L6228Q(2008) 데이터 시트보기 (PDF) - STMicroelectronics

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L6228Q
(Rev.:2008)

DMOS driver for bipolar stepper motor

STMicroelectronics 

L6228Q

4

Circuit description

Circuit description

4.1

Power stages and charge pump

The L6228Q integrates two independent Power MOS Full Bridges. Each Power MOS has an

RDS(ON) = 0.73 Ω (typical value @ 25 °C), with intrinsic fast freewheeling diode. Switching

patterns are generated by the PWM Current Controller and the Phase Sequence Generator

(see below). Cross conduction protection is achieved using a dead time (tDT = 1 µs typical

value) between the switch off and switch on of two Power MOSFETs in one leg of a bridge.

Pins VSA and VSB must be connected together to the supply voltage VS. The device

operates with a supply voltage in the range from 8 V to 52 V. It has to be noticed that the

RDS(ON) increases of some percents when the supply voltage is in the range from 8 V to 12 V.

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 voltage VBOOT is obtained

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

as shown in Figure 8. The oscillator output (VCP) is a square wave at 600 kHz (typical) with

10V amplitude. Recommended values/part numbers for the charge pump circuit are shown

in Table 6.

Table 6.

Charge pump external components values

CBOOT

CP

RP

D1

D2

220 nF

10 nF

100 Ω

1N4148

1N4148

Figure 8. Charge pump circuit

VS

D1

D2

CBOOT

RP

CP

VCP VBOOT

VSA VSB D01IN1328

11/32

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