U210B1 Datasheet, PDF (3/12 Pages) TEMIC Semiconductors – Phase Control Circuit Load Current Feedback Applications

U210B1
Description
Mains Supply
The U210B1 is fitted with voltage limiting and can there-
ă ^{fore 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:
V_M–V_S
R₁=
2 I_S
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
recommended.
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
employed.
~
24 V~
1
2
3
4
5
When the potential on Pin 6 reaches the nominal value
predetermined at Pin 9, then a trigger pulse is generated
whose width t_p is determined by the value of C₂ (the value
of C₂ and hence the pulse width can be evaluated by
assuming 8 ms/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
half cycle.
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.
Voltage Monitoring
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.
R₁
C₁
95 10362
Figure 3. Supply voltage for high current requirements
Phase Control
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.
Soft-Start
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
motor.
C₄ is first charged with typ. 30 mA. 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 mA.
TELEFUNKEN Semiconductors
Rev. A1, 28-May-96
3 (12)