ST AN2758 APPLICATION NOTE

ST AN2758 APPLICATION NOTE

AN2758

Application note

EVAL6226QR demonstration board using a dual full-bridge L6226Q for motor control applications

Introduction

This application note describes the demonstration board of the DMOS dual full-bridge L6226Q designed for motor control applications. The board implements a typical application that can be used as a reference design to drive two-phase bipolar stepper motors with currents up to 1A DC, multiple DC motors and a wide range of inductive loads.

Thanks to the small footprint of the L6226Q (QFN 5 x 5 mm, 32-lead) the PCB is very compact (27 x 24.5 mm).

Figure 1. EVAL6226QR demonstration board

January 2009

Rev 2

1/8

www.st.com

Demonstration board description

AN2758

 

 

1 Demonstration board description

Table 1.

EVAL6226R pin connections

Name

 

Type

Function

 

 

 

 

VS

 

Power supply

Bridge A and bridge B power supply

 

 

 

 

PGND

 

Ground

Power ground terminal

 

 

 

 

IN1A

 

Logic input

Bridge A logic input 1

 

 

 

 

IN2A

 

Logic Input

Bridge A logic input 2

 

 

 

 

ENA

 

Logic input

Bridge A enable (active high). When low, the power DMOSs

 

of bridge A are switched OFF.

 

 

 

 

 

 

 

IN1B

 

Logic input

Bridge B logic input 1

 

 

 

 

IN2B

 

Logic input

Bridge B logic input 2

 

 

 

 

ENB

 

Logic input

Bridge B enable (active high). When low, the power DMOSs

 

of bridge B are switched OFF.

 

 

 

 

 

 

 

 

 

 

Bridge A overcurrent detection and thermal protection pin.

DIAGA

 

Open drain output

An internal open drain transistor pulls to GND when

 

overcurrent on bridge A is detected or in case of thermal

 

 

 

 

 

 

protection.

 

 

 

 

 

 

 

Bridge B overcurrent detection and thermal protection pin.

DIAGB

 

Open drain output

An internal open drain transistor pulls to GND when

 

overcurrent on bridge B is detected or in case of thermal

 

 

 

 

 

 

protection.

 

 

 

 

SGND

 

Ground

Signal ground terminal

 

 

 

 

OUT1A

 

Power output

Bridge A output 1

 

 

 

 

OUT2A

 

Power output

Bridge A output 2

 

 

 

 

OUT1B

 

Power output

Bridge B output 1

 

 

 

 

OUT2B

 

Power output

Bridge B output 2

 

 

 

 

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AN2758

 

Demonstration board description

 

 

 

 

Figure 2.

EVAL6226QR demonstration board description

 

 

 

 

 

ENA

IN2A IN1A DIAGA

PGND VS

 

 

 

OUT1A

 

 

 

OUT2A

SGND

OUT2B

OUT1B

ENB IN1B IN2B DIAGB

The INx input pins drive the corresponding half-bridge. When low logic level is applied the low side MOS is switched on, whereas a high logic level turns on the high side MOS.

Pins ENA and ENB are used to implement overcurrent and thermal protection when connected respectively to the outputs DIAGA and DIAGB.

The output current detection thresholds are selected by the resistor connected between the IC dedicated pins and ground.

Table 2 summarizes the electrical specification of the application and Figure 3 shows the electrical schematic.

Table 2.

EVAL6226QR electrical specification (recommended value)

 

Parameter

Value

 

 

 

 

Supply voltage range (VS)

8 to 52 Vdc

 

 

RMS output current rating (OUTx)

up to 1.4 A

 

 

 

 

Switching frequency

up to 100 kHz

 

 

 

 

Input and enable voltage range

0 to + 5 V

 

 

 

 

OCD pins voltage range

-0.3 to 10 V

 

 

 

 

Operating temperature range

-25 to +125°C

 

 

L6226Q thermal resistance junction to ambient

42°C/W

 

 

 

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