
LTC2754
12
2754f
TIMING DIAGRAMS
Output Ranges
The LTC2754 is a quad, current-output, serial-input preci-
sion multiplying DAC with selectable output ranges. Ranges
can either be programmed in software for maximum
exibility—each of the four DACs can be programmed
to any one of six output ranges—or hardwired through
pin-strapping. Two unipolar ranges are available (0V to 5V
and 0V to 10V), and four bipolar ranges (±2.5V, ±5V, ±10V
and –2.5V to 7.5V). These ranges are obtained when an
external precision 5V reference is used. When a reference
voltage of 2V is used, the ranges become: 0V to 2V, 0V to
4V, ±1V, ±2V, ±4V and –1V to 3V. The output ranges are
linearly scaled for other reference voltages.
Manual Span Conguration
Multiple output ranges are not needed in some applica-
tions. To congure the LTC2754 to operate in a single span
without additional operational overhead, tie the M-SPAN
pin directly to VDD. The active output range for all four
DACs is then set via hardware pin strapping of pins S2,
S1 and S0 (rather than through the SPI port); and Write
and Update commands have no effect on the active output
span. See Figure 1 and Table 3.
Tie the M-SPAN pin to ground for normal SoftSpan
operation.
Figure 1. Using M-SPAN to Congure the LTC2754
for Single-Span Operation (±10V Range Shown).
LTC2754-16
M-SPAN
S2
S1
S0
2754 F01
CS/LD SDI SCK
VDD
DAC A
±10V
DAC B
DAC C
DAC D
–
+
–
+
–
+
–
+
SDI
SRO
Hi-Z
CS/LD
SCK
LSB
2754 TD
LSB
t2
t9
t8
t5
t7
1
2
31
32
t6
t1
LDAC
t3
t4
t11
OPERATION