L6228Q datasheet(25/32 Pages) STMICROELECTRONICS

25 / 32 page

L6228Q

Output current capability and IC power dissipation

Doc ID 14321 Rev 4

25/32

Output current capability and IC power dissipation

In Figure 26, Figure 27, Figure 28 and Figure 29 are shown the approximate relation

between the output current and the IC power dissipation using PWM current control driving

a two-phase stepper motor, for different driving sequences:

●

HALF STEP mode (Figure 26) in which alternately one phase / two phases are

energized.

●

NORMAL DRIVE (FULL-STEP TWO PHASE ON) mode (Figure 27) in which two

phases are energized during each step.

●

WAVE DRIVE (FULL-STEP ONE PHASE ON) mode (Figure 27) in which only one

phase is energized at each step.

●

MICROSTEPPING mode (Figure 29), in which the current follows a sine-wave profile,

provided through the Vref pins.

For a given output current and driving sequence the power dissipated by the IC can be

easily evaluated, in order to establish which package should be used and how large must be

the on-board copper dissipating area to guarantee a safe operating junction temperature

(125 °C maximum).

Figure 26.

IC power dissipation versus output current in HALF STEP mode

No PWM

= 30 kHz (slow decay)

Test Conditions:

Supply Voltage = 24V

I A

I B

IOUT

PD [W]

I OUT [A]

HALF STEP

0.25 0.5 0.75 1

1.25 1.5

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