LB11690 Datasheet, PDF (14/19 Pages) Sanyo Semicon Device – Pre-Driver IC for Brushless Motor Drive in Electric Bicycles

LB11690, 11690H
6. Hall Sensor Input Signals
The outputs of the Hall sensor IC are connected to this IC's Hall sensor inputs. Since the IC includes internal pull-up
resistors (about 10 kΩ) to the 5 V regulator, normally, there is no need for external pull-up resistors. If a Hall sensor
IC with built-in pull-up resistors is used, no problems will occur as long as the Hall sensor IC uses a 5 V power
supply. However, pull-down resistors and voltage clamping
zener diodes must be added to assure that voltages over 5 V are
not applied to this IC if the Hall sensor IC uses a 12 V power
supply.
12 V
Hall sensor IC
5 V LB11690,
11690H
The inputs are comparator inputs with a hysteresis of about 0.9
IN
V. If noise becomes a problem, noise rejection capacitors must
be inserted between the inputs and ground.
If all three of the Hall input signals go to the same input state, all
the outputs, both the high side and low side, will go to the off
state.
7. Undervoltage Protection Circuit
The undervoltage protection circuit detects the voltage applied to the LVS pin and if that voltage falls under the
operating voltage (3.8 V typical), the drive outputs are all set to the off state. This circuit has hysteresis to prevent the
circuit from repeatedly turning the outputs on and off when the supply voltage is close to the protection operating
voltage. Therefore, the output will not recover unless the supply voltage rises to about 0.5 V above the circuit's
operating voltage. Also, the RES pin voltage goes to the low level in the protection operating state.
The protection operating voltage is set to be the detection level
for a 5 V system. The detection level can be increased by
To the detected power supply
inserting a zener diode in the LVS pin to level shift the detection
Vz
level. (The detection voltage will then be the zener voltage (Vz)
plus 3.8 V (typical).) The LVS pin sink current during detection
LVS pin
is about 62 µA. If it is necessary to stabilize the zener diode
voltage increase and to minimize variations in the zener voltage,
insert a resistor between the LVS pin and ground to increase the
zener current. It is also possible to increase the detection voltage
without using a zener diode by using a resistor voltage divider.
To the detected power supply
If the circuit in the figure is used, the detection and release
R1
voltages will be as follows.
Detection voltage ≈ ((3.8 ÷ R2) + 62 µA) × (R1 + R2)
Release voltage ≈ ((4.3 ÷ R2) + 70 µA) × (R1 + R2)
LVS pin
R2
If R1 is 13 kΩ and R2 is 2.2 kΩ, the detection voltage will be
about 27 V and the release voltage will be about 31 V. Note that
errors in the detection voltage due to temperature and sample-to-sample variations increase as the value of the resistor
R2 increases.
If this protection circuit is not used, the LVS pin must not be left open (the outputs are turned off when this pin is
open). Rather, a voltage at a level at which the circuit does not operate must be applied.
8. RES Circuit
When power is first applied, the application must apply an initial reset to the RES pin to assure stable operation. The
initial reset performs the following operations.
• All the drive outputs are turned off.
• The EI⁺ pin voltage is forced to the low level.
• The FV pin voltage is forced to the low level.
Normally, a resistor and a capacitor are inserted between the RES pin and the V5 pin and the RES pin and ground,
respectively, to set the reset time. A resistor with a value of 2.7 kΩ or higher must be used. The time constant must be
set to a value such that R × C ≥ 1 ms (if a 10 kΩ resistor is used, the capacitor must be 0.1 µF or larger). However, in
cases where it is necessary to completely discharge the capacitors on the EI⁺ and FV pins, the reset time must be set to
cover those discharge times. It is also desirable to set the reset time to be longer than the time required to stabilize the
VB voltage after power is first applied.
Continued on next page.
No. 7543-14/19