lv8105w ETC-unknow, lv8105w Datasheet - Page 18

• Manufacturer Part Number: lv8105w
• Description: For Variable Speed Control Three-phase Brushless Motor Predriver
• Manufacturer: ETC-unknow

6. Speed discriminator output amplitude switching circuit
7. Hall input signal
8. S/S switching circuit
9. Braking circuit
By the magnitude relation between the time t that is set by using the capacitor and resistor connected with the RC pin
and the clock period which is input through the CLK pin, the output amplitude of the speed discriminator switches as
follows.
When connect a resistor R between the RC pin and VREG and a capacitor C between the RC pin and GND, the above
time t is calculated as follows.
By the variance of the IC, “0.91” of the above formula has varied from 0.885 to 0.935.
When switching the output amplitude of the speed discriminator by the input voltage to the RC pin is performed, input
that voltage to the RC pin through the resistor of 20kΩ.
The output amplitude of the speed discriminator is switched by the input voltage as follows.
When there is no need for the speed discriminator output amplitude switching, connect the RC pin with GND. In this
instance, the high level output voltage of the speed discriminator becomes VREC-1.0V and the low level output voltage
of the speed discriminator becomes 0.9V.
The input amplitude of 100mVp-p or more (differential) is desirable in the Hall sensor inputs. The closer the input
wave-form is to a square wave, the lower the required input amplitude. Inversely, a higher input amplitude is required
the closer the input waveform is to a triangular wave. Also, note that the input DC voltage must be set to be within the
common-mode input voltage range.
If a Hall sensor IC is used to provide the Hall inputs, those signals can be input to one side (either the + or - side) of the
Hall sensor signal inputs as 0 to VREG level signals if the other side is held fixed at a voltage within the common-mode
input voltage range that applies when the Hall sensors are used.
If noise on the Hall inputs is a problem, that noise must be excluded by inserting capacitors across the inputs. Those
capacitors must be located as close as possible to the input pins.
When the Hall inputs for all three phases are in the same state, all the outputs will be in the off state.
The bias of the Hall element can be cut by supplying the bias of the Hall element from the HB pin while the S/S pin is
a stop mode(Hall bias switch).
The Hall input frequency range possible for the soft current-carrying is determined from 30Hz to 500Hz (IN1
frequency).
When the S/S pin is set to the low level, S/S switching circuit is the start mode. Inversely, when the S/S pin is set to the
high level or open, S/S switching circuit is the stop mode. At the stop mode, all the outputs will be in the off state.
This IC will be in the power save state of decreasing the supply current at the stop mode.
When the BR pin is set to the high level or open, the brake is on. Inversely, when the BR pin is set to the low level, the
brake is released. The brake becomes a short brake that turns on the lower side output transistors for all phases (the UL,
VL and WL side) and turns off the upper side output transistors for all phases (the UH, VH and WH side). Note that the
current limiter does not operate during braking. During braking, the duty is set to 100%, regardless of the motor speed.
The current that flows in the output transistors during braking is determined by the motor back EMF voltage and the
coil resistance. Applications must be designed so that this current does not exceed the ratings of the output transistors
used. (The higher the motor speed at which braking is applied, the more severe this problem becomes).
The braking function can be applied and released with the IC at the start mode. This means that motor startup and stop
control can be performed using the BR pin with the S/S pin held at the low level (the start mode). If the startup time
becomes excessive, it can be reduced by controlling the motor startup and stop with the BR pin rather than with the S/S
pin (Since the IC will be in the power save state at the stop mode, enough time for the VCO circuit to stabilize will be
required at the beginning of the motor start operation).
When the clock period is smaller than t
When the clock period is bigger than t
Low level input (0V to 2V),
High level input (4V to 6V),
t = 0.91 × R × C
<High level output voltage>
<High level output voltage>
LV8105W
VREG-1.0V
VREG-1.7V
VREG-1.0V
VREG-1.7V
<Low level output voltage>
<Low level output voltage>
0.9V
1.6V
0.9V
1.6V
No.A1271-18/21