Datasheet
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DEVICE INFORMATION
R A
1
R A
2
R A
2_3
R A
3
V A
REF
DGND
LDAC
DACA/B
NC
DB11
R B
1
R B
2
R B
2_3
R B
3
V B
REF
V
DD
CLR
R/W
CS
DB0
1
2
3
4
5
6
7
8
9
10
30
29
28
27
26
25
24
23
22
21
DAC7822
11
12
13
14
15
16
17
18
19
20
DB10
DB9
DB8
DB7
DB6
DB5
DB4
DB3
DB2
DB1
40
39
38
37
36
35
34
33
32
31
R A
F
B
I 2A
O
UT
I 1A
OUT
NC
NC
NC
NC
I 1B
OUT
I 2B
OU
T
R B
F
B
DAC7822
SBAS374A – JUNE 2006 – REVISED JULY 2007
RTA PACKAGE
QFN-40
(TOP VIEW)
TERMINAL FUNCTIONS
PIN NO. PIN NAME DESCRIPTION
DAC A 4-Quadrant Resistors. Allows a number of configuration modes, including bipolar operation with
1-4 R
1
A, R
2
A, R
2_3
A, R
3
A
minimum of external components.
5, 26 V
REF
A, V
REF
B DAC Reference Voltage Input Terminals.
6 DGND Digital Ground Pin.
Load DAC Input. Allows asynchronous or synchronous updates to the DAC output. The DAC is asynchronously
7 LDAC updated when this signal goes low. Alternatively, if this line is held permanently low, an automatic or
synchronous update mode is selected whereby the DAC is updated on the rising edge of CS.
8 DAC A/B Selects DAC A or B. Low selects DAC A, and high selects DAC B.
9, 34-37 NC Not internally connected.
10-21 DB11 to DB0 Parallel Data Bits 11 through 0.
Chip Select Input; active low. Used in conjuction with R/ W to load parallel data to the input latch or to read data
22 CS
from the DAC register. Edge sensitive; when pulled high, the DAC data is latched.
Read/Write. When low, used in conjunction with CS to load parallel data. When high, used in conjunction with
23 R/ W
CS to read back contents of DAC register.
24 CLR Active Low Control Input. Clears DAC output and input and DAC registers.
25 V
DD
Positive Power Supply Input. These parts can be operated from a supply of 2.5V to 5.5V.
DAC B 4-Quadrant Resistors. Allow a number of configuration modes, including bipolar operation with a
27-30 R
3
B, R
2_3
B, R
2
B, R
1
B
minimum of external components.
31, 40 R
FB
B, R
FB
A External Amplifier Output.
DAC A Analog Ground. This pin typically should be tied to the analog ground of the system, but can be biased
32 I
OUT
2B
to achieve single-supply operation.
33 I
OUT
1B DAC B Current Output.
38 I
OUT
1A DAC A Current Output.
DAC A Analog Ground. This pin typically should be tied to the analog ground of the system, but can be biased
39 I
OUT
2A
to achieve single-supply operation.
5
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