Datasheet

LTC2704
12
2704fd
OUTPUT RANGES
The LTC2704 is a quad DAC with software-programmable
output ranges. SoftSpan provides two unipolar output
ranges (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 and
analog supplies of ±12V to ±15V are used. When a refer-
ence voltage of 2V and analog supplies of ±5V are used,
the SoftSpan ranges become: 0V to 2V, 0V to 4V, ±1V, ±2V,
±4V and –1V to 3V. The output ranges are linearly scaled
for references other than 2V and 5V (appropriate analog
supplies should be used within the range ±5V to ±15V).
Each of the four DACs can be programmed to any one of
the six output ranges. DAC outputs can swing to ±10V
on ±10.8V supplies (±12V supplies with ±10% tolerance)
while sourcing or sinking 5mA of load current.
OPERATION
Table 1. Command Codes
CODE READBACK POINTER— READBACK POINTER—
C3 C2 C1 C0 COMMAND CURRENT INPUT WORD W
O
NEXT INPUT WORD W
+1
0 0 1 0 Write to B1 Span DAC n Set by Previous Command B1 Span DAC n
0 0 1 1 Write to B1 Code DAC n Set by Previous Command B1 Code DAC n
0 1 0 0 Update B1→B2 DAC n Set by Previous Command B2 Span DAC n
0 1 0 1 Update B1→B2 All DACs Set by Previous Command B2 Code DAC n
0 1 1 0 Write to B1 Span DAC n
Update B1→B2 DAC n
Set by Previous Command B2 Span DAC n
0 1 1 1 Write to B1 Code DAC n
Update B1→B2 DAC n
Set by Previous Command B2 Code DAC n
1 0 0 0 Write to B1 Span DAC n
Update B1→B2 All DACs
Set by Previous Command B2 Span DAC n
1 0 0 1 Write to B1 Code DAC n
Update B1→B2 All DACs
Set by Previous Command B2 Code DAC n
1 0 1 0 Read B1 Span DAC n B1 Span DAC n
1 0 1 1 Read B1 Code DAC n B1 Code DAC n
1 1 0 0 Read B2 Span DAC n B2 Span DAC n
1 1 0 1 Read B2 Code DAC n B2 Code DAC n
1 1 1 0 Sleep DAC n (Note 1) Set by Previous Command B2 Span DAC n
1 1 1 1 No Operation Set by Previous Command B2 Code DAC n
Codes not shown are reserved and should not be used.
Note 1: Normal operation can be resumed by issuing any update B1→B2 command to the sleeping DAC.
Table 2. Address Codes
A3 A2 A1 A0 n READBACK POINTER n
0 0 0 0 DAC A DAC A
0 0 1 0 DAC B DAC B
0 1 0 0 DAC C DAC C
0 1 1 0 DAC D DAC D
1 1 1 1 All DACs DAC A
Codes not shown are reserved and should not be used.
Table 3. Span Codes
S3 S2 S1 S0 SPAN
0 0 0 0 Unipolar 0V to 5V
0 0 0 1 Unipolar 0V to 10V
0 0 1 0 Bipolar –5V to 5V
0 0 1 1 Bipolar –10V to 10V
0 1 0 0 Bipolar –2.5V to 2.5V
0 1 0 1 Bipolar –2.5V to 7.5V
Codes not shown are reserved and should not be used.