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Includes Brake Switch and Drive

1. Host PCB Description

The host PCB receives power input from a 3-phase line and control signals provided by the user. In conjuntion

with the power module the result is a flexible power conversion system, primarily designed for interface with a

3HP Motor, however other 3-phase loads may also be applied. The host PCB supports soft-start function which

reduces inrush current by using an NTC thermistor. Surge suppression is implemented using MOV’s as a further

degree of protection. Also on-board is a regulated low voltage power supply to provide bias for the IR2133 and

other low voltage components. When connected to the power module, the unit is fully protected against overcurrent

and ground faults through DC bus voltage and current feedback. Over-temperature is guarded against through

feedback from a thermistor embedded within the power module. A 16-pin single in line header connector is

provided to interface control signals and two terminal blocks connect 3-phase AC inlet and output to the load.

The user provides 5V CMOS / TTL level signals which are then processed by the IR2133 Control IC and

delivered to the power module.

Signals Available to User

In addition to availability of bias supplies derived for the host PCB, signals from the power module circuits and

those derived and processed on the host PCB such as fault status are available to the user. Current feedback

signal from the low side shunt is available on the IFB pin at 0.025V/A. If filtering of this signal is required to

remove noise, a high impedance buffer stage should be inserted between signal and filter. DC bus voltage

feedback is provided on the VFB pin. This reference is been scaled down by a factor of 100 and should be

protected with a high impedance buffer stage.

Fault Behavior.

The system is designed to tolerate overload conditions for one minute. The user should prevent such conditions

persisting beyond this period. In the event of shutdown initiated by ground-fault, overcurrent or over-temperature,

the inverter outputs are terminated and an LED will light to signal this condition. For more information on fault

IRMDAC2 Kit Overview and System Benefits

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When furnished with user-provided logic level control signals, the IRMDAC2 forms a complete reference

design for a 3HP AC motor. Unlike outdated circuits based upon transformer drive or opto-couplers, the

system uses International Rectifier proprietary level-shifting gate drive circuits integrated within the IR2133

Control IC. Separation of gate drive / control and low-voltage circuits from the power module included in the

kit results in a compact, effecient system. The user benfits from immediate hands-on experience and may

customize at will using shematics and circuit ideas as the basis for production designs.

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Gate drive, control and protection circuits are designed to closely match the operating characteristics of the

power semiconductors. This allows power losses to be minimized and power rating to be enhanced to a

greater extent than is possible by designing with individual components.

IRMDAC2

Reference Design Data Sheet (October 1998)