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)
• INTERNAL CURRENT LIMIT
• LOW DISTORTION
R2
9K
+28V
R1
5K
+
1/2 PA21
COMMAND
INPUT
0/10V
–
A
M
R3
10K
R4
10K
–
B
+
1/2 PA21
R5
10K
+28V
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
R6
10K
FIGURE 1: BIDIRECTIONAL SPEED CONTROL FROM
A SINGLE SUPPLY
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.
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
S
.
EXTERNAL CONNECTIONS
PA26
Connect pins
3 and 10 to pin 7
and connect pins
4 and 9 to pin 6
unless special
functions are re-
quired.
1
2
+
A
–
B
SUB
+
–
3
4
5
6
7
8
9
10
11
12
+IN A
–IN A
–IN B
+V
S
2
OUT A
I
SENSE
/–V
S
OUT B
V
BOOST
/+V
S
I
SENSE
/–V
S
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.
+IN, A
3
–IN, A
4
+V
S
2
V
BOOST
/+V
S
+IN B
OUT, A
1
8
OUT, B
–V
S
+V
S
OUT, B
1
–IN, A
4
3
A
–
+
+IN, A
B
+
–
A
5
OUT, A
TOP VIEW
B
8
–IN, B
5
+IN, B
–IN, B
6
–V
S
6
PA25
7
+IN, B
PA21
7
–V
S
APEX MICROTECHNOLOGY CORPORATION
• TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
PA21/25/26 • PA21A/25A
ABSOLUTE MAXIMUM RATINGS
SUPPLY VOLTAGE, total
OUTPUT CURRENT
POWER DISSIPATION, internal (per amplifier)
POWER DISSIPATION, internal (both amplifiers)
INPUT VOLTAGE, differential
INPUT VOLTAGE, common mode
JUNCTION TEMPERATURE, max
1
TEMPERATURE, pin solder—10 sec max
TEMPERATURE RANGE, storage
OPERATING TEMPERATURE RANGE, case
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
5V to 40V
SOA
25W
36W
±V
S
+V
S
, -V
S
–.5V
150°C
300°C
–65°C to 150°C
–55°C to 125°C
SPECIFICATIONS
PARAMETER
INPUT
OFFSET VOLTAGE, initial
OFFSET VOLTAGE, vs. temperature
BIAS CURRENT, initial
COMMON MODE RANGE
COMMON MODE REJECTION, DC
POWER SUPPLY REJECTION
CHANNEL SEPARATION
GAIN
OPEN LOOP GAIN
GAIN BANDWIDTH PRODUCT
PHASE MARGIN
POWER BANDWIDTH
OUTPUT
CURRENT, peak
CURRENT, limit
SLEW RATE
CAPACITIVE LOAD DRIVE
VOLTAGE SWING
VOLTAGE SWING
VOLTAGE SWING
VOLTAGE SWING
POWER SUPPLY
VOLTAGE, V
SS3
CURRENT, quiescent, total
THERMAL
RESISTANCE, junction to case
DC, single amplifier
DC, both amplifiers
5
AC, single amplifier
AC, both amplifiers
5
RESISTANCE, junction to air
TEMPERATURE RANGE, case
NOTES:
*
1.
2.
3.
4.
5.
5
4
2.5
A
V
= 1
Full temp. range, I
O
= 100mA
Full temp. range, I
O
= 1A
I
O
= 2.5A (PA21, 25)
I
O
= 3.0A (PA21A, PA25A)
Full temperature range
A
V
= 40dB
Full temperature range
V
O(P-P)
= 28V
80
Full temperature range
Full temperature range
Full temperature range
Full temperature range
I
OUT
= 1A, F = 1kHz
–V
S
–.3
60
60
50
TEST CONDITIONS
2
MIN
PA21/25/26
TYP
MAX
PA21A/PA25A
MIN
TYP
MAX
UNITS
1.5
15
35
85
80
68
10
1000
+V
S
–2
*
*
*
*
.5
10
*
*
*
*
4
250
*
mV
µV/°C
nA
V
dB
dB
dB
100
600
65
13.6
*
*
*
*
*
dB
kHz
°
kHz
3
*
*
*
4.0
*
*
*
*
3.0
.5
1.2
.22
|V
S
| –1.0 |V
S
| –0.8
|V
S
| –1.8 |V
S
| –1.4
|V
S
| –3.0 |V
S
| –2.8
|V
S
| –4.0 |V
S
| –3.5
A
A
V/µs
µF
V
V
V
V
30
45
40
90
*
*
*
*
*
V
mA
5.0
3.4
3.7
2.4
30
Meets full range specifications
–25
85
–25
*
*
*
85
°C/W
°C/W
°C/W
°C/W
°C/W
°C
The specification of PA21A/PA25A is identical to the specification for PA21/PA25 in applicable column to the left.
Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation
to achieve high MTTF.
