Datasheet

MAX5703/MAX5704/MAX5705
Ultra-Small, Single-Channel, 8-/10-/12-Bit Buffered Output
Voltage DACs with Internal Reference and SPI Interface
20Maxim Integrated
REF Command
The REF (B[23:20] = 0010) command updates the global
reference setting used for the DAC. Set B[17:16] = 00 to
use an external reference for the DAC or set B[17:16] to
01, 10, or 11 to select either the 2.5V, 2.048V, or 4.096V
internal reference, respectively.
If RF3 (B19) is set to zero (default) in the REF command,
the REF I/O will not be driven by the internal reference
circuit, saving current. If RF3 is set to one, the REF I/O
will be driven by the internal reference circuit, consuming
an additional 25FA (typ) of current when the reference is
powered; when the reference is powered down, the REF
I/O will be high-impedance.
If RF2 (B18) is set to zero (default) in the REF command,
the reference will be powered down any time the DAC
is powered down (in STANDBY mode). If RF2 (B18) is
set to one, the reference will remain powered even if the
DAC is powered down, allowing continued operation of
external circuitry. In this mode, the 1FA shutdown state is
not available. See Table 3.
SOFTWARE Commands
The SOFTWARE (B[23:20] = 0011) commands provide
a means of issuing several flexible software actions. See
Table 4.
The SOFTWARE Command Action Mode is selected by
B[18:16]:
END (000): Used to end any active gate operation,
returning to normal operation (default).
GATE (001): DAC contents will be gated to their
DEFAULT selected values until the gate
condition is removed.
CLEAR (100): All CODE and DAC contents will be
cleared to their DEFAULT selected
values.
RESET (101): All CODE, DAC, RETURN, and
configuration registers reset to their
power-up defaults (including REF,
POWER, and CONFIG settings),
simulating a power cycle reset.
OTHER: No effect.
Table 3. REF (0010) Command Format
Table 4. SOFTWARE (0011) Command Format
B23 B22 B21 B20 B19 B18 B17 B16 B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
0 0 1 0 RF3 RF2 RF1 RF0 X X X X X X X X X X X X X X X X
REF COMMAND
0 = REF Not driven
1 = REF Driven
0 = Off in Standby 1 = On in Standby
Ref Mode:
00 = EXT
01 = 2.5V
10 = 2.0V
11 = 4.0V
Don’t Care Don’t Care
DEFAULT VALUES 0 0 0 0 X X X X X X X X X X X X X X X X
COMMAND BYTE DATA HIGH BYTE DATA LOW BYTE
B23 B22 B21 B20 B19 B18 B17 B16 B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
0 0 1 1 X SW2 SW1 SW0 X X X X X X X X X X X X X X X X
SOFTWARE
COMMANDS
Don’t Care
Mode:
000: END
001: GATE
100: CLR
101: RST
Other: No
Effect
Don’t Care Don’t Care
DEFAULT VALUES X 0 0 0 X X X X X X X X X X X X X X X X
COMMAND BYTE DATA HIGH BYTE DATA LOW BYTE