U211B3 Temic Semiconductors (acquired by ATMEL Corporation), U211B3 Datasheet - Page 4

• Manufacturer Part Number: U211B3
• Description: Phase Control Circuit - General Purpose Feedback
• Manufacturer: Temic Semiconductors (acquired by ATMEL Corporation)

C
typical 45
current to approx. 4
is substantially reduced so that the rotational speed of the
motor only slowly increases. The charging current then
increases as the voltage across C
progressively rising charging function which accelerates
the motor more and more strongly with increasing
rotational speed. The charging function determines the
acceleration up to the set-point. The charging current can
have a maximum value of 55
Frequency to Voltage Converter
The internal frequency to voltage converter (f/V-
converter) generates a DC signal on Pin 10 which is
proportional to the rotational speed using an AC signal
from a tacho-generator or a light beam whose frequency
is in turn dependent on the rotational speed. The high
impedance input Pin 8, compares the tacho-voltage to a
switch-on threshold of typ. –100 mV. The switch-off
threshold is given with –50 mV. The hysteresis
guarantees very reliable operation even when relatively
simple tacho-generators are used. The tacho-frequency is
given by:
where:
U211B2/ B3
4 (20)
3
is first charged up to the starting voltage V
t
t
t
t
t
V
V
1
2
1
3
tot
f
V
C3
12
0
+ t
+
m
A current (t
t
2
1
60
= build-up of supply voltage
= charging of C
= dead time
= run-up time
= total start-up time to required speed
n
n = revolutions per minute
p = number of pulses per revolution
t
2
Figure 4. Soft-start
m
p (Hz)
A, the slope of the charging function
2
). By then reducing the charging
t
tot
m
3
A.
to starting voltage
t
3
3
increases giving a
95 10272
t
0
with
The converter is based on the charge pumping principle.
With each negative half wave of the input signal, a
quantity of charge determined by C
amplified and then integrated by C
output on Pin 10. The conversion constant is determined
by C
the internally adjusted charge transfer gain.
G
The analog output voltage is given by
The values of C
possible input frequency, the maximum output voltage
V
on Pin 9 is .approx. 6.7 k
f/V converter the time constant resulting from R
should be considerably less (1/5) than the time span of the
negative half-cycle for the highest possible input
frequency. The amount of remaining ripple on the output
voltage on Pin 10 is dependent on C
charge amplification.
The ripple V
C
reduced.
The value of this capacitor should be chosen to fit the
particular control loop where it is going to be used.
Pulse Blocking
The output of pulses can be blocked using Pin 18 (standby
operation) and the system reset via the voltage monitor if
V
hysteresis, the output is released when V
followed by a soft-start such as that after turn on.
Monitoring of the rotation can be carried out by
connecting an RC network to Pin 18. In the event of a
short or open circuit, the triac triggering pulses are cut off
by the time delay which is determined by R and C. The
capacitor C is discharged via an internal resistance
R
converter. If there are no more charge transfer processes
C is charged up via R until the switch-off threshold is
exceeded and the triac triggering pulses are cut off. For
operation without trigger pulse blocking or monitoring of
the rotation, Pins 18 and 16 must be connected together.
k = G
V
6
i
O
18
i
V
O
. However, the increasing speed will then also be
= 2 k
I
O
does not exceed 6 V. While C
I
= k
10
5
9
, its charge transfer voltage of V
=
i
–1.25 V. After cycling through the switching point
W
+
@
G
f
i
C
with each charge transfer process of the f/V
8.3
5
C
o
6
V
5
can be reduced by using larger values of
ch
R
and C
6
C
TELEFUNKEN Semiconductors
6
V
5
W
must be such that for the highest
ch
. To obtain good linearity of the
5
is charging up, the R
5
Rev. A1, 29-May-96
, C
6
ch
6
at the converter
, R
5
and the internal
6
is internally
(Pin 10) and
18
i
and C
–1.5 V
5
i