Unless otherwise noted, the following conditions apply:
±V
S
=
±15V,
T
C
= 25°C.
+V
S
and –V
S
denote the positive and negative supply rail respectively. V
SS
denotes the total rail-to-rail supply voltage.
Current limit may not function properly below V
SS
= 6V, however SOA violations are unlikely in this area.
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
subject to temperatures in excess of 850°C to avoid generating toxic fumes. (PA21 and PA25 only. PA26 does not contain
BeO).
CAUTION
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
NORMALIZED BIAS CURRENT, I
B
(X)
INTERNAL POWER DISSIPATION, P(W)
POWER DERATING
40
35
30
25
20
15
10
5
0
0
25
50
75 100 125 150
TEMPERATURE, T (°C)
SINGLE
AMPLIFIER
BOTH
AMPLIFIERS
BIAS CURRENT
1.75
1.5
1.25
1.0
.75
.5
.25
–50 –25 0 25 50 75 100 125
CASE TEMPERATURE, T
C
(°C)
0
–30
–60
80
75
CROSSTALK
CROSSTALK (dB)
70
65
60
55
50
10
AMP 1
I
OUT
= 1A
A
V
= –100
AMP 2
I
OUT
= 0
A
V
= –100
1K
10K 20K
100
FREQUENCY, F (Hz)
SMALL SIGNAL RESPONSE
100
PHASE RESPONSE
50
POWER RESPONSE
OUTPUT VOLTAGE, V
O
(V
PP
)
40
30
25
20
15
10
|+V
S
| + |–V | = 40V
S
5
1K
OPEN LOOP GAIN, A (dB)
80
PHASE,
ϕ
(°)
100 1K 10K 100K 1M
FREQUENCY, F (Hz)
60
40
20
0
1
10
–90
–120
–150
–180
–210
0
10
100 1K 10K .1M
FREQUENCY, F (Hz)
1M
–20
10K
FREQUENCY, F (Hz)
100K
POWER SUPPLY REJECTION, PSR (dB)
NORMALIZED CURRENT LIMIT, I
LIM
(A)
POWER SUPPLY REJECTION
89
PULSE RESPONSE
OUTPUT VOLTAGE, V
O
(V)
10
5
0
A
V
= 1
R
L
=10
Ω
CURRENT LIMIT
1.6
1.4
1.2
1.0
.8
.6
.4
–50 –25 0
25 50 75 100 125
CASE TEMPERATURE, T
C
(°C)
3.5
3
2.5
2
1.5
1
.5
0
0
.5 1 1.5 2 2.5 3
OUTPUT CURRENT, I
O
(A)
3.5
86
83
80
77
74
71
69
66
63
60
0
10 100 1K 10K 100K 1M
FREQUENCY, F (Hz)
–5
–10
0
200
400
600
TIME, t (µs)
800
1K
TOTAL HARMONIC DISTORTION, THD (%)
1
A
V
= –10
V
OUT
= 16V
PP
R
L
= 8
Ω
TOTAL SUPPLY VOLTAGE, V
SS
(V)
40
35
30
25
20
15
10
100
75
50
25
0
.1
.01
–25
.001
10
10K 40K
100
1K
FREQUENCY, F (Hz)
5
–50
.9
1 1.1 1.2 1.3 1.4
.7 .8
NORMALIZED QUIESCENT CURRENT, I
Q
(X)
APEX MICROTECHNOLOGY CORPORATION
• TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
VOLTAGE DROP FROM SUPPLY, (V)
3
HARMONIC DISTORTION
QUIESCENT CURRENT
125
OUTPUT VOLTAGE SWING
CASE TEMPERATURE, T
C
(°C)
PA21/25/26 • PA21A/25A
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.
4
OUTPUT CURRENT FROM +V
S
OR –V
S
(A)
OPERATING
CONSIDERATIONS
* If the inductive load is driven near steady state conditions,
allowing the output voltage to drop more than 6V below the
supply rail while the amplifier is current limiting, the inductor
should be capacitively coupled or the supply voltage must be
lowered to meet SOA criteria.
NOTE: For protection against sustained, high energy flyback,
external fast-recovery diodes should be used.
MONOLITHIC AMPLIFIER
STABILITY CONSIDERATIONS
All monolithic power op amps use output stage topologies
that present special stability problems. This is primarily due to
non-complementary (both devices are NPN) output stages
with a mismatch in gain and phase response for different
polarities of output current. It is difficult for the op amp manu-
facturer to optimize compensation for all operating conditions.
The recommended R-C network of 1 ohm in series with
0.1µF from output to AC common (ground or a supply rail, with
adequate bypass capacitors) will prevent local output stage
oscillations.
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.
3
2
EA
CH
EA
CH
,O
1
s
m
,B
NE
1
OT
LO
H
LO
AD
AD
ED
ED
THERMAL CONSIDERATIONS
T
C
= 25°C
.1
1
2
3
4 5 6
10
20
30 40 50
SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE V
S
–V
O
(V)
CURRENT LIMIT
Current limit is internal to the amplifier, the typical value is
shown in the current limit specification.
