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FEATURES
• WIDE SUPPLY RANGE — ±10 to ±45V
• HIGH OUTPUT CURRENT — ±10A Peak
• LOW COST — Class “C” output stage
• LOW QUIESCENT CURRENT — 3mA
APPLICATIONS
• PROGRAMMABLE POWER SUPPLY
• MOTOR/SYNCRO DRIVER
• VALVE AND ACTUATOR CONTROL
• DC OR AC POWER REGULATOR
• FIXED FREQUENCY POWER OSCILLATOR
DESCRIPTION
The PA61 and PA61A are high output current operational
amplifiers designed to drive resistive, inductive and capaci-
tive loads. Their complementary emitter follower output stage
is the simple class C type and optimized for low frequency
applications where crossover distortion is not critical. These
amplifiers are not recommended for audio, transducer or
deflection coil drive circuits above 1kHz or when distortion is
critical. The safe operating area (SOA) is fully specified and
can be observed for all operating conditions by selection of
user programmable current limiting resistors. Both amplifiers
are internally compensated for all gain settings. For continu-
ous operation under load, mounting on a heatsink of proper
rating is recommended.
This hybrid circuit utilizes thick film conductors, ceramic
capacitors, and semiconductor chips to maximize reliabil-
ity, minimize size, and give top performance. Ultrasonically
bonded aluminum wires provide reliable interconnections at
all operating temperatures. The 8-pin TO-3 package is electri-
cally isolated and hermetically sealed. The use of compres-
sible thermal washers and/or improper mounting torque
voids the product warranty. Please see “General Operating
Considerations”.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATION
Due to its high current drive capability, PA61 applications
often utilize remote sensing to compensate IR drops in the wir-
ing. The importance of remote sensing increases as accuracy
requirements, output currents, and distance between ampli-
fier and load go up. The circuit above shows wire resistance
from the PA61 to the load and back to the local ground via
the power return line. Without remote sensing, a 7.5A load
current across only 0.05 ohm in each line would produce a
0.75V error at the load.
With the addition of the second ratio matched RF/RIN pair
and two low current sense wires, IR drops in the power return
line become common mode voltages for which the op amp
has a very high rejection ratio. Voltage drops in the output and
power return wires are inside the feedback loop. Therefore, as
long as the Power Op Amp has the voltage drive capability to
overcome the IR losses, accuracy remains the same. Applica-
tion Note 7 presents a general discussion of PPS circuits.
EXTERNAL CONNECTIONS
8-PIN TO-3
PACKAGE STYLE CE
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PA61 PA61A
PARAMETER TEST CONDITIONS 2 MIN TYP MAX MIN TYP MAX UNITS
INPUT
OFFSET VOLTAGE, initial TC = 25°C ±2 ±6 ±1 ±4 mV
OFFSET VOLTAGE, vs. temperature Specified temperature range ±10 ±65 * ±40 µV/°C
OFFSET VOLTAGE, vs. supply TC = 25°C ±30 ±200 * * µV/V
OFFSET VOLTAGE, vs. power TC = 25°C ±20 * µV/W
BIAS CURRENT, initial TC = 25°C 12 30 10 20 nA
BIAS CURRENT, vs. temperature Specified temperature range ±50 ±500 * * pA/°C
BIAS CURRENT, vs. supply TC = 25°C ±10 * pA/V
OFFSET CURRENT, initial TC = 25°C ±12 ±30 ±5 ±10 nA
OFFSET CURRENT, vs. temperature Specified temperature range ±50 * pA/°C
INPUT IMPEDANCE, DC TC = 25°C 200 * MΩ
INPUT CAPACITANCE TC = 25°C 3 * pF
COMMON MODE VOLTAGE RANGE3 Specified temperature range ±VS–5 ±VS–3 * * V
COMMON MODE REJECTION, DC3 Specified temperature range 74 100 * * dB
GAIN
OPEN LOOP GAIN at 10Hz Full temp. range, full load 96 108 * * dB
GAIN BANDWIDTH PRODUCT at 1MHz TC = 25°C, full load 1 * MHz
POWER BANDWIDTH TC = 25°C, IO = 8A, VO = 40VPP 10 16 * * kHz
PHASE MARGIN Full temperature range 45 * °
OUTPUT
VOLTAGE SWING3 TC = 25°C, IO = 10A ±VS–7 ±VS–5 ±VS–6 * V
VOLTAGE SWING3 Full temp. range, IO = 4A ±VS–6 ±VS–4 * * V
VOLTAGE SWING3 Full temp. range, IO = 68mA ±VS–5 * V
CURRENT TC = 25°C ±10 * A
SETTLING TIME to .1% TC = 25°C, 2V step 2 * µs
SLEW RATE TC = 25°C, RL = 6Ω 1.0 2.8 * * V/µs
CAPACITIVE LOAD, unit gain Full temperature range 1.5 * nF
CAPACITIVE LOAD, gain>4 Full temperature range SOA *
POWER SUPPLY
VOLTAGE Full temperature range ±10 ±32 ±45 * * * V
CURRENT, quiescent TC = 25°C 3 10 * * mA
