DAC7644的单电源工作连接图示于图2,逻辑真值表见表1。 其中VOUTA Sense:DAC A输出放大器倒相输入; VOUTA:DAC A电压输出; VREFL AB Sense:DAC A和B基准低感测输入; VREFL AB:DAC A和B基准低输入; VREFH AB Sense:DAC A和B基准高感测输入; VREFH AB:DAC A和B基准高输入; VOUT B Sense:DAC B输出放大器倒相输入; VOUT B:DAC B电压输出。 DAC 7644的输出电压由下式给出: VOUT=VREFL+(VREFH-VREFL)·/
65536 式中N是数字输入码。 输出电流由下式给出: IOUT=[(VREFH-VREFL)
/ RSENSE]·[ProgrammedValue / 65536]+(VREFL/RSENSE) 根据图1的4mA~20mA电流输出配置,输出电流如下: IOUT=[[2.5V-0.5V / 125Ω]]·[ProgrammedValue
/ 65536]+[0.5V / 125Ω]
A1
A0
R/W
CS
RST
RSTSEL
LOADDACS
INPUT REGISTER
MODE
DAC
DAC
L
L
H
H
L
L
H
H
X
X
X
XL
H
L
H
L
H
L
H
X
X
X
XL
L
L
L
H
H
H
H
X
X
X
XL
L
L
L
L
L
L
L
H
H
X
XX
X
X
X
X
X
X
X
X
X
↑
↑X
X
X
X
X
X
X
X
X
X
L
HX
X
X
X
X
X
X
X
↑
H
X
XWrite
Write
Write
Write
Read
Read
Read
Read
Hold
Hold
Hold
Hold
Hold
Hold
Hold
Hold
Hold
Hold
Hold
Hold
Reset to Zero
Reset to MidscateWrite Input
Write Input
Write Input
Write Input
Read Input
Read Input
Read Input
Read Input
Update
Hold
Reset to Zero
Reset to MidscateA
B
C
D
A
B
C
D
AII
AII
AII
AII