6

FN6239.2

September 28, 2009

If a device is expected to pass through luggage X-ray

machines numerous times, it is advised to mount a 2-layer

(minimum) PC board on the top, and along with a ground

plane underneath will effectively shield it from from 50 to 100

passes through the machine. Since these machines vary in

X-ray dose delivered, it is difficult to produce an accurate

maximum pass recommendation.

Noise Performance and Reduction

The output noise voltage in a 0.1Hz to 10Hz bandwidth is

bandpass filter made of a 1 pole high-pass filter with a corner

frequency at 0.1Hz and a 2-pole low-pass filter with a corner

frequency at 12.6Hz to create a filter with a 9.9Hz

bandwidth. Wideband noise is reduced by adding capacitor

to the output, but the value should be limited to 1nF or less

to insure stability.

Temperature Drift

The limits stated for output accuracy over-temperature are

governed by the method of measurement. For the -40°C to

130°C temperature range, measurements are made at

+25°C and the two extremes. This measurement method

combined with the fact that FGA references have a fairly

linear temperature drift characteristic insures that the limits

stated will not be exceeded over the temperature range.

FIGURE 15. PRECISION LOW NOISE, LOW DRIFT, 0.6V, 50mA REFERENCE

2N2905

0.6V/50mA

0.001µF

GND

ISL21032

R = 200

Ω

ISL21032