PA61 Просмотр технического описания (PDF) - Apex Microtechnology

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PA61

Power Operational Amplifiers

Apex Microtechnology 

PA61 • PA61A

Product Innova tionFrom

GENERAL

Please read Application Note 1 "General Operating Consider-

ations" which covers stability, supplies, heat sinking, mounting,

current limit, SOA interpretation, and specification interpretation.

Visit www.Cirrus.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 informa-

tion 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 Precision Power product models,

consult the "Evaluation Kit" section for details. For the most

current version of all Apex Precision Power product data sheets,

visit www.Cirrus.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.

SAFE OPERATING AREA (SOA)

10

8.0

6.0

4.0

3.0

2.0

TTCTCC===1822555°°°CCC

1.5

t = 1ms

1.0

.8

.6

.4

.3

.2

.1

10

15

20 25 30

40 50 60 70 80 90

SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE VS – VO (V)

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 analytical efforts.

1. Under transient conditions, capacitive and dynamic* induc-

tive loads up to the following maximum are safe:

CAPACITIVE LOAD

VS

45V

ILIM = 5A ILIM = 10A

200 F

150 F

INDUCTIVE LOAD

ILIM = 5A ILIM = 10A

8mH

2.8mH

40V

400 F

200 F

35V

800 F

400 F

11mH

20mH

4.3mH

5.0mH

30V 1600 F 800 F

35mH 6.2mH

25V 5.0mF 2.5mF

20V

10mF

5.0mF

15V

20mF

10mF

50mH

400mH

**

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

30V

0.5A

1.6A

2.0A

25V

1.2A

2.4A

20V

1.5A

15V

2.0A

3.0A

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.

4

PA61U

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