WM2631
Production Data
DEVICE DESCRIPTION
GENERAL FUNCTION
The WM2631 is an octal 10-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 10-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:
CODE
Output voltage = 2
(VREF
)
1024
INPUT
OUTPUT
1023
1024
11 1111 1111
2
2
(
VREF
)
:
:
511
10 0000 0001
(VREF
)
1024
512
10 0000 0000
01 1111 1111
2
(
VREF
)
= VREF
1024
511
2
2
(
VREF
)
)
1024
:
:
1
00 0000 0001
(
VREF
1024
00 0000 0000
0V
Table 1 Binary Code Table (0V to 2VREF Output), Gain = 2
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
2kΩ 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.
WOLFSON MICROELECTRONICS LTD
PD Rev 1.1 April 2001
8
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
