Datasheet

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PAD01

Rev C

KEY FEATURES

LOW COST
HIGH VOLTAGE – 100 VOLTS
HIGH OUTPUT CURRENT – 5A
30 WATT DISSIPATION CAPABILITY
50 WATT OUTPUT CAPABILITY
SMALL FOOTPRINT – 30mm SQUARE
RoHS COMPLIANT

APPLICATIONS

SMALL MOTOR DRIVE
HIGH VOLTAGE INSTRUMENTATION
SEMICONDUCTOR TESTING
LCD TESTING

DESCRIPTION

The PAD01 compact operational amplifier is constructed with surface mount components to provide a low cost solution for many industrial applications. With a footprint only 30mm square, similar to the footprint area of the TO3 hybrid package, the PAD01 offers outstanding performance that outperforms the more expensive hybrid amplifiers. External compensation tailors the amplifier’s response to the application requirements. Current limit is programmable with a single resistor. The amplifier circuitry is built on a thermally conductive but electrically insulating metal substrate. No BeO is used in the PAD01.

A NEW CONCEPT

A critical task in any power amplifier application is cooling the amplifier. Until now component amplifier manufacturers often treated this task as an after-thought, left for the user to figure out. At Power Amp Design the best heat sink and fan combination is chosen at the start and becomes an integral part of the overall amplifier design. The result is the most compact and volumetric efficient design combination at the lowest cost. In addition, this integrated solution concept offers an achievable real-world power dissipation rating, not the ideal rating usually cited when the amplifier case is somehow kept at 25o C. The user no longer needs to specify, procure or assemble separate components.

CIRCUIT & CONNECTIONS

EQUIVALENT CIRCUIT

PINOUT & CONNECTIONS

ABSOLUTE MAXIMUM RATINGS SPECIFICATIONS

NOTES:

Unless otherwise noted: TC = 25OC, compensation Cc = 100pF, DC input specifications are  value given, power supply voltage is typical rating.
Derate internal power dissipation to achieve high MTBF.
Doubles for every 10OC of case temperature increase.
+Vs and −Vs denote the positive and negative supply voltages.
Limited by fan characteristics. During operation, even though the heat sink may be at 85OC the fan will be at a lower temperature.
Rating applies if the output current alternates between both output transistors at a rate faster than 60Hz.
L10 refers to the time it takes for 10% of a population of fans to fail. Lower ambient temperature increases fan life.
Specifications for the PAD01-1 are the same as for the PAD01 except as shown in this column.
+Vcc and -Vcc not to exceed +Vs and -Vs respectively by more than 20V

OPERATING CONSIDERATIONS

SAFETY FIRST

The operating voltages of the PAD01 are potentially deadly. When developing an application circuit it is wise to begin with power supply voltages as low as possible while checking for circuit functionality. Increase supply voltages slowly as confidence in the application circuit increases. Always use a “hands-off” method whereby test equipment probes are attached only when power is off

COOLING FAN

The PAD01 relies on its fan for proper cooling of the amplifier. Make sure that air flow from the fan and to the heat sink remains unobstructed. Air is drawn into the heat sink fin area and exhausted via the fan out of the top of the amplifier assembly. To eliminate electrical noise created by the cooling fan we recommend a 47µF capacitor placed directly at the point where the fan wires connect to the PCB. See application note AN-24 for further details.

MOUNTING THE PAD01 AMPLIFIER

The amplifier is supplied with four 4-40 M/F hex spacers at the four corners of the amplifier. Once the amplifier is seated, secure the module with the provided 4-40 X 3/16″ nuts and torque to 4.7 in lb [53 N cm] max. See “Dimensional Information” for a detailed drawing. It is recommended that the heat sink be grounded to the system ground. This can easily be done by providing a grounded circuit board pad around any (or all) of the holes for the mounting studs.

MOUNTING THE PAD01-1 AMPLIFIER

In most applications the amplifier must be attached to a heat sink. Spread a thin and even coat of heat sink grease across the back of the PAD01-1 and also the heat sink where the amplifier is to be mounted. Push the amplifier into the heat sink grease on the heat sink while slightly twisting the amplifier back and forth a few times to bed the amplifier into the heat sink grease. On the final twist align the mounting holes of the amplifier with the mounting holes in the heat sink and finish the mounting using 4-40 X 3/16″ X 1/4″ long hex male-female spacers and torque to 4.7 in oz [3.8 N cm] max. Provide grounded pads at the mounting holes. Mount the amplifier to the mother board with 4-40 X 1/4” screws. See Dimensional Information for additional recommendations.

PHASE COMPENSATION

The PAD01 must be phase compensated. The compensation capacitor, CC, is connected between pins 2 and 3. The compensation capacitor must be an NPO type capacitor rated for the full supply voltage (100V). On page 2, under Amplifier Pinout and Connections, you will find a table that gives recommended compensation capacitance value for various circuit gains and the resulting slew rate for each capacitor

value. Consult also the small signal response and phase response plots for the selected compensation value in the Typical Performance Graphs section. A compensation capacitor less than 33pF is not recommended.