Analog Devices Inc./Maxim Integrated

The LM134 is a three-terminal current source designed to operate at current levels from 1µA to 10mA, as set by an external resistor. The device operates as a true two terminal current source, requiring no extra power connections or input signals. Regulation is typically 0.02%/V and terminal-to-terminal voltage can range from 800mV to 40V.Because the operating current is directly proportional to absolute temperature in degrees Kelvin, the device will also find wide applications as a temperature sensor. The temperature dependence of the operating current is 0.336%/°C at room temperature. For example, a device operating at 298µA will have a temperature coefficient of 1mA/°C. The temperature dependence is extremely accurate and repeatable. Devices specified as temperature sensors in the 100µA to 1mA range are the LM134-3, LM234-3 and the LM134-6, LM234-6, with the dash numbers indicating ±3°C and ±6°C accuracies, respectively.If a zero temperature coefficient current source is required, this is easily achieved by adding a diode and a resistor.ApplicationsCurrent Mode Temperature SensingConstant Current Source for Shunt ReferencesCold Junction Compensation Constant-Gain Bias for Bipolar Differential StageMicropower Bias NetworksBuffer for Photoconductive CellCurrent Limiter

The LM336-2.5 is a general purpose shunt regulator diode designed to operate over a wide current range while maintaining good stability with time and temperature. The third terminal allows either the temperature coefficient to be minimized or the reference voltage to be adjusted without changing the temperature coefficient. Because it operates as a shunt regulator it can be used equally well as a positive or negative reference.The LM336-2.5 is available in a TO-92 plastic package.For more demanding precision reference applications requiring very low initial tolerance and temperature coefficients, consult the LT1009 data sheet.ApplicationsReference for 5V Systems8 Bit A/D and D/A ReferenceDigital VoltmetersCurrent Loop Measurement and Control SystemsPower Supply Monitor