2
AN1290.2
June 15, 2009
User-selectable Options (Refer to Figure 3)
Component pads are included to enable a variety of user
selectable circuits to be added to the amplifier differential
inputs, the VREF input, and the amplifier feedback loop. A
voltage divider and filter option can be added to establish a
power supply tracking common mode reference at the VREF
input, or a coaxial connection to the amplifier FB+ pin can be
made at the FB+ BNC connector. The differential inputs have
additional resistor placements for adding input attenuation,
or to establish input DC offsets through the VREF pin.
FIGURE 3. COMPONENT-SELECTABLE OPTIONS
J
9
R
6
R
5
C
3
OPEN
DNP
DNP
VREFA
V+
V-
J
4
VREFA
1
R
13
R
15
R
17
R
18
R
21
R
22
R
23
R
20
R
19
R
16
R
14
J
8
J
10
FB+A
-INA
+INA
0
0
0
DNP
DNP
DNP
DNP
DNP
1k
100k
100k
VREFA
ISL2827xINEVAL1Z Components Parts List
DEVICE #
DESCRIPTION
COMMENTS
C
3
, C
5
CAP, SMD, 0805, 0.1µF, 25V, 10%, X7R, ROHS
Power Supply Decoupling
C
FA
, C
FB
, C
LA
, C
LB
CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS
Optional Amplifier Feedback Caps
Not Populated
C
1
, C
2
CAP, SMD, 1206, 1µF, 25V, 10%, X7R, ROHS
Power Supply Decoupling
C
4
CAP-TANTALUM, SMD, D, 10µF, 35V, 10%, LOW ESR,
ROHS
Optional VREF Filter
Not Populated
D
1
, D
2
DIODE-RECTIFIER, SMD, MELF, 2 Ld, 50V, 1A, GPP,
ROHS
Reverse Power Protection
U
1
ISL28270FAZ or ISL28271FAZ or ISL28272FAZ or
ISL28273FAZ INSTRUMENTATION AMP,16P, QSOP,
ROHS
R
32
, R
33
, R
IN+A
, R
IN+B
, R
IN-A
, R
IN-B
, R
SA
, R
SB
RES, SMD, 0805, 0
Ω
, 1/8W, TF, ROHS
0
Ω
User Selectable Resistors
R
IA
, R
IB
.
RES, SMD, 0805, 1k, 1/8W, 1%,TF, ROHS
R
I
Gain Resistors
R
1
, R
2
RES, SMD, 0805, 10k, 1/8W, 1%,TF, ROHS
ENABLE Pull-up Resistors
R
15
to R
18
RES, SMD, 0805, 100k, 1/10W, 1%, TF, ROHS
R
9
, R
12
, R
20
, R
22
, R
27
, R
29
CAP, SMD, 0805, DNP-PLACE HOLDER, ROHS
User Selectable Resistors
Not Populated
R
FA
, R
FB
(ISL28271, ISL28273)
RES, SMD, 0805, 9.09k, 1/8W, 1%, TF, ROHS
R
F
Gain Resistors - ISL28271,
ISL28272
R
FA
, R
FB
(ISL28270, ISL28272)
RES, SMD, 0805, 100k, 1/8W, 1%, TF, ROHS
R
F
Gain Resistors - ISL28270
R
3
, R
6
, R
10
, R
11
, R
13
, R
14
, R
19
, R
21
, R
23
, R
25
,
R
28
, R
30
, R
LA
, R
LB
, R
X
.
RES, SMD, 0805, DNP-PLACE HOLDER, ROHS
User Selectable Resistors
Not Populated
S
1
, S
2
SWITCH-SEALED MINI TOGGLE, TH, 3P, SP,
ON/NONE/ON, GOLD
Enable/Disable Select Switches
Application Note 1290
