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 -- |Vs2.2V| 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
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.
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.
H T T P : / / W W W . A P E X M I C R O T E C H . C O M ( 8 0 0 ) 5 4 6 - A P E X ( 8 0 0 ) 5 4 6 - 2 7 3 9
M I C R O T E C H N O L O G Y
POWER DUAL OPERATIONAL AMPLIFIERS
PA21/25/26 PA21A/25A
+
SUB
+IN A
IN A
V
BOOST
/+V
S
I
SENSE
/
V
S
OUT A
V
S
+V
S
OUT B
I
SENSE
/
V
S
V
BOOST
/+V
S
IN B
+IN B
+
1
2
3
4
5
6
7
8
9
10
11
12
A
B
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS
PA21/25/26 PA21A/25A
SPECIFICATIONS
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
V/
C
BIAS CURRENT, initial
35
1000
*
250
nA
COMMON MODE RANGE
Full temperature range
V
S
.3
+V
S
2
*
*
V
COMMON MODE REJECTION, DC
Full temperature range
60
85
*
*
dB
POWER SUPPLY REJECTION
Full temperature range
60
80
*
*
dB
CHANNEL SEPARATION
I
OUT
= 1A, F = 1kHz
50
68
*
*
dB
GAIN
OPEN LOOP GAIN
Full temperature range
80
100
*
*
dB
GAIN BANDWIDTH PRODUCT
A
V
= 40dB
600
*
kHz
PHASE MARGIN
Full temperature range
65
*
POWER BANDWIDTH
V
O(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/
s
CAPACITIVE LOAD DRIVE
A
V
= 1
.22
*
F
VOLTAGE SWING
Full temp. range, I
O
= 100mA
|V
S
| 1.0 |V
S
| 0.8
*
*
V
VOLTAGE SWING
Full temp. range, I
O
= 1A
|V
S
| 1.8 |V
S
| 1.4
*
*
V
VOLTAGE SWING
I
O
= 2.5A (PA21, 25)
|V
S
| 3.0 |V
S
| 2.8
V
VOLTAGE SWING
I
O
= 3.0A (PA21A, PA25A)
|V
S
| 4.0 |V
S
| 3.5
V
POWER SUPPLY
VOLTAGE, V
SS
3
5
4
30
40
*
*
*
V
CURRENT, quiescent, total
45
90
*
*
mA
THERMAL
RESISTANCE, junction to case
DC, single amplifier
5.0
*
C/W
DC, both amplifiers
5
3.4
*
C/W
AC, single amplifier
3.7
C/W
AC, both amplifiers
5
2.4
C/W
RESISTANCE, junction to air
30
*
C/W
TEMPERATURE RANGE, case
Meets full range specifications
25
85
25
85
C
SUPPLY VOLTAGE, total
5V to 40V
OUTPUT CURRENT
SOA
POWER DISSIPATION, internal (per amplifier)
25W
POWER DISSIPATION, internal (both amplifiers)
36W
INPUT VOLTAGE, differential
V
S
INPUT VOLTAGE, common mode
+V
S
, -V
S
.5V
JUNCTION TEMPERATURE, max
1
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
PA21A/PA25A
PA21/25/26
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:
V
S
=
15V, T
C
= 25
C.
3.
+V
S
and V
S
denote the positive and negative supply rail respectively. V
SS
denotes the total rail-to-rail supply voltage.
4.
