SYSTEM DESCRIPTION

The L6515 is intended to be used as a microproc-

essor controlled positioning system.

For the motor driver stage only digital operating

bridges are needed like L293E, L298, L6203, L6202.

The system operates in two modes to achieve

high-speed, high-accurancy positioning.

Speed commands for the system originate in the

microprocessor. It is continuously updated on the

motor position by means of pulses from the con-

troller chip, which in turn gets its information from

the encoder. From this basic input, the microproc-

essor computes a 6-bit control word that sets the

system speed and direction dependent on the dis-

tance to travel.

When the motor is stopped and the microproces-

sor orders it to a new position, the system oper-

ates initially in an open-loop configuration as

there is no feedback from the tachometer gener-

ator. Therefore maximum current is fed to the mo-

tor. As maximum speed is reached, the tachome-

ter chip output backs off the processors signal

thus reducing accelerating torque. The motor con-

tinues to run at top speed but under closed-loop

control.

As a target position is approached, the microproc-

essor lowers the value of the speed-demand

word; this reduces the voltage at the main sum-

ming point, in effect braking the motor. The brak-

ing is applied progressively until the motor is run-

ning at minimum speed.

At that time, the microprocessor orders a switch

to the position mode, and within 3 to 4ms the

power stage drives the motor to a null position,

where it is held by electronic ”detening”.

Symbol

Parameter

Value

Unit

Supply Voltage

12

V

Analog Inputs Voltage

-0.3 to 7

V

Logic Inputs Voltage

-0.3 to 7

V

Open Collector Output Current

12

V

Open Collector Current

10

mA

Zener Current

20

mA

Storage Temperature

-40 to 150

°C

Operative Ambient Temperature

0 to 70

°C

ABSOLUTE MAXIMUM RATINGS

PIN CONNECTION (top view)

L6515

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