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INTRODUCTION
Fast, easy breadboarding of circuits using the PA240CX are
possible with the EK34 PC board. Mounting holes are provided
and the provision for standard banana jacks simplifies connec-
tion and testing. The amplifier may be mounted horizontally or
vertically. Components are labeled on both sides of the board
for ease in probing.
A multitude of circuit configurations are possible, so only sev-
eral component locations have specific functions and will usually
be necessary. This kit is not suitable for use with PA240CC.
TYPICAL COMPONENT FUNCTIONS
COMPONENT
FUNCTION
C1,7
Alone is a roll off, with R3, 13 is a current out stability
network (ref. AN19)
C2,6
With R6, 15 forms noise gain compensation network
(ref. AN25)
C3,4
Supply bypass, .22 to 1µF ceramic
C5,8
With R9, 20 forms a Howland stability network, can
jumper both to ground +IN
Cc
Sets compensation to match desired gain
Cs
Normally not used.
D1-4
Flyback protection diodes
R1,11 Inverting inputs, install to input line or to ground
R2,12 Negative feedback, install to V for voltage out or to I
for current output (ref. AN19)
R3,13 With C1, 7 forms a stability network for current output
(ref. AN19)
R4,14 Current sense for current outputs (ref. AN13)
R5,15 With C2, 6 forms noise gain compensation network
(ref. AN25)
R6,17 Input R for Howland current
�½�½�½�½�½
�½�½�½
pump or differential, usually
�½�½�½
shorted for non-inverting
�½�½
�½�½
R7,19 Current sense for Howland
�½�½�½
current pump. Could also be
�½�½
�½�½�½
used to isolate large Cloads
(ref. AN25)
�½�½�½
�½�½�½
R8,21 Positive feedback, install to H
�½�½�½�½
for a Howland current pump, to
D for a differential circuit
R9,20 With C5, 8 forms a Howland
stability net work, can jumper
both to ground +IN
R10
With an equal value R12 pro-
�½�½�½�½�½�½�½�½�½�½
�½�½�½
vides gain = -1 for a bridge slave
(ref. AN3,20)
R18,19 Can provide mid-supply refer-
ence for single supply bridge
(ref. AN3, 20)
Rc
Normally shorted.
�½�½�½�½�½
Rs
Normally not used.
PARTS LIST
Part #
Eval 34
Clamp04
MS11
TW14
HS29
Description
Evaluation Board PA40/140CX
Clamp for HS29
Pin Receptacle, 30 pin strip
Thermal Washer TO220 10/Pack
Heat Sink, 2.7 DEG/W
�½
Quantity
1
2
1
1
1
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APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
1
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