AD8250-EVALZ Analog Devices Inc, AD8250-EVALZ Datasheet - Page 17

• Manufacturer Part Number: AD8250-EVALZ
• Description: BOARD EVALUATION AD8250
• Manufacturer: Analog Devices Inc
• Series: iCMOS®r

Specifications of AD8250-EVALZ

• Channels Per Ic: 1 - Single
• Amplifier Type: Instrumentation
• Output Type: Single-Ended
• Slew Rate: 25 V/µs
• -3db Bandwidth: 10MHz
• Current - Output / Channel: 37mA
• Operating Temperature: -40°C ~ 85°C
• Current - Supply (main Ic): 4.1mA
• Voltage - Supply, Single/dual (±): 10 V ~ 30 V, ±5 V ~ 15 V
• Board Type: Fully Populated
• Utilized Ic / Part: AD8250
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

POWER SUPPLY REGULATION AND BYPASSING
The AD8250 has high PSRR. However, for optimal performance,
a stable dc voltage should be used to power the instrumentation
amplifier. Noise on the supply pins can adversely affect per-
formance. As in all linear circuits, bypass capacitors must be
used to decouple the amplifier.
Place a 0.1 μF capacitor close to each supply pin. A 10 μF tantalum
capacitor can be used farther away from the part (see Figure 51)
and, in most cases, it can be shared by other precision integrated
circuits.
INPUT BIAS CURRENT RETURN PATH
The AD8250 input bias current must have a return path to its
local analog ground. When the source, such as a thermocouple,
cannot provide a return current path, one should be created
(see Figure 52).
Figure 51. Supply Decoupling, REF, and Output Referred to Ground
DGND
+IN
–IN
AD8250
+V
–V
S
S
WR
DGND
A1
0.1µF
0.1µF
A0
REF
10µF
10µF
LOAD
OUT
Rev. B | Page 17 of 24
INPUT PROTECTION
All terminals of the AD8250 are protected against ESD. Note
that 2.2 kΩ series resistors precede the ESD diodes as shown in
Figure 47. The resistors limit current into the diodes and allow
for dc overload conditions 13 V above the positive supply and
13 V below the negative supply. An external resistor should be
used in series with each input to limit current for voltages greater
than 13 V beyond either supply rail. In either scenario, the
AD8250 safely handles a continuous 6 mA current at room
temperature. For applications where the AD8250 encounters
extreme overload voltages, external series resistors and low
leakage diode clamps, such as BAV199Ls, FJH1100s, or SP720s,
should be used.
CAPACITIVELY COUPLED
C
C
THERMOCOUPLE
TRANSFORMER
INCORRECT
AD8250
+V
AD8250
–V
AD8250
+V
–V
+V
–V
S
S
S
S
S
S
Figure 52. Creating an I
REF
REF
REF
f
HIGH-PASS
CAPACITIVELY COUPLED
=
BIAS
2πRC
10MΩ
1
Return Path
C
C
THERMOCOUPLE
TRANSFORMER
R
R
CORRECT
AD8250
AD8250
AD8250
+V
–V
+V
–V
+V
–V
S
S
S
S
S
S
AD8250
REF
REF
REF