Diodes ZXBM1016 - Manual (Page 9)

ZXBM1016
Issue 1 - February 2007 9 www.zetex.com
© Zetex Semiconductors plc 2007
Ph1Hi and Ph2Hi - High-side external H-bridge driver
These are the high side outputs to the external H-bridge and are open collector outputs capable
of sinking 100mA. This signal provides commutation only to the H-bridge.
GND - Circuitry ground return
This is the device supply ground return pin and will generally be the most negative supply pin to
the fan.
V
CC
- Circuitry applied voltage
This provides the supply for the device's internal circuitry and for the H-bridge output stage.
Sense - Current control sense
This pin is used by the current sensing circuit to monitor the current taken by the motor windings.
The signal comes from a sense resistor in the low-side ground return of the external H-bridge
driver.
SetTh - Current control threshold voltage
This pin is used by the current sensing circuit as the reference voltage for the voltage on the sense
pin to be compared against. If the voltage on the sense pin starts to exceed the voltage set on this
pin the current control circuitry starts to back off the PWM voltage and thus the current being
supplied to the motor coil.
SetThRef - SetTh and start-up reference
This pin is derived from an internal start-up circuit and is used as the source voltage for the
potential divider network attached to the SetTh pin.
Under running conditions this will be a voltage of approximately 4.75V, however, during start up
the voltage ramps up from 0V to 4.75V at a rate determined by the capacitor on the C
LCK
pin. Once
the motor is running it will go to its steady state.
This is a low power output capable of supplying a maximum of 200
␮A. It should only be used to
supply the potential divider network attached to the SetTh pin.