lb1661 Sanyo Semiconductor Corporation, lb1661 Datasheet - Page 8

• Manufacturer Part Number: lb1661
• Description: 2-phase Unipolar Brushless Motor Drivers
• Manufacturer: Sanyo Semiconductor Corporation

(2) CR time constant setting method
(3) Restart after lock detection
Output transistor lock
1
2
3
The LB1660 series are so designed that when motor lock
is detected and the output stage transistor is turned off the
drive-off state is kept even after motor lock is released.
The method of restart is shown below.
1
2
Pulse of 2
Pulse of 1
Bias current of CR pin and effect of leakage of C. The value of the charge current at the threshold point is V
0.2/R3. Therefore, this value and the leakage of C must be large enough for the bias current.
The CR pin voltage must not exceed 0.6
rotational speed of a fan is reached and while a fan keeps the normal rotational speed; a malfunction may be caused by
instantaneous drop of power supply.
It should be noted that the CR pin voltage is varied with the combination C and R, even if the CR time constant is the
same.
The allowable CR setting value is given in the diagram.
Turn off the power supply and turn on again. Turn
on after the V
Set the CR pin voltage to be less than 1 V, and then
turn off the power supply in order to cause the lock
detect function to return to normal. (The CR pin can
be also used to provide on-off control.)
Output current, I
CR
has dropped enough.
V
O
(sat) – I
O
O
– A
Generation of discharge pulse
LB1660N, 1661, 1664N, 1665
V
IN
(LB1660N, 1664N) or 0.8
V
Current drain, I
IN
Resistance, R –
-0.3V (LB1661, 1665), until the normal
V
IN
t – R
– I
CC
CC
– mA
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IN