ADR425ARM-REEL7(RevB) View Datasheet(PDF) - Analog Devices

Part Name

Description

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ADR425ARM-REEL7
(Rev.:RevB)

Ultraprecision Low Noise, 2.048 V/2.500 V/3.00 V/5.00 V XFET® Voltage References

Analog Devices 

PARAMETER DEFINITIONS

Temperature Coefficient

The change of output voltage over the operating temperature

range and normalized by the output voltage at 25°C, expressed

in ppm/°C. The equation follows:

( ) TCVO

ppm / °C

= VO (T2 ) –VO (T1 ) × 106

VO (25°C ) × (T2 – T1 )

where

VO (25°C) = VO at 25°C

VO (T1) = VO at Temperature 1

VO (T2) = VO at Temperature 2.

Line Regulation

The change in output voltage due to a specified change in input

voltage. It includes the effects of self-heating. Line regulation is

expressed in either percent per volt, parts-per-million per volt,

or microvolts per volt change in input voltage

Load Regulation

The change in output voltage due to a specified change in load

current. It includes the effects of self-heating. Load regulation is

expressed in either microvolts per milliampere, parts-per-million

per milliampere, or ohms of dc output resistance.

Long-Term Stability

Typical shift of output voltage at 25°C on a sample of parts

subjected to operation life test of 1000 hours at 125°C:

where

∆VO = VO(t0 ) – VO(t1)

∆VO

(

ppm)

=

VO(t0 ) – VO(t1)

VO (t0 )

×

106

VO (t0) = VO at 25°C at Time 0

VO (t1) = VO at 25°C after 1,000 hours operation at 125°C.

ADR420/ADR421/ADR423/ADR425

Thermal Hysteresis

Thermal hysteresis is defined as the change of output voltage

after the device is cycled through temperature from +25°C to

–40°C to +125°C and back to +25°C. This is a typical value

from a sample of parts put through such a cycle.

VO _ HYS = VO (25°C ) –VO _TC

VO _ HYS

( ppm) = VO (25°C ) –VO _TC

VO (25°C )

× 106

where

VO (25°C) = VO at 25°C

VO_TC = VO at 25°C after temperature cycle at +25°C to –40°C

to +125°C and back to +25°C.

Input Capacitor

Input capacitors are not required on the ADR42x. There is no

limit for the value of the capacitor used on the input, but a 1 µF to

10 µF capacitor on the input will improve transient response in

applications where the supply suddenly changes. An additional

0.1 µF in parallel will also help to reduce noise from the supply.

Output Capacitor

The ADR42x does not need output capacitors for stability

under any load condition. An output capacitor, typically 0.1 µF,

will filter out any low-level noise voltage and will not affect

the operation of the part. On the other hand, the load transient

response can be improved with an additional 1 µF to 10 µF

output capacitor in parallel. A capacitor here will act as a source

of stored energy for sudden increase in load current. The only

parameter that will degrade, by adding an output capacitor, is

turn-on time and it depends on the size of the capacitor chosen.

REV. B

–5–

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