L6220 datasheet(8/12 Pages) STMICROELECTRONICS

8 / 12 page

Figure 18 : Allowed Peak Collector-current versus

Duty Cycle for 1, 2, 3 or 4 Contempo-

rary Working Outputs (L6220).

Figure 19 : Allowed Peak Collector Cur-rent ver-

sus Duty Cycle for 1, 2, 3 or 4 Con-

temporary Working Outputs

(L6220N).

APPLICATION INFORMATION

When inductive loads are driven by L6220/N, a

zener diode in series with the integral free-wheeling

diodes increases the voltage across which energy

stored in the load is discharged and therefore

speeds the current decay (Fig. 16). For reliability it

is suggested that the zener is chosen so that Vp +

Vz <35 V.

The reasons for this are two fold :

1) The zener voltage changes in temperature and

current.

2) The instantaneouspower must be limited to

avoid the reverse second breakdown.

The particular internal logic allows an easier full step

driving using only two input signals.

MOUNTING INSTRUCTION

The Rth j-amb of the L6220 can be reduced by solder-

ing the GND pins to a suitable copper area of the

printed circuit board (Fig. 20) or to an external

heatsink (Fig. 21).

The diagram of figure 22 shows the maximum dis-

sipable power Ptot and the Rth j-amb as a function of

the side ”

α” of two equal square copper areas hav-

ing a thickness of 35

µ (1.4 mils). During soldering

the pins temperature must not exceed 260

°C and

the soldering time must not be longer than 12 sec-

onds.

The external heatsink or printed circuit copper area

must be connected to electrical ground.

L6220 - L6220N

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