TABLE 4. OUTPUT COMMUTATION SEQUENCE FOR FOUR PHASE OPERATION

CS1=CS2=0 OUTPUTS ENABLED

S1

S2,S3

FWD/REV = 1

FWD/REV = 0

0

0

O1

O4

1

0

O3

O6

1

1

O4

O1

0

1

O6

O3

7260-110697-5

BRAKE

MOTOR

SUPPLY

Vss

O6

8

5

COMMON

BRAKE

INPUT

7

O4

6

9

O5

LS7262

FORWARD

REVERSE

IN914

2.2K

Inputs from SG1731

or UC1637

F/R

ENABLE

19

10

IN914

LS7260

or

LS7262

FIGURE 3. PRECISION CONTROL BRUSHLESS DC MOTOR DRIVE

FIGURE 2A.

SINGLE-ENDED

DRIVER CIRCUIT

This configuration requires only

one base current limiting resistor

connected from the COMMON

pin to Vss.

For controlled acceleration and deceleration of motors in

the forward or reverse directions, a motor control pulse

width modulator circuit such as the SG1731 or UC1637

can be interfaced with the LS7260 or LS7262.

The logical OR gate made up of the resistor-diode net-

work permits the LS7260 or LS7262 to be enabled when

either the forward or reverse input is high. By applying

the forward input directly to Pin 19, the motor can only

operate in the forward direction when the forward input is

high and only in the reverse direction when the reverse

input is high. Motor direction is determined by relative

pulse widths of the forward and reverse inputs while ac-

celeration or deceleration is determined by variations of

these widths.

For four phase commutation (See Fig. 4), the COMMUTA-

TION SELECT inputs must both be tied low. The S1 input

is driven from one motor position sensor while the S2 and

S3 inputs are connected together and driven by the

second position sensor. The COMMON input must be

connected to Vss. The sensors have an electrical separa-

tion of 90°. Figure 4A indicates the use of Bipolar Tran-

sistors. Figure 4B indicates the use of FETs. In both

cases, the LS7262 is used.