The IC L6235 is an embedded DMOS 3-phase motor driver with an integrated over-current protection. Designed with BCD technology, the device embeds the benefits of isolated DMOS power transistors with CMOS, and with bipolar circuits within the same device.
The chips integrates all the circuitry required for effectively driving a 3-phase BLDC motor, as explained below:
DMOS bridge, a constant off-time PWM current
controller and the decoding logic for single ended
hall sensors for generating the essential 120 degree phase shift sequence for the power stage. With regard to the built-in protections the
L6235 device offers a non-dissipative
over current protection on the high-side power
MOSFETs, protection against ESD, and an automatic thermal shutdown in case the device heats up above the rated value.
A typical L6235 50V 3-phase BLDC motor driver circuit application can be witnessed above, which looks quite straightforward with its implementation procedures.
You just have to hook up the shown elements in place and use the design to operate any BLDC motor with sensors rated within 8V to 50V at 3 amps rate.
The pinout function for the specified circuit can be studied from the following data:
Pin#6, 7, 18, 19 = (GND) These are the Ground terminals of the IC.
Pin#8 = (TACHO) It's designated as the open drain
Frequency-to-voltage open drain output. here each single pulse
from pin H1 is dimensioned in the form of a fixed and adjustable length
Pin#9 = (RCPULSE) Is configured like a parallel RC network attached between this pin and the ground, which fixes the period of the
monostable pulse responsible for the frequency-to-voltage
Pin#10 = (SENSEB) This pin must be connected
together with pin SENSEA to power ground through
a sensing power resistor. Here the inverting input of the sense comparator also needs to be connected
Pin#11 = (FWD/REV) This pinout can be used for changing the rotational direction of the BLDC motor. A HIGH logic level on this pinout will cause a forward motion while, a LOW logic level will allow the BLDc motor to rotate in the opposite reverse direction. For enabling a fixed clockwise or anticlockwise directions, this pinout may be appropriately terminated to a +5V or the ground line..
Pin#12 = (EN) A LOW logic signal will shut OFF all the internal power
MOSFETs and stall the BLDC motor. In case this pinout is intended to be not used, it must be terminated to the +5 V supply rail.
Pin#13 = (VREF). You can see an opamp configured with this pinout. The Vref input of the opamp connected with this pinout can be fed with a linearly adjustable 0 to 7V for changing the speed of the BLDC motor from 0 to max. If not used make sure to connect this pinout to GND.
Pin#14 = (BRAKE) A LOW logic level on this pinout will switch ON all highside
Power MOSFETs, instantly enforcing the brake/stop function. In case not used, this pinout can be held connected to +5 V.
Pin#15 = (VBOOT) It is simply the input pinout for the bootstrap voltage needed for driving the upper Power
MOSFETs. Just connect the parts as indicated
Pin#5, 21, 16 = (3-phase OUT to BLDC motor) Power output which connects with the BLDC motor and powers the motor.
Pin#17 = (VSB) Just connect it as shown in the diagram.
Pin#20 = (VSA) Same as above, needs to eb connected as given in the diagram.
Pin#22 = (VCP) It is the output from the internal charge pump oscillator, connect the parts as shown in the diagram.
Pin#1, 23, 24 = 3-Phase sequential signal from the BLDC single ended Hall sensor can be configured with these pinouts, if the BLDC is a sensorless, you can feed an external 3-phase 120 degree apar input on these pinout at +5V level.
Parts List for the above discussed 50V 3-phase BLDC motor driver circuit
C1 = 100 µF
C2 = 100 nF
C3 = 220 nF
CBOOT = 220 nF
COFF = 1 nF
CPUL = 10 nF
CREF1 = 33 nF
CREF2 = 100 nF
CEN = 5.6 nF
CP = 10 nF
D1 = 1N4148
D2 = 1N4148
R1 = 5.6 K
R2 = 1.8 K
R3 = 4.7 K
R4 = 1 M
RDD = 1 K
REN = 100 K
RP = 100
RSENSE = 0.3
ROFF = 33 K
RPUL 47 K
RH1, RH2, RH3 = 10 K
For more details you can refer to the following datasheet from ST: DMOS driver for 3-phase BLDC motor