General Description

PCD's line of DC Servo Amplifiers has been designed to meet the diverse requirements of a wide variety of control systems. Typically, they are used to drive DC torque motors, servo valves, deflection coils and servo and low inertia DC motors in such applications as numerical control systems, tape drives, camera drives, instrument systems, production test stands, rate tables, etc. Two types of packaging are used: epoxy encapsulation for units rated to 600 watts and fan cooled for larger power ratings. Some special applications including those where operation at altitude is required have supplemental cooling.

The encapsulated units are noted for their compactness and offer exceptional power to volume ratios. All are suited for direct mounting on PC boards with standard 0.2 inch pin spacing. An optional mating socket is available for applications where mounting other than on a PC board is required.

All units operated as either voltage or current amplifiers. Their bandwidth is broad . . . 10 kHz for small signal, l kHz full output . . . resulting in fast response and excellent loop stability. Gain is adjustable. Short circuit protection and current limiting are included. Adjustment of the current limit is made with an external fixed or variable resistor wired into the system. Power sharing maximizes utilization of the power transistors.

All encapsulated units have a heat transfer surface for attachment to an external heat sink. The power transistors are bonded to the internal face of these surfaces to maximize heat transfer.

PCD can provide specials tailored to a specific requirement or in special shapes or configurations to meet unusual space requirements. Also, we can offer any design in a military version.

25 Watt and 50 Watt

The DCA 25, DCA 25/60, and the DCA 50/60 are basically similar units differing in output ratings and physical size. The B+ input for the DCA 25 is 28VDC +/-3. B+ input for the DCA 25/60 is 60 V DC +/-5.

The units consist of a Bridge Power Amplifier preceded by an IC Differential Amplifier of high-gain and wide bandwidth. Included is a current limit loop that senses load current and prevents the load current from increasing during motor use. The current limit loop also acts as a short-circuit protection.

They also include a power-sharing loop. This provides equal dissipation in both halves of the output bridge in the linear, current limiting, and voltage saturation regions of amplifier operation.

Application as a Bridge Amplifier

The DCA 25 or DCA 25/60 may be used as a bridge amplifier to drive a remote NPN power transistor bridge. In such an application, the DCA 25 may be mounted directly on the control card and the external bridge can be affixed to a remotely located heat sink to accommodate the required power dissipation.

200 Watt to 600 Watt

These higher rated units are identical in circuitry to the DCA 25 with the addition of an internal high-current and high-power capacity transistor bridge. In effect, the remote bridge discussed above has been incorporated as an integral part of the package. The DCA 200 and DCA 300 require a B+ supply of 28 V DC +/-3. The DCA 300/60 and DCA 600/60 require B+ of 60 V DC +/-5, while the DCA 600/100 requires 100 V DC +/-5.

Dual-Channel 50 Watts

The DCA 50/2 is a highly reliable compact unit that contains two amplifier channels, but occupies only the board space formerly required for a single channel 25-watt unit. Similar in function to the rest of the line, the greatly reduced size of the DCA 50/2 was achieved through a number of unique innovations without sacrifice in PCD’s rigid standards. It requires a power supply of 28 V DC +/-4.

DCA 200-1, DCA 200-1/60, DCA 300-1, & DCA 300-1/60

PCD’s new line of encapsulated solid state servo amplifiers has extra features such as power sharing, short-circuit protection of outputs to ground, thermal-overload protection, output drive current monitor, and multiple input preamp as standard features. The units weigh only 12 ounces (340.2 grams), measure 2.29” x 3.25” x 1.5” (58.2 x 82.6 x 38.1 mm) and have a standard 25 pin connector for easy installation. A mating heat sink is available.

These highly reliable units have high open-loop gain for wide design options, wide bandwidth for fast response and loop stability, current limiting for amplifier and load protection, and voltage or current feedback for speed or torque control. Available in either standard or MIL versions.

Features

• Power Sharing
  
• Short-Circuit Protection (output to ground)
  
• Thermal Overload Protection
  
• Output Drive Current Monitor
  
• Multiple Input Preamp
  
• High Open-Loop Gain
  
• Wide Bandwidth
  
• Current Limiting
  
• Subminiature Connector
  
• Available with High Reliability Parts