Datasheet

MAX5500/MAX5501
Low-Power, Quad, 12-Bit
Voltage-Output DACs with Serial Interface
8 _______________________________________________________________________________________
SCLK
DIN
DOUT*
CS
SK
SO
SI*
I/O
MAX5500
MAX5501
MICROWIRE
PORT
*THE DOUT-SI CONNECTION IS NOT REQUIRED FOR WRITING TO THE
MAX5500/MAX5501, BUT CAN BE USED FOR READBACK PURPOSES.
Figure 2. Connections for MICROWIRE
Serial-Interface Configurations
The MAX5500/MAX5501s’ 3-wire serial interface is
compatible with both MICROWIRE (Figure 2) and
SPI/QSPI (Figure 3). The serial input word consists of
two address bits and two control bits followed by 12
data bits (MSB first), as shown in Figure 4. The 4-bit
address/control code determines the MAX5500/
MAX5501s’ response outlined in Table 1. The connec-
tion between DOUT and the serial-interface port is not
necessary, but may be used for data echo. Data held in
the shift register can be shifted out of DOUT and
returned to the µP for data verification.
The digital inputs of the MAX5500/MAX5501 are double
buffered. Depending on the command issued through the
serial interface, the input register(s) can be loaded without
affecting the DAC register(s), the DAC register(s) can be
loaded directly, or all four DAC registers can be updated
simultaneously from the input registers (Table 1).
Serial-Interface Description
The MAX5500/MAX5501 require 16 bits of serial data.
Table 1 lists the serial-interface programming com-
mands. For certain commands, the 12 data bits are
don’t-care bits. 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 two DAC address bits (A1, A0) and two control
bits (C1, C0), followed by the 12 data bits D11–D0
(Figure 4). The 4-bit address/control code determines:
• The register(s) to be updated
• The clock edge on which data is to be clocked out
through the serial-data output (DOUT)
• The state of the user-programmable logic output
(UPO)
• If the device is to enter shutdown mode (assuming
PDL is high)
• How the device is configured when exiting out of
shutdown mode
DOUT*
DIN
SCLK
CS
MISO*
MOSI
SCK
I/O
SPI/QSPI
PORT
SS
+5V
CPOL = 0, CPHA = 0
*THE DOUT-MISO CONNECTION IS NOT REQUIRED FOR WRITING TO THE
MAX5500/MAX5501, BUT CAN BE USED FOR READBACK PURPOSES.
MAX5500
MAX5501
Figure 3. Connections for SPI/QSPI
MSB.................................................................................................................................LSB
MSB...........................................................................................LSB
16 BITS OF SERIAL DATA
ADDRESS
BITS
CONTROL
BITS
DATA BITS
4 ADDRESS/
CONTROL BITS
D11..............................................................................................D0
A1 A0 C1 C0
12 DATA BITS
Figure 4. Serial-Data Format