ELM341
Low Power Thermostat
Description
The ELM341 is a complete temperature
measurement and control system in an 8 pin
package. It automatically reverts to a very low power
sleep mode between measurements, making it
suitable for battery operation.
This integrated circuit is designed to compare
two resistances and drive an output pin depending
on the relative value of each. Typically, one of the
resistors will be an NTC thermistor, and the other
one will be a temperature independent resistor
(whether fixed or variable). When the magnitude of
the resistance connected to pin 2 exceeds the value
of the resistance connected to pin 3, the output pin
will be driven to a high state. Hysteresis maintains
the output in that state until the relative values differ
by approximately 8% (or typically 2°C for a 10KΩ
thermistor).
To reduce the possibility of sporadic outputs, a
condition must exist for three successive cycles, or 6
seconds, before the output pin can change state.
Features
• Low power CMOS design
• Wide supply range - 3.0 to 5.5 volt operation
• Built-in proportional hysteresis
• Measurement in progress output
• Time delay on operate improves noise immunity
• Internal pullup resistor on the reset input
• High current drive outputs - up to 25 mA
• Sleep mode reduces power requirements
Connection Diagram
PDIP and SOIC
(top view)
V
DD
R
1
1
2
3
4
8
7
6
5
V
SS
Out
MIP
Cap
Applications
• Backup thermostats
• Under or over temperature alarm circuits
R
2
reset
Block Diagram
V
DD
reset
4
Control
Sleep
Timer
2
Measurement in Progress (busy)
6
MIP
R
1
R
2
3
Overrange
7
Out
5
Analog to
Digital
Converter
R
1
> R
2
3 Consecutive
Measurements
ELM341DSB
Elm Electronics – Circuits for the Hobbyist
1 of 4
ELM [ ELM ELECTRONICS ]
