
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 specication
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 specic 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 ampliers 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 specied 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:
CAPACITIVELOAD INDUCTIVELOAD
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 amplier 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 amplier 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.
SHORTTOVS± SHORTTO
±VS C,L,OREMFLOAD 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 simplied limits may be exceeded with further analysis
using the operating conditions for a specic application.
3. The output stage is protected against transient yback.
However, for protection against sustained, high energy yback,
external fast-recovery diodes should be used.
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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 J OCTOBER 2006 © 2006 Apex Microtechnology Corp.