APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
NOTE: Refer to HS11 Heatsink in Accessories section
INTRODUCTION
This easy-to-use kit provides a platform for the evaluation of
power op amps that use the PA21 pin-out configuration. It can be
used to analyze a multitude of standard or proprietary circuit
configurations. In addition, it is flexible enough to do most standard
amplifier test configurations.
The schematic for 1/2 of the PC board is shown in Figure 2. The
schematic for the other half is identical except part reference
designators are primed (i.e. R1 = R1'). Note that all of the compo-
nents shown on the schematic will probably not be used for any
single circuit. The component locations on the PC board (See
Figure 3) provide maximum flexibility for a variety of configurations.
Also included are loops for current probes as well as connection
pads on the edge of the PC board for easy interconnects.
The hardware required to mount the PC board and the device
under evaluation to the heatsink are included in the kit. Because of
the limitless combination of configurations and component values
that can be used, no other parts are included in this kit. However,
generic formulas and guidelines are included in the APEX
DATABOOK and this evaluation kit documentation.
ASSEMBLY
1. Insert a #6 x 5/16" hex nut in each of the nut socket recesses
located on the bottom of the mating socket.
2. Insert the socket into the pc board until it is firmly pressed against
the ground plane side of the pc board.
3. Solder the socket in place (see Figure 1). Be sure the nuts are
in the recesses prior to soldering.
4. Mount the PC board assembly to the heatsink using the stand-
offs and spacers included.
5. Apply thermal grease or a TW03 to the bottom of the device
under evaluation. Insert into the mating socket through the
heatsink.
6. Use the #6 x 1.25" panhead screws to mount the amplifier to the
heat sink. Do not overtorque. Recommended mounting torque is
4-7 in-lbs (.45-.79 NM).
Mounting precautions, general operating considerations, and
heatsinking information may be found in the APEX DATA BOOK.
BEFORE YOU GET STARTED
All Apex amplifiers should be handled using proper ESD precau-
tions!
Initially set all power supplies to the minimum operating levels
allowed in the device data sheet.
Check for oscillations.
Always use the heatsink included in this kit with thermal grease
or a TW03 and torque the part to the specified 4-7 in-lbs
(.45-.79 NM).
Do not change connections while the circuit is under power.
Never exceed any of the absolute maximums listed in the device
data sheet.
Always use adequate power supply bypassing.
Remember that internal power does not equal load power.
Do not count on internal diodes to protect the output against
sustained, high frequency, high energy kickback pulses.
Teflon Tubing
(2 Opposite Pins
Minimum)
Recessed Nuts
Power Op Amp
Package
Heatsink
Mating Socket
PC Board
#8 Screw
#8 .375"
Hex Spacer
#8 1.00"
Hex Standoff
#6 Screw
Figure 1
ASSEMBLY HINTS
The mating sockets included with this kit have recessed nut
sockets for mounting the device under evaluation. This allows
assembly from one side of the heatsink, making it easy to swap
devices under evaluation. The sizes of the stand-offs were se-
lected to allow proper spacing of the board-to-heatsink and allow
enough height for components when the assembly is inverted.
PARTS LIST
Part #
Description
Quantity
HS11
Heatsink
1
EK21PC
PC Board
1
MS03
Mating Socket
2
HWRE01
Hardware Kit
1
TW03
Thermal Washer
1 Box/10
HWRE01 contains the following:
4
#8 Panhead Screw
4
#6 x 1.25" Panhead Screw
4
#8 .375" Hex Spacer
4
#6 x 5/16" Hex Nut
4
#8 1.00" Hex Stand Off
2
#6 x 1/4" Hex Nut
H T T P : / / W W W . A P E X M I C R O T E C H . C O M ( 8 0 0 ) 5 4 6 - A P E X ( 8 0 0 ) 5 4 6 - 2 7 3 9
M I C R O T E C H N O L O G Y
EVALUATION KIT FOR PA21 PIN-OUT
EK21
APEX MICROTECHNOLOGY CORPORATION TELEPHONE (520) 690-8600 FAX (520) 888-3329 ORDERS (520) 690-8601 EMAIL prodlit@apexmicrotech.com
TYPICAL COMPONENT FUNCTIONS
COMPONENT
FUNCTION
R1
Feedback resistor, A side
R2
Input resistor, B side, bridge mode
R3
Feedback resistor, B side
R4
Input resistor, B side
R5
Input resistor, A side
R6
Input bias current measurement
(Note 4)
R7
Output current sense resistor or
loop for current probe
R8
Output current sense resistor or
loop for current probe
R9
Input bias current measurement
(Note 4)
R10
Noise gain compensation
(Note 1)
R11
Resistor divider network for
single supply bias (Note 2)
R12
Resistor divider network for
single supply bias (Note 2)
R13
Noise gain compensation
(Note 1)
R14
Input bias current measurement
R15
Input bias current measurement
R16
Resistor divider network for
single supply bias (Note 2)
R17
Resistor divider network for
single supply bias (Note 2)
C1
Input coupling
C2
AC gain set
C3
AC gain or stability (Note 1)
C4
Power supply bypass
C5
Power supply bypass
C6
AC gain or stability (Note 1)
C7
AC gain set
C8
Input coupling
C9
Noise gain compensation
(Note 1)
C10
Noise gain compensation
(Note 1)
C11
Power supply bypass (Note 3)
C12
Power supply bypass (Note 3)
D1,2,3,4
Flyback protection (Note 5)
C13-16
Bias node noise bypass (Note 2)
EK21
EVALUATION KIT
FOR PA21 PIN-OUT
2
1
13
3
4
C1
C2
R5
C15
C16
R17
R14
R6
A
C11
C12
D3
D1
R12
R13
C10
C4 C5
C3
R1
R2
J1
R8
R7
D2
B
D4
R3
C6
C7
C8
R4
R10
C9
R11
R16
C13
C14
6
8
9
10
R9
R15
7
+V
S
V
S
V
S
+V
S
A
B
Figure 2
NOTES: Refer to the following sections of the APEX DATA BOOK
as noted.
