lowpowerZONE Products for the week of October 3, 2011
ISL21090: Precision Bandgap Provides ±0.02% Initial Accuracy at Input Voltages of up to 36 V
Delivers Half the Noise at Half the Power of Competing Products
The newest precision voltage reference from Intersil Corporation features low noise, low temperature drift and meets the low power requirements of high end and portable instrumentation systems.
The ISL21090 is a wide input range, low noise precision bandgap voltage reference that provides half the noise of alternative solution with only half the power consumption. The device features exceptionally high initial, or ‘start-up,’ accuracy of +/-0.02%. The combination of low current consumption of 930microAmps, typical, and low noise of only 1.9microVpp (0.1Hz to 10Hz), makes the ISL21090 an excellent choice for high-end instrumentation systems up to 24 bits, and for process control, communications and data acquisition systems. It can accept input voltages up to 36V, compared with typical 18V ratings of alternative products.
It is always nice to see an acquired technology or product line continue to develop under new ownership. This is the case with the Xicor acquisition some years back by Intersil with their floating-gate array technology designed to achieve solidly better accuracies than those previously available with references.
What has seemingly been lacking in this technology has been the ability to achieve noise figures that rival the best and that specification has now been landed with the ISL21090 2.5 V reference.
The ISL21090 offers an output noise voltage of 1.9 µV peak-peak (over 0.1 Hz to 10 Hz with broadband noise voltage at 1.6 µV rms) which is dramatically better than available elsewhere. Added to this the company has achieved a design that allows for a high input voltage range (from 4.7 V to 36 V, with a 1.1 V dropout voltage) and a supply current that is not the best available but which is way up there at 930 µA. The initial accuracy is claimed to be ±0.02% (±0.5 mV for a 2.5 V reference) which is better than the nearest probable competitor, the LT1389, at 0.05%. Long term stability is a typical 20ppm.
Line regulation from the ISL21090 is 8ppm/V while load regulation is 2.5ppm/mA. The tempco is also among the best at 7ppm/ºC maximum. The short-circuit currents are a sourced 55 mA typical and a sunk 61 mA. The ripple reduction at 120 Hz is a typical 90 dB.
There has to be a negative with all this performance, right? Yes, pricing is still high – better than it has been with Xicor-derived parts – but if you need one or more of the ‘better’ numbers offered here then the ISL21090 has to be a serious look-see item. A lot of users would also prefer a smaller package: SOT-23, or even an old-fashioned TO-92. The 2.5 V reference is the first on offer in the family and Intersil plan for other parts at 1.25 V, 3.3 V, 4.096 V, 5 V, 7 V, and 10 V. They will make a huge impression in the voltage reference market especially in instrumentation and process control. The 2.5 V part is obviously ideal for a lot of ADC applications.
The ISL2109 is in production in SOIC-8 with pricing at $2.90 in 1000-piece lots.