L6235D datasheet(11/25 Pages) STMICROELECTRONICS

Part #	L6235D

Description	DMOS DRIVER FOR THREE-PHASE BRUSHLESS DC MOTOR

PDF	25 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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11 / 25 page

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L6235

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.

Figure 10. Area where tON can vary maintaining the PWM regulation.

0.1

100

1.10

Coff [nF]

Roff = 100kΩ

Roff = 47kΩ

Roff = 20kΩ

0.1

100

Coff [nF]

1.5

µs (typ. value)

L6235D Datasheet(PDF) 11 Page - STMicroelectronics