PA51A(2000) Просмотр технического описания (PDF) - Apex Microtechnology
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PA51A Datasheet PDF : 4 Pages
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PA51 • PA51A
OPERATING
CONSIDERATIONS
GENERAL
Please read Application Note 1 "General Operating Consid-
erations" which covers stability, supplies, heat sinking, mount-
ing, current limit, SOA interpretation, and specification inter-
pretation. Visit www.apexmicrotech.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. 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 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.
10
7.0
5.0
3.0
THERMAL
T
C
T
C
=
= 25°C
85°C
2.0
T
C
=
125°C
1.5
1.0
0.7
0.5
0.3
0.2
5
7
10
15 20
30 40 50 70 80
SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE VS –VO (V)
The SOA curves combine the effect of 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 exten-
sive analytical efforts.
1. Under transient conditions, capacitive and dynamic* induc-
tive loads up to the following maximums are safe:
CAPACITIVE LOAD
±VS
ILIM = 5A ILIM = 10A
40V
400µF 200µF
35V
800µF 400µF
30V 1,600µF 800µF
25V
5.0mF 2.5mF
20V
10mF
5.0mF
15V
20mF
10mF
INDUCTIVE LOAD
ILIM = 5A
11mH
20mH
35mH
50mH
400mH
**
ILIM = 10A
4.3mH
5.0mH
6.2mH
15mH
20mH
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.
CURRENT LIMIT
Proper operation requires the use of two current limit
resistors, connected as shown in the external connection
diagram. The minimum value for RCL is .06 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.
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.
PA51U REV. L FEBRUARY 2000 © 2000 Apex Microtechnology Corp.
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