AD584LH Просмотр технического описания (PDF) - Analog Devices

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AD584LH

Pin Programmable Precision Voltage Reference

Analog Devices 

AD584

PERFORMANCE OVER TEMPERATURE

Each AD584 is tested at three temperatures over the –55°C to

+125°C range to ensure that each device falls within the Maxi-

mum Error Band (see Figure 4) specified for a particular grade

(i.e., S and T grades); three-point measurement guarantees per-

formance within the error band from 0°C to +70°C (i.e., J, K,

or L grades). The error band guaranteed for the AD584 is the

maximum deviation from the initial value at +25°C. Thus, given

the grade of the AD584, the designer can easily determine the

maximum total error from initial tolerance plus temperature

variation. For example, for the AD584T, the initial tolerance is

± l0 mV and the error band is ± 15 mV. Hence, the unit is guar-

anteed to be 10.000 volts ± 25 mV from –55°C to +125°C.

needed, and yet respond quickly when the power is turned on

for operation. Figure 6 displays the turn-on characteristic of the

AD584. Figure 6a is generated from cold-start operation and

represents the true turn-on waveform after an extended period

with the supplies off. The figure shows both the coarse and fine

transient characteristics of the device; the total settling time to

within ± 10 millivolt is about 180 µs, and there is no long ther-

mal tail appearing after the point.

Figure 6. Output Settling Characteristic

Figure 4. Typical Temperature Characteristic

OUTPUT CURRENT CHARACTERISTICS

The AD584 has the capability to either source or sink current

and provide good load regulation in either direction, although it

has better characteristics in the source mode (positive current

into the load). The circuit is protected for shorts to either posi-

tive supply or ground. The output voltage vs. output current

characteristics of the device is shown in Figure 5. Source current

is displayed as negative current in the figure; sink current is

positive. Note that the short circuit current (i.e., zero volts out-

put) is about 28 mA; when shorted to +15 volts, the sink cur-

rent goes to about 20 mA.

NOISE FILTERING

The bandwidth of the output amplifier in the AD584 can be re-

duced to filter the output noise. A capacitor ranging between

0.01 µF and 0.1 µF connected between the Cap and VBG termi-

nals will further reduce the wideband and feedthrough noise in

the output of the AD584, as shown in Figure 8. However, this

will tend to increase the turn-on settling time of the device so

ample warm-up time should be allowed.

Figure 7. Additional Noise Filtering with an External

Capacitor

Figure 5. AD584 Output Voltage vs. Sink and Source

Current

DYNAMIC PERFORMANCE

Many low power instrument manufacturers are becoming in-

creasingly concerned with the turn-on characteristics of the

components being used in their systems. Fast turn-on compo-

nents often enable the end user to keep power off when not

REV. A

Figure 8. Spectral Noise Density and Total rms Noise vs.

Frequency

–5–

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