PA74-76U
FEATURES
• LOW COST
• WIDE COMMON MODE RANGE —
• WIDE SUPPLY VOLTAGE RANGE
• HIGH EFFICIENCY — |Vs–2.2V| at 2.5A typ
• HIGH OUTPUT CURRENT — 3A
• LOW DISTORTION
APPLICATIONS
• HALF & FULL BRIDGE MOTOR DRIVERS
• AUDIO POWER AMPLIFIER
• IDEAL FOR SINGLE SUPPLY SYSTEMS
DESCRIPTION
stages to achieve the desired input and output characteristics
of the PA74 and PA76. The input stage utilizes a dual power op
amp on a single chip monolithic that drives the output stages.
The output stages are configured in a non inverting unity gain
buffer configuration. The output stages of the amplifier are also
compensated for stability. The PA74 and PA76 dual amplifiers are
designed with both monolithic and hybrid technologies providing
a cost effective solution for applications requiring multiple ampli-
fiers per board or bridge mode configurations. Both amplifiers
are internally compensated but are not recommended for use
as unity gain followers.
film resistors, ceramic capacitors and monolithic amplifiers to
maximize reliability and power handling capability, minimize size
and give top performance. Ultrasonically bonded aluminum wires
provide reliable interconnections 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.
EQUIVALENT SCHEMATIC
+V
-IN
-V
S
The amplifier design consists of dual monolithic input and output
This dual hybrid circuit utilizes a beryllia (BeO) substrate, thick
S
http://www.cirrus.com
Includes negative supply
Single supply: 5V to 40V
Split supplies: ±2.5V to ±20V
STEREO — 30W RMS per channel
BRIDGE — 60W RMS per package
5V — Peripherals, 12V — Automotive
28V — Avionic
PA74, PA76, PA74A, PA76A
+IN
Power Dual Operational Amplifiers
P r o d u c t
I n n o v a t i o n
P r o d u c t I n n o v a t i o n F r o m
F r o m
MONITOR
THERMAL
PROTECT
I BIAS
ONE CHANNEL
CURRENT
GAIN
CURRENT
GAIN
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
OUT
TYPICAL APPLICATION
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, which is set at mid-supply (14V) by R5 and R6. When
the command input is 5V, the output of amp A is 14V. Since
this is equal to the reference node voltage, the output of amp
B is also 14V, resulting in 0V across the motor. Inputs more
positive than 5V result in motor current flow from left to right
(see Figure 1). Inputs less positive than 5V drive the motor in
the opposite direction.
The extended common mode range allows command inputs
as low as 0V. Its superior output swing abilities let it drive
within 2V of supply at an output current of 2A. This means
that a command input that ranges from 0.714V to 9.286V 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.
EXTERNAL CONNECTIONS (TOp viEws)
PA74
+IN, A
COMMAND
+IN, B
R1 and R2 set up amplifier A in a non-inverting gain of 2.8.
The amplifiers are especially well-suited for this application.
INPUT
0/10V
–IN, A
R1
5K
–IN, B
4
5
PA74/PA76 • PA74A/76A
3
6
_
+
FIGURE 1: BIDIRECTIONAL
SPEED CONTROL FROM A
SINGLE SUPPLY.
+28V
+V
A
–V
A
2
B
7
S
1/2 PA74
S
R2
9K
OUT, A
PA74/76 • PA74A/76A
1
OUT, B
8
PA76
M
APEX − PA74-76UREVE
OUT, A
–IN, A
10K
R3
1/2 PA74
4
+IN, A
5
–V
PACKAGE STYLE CE
S
3
6
– +
10K
R4
A
B
+IN, B
8-PIN TO-3
+V
MAY 2009
+
2
_
S
+
7
B
10K
10K
–
R5
R6
OUT, B
+28V
1
–IN, B
8
1