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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
• LOW DISTORTION
APPLICATIONS
• HALF & FULL BRIDGE MOTOR DRIVERS
• AUDIO POWER AMPLIFIER
STEREO — 30W RMS per channel
BRIDGE — 60W RMS per package
• IDEAL FOR SINGLE SUPPLY SYSTEMS
5V — Peripherals, 12V — Automotive
28V — Avionic
DESCRIPTION
The amplifier design consists of dual monolithic input and output
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.
This dual hybrid circuit utilizes a beryllia (BeO) substrate, thick
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 ONE CHANNEL
TYPICAL APPLICATION
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, 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 amplifiers are especially well-suited for this application.
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 PA76
FIGURE 1: BIDIRECTIONAL
SPEED CONTROL FROM A
SINGLE SUPPLY.
8-PIN TO-3
PACKAGE STYLE CE
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ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
PA74/76 • PA74A/PA76A
ABSOLUTE MAXIMUM RATINGS SUPPLY VOLTAGE, total 5V to 40V
OUTPUT CURRENT SOA
POWER DISSIPATION, internal (per amplifier) 36W
POWER DISSIPATION, internal (both amplifiers) 60W
INPUT VOLTAGE, differential ±VS
INPUT VOLTAGE, common mode +VS, -VS–0.5V
JUNCTION TEMPERATURE, max1 150°C
TEMPERATURE, pin solder–10 sec max 300°C
TEMPERATURE RANGE, storage –65°C to 150°C
OPERATING TEMPERATURE RANGE, case –55°C to 125°C
SPECIFICATIONS
PA74/76 PA74A/PA76A
PARAMETER TEST CONDITIONS2 MIN TYP MAX MIN TYP MAX UNITS
INPUT
OFFSET VOLTAGE, initial 1.5 10 .5 7 mV
OFFSET VOLTAGE, vs. temperature Full temperature range 20 10 µV/°C
BIAS CURRENT, initial 100 500 * 250 nA
COMMON MODE RANGE Full temperature range –VS +VS–1.3 * * V
COMMON MODE REJECTION, DC Full temperature range 60 70 * * dB
POWER SUPPLY REJECTION Full temperature range 60 90 * * dB
CHANNEL SEPARATION IOUT = 1A, F = 1kHz 50 70 * * dB
INPUT NOISE VOLTAGE RS = 100Ω, f = 1 to 100KHz
GAIN
OPEN LOOP GAIN Full temperature range 89 100 * * * dB
GAIN BANDWIDTH PRODUCT AV = 40dB 0.9 1.4 * * MHz
POWER BANDWIDTH VO(P-P) = 28V 13.6 * kHz
OUTPUT
CURRENT, peak 2.5 3 A
SLEW RATE 0.5 1.4 * * V/µs
VOLTAGE SWING Full temp. range, IO = 100mA |VS| –1.1 |VS| –0.9 * * V
VOLTAGE SWING Full temp. range, IO = 1A |VS| –2.0 |VS| –1.7 * * V
VOLTAGE SWING IO = 2.5A (PA74, 76) |VS| –3.5 |VS| –2.9 * * V
VOLTAGE SWING IO = 3.0A (PA74A, PA76A) |VS| –4.0 |VS| –3.3 V
POWER SUPPLY
VOLTAGE, VSS3 30 40 * * * V
CURRENT, quiescent, total 18 40 * * mA
THERMAL
RESISTANCE, junction to case
DC, single amplifier 3.2 3.5 * * °C/W
DC, both amplifiers4 1.9 2.1 * * °C/W
AC, single amplifier 2.4 2.6 * * °C/W
AC, both amplifiers4 1.4 1.6 * * °C/W
RESISTANCE, junction to air 30 * * °C/W
TEMPERATURE RANGE, case Meets full range specifications –25 85 –25 85 °C
NOTES: * The specification of PA74A/PA76A is identical to the specification for PA74/PA76 in applicable column to the left.
1. Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation to
achieve high MTTF.
2. Unless otherwise noted, the following conditions apply: ±VS = ±15V, TC = 25°C.
3. +VS and –VS denote the positive and negative supply rail respectively. VSS denotes the total rail-to-rail supply voltage.
4. Rating applies when power dissipation is equal in the two amplifiers.
The internal substrate contains beryllia (BeO). Do not break the seal. If accidentally broken, do not crush, machine, or
subject to temperatures in excess of 850°C to avoid generating toxic fumes.
CAUTION
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TYPICAL PERFORMANCE
GRAPHS PA74/76 • PA74A/PA76A
APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
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OPERATING
CONSIDERATIONS
PA74/76 • PA74A/PA76A
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.
PA74–76U REV C NOVEMBER 2004 © 2004 Apex Microtechnology Corp.
GENERAL
Please read Application Note 1 "General Operating Consider-
ations" which covers stability, supplies, heatsinking, mounting,
SOA interpretation, and specification interpretation. Visit www.
apexmicrotech.com for design tools that help automate tasks
such as calculations for stability, internal power dissipation,
heatsink selection; Apex's complete Application Notes library;
Technical Seminar Workbook; and Evaluation Kits.
STABILITY CONSIDERATIONS
All monolithic power op amps use output stage topologies
that present special stability problems. This is primarily due to
non-complementary (both devices are NPN) output stages with
a mismatch in gain and phase response for different polarities
of output current. It is difficult for the opamp manufacturer to
optimize compensation for all operating conditions.
SAFE OPERATING AREA (SOA)
The SOA curves combine the effect of all limits for this power
op amp. For a given application, the direction and magnitude
of the output current should be calculated or measured and
checked against the SOA curves. This is simple for resistive
loads but more complex for reactive and EMF generating
loads.
THERMAL CONSIDERATIONS
Thermal grease or an Apex TW03 thermal washer, RCS = .1
to .2°C/W, is the only recommended interface for the PA74/76.
Internal power dissipation increases directly with frequency
therefore it is critical to sufficiently heat sink the PA74 and
PA76. Even unloaded the PA74 and PA76 can dissipate up
to 3 watts while running at higher frequencies.
PARALLEL CONFIGURATION CONSIDERATIONS
LOSSES
The PA74 and PA76 utilize a parallel configuration to
achieve the desired current output requirements. The paral-
lel configuration inherently creates internal losses due to
circulating currents. The circulating currents generate power
losses through the current sharing resistors when delivering
current to the load.
SUPPLY CURRENT
The parallel configuration used in the PA74 and PA76 also
generates supply currents while high voltage sign waves
are seen at the output. Listed below are the supply currents
expected while running at a particular frequency and when VO
≈ 15Vpp, note that the outputs are not loaded.
Frequency Supply Current
100Hz 18mA
1KHz 20mA
5KHz 32mA
10KHz 50mA
15KHz 75mA
SATURATION OPERATION
The parallel configuration used in the PA74 and PA76 is
sensitive to operation in the saturation region. The PA74 and
PA76 may exhibit large peak currents; this is mainly due to
thermal protection limitations.
