Data Sheet

ADR3512

Rev. E | Page 13 of 16

THEORY OF OPERATION

The ADR3512 uses a patented voltage reference architecture to

achieve high accuracy, low TC, and low noise in a CMOS

process. Like all band gap references, the reference combines

two voltages of opposite TCs to create an output voltage that is

nearly independent of ambient temperature. However, unlike

traditional band gap voltage references, the temperature

independent voltage of the reference is arranged to be the base

the silicon). Then, a corresponding positive TC voltage is added

The key benefit of this technique is that the trimming of the

initial accuracy and TC can be performed without interfering

with one another, thereby increasing overall accuracy across

temperature. Curvature correction techniques further reduce

the temperature variation.

produce stable output voltages of 2.5 V and 5.0 V. The output buffer

can source up to +10 mA and sink up to −3 mA of load current.

BAND GAP

VOLTAGE

REFERENCE

ENABLE

GND FORCE

GND SENSE

Figure 36. Block Diagram

The ADR3512 reference leverages Analog Devices patented

DigiTrim technology to achieve high initial accuracy and low

TC. Precision layout techniques lead to very low long-term drift

and thermal hysteresis.

LONG-TERM OUTPUT VOLTAGE DRIFT

One of the key parameters of the ADR3512 reference is long-term

output voltage drift. Independent of the output voltage model

and in a 50°C environment, this device exhibits a typical drift

of approximately 30 ppm after 1000 hours of continuous, unloaded

operation.

It is important to understand that long-term output voltage drift

is not tested or guaranteed by design and that the output from the

device may shift beyond the typical 30 ppm specification. Because

most of the drift occurs in the first 200 hours of device operation,

burning in the system board with the reference mounted can

reduce subsequent output voltage drift over time. See the

AN-713 Application Note, The Effect of Long-Term Drift on Voltage

References, for more information regarding the effects of long-term

drift and how it can be minimized.

POWER DISSIPATION

The ADR3512 voltage reference is capable of sourcing up to 10 mA

of load current at room temperature across the rated input voltage

range. However, when used in applications subject to high ambient

temperatures, carefully monitor the input voltage and load current

to ensure that the device does not exceed its maximum power

dissipation rating. The maximum power dissipation of the

device can be calculated by

]

W

[

JA

A

J

D

T

T

P

θ

−

=

where:

Because of this relationship, the acceptable load current in high

temperature conditions may be less than the maximum current

sourcing capability of the device. The device must not be operated

outside of its maximum power rating because doing so can

result in premature failure or permanent damage to the device.