CMD1668M,CMD1667M
Two-Phase Unipolar Drive Brushless Motor Drivers
Design Documentation (See the application circuit diagrams)
1. Power-supply voltage (V pin)
IN
The resistor R1 (when V = 12 V R1 = 330 Ω, and when V = 24 R1 = about 1.2 kΩ) is inserted between V and
CC
CC
IN
the power supply V pin. When the I current is set in the range 6 to 50 mA, the V pin will be regulated to be
CC
CC
IN
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.
2. Output transistors (OUT1 and OUT2 pins)
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.
Sustained output voltage : V = 65 V minimum (design guarantee)
O
Output current
: I = 1.5 A maximum
O
Output saturation voltage : V sat = 1.25 V/1.0 A (typical)
O
Safe operating range
: I = 1.0 A, V
= 57 V, t = 200 µs
O
OLM
3. Output circuit kickback voltage protection (Z1 and Z2 pins)
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.
—When the Z1 and Z2 pins are shorted
The output protection voltage will be 32 V (typical) using a V = 12 V power supply.
CC
—When the Z1 and Z2 pins are open
The output protection voltage will be 57 V (typical) using a V = 24 V power supply.
CC
—With a Zener diode inserted between Z1 and V or between Z1 and ground
CC
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.
4. Output protection when the motor is lock (C, RD, and FG pins)
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.
When C = 0.47 µF
Lock detection time: about 1 second
Lock protection time (output on): about 0.5 second
(output off): about 3 seconds
The RD pin (CMD1668M) is an open collector output and outputs a low level during drive and a high level when stopped.
The FG pin (CMD1667M) 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.
5. Thermal shutdown
This circuit turns the output off in response to coil shorting or IC overheating.
6. In applications that use an external transistor to turn the cooling fan power on and off, connect a capacitor of about
0.47 to 10 µF between the fan power supply V and ground to provide a regenerative route for the fan motor coil
CC
current.
* All specs and applications shown above subject to change without prior notice.
1F-5 NO.66 SEC.2 NAN-KAN RD ., LUCHU , TAOYUAN, TAIWAN
Tel:886-3-3214525
Email: server@ceramate.com.tw
Http: www.ceramate.com.tw
Rev 1.0 Aug. 23,.2004
Page 7 of 9
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