Datasheet

DAC8234
SBAS464A – AUGUST 2009 – REVISED SEPTEMBER 2009 ........................................................................................................................................... www.ti.com
PIN DESCRIPTIONS (continued)
PIN NO.
PIN
NAME QFN-40 TQFP-48 I/O DESCRIPTION
R
FB2
-0
(1)
14 16 O DAC-0 R
FB2
feedback
R
FB1
-0
(1)
15 17 O DAC-0 R
FB1
feedback
SGND-0 16 18 I DAC-0 signal ground. Connected to REFGND-A.
SGND-1 17 20 I DAC-1 signal ground. Connected to REFGND-A.
R
FB1
-1
(1)
18 21 O DAC-1 R
FB1
feedback
R
FB2
-1
(1)
19 22 O DAC-1 R
FB2
feedback
V
OUT
-1 20 23 O DAC-1 output
AV
DD
21, 30 26, 35 I Positive analog power supply
AGND 22 27 I Analog ground
AV
SS
23, 28 28, 33 I Negative analog power supply
REFGND-A 24 29 I Reference REF-A ground. Connect to AGND.
REF-A 25 30 I Group A (DAC-0, DAC-1) reference input
REF-B 26 31 I Group B (DAC-2, DAC-3) reference input
REFGND-B 27 32 I Reference REF-B ground. Connect to AGND.
Analog monitor output. This pin is either in Hi-Z status, or connected to one of the four DAC outputs
V
MON
29 34 O
or AIN, depending on the content of the Monitor Register.
V
OUT
-3 31 38 O DAC-3 output
R
FB2
-3
(1)
32 39 O DAC-3 R
FB2
feedback
R
FB1
-3
(1)
33 40 O DAC-3 R
FB1
feedback
SGND-3 34 41 I DAC-3 signal ground. Connected to REFGND-B.
SGND-2 35 43 I DAC-2 signal ground. Connected to REFGND-B.
R
FB1
-2
(1)
36 44 O DAC-2 R
FB1
feedback
R
FB2
-2
(1)
37 45 O DAC-2 R
FB2
feedback
V
OUT
-2 38 46 O DAC-2 output
AIN 39 47 I Auxiliary analog input. Connected to the analog monitor mux.
Output mode selection of group B (DAC-2 and DAC-3). When UNI/BIP-A is tied to IOV
DD
, group B
is in unipolar output mode; when tied to DGND, group B is in bipolar output mode.
UNI/BIP-B 40 48 I
The input data written to the DAC are straight binary for unipolar output mode, and twos
complement for bipolar output mode.
1, 12, 19,
NC — 24, 25, 36, Not connected
37, 42
(1) To set the DAC-x gain = 2, connect R
FB1
-x and R
FB2
-x to V
OUT
-x, and set the corresponding GAIN bit in the Command Register to ' 0 ' .
To set the DAC-x gain = 4, connect R
FB1
-x to V
OUT
-x, keep R
FB2
-x open, and set the corresponding GAIN bit in the Command Register
to ' 1 ' . After power-on reset or user reset, the GAIN bits are set to ' 1 ' by default; for gain = 2, the gain bits must be cleared to ' 0 ' .
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