SI9979 Datasheet, PDF (4/7 Pages) Vishay Siliconix – 3-Phase Brushless DC Motor Controller

Si9979
Vishay Siliconix
PIN CONFIGURATION
PIN DESCRIPTION
Pins 1-3: IN_A, IN_B, IN_C
IN_A, IN_B, and IN_C are the commutation sensor inputs, and are
intended to be driven by open collector Hall effect switches.
These inputs have internal pull up resistors tied to V_DD, which
eliminates the need for external pull up resistors.
Pin 4: 60/120
The 60/120 input allows the use of the Si9979 with either a 60°
or 120° commutation sensor spacing. An internal pull up
resistor, which is tied to V_DD, sets the default condition to 60°
spacing. 120° spacing is selected by pulling this input to
ground.
Pin 5: EN (Enable)
A logic “1” on this input allows commutation of the motor. This
is the default condition as this pin is pulled up internally. When
this pin is pulled to ground, all gate drive outputs are turned off.
Pin 6: F/R (Forward/Reverse)
A logic “1” on this input selects commutation for motor rotation
in the “forward” direction. This is the default condition as this
pin is pulled up internally. When this pin is pulled to ground, the
commutation sensor logic levels are inverted internally,
causing reverse rotation.
Pin 7: QS (Quadrature Select)
This input determines whether the bottom MOSFETs or both
bottom and top MOSFETs switch in response to the PWM
signal. A logic “1” on this input enables only the bottom
MOSFETs. This is the default condition as this pin is pulled up
internally. When this pin is pulled to ground, both the bottom
and top MOSFETs are enabled.
Pin 8: PWM
An open collector (drain) or TTL compatible signal is applied to
this input to control the motor speed. The QS input determines
which MOSFETs are switched in response to the PWM signal.
If no PWM signal is being used, this input is left open. It is
pulled up internally, which allows the MOSFETs to follow the
commutation sequence.
Pin 9: BRK
With this input at logic “1”, the top MOSFETs are turned off and
the bottom MOSFETs are turned on, shorting the motor
windings together. This provides a braking torque which is
dependent on the motor speed. This is the default condition as
this pin is pulled up internally. When this pin is pulled to
ground, the MOSFETs are allowed to follow the commutation
sequence.
S-60752-Rev. D, 05-Apr-99
4
FaxBack 408-970-5600, request 70012
www.siliconix.com