1.
See Stability section of "General Operating Considerations."
2.
See "Gen. Operating Considerations," and AN3 "Bridge Circuit Drives."
3.
See Power Supplies section of "General Operating Considerations."
4.
See "Parameter Definitions and Test Methods."
5.
See Amplifier Protection section of "Gen. Operating Considerations."
Figure 3. (Actual size 6" x 8")
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
EK21
1
3
R5
R14
R6
A
C11
C12
D3
D1
C4 C5
R1
R2
J1
R8
R7
D2
B
D4
R3
9
R9
R15
B
A
V
IN
+V
S
V
S
+V
S
V
S
Figure 4
Dual
Supply
Bridge
EVALUATION KIT
FOR PA 21 PIN-OUT
HS11 HEATSINK NOTE
The HS11 Heatsink is provided in this evaluation kit to guarantee adequate thermal design through heat removal from the part under
evaluation. Once maximum power dissipation for the application is determined (refer to "General Operating Considerations" and
Application Note 11 in the APEX DATA BOOK), the final mechanical design will probably require substantially less heatsinking.
APEX MICROTECHNOLOGY makes no representation that the use or interconnection of the circuits described herein will not infringe
on existing or future patent rights, nor do the descriptions contained herein imply the granting of licenses to make, use or sell equipment
constructed in accordance therewith.
equal to R3 to configure the slave amplifier as a unity gain inverter.
Figure 5 shows a typical single supply bridge circuit for an AC
coupled input signal. DC coupled inputs may require a different
topology to accommodate proper gain and offset terms for a desired
transfer function.
The gain and output voltage capability for the single supply bridge
are determined the same way as the dual supply bridge (see AN#2).
The difference is the bias requirement for the slave amplifier. The
noninverting input of the slave amplifier should be biased at mid
supply, and must be bypassed.
2
1
13
3
C1
R5
C15
C16
R17
R14
R6
A
D3
D1
R12
C4 C5
R1
R2
J1
R8
R7
D2
B
D4
R3
R9
R15
4
+V
S
+V
S
+V
S
A
B
Figure 5
Single
Supply
Bridge
should be shorts. The available output voltage swing is Vss
(2*Vsat). If operating a PA21A at 3 Amps and 30 Volts total supply
this translates to:
V
AB
(max) = 30(2*3.5) = 23
Of course this 23 volts may be applied in either direction across
the load. To set the gain of the circuit you must determine the
desired voltage across the load at Vin = full scale. Inserting these
values into the following equation will yield the ratio of R1 to R5.
(V
AB
/(2*Vin)) = R1/R5
The values of R 1,2,3, and 5 should be chosen such that input bias
current will not cause an error voltage that is unacceptable. Set R2
BRIDGE MODE OPERATION
There are two types of bridge mode operation that will be covered
in this section; dual (or split) supply and single supply. The PA21 is
well suited for both types of bridge mode operation. If another
vendor's pin compatible part is to be compared to the PA21, a close
look at output swing and input common mode range is in order. The
features that make the PA21 an excellent choice for bridge opera-
tion are not included in most other amplifiers. A lack of common
mode range may cause permanent damage to other pin compatible
parts and the inability of other amplifiers to swing close to the supply
rails may cause a lack of available output voltage at the load as well
as increase internal dissipation.
The circuit shown in Figure 4 is a dual supply bridge using the
"master-slave" configuration. Resistors R 6,7,8,9,14,15 and J1
This data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. All specifications are subject to change without notice.
EK21U REV. G DECEMBER 1997
1997 Apex Microtechnology Corp.
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