OPERATING
CONSIDERATIONS
PA61 • PA61A
1. Under transient conditions, capacitive and dynamic* induc-
tive loads up to the following maximum are safe:
CAPACITIVE LOAD
INDUCTIVE LOAD
V
S
I
LIM
= 5A
I
LIM
= 10A
I
LIM
= 5A
I
LIM
= 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 I
LIM
= 10A or 15V below the supply rail with
I
LIM
= 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 T
C
=85°C.
SHORT TO V
S
±
SHORT TO
C, L, OR EMF LOAD
COMMON
±V
S
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.
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.
�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½
�½
�½�½�½�½�½�½
�½
�½�½�½�½
�½�½
�½�½�½
�½�½�½
�½�½�½
�½�½�½
�½�½�½
�½�½�½
�½�½�½
�½�½
�½�½
�½�½
�½�½
�½�½
�½�½
�½�½
�½�½
�½�½
�½�½ �½�½
�½�½
�½�½ �½�½ �½�½ �½�½ �½�½
�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½
�½
�½�½�½�½
�½
�½�½�½�½
�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½�½
�½�½�½
�½
�½
�½�½
�½�½�½�½�½
�½
�½
�½�½
�½�½�½�½
�½
�½
�½
�½�½
�½�½�½�½
�½�½
�½�½
�½
�½
�½�½
�½
�½�½
�½
�½�½�½
�½�½�½
�½�½
�½
�½
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.
This data sheet has been carefully checked and is believed to be reliable,
SHANNON ROAD • TUCSON, ARIZONA 85741
omissions. All specifications are subject
1 (800) 546-2739
APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH
however, no responsibility is assumed for possible inaccuracies
•
or
USA • APPLICATIONS HOTLINE:
to change without notice.
�½�½
�½�½
�½
�½�½
�½�½
�½�½
�½
4
PA61U REV I OCTOBER 2003
© 2003 Apex Microtechnology Corp.
APEX [ CIRRUS LOGIC ]