Although R
θJC
is the same for PA21/25/26 there are differ-
ences in the thermal interface between case and heatsink
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
require a thermal washer which is electrically insulating since
the tab is tied to –V
S
. This can result in thermal impedances for
R
θCS
of up to 1°C/W or greater.
V
BOOST
SAFE OPERATING AREA (SOA)
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.
Under transient conditions, capacitive and dynamic* induc-
tive loads up to the following maximum are safe:
+V
S
– IN
+IN
OUT
I
SENSE
R
S
±
Vs
20V
15V
10V
5V
CAPACITIVE LOAD INDUCTIVE LOAD
200µF
500µF
5mF
50mF
7.5mH
25mH
35mH
150mH
– V
S
FIGURE 2. PA26 EQUIVALENT SCHEMATIC (ONE CHANNEL)
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
V
BOOST
The V
BOOST
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 +V
S
it will provide more drive to the
upper output transistor, which is a darlington connected emit-
ter follower. This will better saturate the output transistor.
When V
BOOST
is about 5 Volts greater than +V
S
the positive
output can swing 0.5 Volts closer to the rail. This is as much
improvement as is possible.
V
BOOST
pin requires approximately 10–12mA of current.
Dynamically it represents 1K
Ω
impedance. The maximum
voltage that can be applied to V
BOOST
is 40 volts with respect to
–V
S
. There is no limit to the difference between +V
S
and V
BOOST
.
+V
S
≤
20V
D
B1
7
3
10
C
B1
PA26A
5
C
B2
PA26B
8
SPEAKER
D
B2
+VS
PA26
V
BIAS
VIN
B
R
RL
A
RFB
RIN
IL
R
RS
RS
RIN
R
FB
–VS OR GND
VREF
FIGURE 4. I
SENSE
TRANSCONDUCTANCE BRIDGING
AMPLIFIER
FIGURE 3. SIMPLE BOOTSTRAPPING IMPROVES POSITIVE
OUTPUT SWING. CONNECT PINS 3 AND 10 TO V
S
IF NOT
USED. TYPICAL CURRENTS ARE 12
m
A EACH.
Figure 3 shows a bootstrap which dynamically couples the
output waveform onto the V
BOOST
pin. This causes V
BOOST
to
swing positive from it's initial value, which is equal to +V
S
-0.7 V
(one diode drop), an amount equal to the output. In other
words, if V
BOOST
was initially 19.3, and the output swings
positive 18 Volts, the voltage on the V
BOOST
pin will swing to 19.3
-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
circuit. For example, 20Hz will require > 8uF.
Figure 4 shows the PA26 I
SENSE
feature being used to obtain
a Transconductance function. In this example, amplifier "A" is
the master and amplifier "B" is the slave. Feedback from
sensing resistors R
S
is applied to the summing network and
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
function. In other words, the voltage developed across the
sensing resistors is directly proportional to the output current.
Using this voltage as a feedback source allows expressing the
gain of the circuit in amperes vs input voltage. The transfer
funcion is approximately:
I
L
= (V
IN
– V
REF
) *R
IN
/ R
FB
/ R
s
In the illustration, resistors R
IN
, R
FB
and R
S
determine gain.
V
BIAS
should be set midway between +V
s
and -V
s
, Vref is
usually ground in dual supply systems or used for level
translation in single supply systems.
I
SENSE
The I
SENSE
pin is in series with the negative half of the output
stage only. Current will flow through this pin only when nega-
tive current is being outputted. The current that flows in this pin
is the same current that flows in the output (if –1A flows in the
output, the I
SENSE
pin will have 1A of current flow, if +1A flows
in the output the I
SENSE
pin will have 0 current flow).
The resistor choice is arbitrary and is selected to provide
whatever voltage drop the engineer desires, up to a maximum
of 1.0 volt. However, any voltage dropped across the resistor
will subract from the swing to rail. For instance, assume a +/–
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.
MOUNTING PRECAUTIONS
1. Always use a heat sink. Even unloaded, the PA26 can
dissipate up to 3.6 watts. A thermal washer or thermal
grease should always be used.
2. Avoid bending the leads. Such action can lead to internal
damage.
3. Always fasten the tab to the heat sink before the leads are
soldered to fixed terminals.
4. Strain relief must be provided if there is any probability of
axial stress to the leads.
This data sheet has been carefully
CORPORATION
• TELEPHONE
however, no responsibility is assumed for possible inaccuracies or omissions. All specifications
prodlit@apexmicrotech.com
APEX MICROTECHNOLOGY
checked and is believed to be reliable,
(520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL
are subject to change without notice.
PA21/25/26U REV. G FEBRUARY 2000
© 2000 Apex Microtechnology Corp.
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