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AS1536/AS1537

Datasheet - D e t a i l e d D e s c r i p t i o n

Figure 30. Supply Current vs. Sampling Rate

Figure 31. Powerup Time vs. Time in Shutdown

Internal 2.5V Reference (AS1536)

The AS1536 internal 2.5V reference output is connected to pin REF and also drives the internal DAC (see Figure 24

on page 12). REF output can be used as a reference voltage source for other components and can source up to

400µA.

The internal reference is enabled by pulling pin SHDNN high. Letting SHDNN float disables the internal reference,

which allows the use of an external reference (see External Reference on page 16).

Pin REF should be bypassed with a 4.7µF capacitor as shown in Figure 23 on page 12. Larger capacitors increase

wake-up time when the devices exit shutdown mode (see Layout Considerations on page 19)

External Reference

Both devices can operate with an external reference at pin REF. The external reference should be within the +1.0V to

Ω for DC currents.

Note: To use an external reference with the AS1536, disable the internal reference by letting pin SHDNN float.

During conversion, the external reference should be capable of delivering up to 250µA of DC load current and have an

output impedance

≤ 10Ω. The recommended minimum value for the bypass capacitor is 0.1µF. If the reference has

higher output impedance or is noisy, bypass it close to pin REF with a 4.7µF capacitor.

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Internal Reference

External Reference

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Internal Reference