Zxbm2004 – Diodes ZXBM2004 User Manual
Page 9
ZXBM2004
TWO PHASE VARIABLE SPEED
MOTOR CONTROL PRE-DRIVER
ZXBM2004
Document number: DS33433 Rev. 5 - 2
9 of 19
February 2012
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Application Note
The ZXBM2004 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 necessary to compensate for motor none linearity, inclusion of the
Minimum speed feature etc.
Full applications details and further examples of how to control the ZXBM2004 are available in the Applications Notes AN41,
AN42 and AN43.
Fig 1. 12V Typical Circuit for Thermistor Controlled Speed