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AN1625
APPLICATION NOTE
October 2003
1 INTRODUCTION
For small-motor applications many appliance designers favor modern three phase brushless DC motors be-
cause of the high efficiency (as great as 95%) and small size for a given delivered power. Designers have to
handle control logic, torque and speed control, power-delivery issues and ensure safe operation in every load
condition. The L6235 is a highly integrated, mixed-signal power IC that allows to easily design a complete motor
control system for BLDC motor. Figure 1 shows the L6235 block diagram. The IC integrates six Power DMOS,
a centralized logic circuit to decode hall effect sensors and a constant t
OFF
PWM current control technique (Syn-
chronous mode) plus other added features for safe operation and flexibility.
Figure 1. L6235 Block Diagram.
CHARGE
PUMP
VOLTAGE
REGULATOR
HALL-EFFECT
SENSORS
DECODING
LOGIC
THERMAL
PROTECTION
TACHO
MONOSTABLE
OCD1
OCD
OCD
OCD2
10V 5V
VCP
VS
A
GATE
LOGIC
VBOOT V
BOOT
OUT
1
OUT
2
SENSE
A
VS
B
OUT
3
SENSE
B
DIAG
EN
FWD/REV
BRAKE
H
3
H
1
RCPULSE
D99IN1095B
TACHO
RCOFF
H
2
OCD3
ONE SHOT
MONOSTABLE
MASKING
TIME
V
BOOT
OCD1
10V
V
BOOT
OCD2
10V
V
BOOT
OCD3
10V
SENSE
COMPARATOR
+
-
PWM
VREF
by Vincenzo Marano
L6235 THREE PHASE BRUSHLESS DC MOTOR DRIVER
Modern motion control applications need more flexibility that can be addressed only with specialized
ICs products. The L6235 is a fully integrated motor driver IC specifically developed to drive a wide range
of BLDC motors with Hall effect sensors. This IC is a one-chip cost effective solution that includes
several unique circuit design features. These features, including a universal decoding logic that allows
the device to be used with most common Hall effect spacing, will be described. The principal aim of this
development project was to produce an easy to use, fully protected power IC. In addition several key
functions as protection circuit and high speed PWM current control allow to drastically reduce the
external components count to meet requirements for many different applications.
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