Diodes ZXBM1004 - Manual (Page 7)

V
CC
- Applied Voltage
This is the device internal circuitry supply voltage. For
5V to 12V fans this can be supplied directly from the Fan
Motor supply. For fans likely to run in excess of the 18V
maximum rating for the device this will be supplied
from an external regulator such as a Zener diode.
RD Timing Waveform:
Applications Information
The ZXBM1004 is primarily controlled by a voltage on
the SPD pin. A voltage of 1V represents a 100% PWM at
the Phase Outputs and in turn represents full speed. 3V
on the SPD pin conversely represents 0% PWM. The
motor can therefore be controlled simply by applying a
control voltage onto the SPD pin with the minimal use
of external components.
This voltage control method easily lends itself to
control by other signal types. For example if a
thermistor is applied to the SPD pin a varying voltage
can be generated at the SPD pin as the resistance of the
thermistor varies with temperature.
A common form of control of fans is by a PWM signal
derived from a central processor or controller. This
signal can be converted into a voltage and that voltage
adjusted as neccesary to compensate for motor none
linearity, inclusion of the Minimum speed feature etc.
Full applications details and further examples of how to
control the ZXBM1004 are available in the Applications
Notes AN41, AN42 and AN43.
ZXBM1004
S E M I C O N D U C T O R S
ISSUE 6 - MAY 2007
7
T Lock T Off T On
Hall
C LCK
FG
RD
V THH
V THL