WM2630

Production Data

WOLFSON MICROELECTRONICS LTD

PD Rev 1.1 February 2001

8

DEVICE DESCRIPTION

GENERAL FUNCTION

The WM2630 is an octal 12-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 12-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 =

()

4096

CODE

V

2

REF

INPUT

OUTPUT

1111

1111

1111

()

4096

4095

V

2

REF

::

1000

0000

0001

()

4096

2049

V

2

REF

1000

0000

0000

()

REF

REF

V

4096

2048

V

2

=

0111

1111

1111

()

4096

2047

V

2

REF

::

0000

0000

0001

()

4096

1

V

2

REF

0000

0000

0000

0V

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.

PROGRAMMABLE REFERENCE

The DAC reference can be sourced internally or externally under software control. If an external reference

voltage is applied to the REF pin, the device must be configured to accept this. If an internal reference is

selected, a voltage of 1.024V or 2.048 is available. The internal reference can source up to 1mA and can

therefore be used as an external system reference.