u6081b ETC-unknow, u6081b Datasheet - Page 2

• Manufacturer Part Number: u6081b
• Description: Power Control With Duty Cycle Switch
• Manufacturer: ETC-unknow

Pin Description
Functional Description
Pin 1, Supply Voltage, V
Overvoltage Detection
Stage 1:
If V
switched off and switched on again at V
(hysteresis).
Stage 2:
If V
(load-dump protection). At the same time the voltage li-
mitation of the IC is reduced from V
This leads to a hysteresis characteristic so that the load-
dump detection is switched off again only at V
In this case the short–circuit protection is not in operation.
Undervoltage Detection
In the event of voltages of approximately V
the external FET is switched off and the latch for short-
circuit detection is reset.
A hysteresis ensures that the FET is switched on again at
approximately V
Pin 2, GND
Ground-Wire Breakage
To protect the FET in the case of ground-wire breakage,
a 820-k
mended to provide proper switch-off conditions.
Pin 3, Control Input
The pulse width is controlled by means of an external
potentiometer (47 k
rotation/duty cycle) is linear. The duty cycle can be varied
from 0 to 100%. To avoid inadmissibly high filament cold
currents, the dimmer is switched off at duty cycles of
approximately < 10% or is switched on only at duty
cycles of approximately > 13% (hysteresis). It is possible
to further restrict the duty cycle with the resistors R
U6081B
2 (8)
Batt
Batt
GND
Osc
> 28 V, the external transistor is switched on again
V
W
V
> 20 V occurs the external transistor will be
S
I
resistor between gate and source is recom-
1
3
2
4
Batt

W
). The characteristic (angle of
5.4 V.
s
or V
95 9944
S
Batt
26 V to V
8
7
6
5
Batt
Output
Delay
Sense
Batt
2 V
Batt
< 18.5 V
S
S
< 5.0 V,
< 23 V.
1
20 V.
and
R
to V
Output Slope Control
The rise and fall time (t
limited to reduce radio interference. This is done with an
integrator which controls a power MOSFET as source
follower. The slope time is controlled by an external
capacitor C4 and the oscillator current (see figure 2).
Calculation:
t
With V
obtain a controlled slope of
t
A 100-
device oscillations (see figure 2).
Pin 4, Oscillator
The oscillator determines the frequency of the output
voltage. This is defined by an external capacitor, C
charged with a constant current, I, until the upper
switching threshold is reached. A second current source
is then activated which taps a double current, 2 I, from
the charging current. The capacitor, C
by the current, I, until the lower switching threshold is
reached. The second source is then switched off again and
the procedure starts again.
Example for oscillator frequency calculation:
V
V
V
where
f
f
2
T100
T
TL
Pin
+
+
¦
1
2
3
4
5
6
7
8
(see figure 2). Pin 3 is protected against short-circuit
100
Batt
+
+
t
t
r
r
W
Batt
+
+
+
V
and ground GND (V
V
resistor in series to C4 is recomended to damp
S
Symbol
V
V
= 12 V, C
12 V
Output
S
Delay
Sense
GND
2 V
Osc
S
Batt
V
V
a
S
I
S
a
3
1
a
+
+
2
I
C
4
470 pF
+
osc
40
( V
Supply voltage V
IC ground
Control input (duty cycle)
Oscillator
Short circuit protection delay
Current sensing
Voltage doubler
Output
4
= 470 pF and I
TELEFUNKEN Semiconductors
( V
Batt
( V
r
m
, t
Batt
A
Batt
f
*
) of the lamp voltage can be
Batt
*
+
*
I
S
I
x
S
141
I
Function
S
16.5 V).
osc
2
R
Rev. A1, 14-Feb-97
, is thus discharged
m
R
3
S
s
= 40
)
R
3
)
3
)
m
a
A, we thus
a
3
1
a
2
2
. It is