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HT66FM5440
Brushless DC Motor A/D Flash MCU
HT66FM5440
Brushless DC Motor A/D Flash MCU
Detection and Protection Function Configuration
Brushless motor driving requires instant detection for system voltage, current and speed. Once
an abnormal situation occurs, the driving circuit must be immediately switched off to protect
the peripheral hardware thus ensuring system security. The motor dedicated 16-bit capture timer
contains motor stalling protection related configurations and can be used to monitor the motor speed.
When the stalling situation occurs, the PWM signals will be directly switched off to prevent large
motor static current from occurring.
The OCP function of the HT66FM5440 is composed of an OPA, a CMP and a DAC. The DAC
provides a reference value, when the motor current amplified by the OPA is larger than the reference
value, it means that an over current situation has occurred, in which condition, the PWM signals
can be switched off directly to prevent damage to the power transistor. Those important information
including voltage, current and temperature, can be detected by the A/D auto-scan function at fixed
internals. And then with the interrupt priority function and interrupt preempt function, users can
configure the over current interrupt and A/D auto-scan interrupt into the highest two priority levels
to achieve the most secure motor driving protection.
Hardware Block Diagram
Here use the low voltage and Hall sensor driving solution to introduce the BLDC motor control
system.
OCP
Hall Sensor
Decoder
HT8-1T
12-bit
ADC
BLDC
Motor
Detect V
DC
bus current
Detect
V
DC
bus
voltage
BLDC
Motor
Control
Circuit
V
DC
bus
LDO
HT66FM5440
P-N
MOSFET
× 3 Pairs
Speed
Command
DC
Power
Pre-Driver
Hall-A
Hall
Sensor
× 3
Hall-B
Hall-C
Hall Noise
Filter
R_Shunt
BLDC Motor Control with Hall Sensor
1. The DC power is a low voltage system which provides power for the LDO, VDC bus voltage
detection circuit, pre-driver circuit and P-N MOSFET circuit.
2. The LDO outputs 5V standard power for the MCU, Hall sensor and speed command component.
3. The speed command component is a variable resistor. It outputs a voltage from 0V to 5V as the
speed adjustment command.
4. The VDC is first decreased via the voltage detection circuit and then input to the MCU A/D
channel, in which way the A/D converter can check the current system voltage.
5. The pre-driver circuit is controlled by the BLDC motor control circuit, and its outputs are used to
drive the P-N MOSFET gate driver.
6. The inverter in the three-phase BLDC motor system consists of three pairs of top and bottom
MOSFETs. In a low voltage and small current system, a P MOSFET is usually used for the top
gate in order to eliminate the bootstrap component. Here the inverter uses the P-N MOSFETs to
drive the motor.
7. When the motor is loaded, the Hall signals are susceptible to noise interference. Therefore the
signals of the three Hall sensors, Hall-A, Hall-B and Hall-C should first be input to the Hall sensor
noise filter. After being filtered, these signals will be transfer to the interrupt controller, capture
timer and Hall sensor decoder.