Rainbow Electronics MAX5353 - Manual (Page 10)

MAX5352/MAX5353
Low-Power, 12-Bit Voltage-Output DACs
with Serial Interface
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to recall the output state prior to entering shutdown.
Exit shutdown mode by either recalling the previous
configuration or by updating the DAC with new data.
When powering up the device or bringing it out of shut-
down, allow 20µs for the output to stabilize.
Serial-Interface Configurations
The MAX5352/MAX5353’s 3-wire serial interface is
compatible with both Microwire™ (Figure 2) and
SPI™/QSPI™ (Figure 3). The serial input word consists
of three control bits followed by 12+1 data bits (MSB
first), as shown in Figure 4. The 3-bit control code
determines the MAX5352/MAX5353’s response outlined
in Table 1.
The MAX5352/MAX5353’s digital inputs are double
buffered. Depending on the command issued through
the serial interface, the input register can be loaded
without affecting the DAC register, the DAC register
can be loaded directly, or the DAC register can be
updated from the input register (Table 1).
The +3.3V MAX5353 can also directly interface with
+5V logic.
Serial-Interface Description
The MAX5352/MAX5353 require 16 bits of serial data.
Table 1 lists the serial-interface programming com-
mands. For certain commands, the 12+1 data bits are
“don’t cares.” Data is sent MSB first and can be sent in
two 8-bit packets or one 16-bit word (CS must remain
low until 16 bits are transferred). The serial data is com-
posed of three control bits (C2, C1, C0), followed by
the 12+1 data bits D11...D0, S0 (Figure 4). Set the
sub-bit (S0) to zero. The 3-bit control code determines:
•
the register to be updated,
•
the configuration when exiting shutdown.
Figure 5 shows the serial-interface timing requirements.
The chip-select pin (CS) must be low to enable the
DAC’s serial interface. When CS is high, the interface
control circuitry is disabled. CS must go low at least
t
CSS before the rising serial clock (SCLK) edge to prop-
erly clock in the first bit. When CS is low, data is
clocked into the internal shift register via the serial-data
input pin (DIN) on SCLK’s rising edge. The maximum
guaranteed clock frequency is 10MHz. Data is latched
into the MAX5352/MAX5353 input/DAC register on CS’s
rising edge.
SCLK
DIN
CS
SK
SO
I/O
MAX5352
MAX5353
MICROWIRE
PORT
Figure 2. Connections for Microwire
DIN
SCLK
CS
MOSI
SCK
I/O
SPI/QSPI
PORT
SS
+5V
CPOL = 0, CPHA = 0
MAX5352
MAX5353
Figure 3. Connections for SPI/QSPI
Figure 4. Serial-Data Format
3 Control
Bits
12+1 Data Bits
D11 .....................................D0, S0 C2 C1 C0
Data Bits
MSB ................................LSB Sub-Bit
Control
Bits
16 Bits of Serial Data
MSB ..................................................................................LSB