siderations" which covers stability, supplies, heat sinking,
mounting, current limit, SOA interpretation, and specification
interpretation. Visit www.apexanalog.com for design tools that
help automate tasks such as calculations for stability, internal
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. Evalu-
ation Kits are available for most Apex Precision Power product
models, consult the "Evaluation Kit" section for details. For the
most current version of all Apex Microtechnology product data
sheets, visit www.apexanalog.com.
1. For sine wave outputs, use Power Design
1
to plot a load
line. Make sure the load line does not cross the 0.5ms limit
and that excursions beyond any other second breakdown
line do not exceed the time label, and have a duty cycle of
no more than 10%.
For other waveform outputs, manual load line plotting
is recommended. Applications Note 22, SOA AND LOAD
LINES, will be helpful. A Spice type analysis can be very
useful in that a hardware setup often calls for instruments
or amplifiers with wide common mode rejection ranges.
2. EMF generating or reactive load and short circuits to the
supply rail or shorts to common are safe if the current limits
are set as follows at T
C
= 85°C.
±V
S
34V
30V
25V
20V
15V
SHORT TO ±V
S
C, L, OR EMF LOAD
.58A
.46A
.61A
.86A
1.3A
SHORT TO
COMMON
1.1A
1.4A
1.7A
2.1A
2.9A
SAFE OPERATING AREA (SOA)
The output stage of most power amplifiers has three 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.
5.0
4.0
3.0
2.0
1.5
1.0
.8
.6
.4
.3
10
Tc
=8
5°C
12
ste
ad
Tc
=
ys
t=
ta
te
5m
TH
E
RM
5°C
SE
CO
s
t=
t=
1m
0.5
s
ms
BR
E
3. The output stage is protected against occaisional transient
flyback. However, for protection against sustained, high
energy flyback, external fast-recovery diodes should be
used.
AL
ND
CURRENT LIMIT
Proper operation requires the use of two current limit resis-
tors, connected as shown, in the external connection diagram.
The minimum value for R
CL
is 0.12 ohm; however, for optimum
reliability it should be set as high as possible. Refer to the
“General Operating Considerations” section of the handbook
for current limit adjust details.
AK
D
OW
N
PA01 LIMIT
15
20
25
30 35 40
50
60
The SOA curves combine the effect of these limits. 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.
1
Note 1. Power Design is a self-extracting Excel spreadsheet
available free from www.apexanalog.com
4
PA01-73U
PA01 • PA73
NEED TECHNICAL HELP? CONTACT APEX SUPPORT!
For all Apex Microtechnology product questions and inquiries, call toll free 800-546-2739 in North America.
For inquiries via email, please contact apex.support@apexanalog.com.
International customers can also request support by contacting their local Apex Microtechnology Sales Representative.
To find the one nearest to you, go to www.apexanalog.com
IMPORTANT NOTICE
Apex Microtechnology, Inc. has made every effort to insure the accuracy of the content contained in this document. However, the information is subject to change
without notice and is provided "AS IS" without warranty of any kind (expressed or implied). Apex Microtechnology reserves the right to make changes without further
notice to any specifications or products mentioned herein to improve reliability. This document is the property of Apex Microtechnology and by furnishing this informa-
tion, Apex Microtechnology grants no license, expressed or implied under any patents, mask work rights, copyrights, trademarks, trade secrets or other intellectual
property rights. Apex Microtechnology owns the copyrights associated with the information contained herein and gives consent for copies to be made of the informa-
tion only for use within your organization with respect to Apex Microtechnology integrated circuits or other products of Apex Microtechnology. This consent does not
extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.
APEX MICROTECHNOLOGY PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN PRODUCTS USED FOR
LIFE SUPPORT, AUTOMOTIVE SAFETY, SECURITY DEVICES, OR OTHER CRITICAL APPLICATIONS. PRODUCTS IN SUCH APPLICATIONS ARE UNDER-
STOOD TO BE FULLY AT THE CUSTOMER OR THE CUSTOMER’S RISK.
Apex Microtechnology, Apex and Apex Precision Power are trademarks of Apex Microtechnolgy, Inc. All other corporate names noted herein may be trademarks
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