POWER DUAL OPERATIONAL AMPLIFIERS
PA21/25/26 • PA21A/25A
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HTTP://WWW.APEXMICROTECH.COM (800) 546-APEX (800) 546-2739
FEATURES
• LOW COST
• WIDE COMMON MODE RANGE —
Includes negative supply
• WIDE SUPPLY VOLTAGE RANGE
Single supply: 5V to 40V
Split supplies: ±2.5V to ±20V
• HIGH EFFICIENCY — |Vs–2.2V| at 2.5A typ
• HIGH OUTPUT CURRENT — 3A min (PA21A)
• INTERNAL CURRENT LIMIT
R2
9K
R3
R4
+28V
10K
10K
• LOW DISTORTION
+28V
R1
5K
APPLICATIONS
R5
10K
–
–
B
+
A
M
• HALF & FULL BRIDGE MOTOR DRIVERS
• AUDIO POWER AMPLIFIER
STEREO — 18W RMS per channel
BRIDGE — 36W RMS per package
• IDEAL FOR SINGLE SUPPLY SYSTEMS
5V — Peripherals
+
1/2 PA21
1/2 PA21
R6
10K
COMMAND
INPUT
0/10V
12V — Automotive
28V — Avionic
FIGURE 1: BIDIRECTIONAL SPEED CONTROL FROM
A SINGLE SUPPLY
DESCRIPTION
The amplifiers areespecially well-suited for this application.
The extended common mode range allows command inputs
aslowas0V.Itssuperioroutputswingabilitiesletitdrivewithin
2V of supply at an output current of 2A. This means that a
command input that ranges from 0V to 10V will drive a 24V
motor from full scale CCW to full scale CW at up to ±2A. A
single power op amp with an output swing capability of Vs –6
would require ±30V supplies and would be required to swing
48V p-p at twice the speed to deliver an equivalent drive.
The amplifiers consist of a monolithic dual power op amp
in a 8-pin hermetic TO-3 package (PA21 and PA25) and a 12-
pin SIP package (PA26). Putting two power op amps in one
package and on one die results in an extremely cost effective
solution for applications requiring multiple amplifiers per
board or bridge mode configurations.
The wide common mode input range includes the negative
rail, facilitating single supply applications. It is possible to
have a “ground based” input driving a single supply amplifier
with ground acting as the “second” or “bottom” supply of the
amplifier.
EXTERNAL CONNECTIONS
The output stages are also well protected. They possess
internal current limit circuits. While the device is well pro-
tected, the Safe Operating Area (SOA) curve must be ob-
served. Proper heatsinking is required for maximum reliabil-
ity.
This hybrid integrated circuit utilizes thick film (cermet)
resistors, ceramic capacitors and semiconductor chips to
maximize reliability, minimize size and give top performance.
Ultrasonically bonded aluminum wires provide reliable inter-
connections at all operating temperatures. The 8-pin TO-3
package is hermetically sealed and electrically isolated. The
use of compressible isolation washers voids the warranty.
The tab of the SIP12 plastic package is tied to –VS.
PA26
Connect pins
3 and 10 to pin 7
andconnectpins
4 and 9 to pin 6
unless special
functions are re-
quired.
+
–
+
–
A
B
SUB
1
2
3
4
5
6
7
8
9
10 11 12
+VS
2
TYPICAL APPLICATION
+VS
2
+IN, A
3
OUT, A
1
R1 and R2 set up amplifier A in a non-inverting gain of 2.8.
Amp B is set up as a unity gain inverter driven from the output
of amp A. Note that amp B inverts signals about the reference
node,whichissetatmid-supply(14V)byR5andR6.Whenthe
command input is 5V, the output of amp A is 14V. Since this is
equaltothereferencenodevoltage,theoutputofampBisalso
14V, resulting in 0V across the motor. Inputs more positive
than5Vresultinmotorcurrentflowfromlefttoright(seeFigure
1). Inputs less positive than 5V drive the motor in the opposite
direction.
3
–IN, A
OUT, B
1
A
B
–IN, A
4
4
–
+
+IN, A
A
B
+
–
5
5
8
+IN, B
TOP VIEW
8
OUT, A
OUT, B
6
–IN, B
6
–VS
7
–VS
–IN, B
PA21
7
PA25
+IN, B
APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com