Current limit may not function properly below V
SS
= 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
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 TELEPHONE (520) 690-8600 FAX (520) 888-3329 ORDERS (520) 690-8601 EMAIL prodlit@apexmicrotech.com
TYPICAL PERFORMANCE
GRAPHS
PA21/25/26 PA21A/25A
0
25
50
75
100
125
TEMPERATURE, T (C)
0
5
15
25
POWER DERATING
INTERNAL POWER DISSIPATION, P(W)
50
0
100
.25
.75
1.5
1.75
BIAS CURRENT
1.0
.5
50
0
75
125
CASE TEMPERATURE, T (C)
NORMALIZED CURRENT LIMIT, I (A)
1
100
1M
FREQUENCY, F (Hz)
20
0
60
SMALL SIGNAL RESPONSE
OPEN LOOP GAIN, A (dB)
20
40
80
100
0
100
.1M
210
150
60
0
PHASE RESPONSE
90
30
1K
100K
FREQUENCY, F (Hz)
5
OUTPUT VOLTAGE, V (V )
O
100
1K
40K
FREQUENCY, F (Hz)
.001
3
HARMONIC DISTORTION
TOTAL HARMONIC DISTORTION, THD (%)
.1
1
.7
1.4
NORMALIZED QUIESCENT CURRENT, I (X)
5
10
40
QUIESCENT CURRENT
TOTAL SUPPLY VOLTAGE, V (V)
15
35
0
1.5
2.5
OUTPUT CURRENT, I (A)
.5
3
OUTPUT VOLTAGE SWING
VOLTAGE DROP FROM SUPPLY, (V)
1.5
2.5
0
10K
FREQUENCY, F (Hz)
60
POWER SUPPLY REJECTION
POWER SUPPLY REJECTION, PSR (dB)
69
77
89
100K
10
100
0
TIME, t (s)
PULSE RESPONSE
OUTPUT VOLTAGE, V (V)
10
1K
10K
FREQUENCY, F (Hz)
50
75
CROSSTALK
CROSSTALK (dB)
70
10K
O
.5
3.5
0
CURRENT LIMIT
50
.4
.8
1.0
LIM
1K
25
25
50
75
1.25
10
40
POWER RESPONSE
PP
10K
.8
.9
1
1.1 1.2
30
100
60
65
10
1K
10K 100K
150
20
30
10
10K
1M
FREQUENCY, F (Hz)
PHASE, (
)
NORMALIZED BIAS CURRENT, I (X)
B
55
1K
1M
63
74
83
200
400
600
800
1K
10
5
0
5
10
O
10
15
20
25
40
50
.01
3
Q
20
SS
125
20K
80
CASE TEMPERATURE, T (C)
C
180
120
1.2
1.4
1.6
2
35
BOTH
AMPLIFIERS
SINGLE
AMPLIFIER
I = 1A
A
V
= 100
OUT
AMP 1
I = 0
A
V
= 100
OUT
AMP 2
30
|+V | + |V | = 40V
S
S
66
71
80
86
A
V
= 1
R =10
L
25
25
100
.6
C
A
V
= 10
V = 16V
R = 8
OUT
L
10
1.3
50
25
0
25
50
75
100
125
CASE TEMPERATURE, T (
C)
C
1
3.5
1
2
25
PP
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
OPERATING
CONSIDERATIONS
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.
CURRENT LIMIT
Current limit is internal to the amplifier, the typical value is
shown in the current limit specification.
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:
Vs
CAPACITIVE LOAD INDUCTIVE LOAD
20V
200
F
7.5mH
15V
500
F
25mH
10V
5mF
35mH
5V
50mF
150mH
* 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
0.1
F 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.
THERMAL CONSIDERATIONS
Although R
JC
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
CS
= .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
CS
of up to 1
C/W or greater.
3
2
1
.1
1
2
3
4
5 6
10
20
30
50
SUPPLY TO OUTPUT DIFFERENTIAL VOLTAGE V V (V)
S
O
OUTPUT CURRENT FROM +V OR
V (A)
SS
EACH, ONE LOADED
40
4
EACH, BOTH LOADED
T = 25C
C
1 ms
IN
+IN
V
S
R
S
I
SENSE
OUT
V
BOOST
+V
S
FIGURE 2. PA26 EQUIVALENT SCHEMATIC (ONE CHANNEL)
APEX MICROTECHNOLOGY CORPORATION TELEPHONE (520) 690-8600 FAX (520) 888-3329 ORDERS (520) 690-8601 EMAIL prodlit@apexmicrotech.com
ADDITIONAL PA26 PIN FUNCTIONS
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.
PA21/25/26U REV. G FEBRUARY 2000
2000 Apex Microtechnology Corp.
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
impedance and the lowest frequency required by the
circuit. For example, 20Hz will require > 8uF.
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
resistor is used for current sense (which will drop 1 Volt
at 1 Amp) then the output could swing +10.2, 9.2 Volts.
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.
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.
10
3
7
5
8
PA26A
PA26B
+V
S
20V
D
B1
D
B2
C
B1
SPEAKER
C
B2
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.
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 1012mA of current.
Dynamically it represents 1K
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
.
OPERATING
CONSIDERATIONS
PA21/25/26 PA21A/25A
V
BOOST
A
B
V
BIAS
+VS
VIN
VREF
VS OR GND
RS
RS
IL
RL
RIN
RIN
R
PA26
R
RFB
R
FB
FIGURE 4. I
SENSE
TRANSCONDUCTANCE BRIDGING
AMPLIFIER
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