5

Aeroflex Circuit Technology

SCD5101-1 REV D 5/14/01 Plainview NY (516) 694-6700

FUNCTION

PIN #

DESCRIPTION

V+ A

11

High Voltage D.C. Bus, Phase A

V+ B

7

High Voltage D.C. Bus, Phase B

V+ C

3

High Voltage D.C. Bus, Phase C

+15V

12

+15 VDC input required to power gate drive supply and gate drive circuitry of all

three phases.

GND

19,22,26

Reference for LOGIC supply, +15V supply, and digital inputs.

RTN A

8

Return for High Voltage Bus, Phase A.

RTN B

5

Return for High Voltage Bus, Phase B

RTN C

1

Return for High Voltage Bus, Phase C

PHASE A

9

Output to motor winding Phase A

PHASE B

6

Output to motor winding Phase B

PHASE C

2

Output to motor winding Phase C

UA

18

Digital input to Phase A upper transistor

LA

17

Digital input to Phase A lower transistor

UB

21

Digital input to Phase B upper transistor

LB

20

Digital input to Phase B lower transistor

UC

25

Digital input to Phase C upper transistor

LC

24

Digital input to Phase C lower transistor

SD

23

Digital shut-down input to enable / disable all six gate drives

N/C

4,10,13-16

No connection Internally

DIGITAL INPUT STAGE

The ACT5101-1 offers complete flexibility by allowing the user to turn on/off each of the 6 IGBTS in any order

or combination desired which enables the hybrid to be commutated in a 6 step trapezoidal mode. The only

unacceptable combination would be to turn on an upper and lower transistor of the same phase. This is not

a desirable condition for normal operation and is therefore not allowed. The ACT5101-1 has a digital lockout

feature that prevents turn-on of two in-line transistors. Damage to one or both of the transistors would occur

if this protection circuitry was not present in the hybrid. As a safety precaution, it is still recommended that a

500 nsec dead time be installed between commands at the inputs of the upper and lower transistors of the

same phase. This will compensate for any lag in transistor turn-off due to the inductive load.

The SD input allows the user to enable/disable the drive stage of the ACT5101-1 on demand. This input can

be incorporated into the user's temperature or current monitoring circuitry to shutdown the hybrid if

excessive current or case temperatures are sensed.

The digital input circuits are of the Schmitt trigger type with hystersesis of at least 1.6 volts, thus greatly

enhancing the input noise immunity. The inputs are internally pulled up to 15 volts so that an uncommitted

input is sensed as "OFF", providing a measure of protection against an accidental input disconnect.

GATE DRIVE

The ACT5101-1 includes a gate drive supply which provides a floating voltage for each upper and lower

transistor. This constant voltage allows the motor to be operated at very low duty cycles or driven into a stall

without any loss of upper or lower gate drive. This performance could not be obtained with only a

conventional boot strap design.