U211B ATMEL Corporation, U211B Datasheet - Page 7

• Manufacturer Part Number: U211B
• Description: as U209B + Foldback
• Manufacturer: ATMEL Corporation

Design Hints
Practical trials are normally needed for the exact
determination of the values of the relevant components in
the load limiting. To make this evaluation easier, the
P
P
t
t
n.e
Pulse-Output Stage
The pulse-output stage is short-circuit protected and can
typically deliver currents of 125 mA. For the design of
smaller triggering currents, the function I
be taken from figure 20.
Automatic Retriggering
The variable automatic retriggering prevents half cycles
without current flow, even if the triac is turned off earlier,
e.g., due to a collector which is not exactly centered
(brush lifter) or in the event of unsuccessful triggering. If
necessary, another triggering pulse is generated after a
time lapse which is determined by the repetition rate set
by resistance between Pin 5 and Pin 3 (R
maximum repetition rate (Pin 5 directly connected to
Pin 3), the next attempt to trigger comes after a pause of
4.5 t
half cycle finishes. If Pin 5 is not connected, then only one
trigger pulse per half cycle is generated. Because the
value of R
repetition rate set using R
of C
Rev. A4, 03-Aug-01
P
P
P
t
t
d
r
d
r
max
min
max
min
max
2
p
.
and this is repeated until either the triac fires or the
/
– maximum continuous power dissipation
– power dissipation with no rotation
– operation delay time
– recovery time
– no effect
min
Parameters
5-3
determines the charging current of C
5-3
is only valid for a fixed value
increases
increases
increases
n.e.
n.e.
R
10
Increasing
GT
5-3
= f(R
). With the
GT
2
, any
) can
P
P
1
1
decreases
decreases
n.e.
increases
increases
= f
= f
following table shows the effect of the circuitry on the
important parameters of the load limiting and summa-
rizes the general tendencies.
General Hints and Explanation of Terms
To ensure safe and trouble-free operation, the following
points should be taken into consideration when circuits
are being constructed or in the design of printed circuit
boards.
– The connecting lines from C
– The common (earth) connections of the set-point
– The tacho generator should be mounted without
– The connections from R
To achieve a high noise immunity, a maximum ramp
voltage of 6 V should be used.
The typical resistance R
follows:
A 10% lower value of R
is recommended.
(n)
(n)
should be as short as possible. The connection to Pin 2
should not carry any additional high current such as
the load current. When selecting C
temperature coefficient is desirable.
generator, the tacho generator and the final
interference suppression capacitor C
converter should not carry load current.
influence by strong stray fields from the motor.
as possible.
R
n 0 0
n = 0
R
ö
Component
T = Period duration for mains frequency
C
9
(kW) +
ö
Increasing
= Ramp capacitor, max. ramp voltage 6 V
(10 ms at 50 Hz)
and constant voltage drop at R
T(ms)
C(nF)
ö
ö
(under worst case conditions)
can be calculated from I
n.e.
n.e.
n.e.
increases
increases
10
1.13(V)
and C
6(V)
C
2
9
to Pin 7 and Pin 2
5
Increasing
should be as short
U211B
10
4
3
ö
of the f/V
2
, a low
= 1.13 V.
7 (21)
ö
as