POWER DUAL OPERATIONAL AMPLIFIERS

PA21/25/26 • PA21A/25A
M I C R O T E C H N O L O G Y HTTP://WWW.APEXMICROTECH.COM (800) 546-APEX (800) 546-2739

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)
R2 R3
• INTERNAL CURRENT LIMIT +28V
• LOW DISTORTION 9K 10K
+28V R4
10K
APPLICATIONS R1
– – R5
10K
• HALF & FULL BRIDGE MOTOR DRIVERS 5K A M B
+ +
• AUDIO POWER AMPLIFIER 1/2 PA21 1/2 PA21
STEREO — 18W RMS per channel R6
BRIDGE — 36W RMS per package COMMAND 10K
INPUT
• IDEAL FOR SINGLE SUPPLY SYSTEMS 0/10V
5V — Peripherals
12V — Automotive
28V — Avionic FIGURE 1: BIDIRECTIONAL SPEED CONTROL FROM
A SINGLE SUPPLY
DESCRIPTION
The amplifiers are especially well-suited for this application.
The amplifiers consist of a monolithic dual power op amp The extended common mode range allows command inputs
in a 8-pin hermetic TO-3 package (PA21 and PA25) and a 12- as low as 0V. Its superior output swing abilities let it drive within
pin SIP package (PA26). Putting two power op amps in one 2V of supply at an output current of 2A. This means that a
package and on one die results in an extremely cost effective command input that ranges from 0V to 10V will drive a 24V
solution for applications requiring multiple amplifiers per motor from full scale CCW to full scale CW at up to ±2A. A
board or bridge mode configurations. single power op amp with an output swing capability of Vs –6
The wide common mode input range includes the negative would require ±30V supplies and would be required to swing
rail, facilitating single supply applications. It is possible to 48V p-p at twice the speed to deliver an equivalent drive.
have a “ground based” input driving a single supply amplifier
with ground acting as the “second” or “bottom” supply of the
amplifier. EXTERNAL CONNECTIONS
The output stages are also well protected. They possess
internal current limit circuits. While the device is well pro- PA26
tected, the Safe Operating Area (SOA) curve must be ob-
Connect pins
served. Proper heatsinking is required for maximum reliabil- 3 and 10 to pin 7
ity. and connect pins + +
This hybrid integrated circuit utilizes thick film (cermet) 4 and 9 to pin 6 A B
resistors, ceramic capacitors and semiconductor chips to – SUB –
unless special
maximize reliability, minimize size and give top performance. functions are re-
Ultrasonically bonded aluminum wires provide reliable inter- quired.
connections at all operating temperatures. The 8-pin TO-3 1 2 3 4 5 6 7 8 9 10 11 12

package is hermetically sealed and electrically isolated. The

+IN A
–IN A
VBOOST/+VS
ISENSE/–VS
OUT A
–VS
+VS
OUT B
ISENSE/–VS
VBOOST/+VS
–IN B
+IN B

use of compressible isolation washers voids the warranty.

The tab of the SIP12 plastic package is tied to –VS.

TYPICAL APPLICATION +VS

+VS
+IN, A 2 2
R1 and R2 set up amplifier A in a non-inverting gain of 2.8. OUT, B –IN, A 3 OUT, A
3
Amp B is set up as a unity gain inverter driven from the output 1 1
A
of amp A. Note that amp B inverts signals about the reference –IN, A
4 4
node, which is set at mid-supply (14V) by R5 and R6. When the – + +IN, A
command input is 5V, the output of amp A is 14V. Since this is A B B
equal to the reference node voltage, the output of amp B is also + –
5
14V, resulting in 0V across the motor. Inputs more positive 5
OUT, A TOP VIEW 8 +IN, B 8
than 5V result in motor current flow from left to right (see Figure OUT, B
–VS 6 –IN, B 6
1). Inputs less positive than 5V drive the motor in the opposite 7 –IN, B 7
direction. PA25 +IN, B PA21 –VS

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 ABSOLUTE MAXIMUM RATINGS
PA21/25/26 • PA21A/25A SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS SUPPLY VOLTAGE, total 5V to 40V

OUTPUT CURRENT SOA
POWER DISSIPATION, internal (per amplifier) 25W
POWER DISSIPATION, internal (both amplifiers) 36W
INPUT VOLTAGE, differential ±VS
INPUT VOLTAGE, common mode +VS, -VS–.5V
JUNCTION TEMPERATURE, max1 150°C
TEMPERATURE, pin solder—10 sec max 300°C
TEMPERATURE RANGE, storage –65°C to 150°C
OPERATING TEMPERATURE RANGE, case –55°C to 125°C

