mtd6501c Microchip Technology Inc., mtd6501c Datasheet - Page 9

• Manufacturer Part Number: mtd6501c
• Description: 3-phase Brushless Dc Sinusoidal Sensorless Fan Motor Driver
• Manufacturer: Microchip Technology Inc.

3.7
The Boost mode is an optional BEMF pre-amplification
by a factor of 3. The interest of the Boost mode is to
compensate for motors with a low coupling coefficient
(= BEMF coefficient), thus allowing to cover an even
wider range of motor characteristics. Notice that the
Boost mode impacts the mechanical performance of
the motor altogether. In Boost mode, the speed of the
motor will adjust faster to variations of the control (V
or PWM) and/or of the load, including at start-up. On
the other hand, however, when the BEMF is amplified
too much, the mechanical performance (in terms of
vibration and acoustic noise) may start degrading.
Thus, the Boost mode may be inappropriate, for motors
that already have a good coupling coefficient. The opti-
mum choice (between normal mode and Boost mode)
depends both on the application requirements and on
the motor characteristics.
Refer to Table 3-1 for the usage of the “BOOST” pin #9:
leaving this pin floating results the normal mode of
operation, tying this pin to GND activates the Boost
mode.
TABLE 3-1:
 2010 Microchip Technology Inc.
Tied to GND
BOOST Pin
Floating
Boost Mode (MTD6501D)
POSSIBLE MODES OF
OPERATION BASED ON THE
BOOST PIN CONNECTION
Mode of Operation
Normal
Boost
CC
MTD6501C/MTD6501D
DS22263A-page 9