zxbm1016 Zetex Semiconductors plc., zxbm1016 Datasheet - Page 7

• Manufacturer Part Number: zxbm1016
• Description: High Efficiency Variable Speed Single-phase Fan Motor Controller
• Manufacturer: Zetex Semiconductors plc.

SPD - Speed control input
The voltage applied to the SPD pin provides control over the fan motor speed by varying the Pulse
Width Modulated (PWM) drive ratio at the Ph1Lo and Ph2Lo outputs. The input voltage range for
the control signal is 3V to 1V, representing 0% to 100% drive respectively.
If variable speed control is not required this pin can be left with an external potential divider to
set a fixed speed or tied through a 10k
drive.
The advantage of a fixed potential divider is that the benefit of the current limit and tail-end
current control can be achieved. Neither function will operate with the pin tied directly to ground.
If full speed with current limit and tail-end current control is required then connect the SPD pin
ground through a 10k
tail-end current control shaping.
If required this pin can also be used as an enable pin. The application of a voltage >3.0V will force
the PWM drive fully off, in effect disabling the drive.
S
A voltage can be set on this pin using a potential divider between the ThRef and Gnd. This voltage
is monitored by the SPD pin such that the SPD voltage cannot rise above the S
higher voltage on the SPD pin represents a lower speed it therefore restricts the lower speed
range of the motor. If this feature is not required the pin is left tied to ThRef so no minimum speed
will be set.
If the fan is being controlled from an external voltage source and the minimum speed feature is
required then a 10k resistor should be placed in series with the external control voltage and the
SPD pin.
C
The C
whilst running and when in the lock condition.
When a motor is running under normal conditions this pin provides a triangular waveform related
to the speed of the motor. This waveform is used by the tail-end current control circuit to
determine the end of the commutation cycle.
If the fan stops rotating for any reason then this pin takes on the conventional operation of a
Locked Rotor monitor. In this condition and after the motor has stopped, a predetermined time
(T
defined period (T
in an attempt to re-start the fan. This cycle of (T
the fan re-starts.
The cycle of (T
start-up function in conjunction with the current monitor circuit described towards the end of this
section.
The time period of (T
pin. Any selection of the value will need consideration when in the run and lock modes. Typically
a 0.47 F will provide for most applications.
Issue 1 - February 2007
© Zetex Semiconductors plc 2007
MIN
LCK
OFF
- Locked rotor and run mode timing capacitor
) will elapse during which the motor will not be driven. After this delay the circuitry uses a
- Minimum speed threshold voltage
LCK
pin will have a capacitor connected to ground. It is a dual function pin providing timing
OFF
ON
) and (T
) to attempt to re-enable the output drive by going through a start-up routine
OFF
resistor with a 0.1 F capacitor in parallel. This capacitor is used for the
) and (T
ON
) is also used to start the fan from power-up and so this pin forms a
ON
) is determined by the value of capacitor applied to the C
resistor to ground to provide full speed i.e. 100% PWM
OFF
7
) and (T
ON
) will be repeated indefinitely or until
ZXBM1016
MIN
www.zetex.com
voltage. As a
LCK