EVB90401 Datasheet, PDF (3/6 Pages) Melexis Microelectronic Systems – MLX90401 Demo Board

EVB90401
MLX90401 Demo Board
1.3 Functional Description
The Demo Board mainly consists of the following blocks:
• 15V regulator with an On/Off switch and a power-on indication LED
• Connectors for power supply, Hall effect sensors and brushless DC motor
• Three push button switches for controlling the motor: Brake, Forward/Reverse (Fw/Rev) and
Disable
• One push button switch for setting 60° or 120° sensor electrical phasing of the motor (60/120)
• A potentiometer to control motor speed (Speed adjust)
• 1 on-board MLX90401 Brushless DC Motor Controller
• External components for oscillator, charge boost and protection.
The main purpose of the board is to demonstrate the functionality and capabilities of the MLX90401.
With a power supply and a brushless DC motor connected, the buttons and potentiometer can be used to
fully control the motor.
An on-board zener diode regulator provides a voltage of 15V for the chip. That way the external power
supply – which is also supplied to the motor - can be as high as 40V. R1 (and if necessary also the zener
diode) can be optimized for a specific power supply voltage (see Remarks below). Two versions of the
Demo Board can be ordered, each for a specific power supply voltage range. (See Order Information for
more details.)
The Vref pin (output of the MLX90401) serves as a 12V supply for the Hall effect sensors.
The Disable input can be used for protection purposes. Pulling the Disable input low turns off all drivers.
When the motor is disabled in such a way, it will come to a standstill due to friction. No active braking is
applied.
Any sort of switch can be used to pull the Disable input low.
An option is the use of a thermal switch. This thermal switch can be used to monitor the temperature of
the drivers MOSFETs. If the MOSFETs get too hot, the thermal switch will pull the Disable input low.
R3
10k
C3
4n7
P1 _R4
100k _1k
Speed
Fw/Rev
Brake
60/120
6 Fwd/Rev Input Feedback "B" 19
7
Speed Adjust
Input / Disable
Cap Boost "C"
18
C6
100n
8 Oscillator R/C Gate Top "C" 17
Q3
9
/Brake Input Feedback "C" 16
10
Analog Ground
Gate Bottom
"A"
15
Q4
11
60°/120°
Select Input
Gate Bottom
"B"
14
Q5
12
Power Ground
Gate Bottom
"C"
13
Q6
°T
Disable
Thermally
linked
Another possibility is the use of a Hall effect switch. When the current through the driver MOSFETs
reaches a certain threshold, the magnetic field induced in the sense coil will exceed the Hall effect switch
threshold. The Hall effect switch should then switch to the “ON” state, and in that way pull the Disable
input low. This in turn switches off all drivers.
390119040101
Rev 002
Page 3 of 6
Application Note
15-Jul-05