The U210B1 is fitted with voltage limiting and can there-
ăfore be supplied directly from the mains. The supply
voltage between Pin 2 (+pol/ ) and Pin 3 builds up
across D1 and R1 and is smoothed by C1. The vaIue of the
series resistance can be approximated using:
Further information regarding the design of the mains
supply can be found in the data sheets in the appendix.
The reference voltage source on Pin 13 of typ. –8.9 V is
derived from the supply voltage. It represents the refer-
ence level of the control unit.
Operation using an externally stabiIised dc voltage is not
If the supply cannot be taken directly from the mains be-
cause the power dissipation in R1 would be too large, then
the circuit shown in the following figure 3 should be
When the potential on Pin 6 reaches the nominal value
predetermined at Pin 9, then a trigger pulse is generated
whose width tp is determined by the value of C2 (the value
of C2 and hence the pulse width can be evaluated by
assuming 8 m s/nF). At the same time, a latch is set, so that
as long as the automatic retriggering has not been
activated, then no more pulses can be generated in that
The current sensor on Pin 1 ensures that, for operation
with inductive loads, no pulse will be generated in a new
half cycle as long as current from the previous half cycle
is still flowing in the opposite direction to the supply volt-
age at that instant. This makes sure that “Gaps” in the load
current are prevented.
The control signal on Pin 9 can be in the range 0 V to –7 V
(reference point Pin 2).
If V9 = –7 V then the phase angle is at maximum = a max
i .e. the current flow angle is a minimum. The minimum
phase angle a min is when V9 = V2.
As the voltage is built up, uncontrolled output pulses are
avoided by internal voltage surveillance. At the same
time, all of the latches in the circuit (phase control, soft
start) are reset and the soft-start capacitor is short cir-
cuited. Used with a switching hysteresis of 300 mV, this
system guarantees defined start-up behaviour each time
the supply voltage is switched on or after short interrup-
tions of the mains supply.
Figure 3. Supply voltage for high current requirements
The function of the phase control is largely identical to
that of the well known component TEA1007. The phase
angle of the trigger pulse is derived by comparing the
ramp voltage, which is mains synchronized by the voltage
detector, with the set value on the control input Pin 9. The
slope of the ramp is determined by C2 and its charging
current. The charging current can be varied using R2 on
Pin 5. The maximum phase angle a max can also be
adjusted using R2.
As soon as the supply voltage builds up (t1), the integrated
soft-start is initiated. The figure below shows the
behavior of the voltage across the soft-start capacitor and
is identical with the voltage on the phase control input on
Pin 9. This behaviour allows a gentle start-up for the
C4 is first charged with typ. 30 m A. The charging current
then increases as the voltage across C4 increases giving a
progressively rising charging function with more and
more strongly accelerates the motor with increasing rota-
tional speed. The charging function determines the
acceleration up to the set point. The charging current can
have a maximum value of 85 m A.
Rev. A1, 28-May-96