Zxbm2004 – Diodes ZXBM2004 User Manual
Page 8
ZXBM2004
TWO PHASE VARIABLE SPEED
MOTOR CONTROL PRE-DRIVER
ZXBM2004
Document number: DS33433 Rev. 5 - 2
8 of 19
February 2012
© Diodes Incorporated
NEW PROD
UC
T
Functional Descriptions
(cont.)
FG -Frequency Generator (tachometer) Output
This is the Frequency Generator output and is a buffered signal from the Hall sensor.
This is an open collector drive giving an active pull down with the high level being provided by an external pull up resistor.
Ph1 and Ph2 Output Drives
This pair of outputs drives the external devices. These outputs provide both the commutation and PWM waveforms. The
outputs are of the Darlington emitter follower type with an active pull-down to help faster switch off when using bipolar
devices. When in the high state the outputs will provide up to 80mA of drive into the base or gates of external transistors as
shown in the Typical Application circuit following.
When in the low state the active Phase drive is capable of sinking up to 16mA when driving low to aid turn off times during
PWM operation. When the Phase is inactive the output is held low by an internal pull-down resistor.
V+OP Phase Outputs Supply Voltage
This pin is the supply to the Phase outputs and will be connected differently dependant upon external transistor type. For
bipolar devices this pin will be connected by a resistor to the V
CC
pin. The resistor is used to control the current into the
transistor base so its value is chosen accordingly. For MOSFET devices the pin will connect directly to the V
CC
pin.
V
CC
– Supply 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.