small load currents. Difference amplifiers typically have a gain of 1 V/V. When the gain is adjustable, these

amplifiers use external resistors that are not conducive to low-drift applications.

10.2.1.2.3 Voltage Reference

The voltage reference for this application should have the following features:

1. Dual output (3.0 V and 1.5 V),

2. Low drift, and

3. Low tracking errors between the two outputs.

For this design, the REF2030 is used. The REF20xx topology is as shown in the Section 9.2 section.

The REF2030 is an excellent choice for this application because of its dual output. The temperature drift of

8 ppm/°C and initial accuracy of 0.05% make the errors resulting from the voltage reference minimal in this

application. In addition, there is minimal mismatch between the two outputs and both outputs track very well

across temperature, as shown in Figure 10-4 and Figure 10-5.

0

10

20

30

40

V

REF and VBIAS Matching (ppm)

C004

Figure 10-4. VREF – 2 × VBIAS Distribution (At TA =

25°C)

0

10

20

30

40

50

60

0

1

2

3

4

5

6

V

REF and VBIAS Tracking Over Temperature (ppm/ƒC)

C016

Figure 10-5. Distribution of VREF – 2 × VBIAS Drift

Tracking Over Temperature

10.2.1.2.4 Results

Table 10-1 summarizes the measured results.

Table 10-1. Measured Results

ERROR

UNCALIBRATED (%)

CALIBRATED (%)

Error across the full load current range (25°C)

±0.0355

±0.004

Error across the full load current range (–40°C to 125°C)

±0.0522

±0.0606

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REF2025, REF2030, REF2033, REF2041

SBOS600E – JULY 2018 – REVISED FEBRUARY 2022

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Product Folder Links: REF2025 REF2030 REF2033 REF2041