Data Sheet

ADR5040/ADR5041/ADR5043/ADR5044/ADR5045

Rev. B | Page 11 of 16

THEORY OF OPERATION

The ADR504x family uses the band gap concept to produce

a stable, low temperature coefficient voltage reference suitable

for high accuracy data acquisition components and systems. The

devices use the physical nature of a silicon transistor base-emitter

voltage in the forward-biased operating region. All such transistors

have approximately a −2 mV/°C temperature coefficient (TC),

making them unsuitable for direct use as a low temperature

coefficient reference. Extrapolation of the temperature charac-

teristic of any one of these devices to absolute zero (with the

collector current proportional to the absolute temperature),

silicon band gap voltage. Therefore, if a voltage develops with

temperature coefficient reference results.

APPLICATIONS INFORMATION

The ADR5040/ADR5041/ADR5043/ADR5044/ADR5045 are

a series of precision shunt voltage references. They are designed

to operate without an external capacitor between the positive

and negative terminals. If a bypass capacitor is used to filter the

supply, the references remain stable.

For a stable voltage, all shunt voltage references require an

based on the following considerations:



to the ADR5040/ADR5041/ADR5043/ADR5044/ADR5045,

even when the supply voltage is at its minimum value and

the load current is at its maximum value.



when the supply voltage is at its maximum value and the

load current is at its minimum value.

ADR5040/ADR5041/ADR5043/ADR5044/ADR5045 output

IN

L

OUT

S

BIAS

I

I

V

V

R







(3)

ADR5040/ADR5041/

ADR5043/ADR5044/

ADR5045

Figure 19. Shunt Reference

Precision Negative Voltage Reference

The ADR5040/ADR5041/ADR5043/ADR5044/ADR5045 are

suitable for applications where a precise negative voltage is desired.

Figure 20 shows the ADR5045 configured to provide a negative

output. Caution should be exercised in using a low temperature

sensitive resistor to avoid errors from the resistor.

ADR5045

–5V

Figure 20. Negative Precision Reference Configuration

Stacking the ADR504x for User-Definable Outputs

Multiple ADR504x parts can be stacked together to allow the

user to obtain a desired higher voltage. Figure 21a shows three

ADR5045 devices configured to give 15 V. The bias resistor,

flows through all the shunt references in series. Figure 21b shows

calculated in the same manner as before. Parts of different voltages

can also be added together; that is, an ADR5041 and an ADR5045

can be added together to give an output of +7.5 V or −7.5 V, as

desired. Note, however, that the initial accuracy error is the sum

of the errors of all the stacked parts, as are the temperature

coefficient and output voltage change vs. input current.

–15V

ADR5045

ADR5045

ADR5045

+15V

ADR5045

ADR5045

ADR5045

(a)

(b)

Figure 21. ±15 V Output with Stacked ADR5045 Devices