max5251aepp Maxim Integrated Products, Inc., max5251aepp Datasheet - Page 9

• Manufacturer Part Number: max5251aepp
• Description: Max5251 +3v, Quad, 10-bit Voltage-output Dac With Serial Interface
• Manufacturer: Maxim Integrated Products, Inc.

In shutdown mode, the MAX5251 output amplifiers and
the reference inputs enter a high-impedance state. The
serial interface remains active. Data in the input regis-
ters is retained in shutdown, allowing the MAX5251 to
recall the output states prior to entering shutdown. Exit
shutdown mode either by recalling the previous config-
uration or by updating the DACs with new data. When
powering up the device or bringing it out of shutdown,
allow 20µs for the outputs to stabilize.
The MAX5251’s 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 10+2 data bits
(MSB first), as shown in Figure 4. The 4-bit address/
control code determines the MAX5251’s response out-
lined in Table 1. The connection between DOUT and
the serial-interface port is not necessary, but may be
used for data echo. Data held in the MAX5251’s shift
register can be shifted out of DOUT and returned to the
microprocessor (µP) for data verification.
The MAX5251’s digital inputs 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).
The MAX5251 requires 16 bits of serial data. Table 1
lists the serial-interface programming commands. For
certain commands, the 10+2 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 two DAC address bits (A1, A0) and two con-
trol bits (C1, C0), followed by the 10+2 data bits
D9…D0, S1, S0 (Figure 4). Set both sub-bits (S0, S1) to
zero. 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 part is to go into shutdown mode (assuming
PDL is high)
How the part is configured when exiting shutdown
mode.
Serial-Interface Configurations
_______________________________________________________________________________________
Serial-Interface Description
+3V, Quad, 10-Bit Voltage-Output DAC
Figure 2. Connections for Microwire
Figure 3. Connections for SPI/QSPI
Figure 4. Serial-Data Format
MSB ..................................................................................LSB
Address
A1
*THE DOUT-MISO CONNECTION IS NOT REQUIRED FOR WRITING TO THE MAX5251,
*THE DOUT-SI CONNECTION IS NOT REQUIRED FOR WRITING TO THE MAX5251,
BUT CAN BE USED FOR READBACK PURPOSES.
BUT CAN BE USED FOR READBACK PURPOSES.
Bits
Control Bits
4 Address/
with Serial Interface
A0
MAX5251
MAX5251
C1
Control
Bits
DOUT*
DOUT*
C0
SCLK
SCLK
DIN
DIN
16 Bits of Serial Data
CS
CS
MSB.................................LSB
D9 ...................................D0 S1 S0
10+2 Data Bits
CPOL = 0, CPHA = 0
Data Bits
SK
SO
SI*
I/O
MISO*
MOSI
SCK
I/O
MICROWIRE
SPI/QSPI
PORT
PORT
+3.3V
SS
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