2, 3)
MIN
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CONDITIONS
TYP
MAX ±1 ±1
UNITS µA µA V V µA µA V V
VCC = 5.25V VCC = 4.75V VIN = VCC VIN = 0V VCC = 4.75V, IOUT = 10µA VCC = 4.75V, IOUT = 360µA VCC = 4.75V, IOUT = 1.6mA CS = High VOUT = 0V VOUT = VCC CS = High CS = Low, VCC = 5V See Figure 1 .