Rainbow Electronics MAX5355 - Manual (Page 10)

MAX5354/MAX5355
10-Bit Voltage-Output DACs
in 8-Pin µMAX
10 ______________________________________________________________________________________
In shutdown mode, the amplifier’s output and the refer-
ence input enter a high-impedance state. The serial
interface remains active. Data in the input register is
retained in shutdown, allowing the MAX5354/MAX5355
to recall the output state prior to entering shutdown. Exit
shutdown mode by either recalling the previous configu-
ration or updating the DAC with new data. When power-
ing up the device or bringing it out of shutdown, allow
20µs for the outputs to stabilize.
Serial-Interface Configurations
The MAX5354/MAX5355’s 3-wire serial interface is com-
patible with both Microwire™ (Figure 2) and
SPI™/QSPI™ (Figure 3). The serial input word consists of
three control bits followed by 10+3 data bits (MSB first),
as shown in Figure 4. The 3-bit control code determines
the MAX5354/MAX5355’s response outlined in Table 1.
The MAX5354/MAX5355’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 MAX5355 can also directly interface with +5V
logic.
Serial-Interface Description
The MAX5354/MAX5355 require 16 bits of serial data.
Table 1 lists the serial-interface programming com-
mands. For certain commands, the 10+3 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
10+3 data bits D9...D0, S2, S1, S0 (Figure 4). Set the
sub-bits (S2, S1, 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
properly 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 MAX5354/MAX5355 input/DAC register on CS’s
rising edge.
SCLK
DIN
CS
SK
SO
I/O
MAX5354
MAX5355
MICROWIRE
PORT
Figure 2. Connections for Microwire
DIN
SCLK
CS
MOSI
SCK
I/O
SPI/QSPI
PORT
SS
+5V
CPOL = 0, CPHA = 0
MAX5354
MAX5355
Figure 3. Connections for SPI/QSPI
Figure 4. Serial-Data Format
3 Control
Bits
10+3 Data Bits
D9 ...............................D0, S2, S1, S0 C2 C1 C0
Data Bits
MSB............................LSB Sub-Bits
Control
Bits
16 Bits of Serial Data
MSB ..................................................................................LSB