Low-Power, +2.5V to +5.5V, 8-Bit
Voltage-Output DAC in µMAX
Table 2. Serial-Interface Programming Commands
CONTROL BYTE
DATA BYTE
Loaded First
Loaded Last
UB1 UB2 UB3 C2 C1 C0 AB1 AB2 D7 D6 D5 D4 D3 D2 D1 D0
COMMAND
X
X
X
0
0
0
0
1
X
X
X
X
X
X
X
X
On CS’s rising edge, wake up DAC.
DAC register unchanged.
X X X X X 1 X X X X X X X X X X Unassigned command
XXX01001
8-bit DAC data
On CS’s rising edge, load DAC register.
Wake up DAC (if previously powered
down).
On CS’s rising edge, power down DAC.
X X X 1 0 0 0 1 X X X X X X X X DAC output goes to zero. DAC register
unchanged.
XXX11001
8-bit DAC data
On CS’s rising edge, power down DAC
and update DAC register. DAC output
goes to zero.
X = Don’t Care
Table 3. Example Input Word
Loaded First
Loaded Last
UB1 UB2 UB3 C2 C1 C0 AB1 AB2 D7 D6 D5 D4 D3 D2 D1 D0
X
X
X
0
1
0
0
1
1
0
0
0
0
0
0
0
X = Don’t Care
Table 4. Analog Output vs. Code
DAC REGISTER CONTENTS
D7 D6 D5 D4 D3 D2 D1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
1
0
0
0
0
0
0
0
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
ANALOG
D0
OUTPUT (V)
1 +VREF x (255/256)
1 +VREF x (129/256)
0 +VREF x (128/256) = +VREF/2
1 +VREF x (127/256)
1 +VREF x (1/256)
00
Note: 1LSB = VREF x 2-8 = VREF(1/256)
ANALOG OUTPUT = +VREF(I/256), where I = Integer Value of Digital Input and wake up DAC (if previously powered down)
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