LB11600JV_11 Datasheet, PDF (29/30 Pages) Sanyo Semicon Device – Brushless Motor Predriver IC for Automotive Applications

LB11600JV
12. One-Shot Multivibrator Circuit Block (CEG, CR, and FV pins)
The LB11600JV includes a built-in one-shot multivibrator circuit to allow it to support speed feedback control. The signal
used for speed control is a rotation pulse detection signal that is created in the CEG pin circuit block with the timing of the
fall (high to low) of the UH output signal, one of the three output phases. The LB11600JV detects the rotation period from
this signal. The rotation pulse detection signal time is set by the discharge time of the capacitor connected to the CEG pin.
Rotation pulse detection signal time: Tps = Ce × VBE/Iceg (s)
Ce:
VBE:
CEG pin external capacitor (connected between VCC and CEG)
VBE for the transistor in the CEG edge detection circuit: 0.7V (typical)
Iceg:
CSET pin discharge current: 50µA (typical)
The CR pin sets the pulse width (high period) generated at the FV pin at each signal
from the CEG pin.
To the VCC pin
The pulse width is set by connecting a resistor and a capacitor between the CR pin
and VCC and ground, respectively.
CR pin
The pulse width TRC can be calculated approximately with the following formula.
TRC ≈ 1.1 × R × C (s)
Normally, a smoothing circuit consisting of a resistor and capacitor as shown in the
figure is connected to the FV pin. A resistor with a value of at least 25kΩ must be
selected. The value of the capacitor must be selected so that adequate smoothing of ^{FV pin}
the FV voltage is provided when the motor speed is low.
Normally, this circuit is set up so that the following relationship holds when fUH
(Hz) is the UH output frequency at the highest motor speed.
TRC ≤ 1/(2 × fUH) (s)
In this case, the FV voltage will change from 0 to about 5V according to the motor speed.
If the FV output is not used, connect the CR pin to ground and leave the FV pin open.
R
C
FV
voltage
13. Power Supply Stabilization
Since the LB11600JV adopts a switching-based drive method, the power supply line level is easily disturbed. Therefore it
is necessary to connect a capacitor with adequate capacitance to stabilize the power supply between the VCC pin and
ground.
If diodes are inserted in the power supply lines to prevent damage if the power supply is inadvertently connected with
reverse polarity, the power supply line will be even more sensitive to disruption. Here, an even larger capacitance must be
provided.
If the switch and the capacitor are widely separated when the power supply is turned on and off, such as during switching,
the supply voltage may swing widely due to the surge current between the line inductance and the capacitor. Voltages that
exceed the LB11600JV's voltage handling capacity may occur. In applications such as this, do not use components, such
as ceramic capacitors, which have a low capacitor series impedance, but rather use electrolytic capacitors and implement
measures to minimize the surge current and prevent voltage increases.
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