L6227N データシートの表示（PDF） - STMicroelectronics

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L6227N

DMOS DUAL FULL BRIDGE DRIVER WITH PWM CURRENT CONTROLLER

STMicroelectronics 

L6227

be bigger than tRCRISE for allowing a good current regulation by the PWM stage. Furthermore, the on time tON

can not be smaller than the minimum on time tON(MIN).

tON > tON(MIN) = 2.5µ s (typ. value)





tON

>

tRCRISE

–

tDT

tRCRISE = 600 · COFF

Figure 10 shows the lower limit for the on time tON for having a good PWM current regulation capacity. It has to

be said that tON is always bigger than tON(MIN) because the device imposes this condition, but it can be smaller

than tRCRISE - tDT. In this last case the device continues to work but the off time tOFF is not more constant.

So, small COFF value gives more flexibility for the applications (allows smaller on time and, therefore, higher

switching frequency), but, the smaller is the value for COFF, the more influential will be the noises on the circuit

performance.

Figure 9. tOFF versus COFF and ROFF

1 .104

Roff = 100kΩ

1 .103

Roff = 47kΩ

Roff = 20kΩ

100

10

1

0.1

1

10

100

Coff [nF]

11/22

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