LM3911

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/Distributors for availability and specifications.
Supply Current (Externally Set) .................10 mA
Output Collector Voltage, V⁺⁺ ...................36V
Feedback Input Voltage Range ...............0V to a7.0V
Output Short Circuit Duration .................Indefinite
Operating Temperature Range ............-25°C to a85°C
Storage Temperature Range .............-65°C to a150°C
Lead Temperature (Soldering, 10 seconds) ...........260°C

The LM3911 is a highly accurate temperature measurement and/or control system for use over a b25°C to a85°C temperat ure range. Fabricated on a single monolithic chip, it includes a temperature sensor, a stable voltage reference and an operational amplifier.

The output voltage of the LM3911 is directly proportional to temperature in degrees Kelvin at 10 mV/°K. Using the internal op amp with external resistors any temperature scale factor is easily obtained. By connecting the op amp as a comparator, the output will switch as the temperature transverses the set-point making the device useful as an on-off temperature controller.

An active shunt regulator is connected across the power leads of the LM3911 to provide a stable 6.8V voltage reference for the sensing system. This allows the use of any power supply voltage with suitable external resistors.

The input bias current is low and relatively constant with temperature, ensuring high accuracy when high source impedance is used. Further, the output collector can be returned to a voltage hig her than 6.8V allowing the LM3911 to drive lamps and relays up to a 35V supply.

The LM3911 uses the difference in emitter-base voltage of transistors operating at different current densities as the basic temperature sensitive element. Since this output depends on ly on transistor matching the same reliability and stability as present op amps can be expected.

The LM3911 is available in two package styles, a metal can TO-46 and an 8-lead epoxy mini-DIP. In the epoxy package all electrical connections are made on one side of the device allowing the other 4 leads to be used for attaching the LM3911 to the temperature souce. The LM3911 is rated for operation over a b25°C to a85°C temperature range.