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Revision 0.96

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AS1530, AS1531

Data Sheet

Reference

Additionally the bandgap voltage can be adjusted about ±100mV by forcing a voltage to the REFADJ pin. The REFADJ

input impedance is typically 17k

Ω. Figure 32 shows a possible arrangement.

Figure 32. Reference Adjust Circuit

External Reference

An external reference can be connected directly at pin REF. To use the external reference, the internal buffer must be

disabled by connecting pin REFADJ to pin VDD. The input resistance is typically 15k

Ω.

During conversion, an external reference at pin REF must deliver up to 350µA DC load current and have 10

Ω or less

output impedance. If the reference has a higher output impedance or is noisy, bypass it with a 4.7µF capacitor placed

as close to pin REF as possible.

Note:

Using the REFADJ input makes buffering the external reference unnecessary.

0.01µF

GND

100k

Ω

DGND

24k

Ω

510k

Ω

+3.3V

12

REFADJ

AS1530/

AS1531