AD8250ARZ Просмотр технического описания (PDF) - Analog Devices
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AD8250ARZ Datasheet PDF : 8 Pages
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Preliminary Technical Data
AD8250
PIN CONFIGURATIONS AND FUNCTIONAL DESCRIPTIONS
-IN 1
10 +IN
DGND 2 AD8250 9 VREF
-VS 3 TOP VIEW 8 +VS
A0 4 (Not to Scale) 7 VOUT
A1 5
6 WR
TRANSPARENT GAIN SETTING MODE:
In this mode, the gain is set by toggling A0 and A1 to HIGH or
LOW. To enable transparent mode, tie WR to –Vs. This
configures the AD8250 to change gains when A0 and A1 are set
according to Table 4.
Figure 4. 10-Lead MSOP
Table 4. . Transparent Mode Gain Settings
G WR A1 A0
1 -Vs LO LO
2 -Vs LO HI
5 -Vs HI LO
10 -Vs HI HI
Table 3. Pin Function Descriptions—
10-Lead MSOP(ARM PACKAGE)
Pin No. Name Description
1
-IN
Inverting Input Terminal (True
differential input)
2
DGND Digital Ground.
3
-Vs
Negative Supply Terminal
4
A0
Gain Setting Pin (LSB)
5
A1
Gain Setting Pin (MSB)
6
WR
Write Enable
7
VOUT Output Terminal
8
+Vs
Positive Supply Terminal
9
VREF
Reference Voltage Terminal (drive this
pin with a low impedance voltage
source to level shift the output signal)
10
+IN
Non-inverting Input Terminal (True
differential input)
GAIN SETTING
The AD8250’s gains are set digitally. The A0 and A1 pins must
be set either HIGH or LOW with respect to digital ground,
DGND. The WR pin is a tri-state switch. It may be set to one of
three levels, HIGH, LOW or to –VS. A HIGH signal is typically
greater than 4V but less than 6V and a LOW signal is typically
less than 1V but higher than DGND, 0V. Gains can be
programmed using the following methods:
WRITE ENABLE GAIN SETTING MODE:
In this mode, the gains are changed only during the negative
edge of the WR strobe. So for instance, the gain is determined
by the two bit value held on A0 and A1 at the time the WR
strobe transitions from HIGH to LOW.
WR
A0, A1
tWR-HI
tWR-LO
tSU
tHD
Table 5. : Write Enable Mode Gain Settings
Gain (changes to) WR
A1 A0
1
HI -> LO LO LO
2
HI -> LO LO HI
5
HI -> LO HI LO
10
HI -> LO HI HI
No Change
LO->LO X X
No Change
LO->HI X X
No Change
HI-> HI X X
X = don’t care
.
Rev. PrB| Page 7 of 8
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