WM2629

Production Data

WOLFSON MICROELECTRONICS LTD

PD Rev 1.0 April 2001

8

DEVICE DESCRIPTION

GENERAL FUNCTION

The WM2629 is an octal 8-bit, voltage output DAC. It contains a serial interface, control logic for

speed and power down, a programmable voltage reference, and eight digital to analogue converters.

Each converter uses a resistor string network buffered with an op amp to convert 8-bit digital data to

analogue voltage levels (see Block Diagram). The output voltage is determined by the reference

input voltage and the input code according to the following relationship:

Output voltage =

()

256

2

CODE

INPUT

OUTPUT

1111

1111

()

256

255

2

REF

V

::

1000

0001

()

256

129

2

REF

V

1000

0000

()

REF

REF

V

V

=

256

128

2

0111

1111

()

256

127

2

REF

V

::

0000

0001

()

256

1

2

REF

V

0000

0000

0V

Table 1 Binary Code Table

POWER ON RESET

An internal power-on-reset circuit resets the DAC register to all 0s on power-up.

BUFFER AMPLIFIER

The output buffer has a near rail-to-rail output with short circuit protection and can reliably drive a

2k

Ω load with a 100pF load capacitance.