Rainbow Electronics MAX5223 - Manual (Page 9)

MAX5223
Low-Power, Dual, 8-Bit, Voltage Output
Serial DAC in 8-Pin SOT23
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Table 2. Serial-Interface Programming Commands
Table 3. Example of a 16-Bit Input Word
X = Don’t care.
* = Not shown, for the sake of clarity. The functions of loading and shutting down the DACs and programming the logic can be combined in a single
command.
CONTROL DATA
FUNCTION
D0
LSB
D1 D2 D3 D4 D5 D6
D7
MSB
LA LB UB4 SA SB UB3 UB2 UB1
X X 1 * * 0 0 0 X X X X X X X X No Operation to DAC Registers
Unassigned Command
Load Register to DAC B
Load Register to DAC A
Load Both DAC Registers
All DACs Active
Unassigned Command
Shutdown
Shutdown
Shutdown X
X
X
X
X X
X
X
X
X X
X
X
X
X
8-Bit DAC Data
8-Bit DAC Data
8-Bit DAC Data
X
X
X
X
X X
X
X
X
X X
X
X
X
X X
X
X
X
X X
X
X
X
X *
*
*
*
*
1
1
0
0 0
1
0
1
*
*
*
*
*
0
0
0
0
0
0
0
0
0
*
*
*
*
0
0
0
1
1
*
*
*
*
0
0
1
0
1
1
1
1
1
1
1
1
1
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
LOADED LOADED
IN FIRST IN LAST
UB1 UB2
X X
UB3
1
SB
0
SA
0
UB4
0
LB
1
LA
1
D7
1
D6
0
D5
0
D4
0
D3
0
D2
0
D1
0
D0
0
Digital Inputs
The digital inputs are compatible with CMOS logic.
Supply current increases slightly when toggling the
logic inputs through the transition zone between
0.3
✕ V
DD
and 0.7 ✕ V
DD
.
Microprocessor Interfacing
The MAX5223 serial interface is compatible with
MICROWIRE, SPI, and QSPI. For SPI, clear the CPOL
and CPHA bits (CPOL = 0 and CPHA = 0). CPOL = 0
sets the inactive clock state to zero, and CPHA = 0
changes data at the falling edge of SCLK. This setting
allows SPI to run at full clock speeds. If a serial port is
not available on your µP, three bits of a parallel port can
be used to emulate a serial port by bit manipulation.
Minimize digital feedthrough at the voltage outputs by
operating the serial clock only when necessary.