U6084B
Pin Description
Pin
1
Symbol
GND
Function
GND
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
S
IC ground
2
En / Dis Enable/disable
Control input (duty cycle)
Reduct Duty cycle reduction
En / Dis
NC
3
V
I
4
V
I
Output
5
NC
Osc
Attenuation
6
Oscillator
7
NC
Not connected
Not connected
Status short circuit latch
Not connected
Short circuit protection delay
Current sensing
Voltage doubler
Output
Reduct
2 V
S
8
NC
9
Latch
NC
Attenuation
Osc
Sense
Delay
10
11
12
13
14
15
16
Delay
Sense
2V
NC
S
NC
NC
Output
NC
Not connected
Latch
V
S
Supply voltage V
S
95 9754
Pin 4, Duty Cycle Reduction
Functional Description
With Pin 4 connected according to figure 2, the set duty
cycle is reduced as from V 12.5 V. This causes a
power reduction in the FET and in the lamps. In addition,
the brightness of the lamps is largely independent of the
Pin1, GND
Batt
Ground-Wire Breakage
supply voltage range, V
= 12.5 to 16 V.
Batt
To protect the FET in the case of ground-wire breakage,
a 820 k resistor between gate and source it is recom-
mended to provide proper switch-off conditions.
Output Slope Control
The rise and fall time (t , t ) of the lamp voltage can be
r
f
limited to reduce radio interference. This is done with an
integrator which controls a power MOSFET as source fol-
lower. The slope time is controlled by an external
capacitor C4 and the oscillator current (see figure 2).
Pin 2, Enable/Disable
The dimmer can be switched on or off with pin 2 indepen-
dently of the set duty cycle.
Calculation:
C4
tf
tr
VBatt
V
Function
Disable
Iosc
2
Approx. >0.7 V or open
With V
Batt
= 12 V, C = 470 pF and I = 40 A,we thus
4
osc
obtain a controlled slope of
< 0.7 V or connected to Pin 1 Enable
470 pF
tf
tr
12 V
141 s
Pin 3, Control Input
40
A
Pin 5, Attenuation
The pulse width is controlled by means of an external po-
tentiometer (47 k ). The characteristic (angle of
rotation/duty cycle) is linear. The duty cycle can be varied
from 0 to 100%. It is possible to further restrict the duty
Capacitor C connected to Pin 5 damps oscillation
4
tendencies.
Pin 6, Oscillator
cycle with the resistors R and R (see figure 2).
1
2
Pin 3 is protected against short-circuit to V
and ground
The oscillator determines the frequency of the output
Batt
GND (V
16.5 V).
voltage. This is defined by an external capacitor, C . It is
Batt
2
2 (8)
TELEFUNKEN Semiconductors
Rev. A1, 14-Feb-97
TEMIC [ TEMIC SEMICONDUCTORS ]
