PA03 • PA03A
Please read the “General Operating Considerations” section,
which covers stability, supplies, heatsinking, mounting, current
limit, SOA interpretation, and specification interpretation. Addi-
tional information can be found in the application notes. For
information on the package outline, heatsinks, and mounting
hardware, consult the “Accessory and Package Mechanical Data”
section of the handbook.
The PA03 copper base is very soft and easily bent. Do not put
any stress on the mounting ears of this package. This calls for
caution when pushing the amplifier into certain types of packaging
foam and particularly when inserting the device into a socket.
Insert the amplifier into the socket only by pushing on the perimeter
of the package lid. Pushing the unit into the socket by applying
pressure to the mounting tabs will bend the base due to the high
insertion force required. The base will then not contact the heatsink
evenly resulting in very poor heat transfer. To remove a unit from
a socket, pry the socket away from the heatsink so that the
heatsink will support the amplifier base evenly. Recommended
mounting torque is 8–10 in.-lbs. (.9–1.13 N•m).
SAFE OPERATING AREA (SOA)
Due to the internal (non-adjustable) current limit of the PA03,
worst case power dissipation calculations must assume current
capability of 46 amps. Application specific circuits should be
checked against the SOA curve when relying upon current limit for
SAFE OPERATING AREA CURVES
Second breakdown limitations do apply to the PA03 but are
less severe, since junction temperature limiting responds
within 10ms. Stress levels shown as being safe for more than
CURRENT LIMIT ZONE
tivation of the 5
down is a sign
that the inter-
TC = 25°C
50 100 150
SUPPLY TO OUTPUT DIFFERENTIAL VS –VO (V)
175°C. Thermal shutdown is a short term safety feature. If the
conditions remain that cause thermal shutdown, the amplifier
will oscillate in and out of shutdown, creating peak high power
stresses, destroying useful signals, and reducing the reliability
of the device.
The voltage offset of the PA03 may be externally adjusted to
zero. To implement this adjustment install a 100 to 200 ohm
potentiometer between pins 11 and 12 and connect the wiper arm
to the positive supply. Bypass pins 11 and 12 each with at least a
.01µF ceramic capacitor.
If the optional adjust provision is not used, connect both pins 11
and 12 to the positive supply.
OUTPUT STAGE SHUTDOWN
The entire power stage of the PA03 may be disabled using one
of the circuits shown in Figure 1. There are many applications for
this function. One is a load protection based on power delivered to
the load or thermal rise. Another one is conservation of power
when using batteries. The control voltage requirements accom-
modate a wide variety logic drivers.
1. CMOS operating at +5V can drive the control pins directly.
2. CMOS operating at greater than 5V supplies need a voltage
3. TTL logic needs a pull up resistor to +5V to provide a swing to
the fully disabled voltage (3.5V). When not using the shutdown
feature, connect both pins 3 and 4 to common.
At low gain settings an external compensation capacitor is
required to insure stability. In addition to the resistive feedback
network, roll off or integrating capacitors must also be considered.
A frequency of 1 MHz is most appropriate to calculate gain.
Operation at gains below 10, without the external compensation
capacitor opens the possibility of oscillations near output satura-
tion regions when under load, the improper operation of the
thermal shutdown circuit. This can result in amplifier destruction.
At gains of 10 or more:
1. No external components are required.
2. Typical slew rate will be 8V/µs.
3. Typical phase margin will be 70°.
At a gain of 3:
1. Connect a 470pF compensation capacitor between pins 9 and
2. Typical slew rate will be 5V/µs.
3. Typical phase margin will be 45°.
At unity gain:
1. Connect a 1.8nF compensation capacitor between pins 9 and
2. Typical slew rate will be 1.8V/µs.
3. Typical phase margin will be 65°.
0 = OPERATE
1 = SHUT DN
* NOT REQUIRED
0 = SHUT DN
1 = OPERATE CMOS
** SELECT SHUTOFF
SELECT R4 FOR 5V
DROP ON R2
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.
PA03U REV. I FEBRUARY 1998 © 1998 Apex Microtechnology Corp.