Analog Integrated Circuit Device Data

10

Freescale Semiconductor

17550

TYPICAL APPLICATIONS

INTRODUCTION

TYPICAL APPLICATIONS

INTRODUCTION

The 17550's built-in DC/DC converter must be connected

to an external inductor, rectifier, and filter capacitor. This

required by the internal gate driver circuits. Although there is

some latitude in selecting the values for the external

14 V. Additionally, too low an inductance will cause large

instantaneous switching currents, which may damage the

device.

Important Do not use an inductance lower than 330

µH.

To attain high-efficiency operation, the rectifier should be

a Schottky diode, and the filter capacitor should be of the low

Equivalent Series Resistance (ESR) type. Attention should

be paid to proper switch mode power supply PCB layout

practice. Some experimentation may be required to

determine optimal external component values. The

recommended starting values are L = 1.0 mH, C = 2.2

µF.

The DC/DC converter includes its own internal oscillator

and does not require an external clock input.

TYPICAL APPLICATION

Two typical application schematics are shown in Figure 6.

and Figure 7.

Figure 6. Typical 17550 Application - Controlling Stepper Motors

2.2

L = 1.0 mH

10

VDD

VM

GND

PSB

OE

INAR

INAF

INBF

INBR

INCR

INCF

INDF

INDR

VG

LX

HBAF

HBAR

HBBR

HBBF

HBCF

HBCR

HBDR

HBDF

MCU

N

S

N

S

17550

47