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APPLICATION INFORMATION

MICROCONTROLLER INTERFACING

ADS8406 to 8-Bit Microcontroller Interface

CS

RD

CONVST

BUSY

BDGND

+VBD

DB[15:8]

Micro

Controller

RD

GPIO

INT

10

µF

0.1

µF

Analog 5 V

0.1

µF

Digital 3 V

Ext Ref Input

Analog Input

ADS8406

0.1

µF

1

µF

AGND

BDGND

GPIO

BYTE

P[7:0]

GPIO

0.1

µF

1

µF

0.1

µF

10

µF

Analog 5 V

ADS8406

AGND

AGND

PRINCIPLES OF OPERATION

ADS8406

SLAS426A – AUGUST 2004 – REVISED DECEMBER 2004

Figure 31 shows a parallel interface between the ADS8406 and a typical microcontroller using the 8-bit data bus.

The BUSY signal is used as a falling-edge interrupt to the microcontroller.

Figure 31. ADS8406 Application Circuitry (using external reference)

Figure 32. Use Internal Reference

The ADS8406 is a high-speed successive approximation register (SAR) analog-to-digital converter (ADC). The

architecture is based on charge redistribution, which inherently includes a sample/hold function. See Figure 31

for the application circuit for the ADS8406.

The conversion clock is generated internally. The conversion time of 650 ns is capable of sustaining a 1.25-MHz

throughput.

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