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Section 6 – digital-to-analog converter (dac), 1 – detailed description – Maxim Integrated DS4830A Optical Microcontroller User Manual

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DS4830A User’s Guide

45

SECTION 6 – DIGITAL-TO-ANALOG CONVERTER (DAC)

The DS4830A contains eight 12-bit digital-to-analog converters (DACs). Each DAC has a voltage output buffer.
Each DAC can independently select between a 2.5V internal reference and external reference at REFINA pin for
DAC0 to DAC3 and at REFINB pin for DAC4 to DAC7.

12-Bit

Decoder

Data Bus

To DAC Switches

R

R

R

R

R

DAC Output

Internal

Reference

External

Reference

Ref Selection

4095

1

0

4094

4093

MUX

10b

01b

Output

Buffer

Figure 6-1: DAC Functional Diagram

6.1 – Detailed Description

The DS4830A DAC architecture consists of a resistor string with switches and decoder followed by a voltage buffer.
The DS4830A has eight independent DACs, each having the same architecture. As shown in Figure 6-1, each
DAC’s reference is software selectable. Each DAC is independently configurable using the DAC configuration and
DAC data registers. The DAC configuration register (DACCFG) provides the facility to enable or disable DACs
independently and select the reference. Each DAC can be configured for either an internal (2.5V) or an external
reference.

The DAC Data register programs the DAC for a particular voltage output depending on the value of this register and
the reference setting. The DAC outputs are voltage buffered and have the capability to sink or source current. Each
DAC output has output impedance which limits the DAC operating range if configured to sink current (refer to the