UC3717A

The

duced by soldering the GND pins to a suitable copper

area of the printed circuit board or to an external heat

sink. Due to different lead frame design,

ramic J package cannot be similarly reduced.

The diagram of Figure 11 shows the maximum package

two equal square copper areas having a thickness of 35

µ

(see Figure 10).

During soldering the pins’ temperature must not exceed

260°C and the soldering time must not be longer than 12

seconds.

The printed circuit copper area must be connected to

electrical ground.

APPLICATIONS

A typical chopper drive for a two phase bipolar perma-

nent magnet or hybrid stepping motor is shown in Figure

12. The input can be controlled by a microprocessor,

TTL, LS, or CMOS logic.

The timing diagram in Figure 13 shows the required sig-

nal input for a two phase, full step stepping sequence.

Figure 14 shows the required input signal for a one

phase-two phase stepping sequence called half-step-

ping.

The circuit of Figure 15 provides the signal shown in Fig-

ure 13, and in conjunction with the circuit shown in Fig-

ure 12 will implement a pulse-to-step two phase, full

step, bi-directional motor drive.

The schematic of Figure 16 shows a pulse to half step

circuit generating the signal shown in Figure 14. Care

has been taken to change the phase signal the same

time the current inhibit is applied. This will allow the cur-

rent to decay faster and therefore enhance the motor

performance at high step rates.

Figure 10. Example of P.C. Board Copper

Area which is used as Heatsink.

MOUNTING INSTRUCTIONS

Figure 12. Typical Chopper Drive for a Two

Phase Permanent Magnet Motor.

Figure 11. Maximum Package Power and Junction

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