L6235 datasheet(11/35 Pages) STMICROELECTRONICS

11 / 35 page

DocID7618 Rev 2

11/35

L6235

Circuit description

5.1

Power stages and charge pump

The L6235 device integrates a 3-phase bridge, which consists of 6 Power MOSFETs

connected as shown in Figure 1: Block diagram on page 3. Each power MOS has an

RDS(ON) = 0.3 (typical value at 25 °C) with intrinsic fast freewheeling diode. Switching

patterns are generated by the PWM current controller and the hall effect sensor decoding

logic (see Section 6: PWM current control on page 13 and Section 8: Decoding logic on

page 18). Cross conduction protection is implemented by using a deadtime (tDT = 1 µs

typical value) set by internal timing circuit between the turn off and turn on of two Power

MOSFETs in one leg of a bridge.

Pins VSA and VSB MUST be connected together to the supply voltage (VS).

Using N-channel power MOS for the upper transistors in the bridge requires a gate drive

voltage above the power supply voltage. The bootstrapped supply (VBOOT) is obtained

through an internal oscillator and few external components to realize a charge pump circuit

as shown in Figure 5. The oscillator output (pin VCP) is a square wave at 600 KHz

(typically) with 10 V amplitude. Recommended values/part numbers for the charge pump

circuit are shown in Table 6.

Figure 5. Charge pump circuit

Table 6. Charge pump external component values

Component

Value

CBOOT

22 0nF

10 nF

100



1N4148

CBOOT

VSA

VCP

VBOOT

VSB

D01IN1328

L6235 데이터시트(PDF) 11 Page - STMicroelectronics