ST AN2759 APPLICATION NOTE
AN2759
Application note
EVAL6227QR demonstration board using a dual full-bridge L6227Q
for motor control applications
Introduction
This application note describes the demonstration board of the DMOS dual full-bridge
L6227Q 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 L6227Q (QFN 5 x 5 mm, 32-lead) the PCB is very
compact (27 x 32 mm).
Figure 1. EVAL6227QR demonstration board
January 2009 Rev 2 1/9
www.st.com
Demonstration board description AN2759
1 Demonstration board description
Table 1. EVAL6227QR 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
IN1B Logic input Bridge B logic input 1
IN2B Logic input Bridge B logic input 2
Bridge A enable (active high). When low, the power DMOSs
of bridge A are switched OFF.
ENB Logic input
DIAGA Open drain output
DIAGB Open drain output
SGND Ground Signal ground terminal
REFA Analog input Bridge A current controller reference voltage
REFB Analog input Bridge B current controller reference voltage
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
Bridge B enable (active high). When low, the power DMOSs
of bridge B are switched OFF.
Bridge A diagnostic pin. When low, an overcurrent or
overtemperature event of bridge A is signaled.
Bridge B diagnostic pin. When low, an overcurrent or
overtemperature event of bridge B is signaled.
2/9
AN2759 Demonstration board description
Figure 2. EVAL6227QR demonstration board description
SGND
IN1B
IN2B
REFB
DIAGB
IN2A
REFA
IN1A
DIAGA
ENB
ENA
PGND
VS
OUT1B
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.
OUT2B
OUT2A
OUT1A
To perform the PWM current control an analog reference voltage should be provided to each
channel of the driver. A fixed reference voltage can be easily obtained through a resistive
divider from an external voltage rail and GND (can be the one supplying the microcontroller
or the rest of the application).
Otherwise a very simple way to obtain a variable voltage without using a DAC is to low-pass
filter a PWM output of a microcontroller.
Table 2 summarizes the electrical specification of the application and Figure 3 shows the
electrical schematic.
Table 2. EVAL6227QR 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
Voltage reference range (REFA, REFB) 0 to + 5 V
Operating temperature range -25 to +125°C
L6227Q thermal resistance junction to ambient 42°C/W
3/9
Loading...