LNBP8L STMicroelectronics, LNBP8L Datasheet - Page 10

• Manufacturer Part Number: LNBP8L
• Description: LNB SUPPLY AND CONTROL VOLTAGE REGULATOR
• Manufacturer: STMicroelectronics

Detailed description and application hints
Figure 6.
6.1
6.2
10/21
23V
C1
10µF
7.
Equation 1
V
where V
V
EXTM application circuit
Input voltage protection
In some cases two or more receivers share the same coaxial cable, rendering their outputs
hard-paralleled, so the same voltage is present at the outputs of the receivers. If a receiver
is not disconnected at the mains, a current will flow from the OUTPUT to the V
pins, depending the EN/VSEL pin setting. To avoid this, two diodes (only one for the IPPAK
package) in series are recommended at input pins V
diodes do not cause a change at V
using Schottky diodes. Diodes used in
current of almost 1 A and a breakdown voltage of 30 V (suggested type is 1N4001 or
BYV10-30). Be aware that the minimum voltage needed at the V
considering the voltage drop across the input diodes).
Single supply for the DFN package
If only one power supply source is available, the V
same power source without affecting the performance of other circuits, at the cost of higher
power losses in the device and higher heat sink surface. Also, in order to reduce the power
dissipation in the device, an appropriate-value resistor can be inserted in series with the
OUT
EXTM
EXTM modulates the V
The following equation is used to calculate the peak-to-peak voltage of V
Vextm
(AC) = V
. G
OUT
D1
1N4001
EXTM
time T
has elapsed, the output goes low for a time of T
power dissipated by the device low in overload conditions, and avoids the need for
an oversized heat sink in this condition. For the IPPAK package, when the
overload or the short-circuit occurs, the device clamps the output current in a
range between 550 mA and 850 mA.
C2
220nF
(AC) and V
C4
1µF
EXTM
is the external modulation gain.
ON
(AC) x G
depending on the C
EXTM
VCC
OUT
EXTM
EXTM
EN/VSEL (Tristate)
(AC) are, respectively, the peak-to-peak voltage of V
Doc ID 15153 Rev 2
by means of a capacitor connected in series (see
LNBP8/9L
OUT
, but only a voltage drop, which can be minimized by
Figure 4
EXT
GND
value (see
and
OUTPUT
CC1
LNBP8L, LNBP9L, LNBP10L, LNBP11L
Figure 5
CC1
and V
Figure 24
and V
OFF
CC2
D2
1N5818
must withstand a continuous
= 12 x T
CC2
pins can be powered by the
CC
and
(see
pins must be respected,
C3
100nF
Figure
ON
LNB OUTPUT
Figure
. This keeps the
25). When T
OUT
CC1
3). These
OUT
:
Figure
or V
and
CC2
ON
6).