Rainbow Electronics MAX522 - Manual (Page 10)

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 MAX522 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 (0.5MHz). 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.
MAX522
Dual, 8-Bit, Voltage-Output
Serial DAC in 8-Pin SO Package
10 ______________________________________________________________________________________
1LSB REF 2 REF
1
256
ANALOG OUTPUT REF
D
256
8 = Ч = Ч

 

= Ч

 

−
Table 4. Code Table
CS
SCLK
DIN
t DS
t DH
t CL
t CH
t CSS
t CSPWH
t CSH
Figure 3. MAX522 Detailed Serial-Interface Timing Diagram
0V 0 0 0 0 0 0 0 0
+ × 



REF
1
256
1 0 0 0 0 0 0 0
+ × 



REF
127
256
1 1 1 1 1 1 1 0
+ × 

 = +
REF
128
256
REF
2
0 0 0 0 0 0 0 1
+ × 



REF
129
256
1 0 0 0 0 0 0 1
+ × 



REF
255
256
1 1 1 1 1 1 1 1
ANALOG
OUTPUT
B0 B1 B2 B3 B4 B5 B6 B7
DAC CONTENTS
Note:
where D = Decimal
Value of Digital Input