SPECIFICATIONS PA21/25/26 PA21A/PA25A

PARAMETER TEST CONDITIONS 2 MIN TYP MAX MIN TYP MAX UNITS

INPUT
OFFSET VOLTAGE, initial 1.5 10 .5 4 mV
OFFSET VOLTAGE, vs. temperature Full temperature range 15 10 µV/°C
BIAS CURRENT, initial 35 1000 * 250 nA
COMMON MODE RANGE Full temperature range –VS–.3 +VS–2 * * V
COMMON MODE REJECTION, DC Full temperature range 60 85 * * dB
POWER SUPPLY REJECTION Full temperature range 60 80 * * dB
CHANNEL SEPARATION IOUT = 1A, F = 1kHz 50 68 * * dB

GAIN
OPEN LOOP GAIN Full temperature range 80 100 * * dB
GAIN BANDWIDTH PRODUCT AV = 40dB 600 * kHz
PHASE MARGIN Full temperature range 65 * °
POWER BANDWIDTH VO(P-P) = 28V 13.6 * kHz

OUTPUT
CURRENT, peak 2.5 3 A
CURRENT, limit 3.0 4.0 A
SLEW RATE .5 1.2 * * V/µs
CAPACITIVE LOAD DRIVE AV = 1 .22 * µF
VOLTAGE SWING Full temp. range, IO = 100mA |VS| –1.0 |VS| –0.8 * * V
VOLTAGE SWING Full temp. range, IO = 1A |VS| –1.8 |VS| –1.4 * * V
VOLTAGE SWING IO = 2.5A (PA21, 25) |VS| –3.0 |VS| –2.8 V
VOLTAGE SWING IO = 3.0A (PA21A, PA25A) |VS| –4.0 |VS| –3.5 V

POWER SUPPLY
VOLTAGE, VSS3 54 30 40 * * * V
CURRENT, quiescent, total 45 90 * * mA

THERMAL
RESISTANCE, junction to case
DC, single amplifier 5.0 * °C/W
DC, both amplifiers5 3.4 * °C/W
AC, single amplifier 3.7 °C/W
AC, both amplifiers5 2.4 °C/W
RESISTANCE, junction to air 30 * °C/W
TEMPERATURE RANGE, case Meets full range specifications –25 85 –25 85 °C

NOTES: * The specification of PA21A/PA25A is identical to the specification for PA21/PA25 in applicable column to the left.
1. Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation
to achieve high MTTF.
2. Unless otherwise noted, the following conditions apply: ±VS = ±15V, TC = 25°C.
3. +VS and –VS denote the positive and negative supply rail respectively. VSS denotes the total rail-to-rail supply voltage.
4. Current limit may not function properly below VSS = 6V, however SOA violations are unlikely in this area.
5. Rating applies when power dissipation is equal in the two amplifiers.
The internal substrate contains beryllia (BeO). Do not break the seal. If accidentally broken, do not crush, machine, or
CAUTION subject to temperatures in excess of 850°C to avoid generating toxic fumes. (PA21 and PA25 only. PA26 does not contain
BeO).

APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
TYPICAL PERFORMANCE
GRAPHS PA21/25/26 • PA21A/25A

POWER DERATING BIAS CURRENT CROSSTALK

INTERNAL POWER DISSIPATION, P(W)

NORMALIZED BIAS CURRENT, I B (X)

40 1.75 80

35
1.5 75 AMP 1
30 I OUT = 1A

CROSSTALK (dB)
BOTH 1.25 70 AV = –100
25 AMPLIFIERS
20 1.0 65
15 SINGLE AMP 2
AMPLIFIER .75 60 I OUT = 0
10 AV = –100
.5 55
5
0 .25 50
0 25 50 75 100 125 150 –50 –25 0 25 50 75 100 125 10 100 1K 10K 20K
TEMPERATURE, T (°C) CASE TEMPERATURE, TC (°C) FREQUENCY, F (Hz)

SMALL SIGNAL RESPONSE PHASE RESPONSE POWER RESPONSE

100 0 50
40

OUTPUT VOLTAGE, VO (VPP )

–30
OPEN LOOP GAIN, A (dB)

80
30
–60
60 25
PHASE, ϕ (°)

–90 20
40
–120 15

20
–150 10
0 |+VS | + |–VS | = 40V
–180

–20 –210 5
1 10 100 1K 10K 100K 1M 0 10 100 1K 10K .1M 1M 1K 10K 100K
FREQUENCY, F (Hz) FREQUENCY, F (Hz) FREQUENCY, F (Hz)