THERMAL
RESISTANCE, AC, junction to case4 F > 60Hz 1.0 1.2 * * °C/W
RESISTANCE, DC, junction to case F < 60Hz 1.5 1.8 * * °C/W
RESISTANCE, junction to air 30 * °C/W
TEMPERATURE RANGE, case Meets full range specification –25 25 +85 * * * °C
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS SUPPLY VOLTAGE, +VS to –VS 90V
OUTPUT CURRENT, within SOA 10A
POWER DISSIPATION, internal 97W
INPUT VOLTAGE, differential ±VS–3V
INPUT VOLTAGE, common mode ±VS
TEMPERATURE, pin solder-10s 300°C
TEMPERATURE, junction1 200°C
TEMPERATURE RANGE, storage –65 to +150°C
OPERATING TEMPERATURE RANGE, case –55 to +125°C
PA61 • PA61A
NOTES: * The specification of PA61A is identical to the specification for PA61 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. The power supply voltage for all specifications is the TYP rating unless noted as a test condition.
3. +VS and –VS denote the positive and negative supply rail respectively. Total VS is measured from +VS to –VS.
4. Rating applies if the output current alternates between both output transistors at a rate faster than 60Hz.
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
APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
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TYPICAL PERFORMANCE
GRAPHS PA61 • PA61A
APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
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OPERATING
CONSIDERATIONS
PA61 • PA61A
GENERAL
Please read Application Note 1 "General Operating Con-
siderations" which covers stability, supplies, heat sinking,
mounting, current limit, SOA interpretation, and specification
interpretation. Visit www.apexmicrotech.com for design tools
that help automate tasks such as calculations for stability, in-
ternal power dissipation, current limit and heat sink selection.
The "Application Notes" and "Technical Seminar" sections
contain a wealth of information on specific types of applications.
Package outlines, heat sinks, mounting hardware and other
accessories are located in the "Packages and Accessories"
section. Evaluation Kits are available for most Apex product
models, consult the "Evaluation Kit" section for details. For
the most current version of all Apex product data sheets, visit
www.apexmicrotech.com.
SAFE OPERATING AREA (SOA)
The output stage of most power amplifiers has 3 distinct
limitations:
1. The current handling capability of the transistor geometry
and the wire bonds.
2. The second breakdown effect which occurs whenever the
simultaneous collector current and collector-emitter voltage
exceeds specified limits.
3. The junction temperature of the output transistors.
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. The following guidelines may save extensive analyti-
cal efforts.
1. Under transient conditions, capacitive and dynamic* induc-
tive loads up to the following maximum are safe:
CAPACITIVE LOAD INDUCTIVE LOAD
VS ILIM = 5A ILIM = 10A ILIM = 5A ILIM = 10A
45V 200 F 150 F 8mH 2.8mH
40V 400 F 200 F 11mH 4.3mH
35V 800 F 400 F 20mH 5.0mH
30V 1600 F 800 F 35mH 6.2mH
25V 5.0mF 2.5mF 50mH 15mH
20V 10mF 5.0mF 400mH 20mH
15V 20mF 10mF ** 100mH
* If the inductive load is driven near steady state conditions,
allowing the output voltage to drop more than 8V below the
supply rail with ILIM = 10A or 15V below the supply rail with
ILIM = 5A while the amplifier is current limiting, the inductor
should be capacitively coupled or the current limit must be
lowered to meet SOA criteria.
** Second breakdown effect imposes no limitation but thermal
limitations must still be observed.
2. The amplifier can handle any EMF generating or reactive
load and short circuits to the supply rail or shorts to common
if the current limits are set as follows at TC=85°C.
SHORT TO VS ± SHORT TO
±VS C, L, OR EMF LOAD COMMON
45V 0.1A 1.3A
40V 0.2A 1.5A
35V 0.3A 1.6A
30V 0.5A 2.0A
25V 1.2A 2.4A
20V 1.5A 3.0A
15V 2.0A 4.0A
These simplified limits may be exceeded with further analysis
using the operating conditions for a specific application.
3. The output stage is protected against transient flyback.
However, for protection against sustained, high energy flyback,
external fast-recovery diodes should be used.
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.
PA61U REV I OCTOBER 2003 © 2003 Apex Microtechnology Corp.
