WM2636
Production Data
SOFTWARE CONFIGURATION OPTIONS
The 16 bits of data can be transferred with the sequence shown in Table 2. D11-D0 contains
the 12-bit data word. D15-D12 hold the programmable options.
D15 D14 D13 D12 D11 D10 D9
D8
D7
D6
D5
D4
D3
D2
D1
D0
R1 SPD PWR R0
New DAC or control register value (12 bits)
Table 2 Serial Word Format
PROGRAMMABLE SETTLING TIME
Settling time is a software selectable 3.5µs or 1µs, typical to within ±0.5LSB of final value. This
is controlled by the value of D14. A ONE defines a settling time of 1µs, a ZERO defines a
settling time of 3.5µs.
PROGRAMMABLE POWER DOWN
The power down function is controlled by D13. A ZERO configures the device as active, or fully
powered up, a ONE configures the device into power down mode. When the power down
function is released the device reverts to the DAC code set prior to power down.
REGISTER ADDRESSING
A separate internal control register is available. This is accessed from the register access bits
R1 (Bit D15) and R0 (Bit D12).
R1
R0
REGISTER
(BIT D15)
(BIT D12)
0
0
1
1
0
1
0
1
Write data to DAC
Reserved
Reserved
Write data to control register
Table 3 Register Access Control
The contents of the control register, shown below in Table 4, are used to program the internal
reference function.
D11 D10 D9
D8
x
D7
x
D6
x
D5
x
D4
x
D3
x
D2
X
D1
D0
x
x
X
REF1 REF0
Table 4 Control Register Contents
PROGRAMMABLE INTERNAL REFERENCE
The 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 external reference is selected, the reference voltage input is buffered which makes the
DAC input resistance independent of code. The REF pin has an input resistance of 10MΩ and
an input capacitance of typically 55pF. The reference voltage determines the DAC full-scale
output.
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.
REF1
REF0)
REGISTER
0
0
1
1
0
1
0
1
External
1.024V
2.048V
External
Table 5 Programmable Internal Reference
WOLFSON MICROELECTRONICS LTD
PD Rev 1.0 July 1999
8
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