POWER SUPPLY REJECTION PULSE RESPONSE CURRENT LIMIT

POWER SUPPLY REJECTION, PSR (dB)

NORMALIZED CURRENT LIMIT, I LIM (A)

89 1.6
AV = 1
86 10
R L =10 Ω
OUTPUT VOLTAGE, VO (V)

1.4
83
80 5
1.2
77
74 0 1.0
71
–5 .8
69
66
.6
63 –10
60 .4
0 10 100 1K 10K 100K 1M 0 200 400 600 800 1K –50 –25 0 25 50 75 100 125
FREQUENCY, F (Hz) TIME, t (µs) CASE TEMPERATURE, TC (°C)
TOTAL HARMONIC DISTORTION, THD (%)

HARMONIC DISTORTION QUIESCENT CURRENT OUTPUT VOLTAGE SWING

3 125
VOLTAGE DROP FROM SUPPLY, (V)

40 3.5
TOTAL SUPPLY VOLTAGE, VSS (V)

AV = –10
CASE TEMPERATURE, TC (°C)

1 V OUT = 16VPP 35 100 3

RL = 8Ω
30 75 2.5

.1 25 50 2

20 25 1.5

.01 15 0 1

10 –25 .5

.001 5 –50 0
10 100 1K 10K 40K .7 .8 .9 1 1.1 1.2 1.3 1.4 0 .5 1 1.5 2 2.5 3 3.5
FREQUENCY, F (Hz) NORMALIZED QUIESCENT CURRENT, I Q (X) OUTPUT CURRENT, I O (A)

APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
 OPERATING
PA21/25/26 • PA21A/25A CONSIDERATIONS

GENERAL
Please read Application Note 1 "General Operating Consid- * If the inductive load is driven near steady state conditions,
erations" which covers stability, supplies, heat sinking, mount- allowing the output voltage to drop more than 6V below the
ing, current limit, SOA interpretation, and specification inter- supply rail while the amplifier is current limiting, the inductor
pretation. Visit www.apexmicrotech.com for design tools that should be capacitively coupled or the supply voltage must be
help automate tasks such as calculations for stability, internal lowered to meet SOA criteria.
power dissipation, current limit and heat sink selection. The
"Application Notes" and "Technical Seminar" sections contain NOTE: For protection against sustained, high energy flyback,
a wealth of information on specific types of applications. external fast-recovery diodes should be used.
Package outlines, heat sinks, mounting hardware and other
accessories are located in the "Packages and Accessories" MONOLITHIC AMPLIFIER
section. Evaluation Kits are available for most Apex product STABILITY CONSIDERATIONS
models, consult the "Evaluation Kit" section for details. For the
most current version of all Apex product data sheets, visit All monolithic power op amps use output stage topologies
www.apexmicrotech.com. that present special stability problems. This is primarily due to
non-complementary (both devices are NPN) output stages
4 with a mismatch in gain and phase response for different
3 polarities of output current. It is difficult for the op amp manu-
OUTPUT CURRENT FROM +V S OR –VS (A)

EA
CH facturer to optimize compensation for all operating conditions.
2 ,O
1

EA The recommended R-C network of 1 ohm in series with

m

CH NE
s

,B
OT
LO 0.1µF from output to AC common (ground or a supply rail, with
AD
1 H
LO ED adequate bypass capacitors) will prevent local output stage
AD oscillations.
ED
This network is provided internally on the PA21 but must be
supplied externally on the PA25 and PA26. The amplifiers are
internally compensated for unity gain stability, no additional
compensation is required.

THERMAL CONSIDERATIONS
T C = 25°C
Although R θJC is the same for PA21/25/26 there are differ-
.1
1 2 3 4 5 6 10 20 30 40 50 ences in the thermal interface between case and heatsink
SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE V S –VO (V) which will limit power dissipation capability. Thermal grease or
an Apex TW03 thermal washer, R θCS = .1-.2°C/W, is the only
recommended interface for the PA21/25. The PA26 may
CURRENT LIMIT require a thermal washer which is electrically insulating since
the tab is tied to –VS. This can result in thermal impedances for
Current limit is internal to the amplifier, the typical value is R θCS of up to 1°C/W or greater.
shown in the current limit specification.
VBOOST

SAFE OPERATING AREA (SOA)

+VS
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 – IN +IN OUT
loads. The following guidelines may save extensive analytical
efforts.
Under transient conditions, capacitive and dynamic* induc- ISENSE
tive loads up to the following maximum are safe:
RS
±Vs CAPACITIVE LOAD INDUCTIVE LOAD
– VS
20V 200µF 7.5mH FIGURE 2. PA26 EQUIVALENT SCHEMATIC (ONE CHANNEL)
15V 500µF 25mH
10V 5mF 35mH
5V 50mF 150mH

APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: 1 (800) 546-2739
OPERATING
CONSIDERATIONS PA21/25/26 • PA21A/25A

ADDITIONAL PA26 PIN FUNCTIONS

+VS
VBOOST
PA26
The VBOOST pin is the positive terminal for the load of the
second stage of the amplifier. When that terminal is connected
to a voltage greater than +VS it will provide more drive to the
upper output transistor, which is a darlington connected emit- B
VBIAS
R
ter follower. This will better saturate the output transistor.
RL IL
When VBOOST is about 5 Volts greater than +VS the positive R
VIN
output can swing 0.5 Volts closer to the rail. This is as much A
improvement as is possible. RFB
VBOOST pin requires approximately 10–12mA of current. RIN
Dynamically it represents 1K Ω impedance. The maximum
voltage that can be applied to VBOOST is 40 volts with respect to
–VS . There is no limit to the difference between +VS and VBOOST. RS RIN
RS RFB
+VS ≤ 20V
DB1 DB2 –VS OR GND VREF

7 3 10
FIGURE 4. ISENSE TRANSCONDUCTANCE BRIDGING
CB1
AMPLIFIER
PA26A 5 Figure 4 shows the PA26 ISENSE feature being used to obtain
a Transconductance function. In this example, amplifier "A" is
CB2 SPEAKER the master and amplifier "B" is the slave. Feedback from
sensing resistors RS is applied to the summing network and
PA26B 8 scaled to the inverting input of amplifier "A" where it is com-
pared to the input voltage. The current sensing feedback
imparts a Transconductance feature to the amplifiers transfer
FIGURE 3. SIMPLE BOOTSTRAPPING IMPROVES POSITIVE
OUTPUT SWING. CONNECT PINS 3 AND 10 TO VS IF NOT function. In other words, the voltage developed across the
USED. TYPICAL CURRENTS ARE 12mA EACH. sensing resistors is directly proportional to the output current.
Using this voltage as a feedback source allows expressing the
Figure 3 shows a bootstrap which dynamically couples the gain of the circuit in amperes vs input voltage. The transfer
output waveform onto the VBOOST pin. This causes VBOOST to funcion is approximately:
swing positive from it's initial value, which is equal to +VS -0.7 V
(one diode drop), an amount equal to the output. In other
words, if VBOOST was initially 19.3, and the output swings IL= (VIN – VREF) *RIN/ RFB/ Rs
positive 18 Volts, the voltage on the VBOOST pin will swing to 19.3 In the illustration, resistors RIN, RFB and RS determine gain.
-0.7 + 18 or 36.6. The capacitor needs to be sized based on a
1K Ω impedance and the lowest frequency required by the VBIAS should be set midway between +Vs and -Vs, Vref is
circuit. For example, 20Hz will require > 8uF. usually ground in dual supply systems or used for level
translation in single supply systems.
ISENSE
MOUNTING PRECAUTIONS
The ISENSE pin is in series with the negative half of the output
stage only. Current will flow through this pin only when nega- 1. Always use a heat sink. Even unloaded, the PA26 can
tive current is being outputted. The current that flows in this pin dissipate up to 3.6 watts. A thermal washer or thermal
is the same current that flows in the output (if –1A flows in the grease should always be used.
output, the ISENSE pin will have 1A of current flow, if +1A flows 2. Avoid bending the leads. Such action can lead to internal
in the output the ISENSE pin will have 0 current flow). damage.
The resistor choice is arbitrary and is selected to provide 3. Always fasten the tab to the heat sink before the leads are
whatever voltage drop the engineer desires, up to a maximum soldered to fixed terminals.
of 1.0 volt. However, any voltage dropped across the resistor 4. Strain relief must be provided if there is any probability of
will subract from the swing to rail. For instance, assume a +/– axial stress to the leads.
12 volt power supply and a load that requires +/–1A. With no
current sense resistor the output could swing +/–10.2 volts. If
a 1 Ω resistor is used for current sense (which will drop 1 Volt
at 1 Amp) then the output could swing +10.2, –9.2 Volts.

APEX MICROTECHNOLOGY
This data CORPORATION
sheet has been carefully checked • TELEPHONE
and is believed to be reliable,(520) 690-8600
however, • FAXis(520)
no responsibility assumed888-3329
for possible •inaccuracies
ORDERS (520) 690-8601
or omissions. • EMAILare
All specifications prodlit@apexmicrotech.com
subject to change without notice.
PA21/25/26U REV. G FEBRUARY 2000 © 2000 Apex Microtechnology Corp.