LB1668 SANYO [Sanyo Semicon Device], LB1668 Datasheet - Page 5

• Manufacturer Part Number: LB1668
• Description: Two-Phase Unipolar Drive Brushless Motor Drivers
• Manufacturer: SANYO [Sanyo Semicon Device]

Design Documentation (See the application circuit diagrams)
1. Power-supply voltage (V
2. Output transistors (OUT1 and OUT2 pins)
3. Output circuit kickback voltage protection (Z1 and Z2 pins)
4. Output protection when the motor is lock (C, RD, and FG pins)
5. Thermal shutdown
6. In applications that use an external transistor to turn the cooling fan power on and off, connect a capacitor of about
The resistor R1 (when V
the power supply V
6.7 V. Not only does this provide stability with respect to power-supply voltage variations and motor kickback, but it
also provides adequate strength to withstand surges.
A Zener diodes with the following characteristics is inserted between the collector and base of each output transistor
to absorb kickback voltages at 57 V (typical) and provide output protection.
These ICs support output protection that minimizes kickback noise by changing the kickback absorption voltage and
absorption method according to the output current and power-supply voltage used.
This circuit detects motor stopping due to, for example, overloading, and cuts the coil current. It also automatically
recovers drive and motor turning from the output stopped state when the load returns to an appropriate level. The lock
detection time is set with the value of an external capacitor.
The RD pin (LB1668) is an open collector output and outputs a low level during drive and a high level when stopped.
The FG pin (LB1667) is an open collector output and is switched between high and low by the drive phase. It goes to
the high level when the motor is stopped.
This circuit turns the output off in response to coil shorting or IC overheating.
0.47 to 10 µF between the fan power supply V
current.
— When the Z1 and Z2 pins are shorted
— When the Z1 and Z2 pins are open
— With a Zener diode inserted between Z1 and V
Sustained output voltage : V
Output current
Output saturation voltage : V
Safe operating range
The output protection voltage will be 32 V (typical) using a V
The output protection voltage will be 57 V (typical) using a V
This technique handles 120 mm H speed applications which require large output currents and involve large
amounts of heat generated in the IC by dissipating the motor coil switching loss in external Zener diodes.
When C = 0.47 µF
CC
pin. When the I
Lock detection time: about 1 second
Lock protection time (output on): about 0.5 second
CC
IN
pin)
= 12 V R1 = 330 Ω, and when V
: I
: I
O
O
O
O
= 1.5 A maximum
= 1.0 A, V
LB1668, LB1668M, LB1667, LB1667M
= 65 V minimum (design guarantee)
sat = 1.25 V/1.0 A (typical)
CC
current is set in the range 6 to 50 mA, the V
OLM
(output off): about 3 seconds
CC
and ground to provide a regenerative route for the fan motor coil
= 57 V, t = 200 µs
CC
or between Z1 and ground
CC
= 24 R1 = about 1.2 kΩ) is inserted between V
CC
CC
= 12 V power supply.
= 24 V power supply.
IN
pin will be regulated to be
No. 4944-5/7
IN
and