LA-800/1500 Series Linear Amplifiers

The LA Linear Servo Amplifier Series are the perfect choice for systems requiring low radiated noise and zero distortion. These high power linear amplifiers are well suited to drive loads such as brushless and brush servo motors or voice coils. Our designs incorporate class AB linear output stages for true linear output.

The design of these amplifiers includes an onboard high-speed DSP that monitors all key system functions in real time, and provides protection for the outputs by limiting output power to a “Safe Operating Area”. An intelligent user interface allows setup and storage of all system parameters via the serial interface. Non-volatile memory provides storage of the parameters during power off conditions.

Modes of Operation

Current Mode

In current mode the amplifier is commutated by an external controller. Our Linear Amplifier Series are designed to drive single & 3-phase loads by analog input commands.

These current mode linear amplifiers are available in the following standard configurations:

“T-Mode” – Three-phase current output. This configuration is used for driving three phase rotary or linear motors with a full-bridge output configuration. In this configuration the amplifier receives two sinusoidal current commands for phases A and B (ABSine). The phase C command is generated internally in the amplifier.

“S-Mode” – Single-phase H-Bridge type output. This configuration is used for driving single phase loads such as brush-type motors or voice coils. In this mode the amplifier can deliver the full rail-to-rail bipolar bus voltage to the load.

The following is an example of S-Mode operation. When operating in full-bridge configuration (Phase to Phase), the maximum bus voltage that can be applied to the voice coil is the full B+ to B- voltage. For example if you are using a +/-50VDC bus and a full-bridge connected voice coil, the maximum voltage that can be applied to the voice coil is +100V or -100V. This is illustrated in the following picture which shows positive current from PhaseB to PhaseC (+100V):

Linear Amplifier Sizing — S-Mode Operation

“D-Mode” – Dual independent Half-Bridge type outputs. This mode is used to drive two independent single phase loads, such as brush-type motors or voice coils, with one amplifier module. In this mode the amplifier can deliver half of the full rail-to-rail bipolar bus voltage to the load. The sum total wattage requirements of the two independent loads must be within the capabilities of the amplifier module.

The following is an example of D-Mode operation, (or one or two voice coil connected to a T-Mode amplifier). When operating in Half-Bridge configuration (Phase to Common), the maximum bus voltage that can be applied to the voice coil is 1/2 of the full +/-Bus supply. For example if you are using a +/-50VDC bus and a half-bridge connected voice coil, the maximum voltage that can be applied to the voice coil is +50V or -50V. This is illustrated in the following picture which shows positive current from phaseB to Common (+50V):

Internally Commutated Current Mode

Our optional VMC2* plug-in board can interface with the encoder to allow the amplifier full sinusoidal commutation.

Velocity Mode & Position Mode

Our optional VMC2* plug-in board can interface with your feedback device to provide velocity & position mode.

*Please contact Varedan for more information.

Request Application Assistance

Tell us about your application so we can help you select the right solution.

Please use this fillable PDF form to guide you through the information about your application that we need to properly size and select an amplifier for your application. Please also see out Amplifier Sizing & Tools page for sizing calculators, white papers and other tools.

Standard Models

Amplifier Series	Current Continuous/Peak	Power Continuous/Peak	±VDC Bus Voltage	Dimensions	Weight
LA-830	15/30 Amps	800/3000 Watts	±12 - ±150VDC	8.00" x 8.16" x 4.45"	7.8 lbs.
LA-835	18/35 Amps	800/4500 Watts	±12 - ±150VDC	8.00” x 8.16” x 4.45”	7.8 lbs.
LA-840	20/40 Amps	800/6000 Watts	±12 - ±150VDC	8.00” x 8.16” x 4.45”	7.8 lbs.
LA-1535	20/35 Amps	1500/3000 Watts	±12 - ±150VDC	8.00" x 8.16" x 5.85"	9.8 lbs.
LA-1545	25/45 Amps	1500/4500 Watts	±12 - ±150VDC	8.00" x 8.16" x 5.85"	9.8 lbs.
LA-1555	30/55 Amps	1500/6000 Watts	±12 - ±150VDC	8.00" x 8.16" x 5.85"	9.8 lbs.

Key Design Benefits

True Rail to Rail Output
DSP Fault – Set when the internal DSP checksum fails following reset
NVM Fault – Set when NVM checksum fails following reset. Parameter defaults set
External +5V – Set when on board +5V supply for Halls is out of range
Autobalance Fault – Set when autobalance can’t balance amplifier outputs
ABS Overcurrent – Set when instantaneous overcurrent condition is detected
SOA – Set when Safe Operating Area protection detects an over power condition
5 VDC Reference error – Set when internal +5 reference supply is out of range
Bus Over Voltage – Set when Bus voltage is greater than maximum allowed (75 VDC)

Hall Error – Set when hall sequence is invalid (0 or 7 value is read on hall inputs)
Fatal Error – Set if the DSP encounters an unidentified problem
Amplifier Over Temp – Set when amplifier heat sink temperature exceeds 70 C
Motor Over Temp – Set when motor temperature input is open
Over-current – Set when amplifier detects an overcurrent condition
Bus Under Voltage – Set when Bus voltage is less than the minimum allowed (10 Vdc)
Bias error – Set when Bias voltage input +/-15 is outside allowable range
5V Reference error – Set when internal 2.5V supply is out of range

Factory or Customer Programable Options:
- RMS Over-current Trip Level
- RMS Over-current Trip Time
- Absolute Over-current Trip Level
- Enable level
- Enable Source
- Fault level

	Datasheet	Manual
Amplifier Module - For high density or OEM applications. Available without covers.
Stand-Alone Amplifier Package - For "plug & play" applications. Available in a fully enclosed package with built in fan and power supply.
Single Axis Package (needs external isolation transformer) - Mounted on a baseplate with built in fan.	Contact Varedan	Contact Varedan
2 Axis Package (needs external isolation transformer) - Mounted on a baseplate with built in fan.	Contact Varedan	Contact Varedan

	Datasheet	Manual
Amplifier Module - For high density or OEM applications. Available without covers.
Single Axis Package (needs external isolation transformer) - Mounted on a baseplate with built in fan.	Contact Varedan	Contact Varedan
2 Axis Package (needs external isolation transformer) - Mounted on a baseplate with built in fan.	Contact Varedan	Contact Varedan