U211B-XFPG3Y ATMEL Corporation, U211B-XFPG3Y Datasheet - Page 9

• Manufacturer Part Number: U211B-XFPG3Y
• Description: Phase Control IC with Overload Limitation for Tacho Applications
• Manufacturer: ATMEL Corporation

7.4
7.5
7.6
4752B–INDCO–09/05
Design Hints
Pulse-output Stage
Automatic Retriggering
Practical trials are normally needed for the exact determination of the values of the relevant
components for load limiting. To make this evaluation easier, the following table shows the effect
of the circuitry on the important parameters for load limiting and summarizes the general
tendencies.
Table 7-1.
P
P
t
t
n.e.
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
10-12 on page
The variable automatic retriggering prevents half cycles without current flow, even if the triac has
been 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
With the maximum repetition rate (pin 5 directly connected to pin 3), the next attempt to trigger
comes after a pause of 4.5 t
ishes. If pin 5 is not connected, only one trigger pulse per half cycle is generated. Since the
value of R
for a fixed value of C
d
r
Parameters
P
P
P
t
t
max
min
d
r
max
min
max/min
5-3
determines the charging current of C
- Maximum continuous power dissipationP
- Power dissipation with no rotation
- Operation delay time
- Recovery time
- No effect
Load Limiting Parameters
18.
2
.
Component
R
Increases
Increases
Increases
n.e.
n.e.
10
Increasing
p
and this is repeated until either the triac fires or the half cycle fin-
Component
R
Decreases
Decreases
n.e.
Increases
Increases
9
Increasing
2
, any repetition rate set using R
P
1
1
= f
= f
GT
(n)
(n)
= f(R
n
n = 0
GT
0
C
Component
n.e.
n.e.
n.e.
Increases
Increases
9
) can be taken from
Increasing
5-3
U211B
is only valid
Figure
5-3
).
9