L6228 datasheet(21/26 Pages) STMICROELECTRONICS

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L6228

Figure 26. IC Power Dissipation versus Output Current in WAVE Mode (full step one phase on).

Figure 27. IC Power Dissipation versus Output Current in MICROSTEPPING Mode.

Thermal Management

In most applications the power dissipation in the IC is the main factor that sets the maximum current that can

be delivered by the device in a safe operating condition. Therefore, it has to be taken into account very carefully.

Besides the available space on the PCB, the right package should be chosen considering the power dissipation.

Heat sinking can be achieved using copper on the PCB with proper area and thickness. Figures 28, 29 and 30

show the Junction-to-Ambient Thermal Resistance values for the PowerSO36, PowerDIP24 and SO24 packag-

es.

For instance, using a PowerSO package with copper slug soldered on a 1.5mm copper thickness FR4 board

with 6cm2 dissipating footprint (copper thickness of 35µm), the Rth(j-amb) is about 35°C/W. Fig. 31 shows mount-

ing methods for this package. Using a multi-layer board with vias to a ground plane, thermal impedance can be

reduced down to 15°C/W.

No PW M

fSW = 3 0 kHz (slow decay)

Test Conditions:

Supply Voltage = 24V

I A

I B

IOUT

WAVE DRIVE

PD [W]

I OUT [A]

0.25 0.5 0.75 1

1.25 1.5

fSW = 50 k

Hz (slow decay)

fSW = 30 k