APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com

FEATURES

• LOW COST

• WIDE COMMON MODE RANGE —

Includes negative supply

• WIDE SUPPLY VOLTAGE RANGE

Single supply: 5V to 40V

Split supplies:

±2.5V to ±20V

• HIGH EFFICIENCY — |Vs–2.2V| at 2.5A typ

• HIGH OUTPUT CURRENT — 3A min (PA21A)

• INTERNAL CURRENT LIMIT

• LOW DISTORTION

APPLICATIONS

• HALF & FULL BRIDGE MOTOR DRIVERS

• AUDIO POWER AMPLIFIER

STEREO — 18W RMS per channel

BRIDGE — 36W RMS per package

• IDEAL FOR SINGLE SUPPLY SYSTEMS

5V — Peripherals

12V — Automotive

28V — Avionic

DESCRIPTION

The amplifiers consist of a monolithic dual power op amp

in a 8-pin hermetic TO-3 package (PA21 and PA25) and a 12-

pin SIP package (PA26). Putting two power op amps in one

package and on one die results in an extremely cost effective

solution for applications requiring multiple amplifiers per

board or bridge mode configurations.

The wide common mode input range includes the negative

rail, facilitating single supply applications. It is possible to

have a “ground based” input driving a single supply amplifier

with ground acting as the “second” or “bottom” supply of the

amplifier.

The output stages are also well protected. They possess

internal current limit circuits. While the device is well pro-

tected, the Safe Operating Area (SOA) curve must be ob-

served. Proper heatsinking is required for maximum reliabil-

ity.

This hybrid integrated circuit utilizes thick film (cermet)

resistors, ceramic capacitors and semiconductor chips to

maximize reliability, minimize size and give top performance.

Ultrasonically bonded aluminum wires provide reliable inter-

connections at all operating temperatures. The 8-pin TO-3

package is hermetically sealed and electrically isolated. The

use of compressible isolation washers voids the warranty.

The tab of the SIP12 plastic package is tied to –V

TYPICAL APPLICATION

R1 and R2 set up amplifier A in a non-inverting gain of 2.8.

Amp B is set up as a unity gain inverter driven from the output

of amp A. Note that amp B inverts signals about the reference

node, which is set at mid-supply (14V) by R5 and R6. When the

command input is 5V, the output of amp A is 14V. Since this is

equal to the reference node voltage, the output of amp B is also

14V, resulting in 0V across the motor. Inputs more positive

than 5V result in motor current flow from left to right (see Figure

1). Inputs less positive than 5V drive the motor in the opposite

direction.

EXTERNAL CONNECTIONS

PA25

PA21

PA26

The amplifiers are especially well-suited for this application.

The extended common mode range allows command inputs

as low as 0V. Its superior output swing abilities let it drive within

2V of supply at an output current of 2A. This means that a

command input that ranges from 0V to 10V will drive a 24V

motor from full scale CCW to full scale CW at up to

±2A. A

single power op amp with an output swing capability of Vs –6

would require

±30V supplies and would be required to swing

48V p-p at twice the speed to deliver an equivalent drive.

A

B

1

2

3

4

5

6

7

8

+V

S

+IN, A

–IN, A

OUT, A

–V

S

+IN, B

–IN, B

OUT, B

TOP VIEW

–

+

–

+

A

1

2

3

4

5

6

7

8

+V

S

–IN, A

+IN, A

+IN, B

–IN, B

–V

S

OUT, B

OUT, A

B

A

B

M

R2

9K

R3

10K

R4

10K

+28V

1/2 PA21

R1

5K

COMMAND

INPUT

0/10V

1/2 PA21

+28V

R5

10K

R6

10K

+

–

+

–

FIGURE 1: BIDIRECTIONAL SPEED CONTROL FROM

A SINGLE SUPPLY

Connect pins

3 and 10 to pin 7

and connect pins

4 and 9 to pin 6

unless special

functions are re-

quired.

HTTP://WWW.APEXMICROTECH.COM

(800) 546-APEX

(800) 546-2739

MICROTECHNOLOGY

POWER DUAL OPERATIONAL AMPLIFIERS

PA21/25/26 • PA21A/25A

–

+

SUB

–

+

1

2

3

4

5

6789

10

11

12

A

B