8284
ADVANCE INFORMATION
(Subject to change without notice)
December 22, 2000
TWO-OUTPUT LNB SUPPLY AND
CONTROL-VOLTAGE REGULATOR
Intended for analog and digital satellite receivers, the low noise block
converter regulator (LNBR) is a monolithic linear and switching voltage
regulator designed to provide power and interface signals to the LNB
downconverter via the coaxial cable. Because most satellite receivers have two
antenna ports, the output voltage of the regulator is available at one of two
logic-selectable output terminals (LNBA, LNBB). If the device is in stand-by
mode (EN terminal LOW), both regulator outputs are disabled, allowing the
antenna downconverters to be supplied and controlled by other satellite
receivers sharing the same coaxial cable. Similar single-output devices, with a
bypass function for slave operation in single-dish dual-receiver systems, are the
A8283SB/SLB.
The regulator outputs are set to 12, 13, 18, or 20 V by the VSEL terminals.
Additionally, it is possible to increase the selected voltage by 1 V to compen-
sate for the voltage drop in the coaxial cable (LLC terminal HIGH).
The LNBR combines a tracking switching regulator and low-noise linear
regulators. Logic inputs (VSEL0, VSEL1, and LLC) select the desired output
voltage. A tracking current-mode buck converter provides the linear regulator
input voltage that is set to the output voltage plus typically 0.8 V. This
maintains constant voltage drop across the linear regulators while permitting
adequate voltage range for tone injection.
The device is supplied in a 24-pin plastic DIP with batwing tabs
(A8284SB), or a 24-lead SOIC power-tab package (A8284SLB). In both cases,
the power tab is at ground potential and needs no electrical isolation.
Data Sheet
27448.1
A8284SLB
OSEL
OLF
VBULK
LNBB
NC
GND
GND
SENSE
LNBA
LX
VIN
TCAP
1
2
3
4
5
6
7
8
9
9
10
11
12
BUCK
REG.
24
23
22
EXTM
VINT
PUMPX
VPUMP
CPUMP
GND
GND
ENT
EN
VSEL0
VSEL1
LLC
21
20
19
18
17
16
15
14
Note that the A8284SB (dual in-line package)
and A8284SLB (small-outline IC package) are
electrically identical and share a common
terminal number assignment.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, V
IN
..........................
47 V
Output Current, I
O
....
Internally Limited
Logic Input Voltage Range,
V
I
...................................
-0.5 V to +7 V
Flag Output Voltage, V
OLF
..................
7 V
Operating Temperature Range,
T
A
...............................
-20
擄
C to +85
擄
C
Storage Temperature Range,
T
S
.............................
-40
擄
C to +150
擄
C
T
C
A
T
N
O
C
13
Dwg. PP-072-1A
Y
R
O
T
C
A
F
VOLTAGE
CONTROL
CHARGE
PUMP
FEATURES
I
I
I
I
I
I
I
I
I
I
Complete Interface for Two LNBs Remote Supply and Control
LNB Selection and Stand-By Function
Built-In Tone Oscillator Factory Trimmed to 22 kHz, Facilitates
DiSEqC鈩?(a trademark of EUTELSAT) Encoding
Full Modulation With No Load
Tracking Switch-Mode Power Converter for Lowest Dissipation
Externally Adjustable Short-Circuit Protection
LNB Short-Circuit Protection and Diagnostics
Auxiliary Modulation Input
Cable Length Compensation
Internal Over-Temperature Protection
This device incorporates features that have patents pending.
Always order by complete part number, e.g.,
A8284SLB
.
ALLEGRO
1
2
3
4
5
6
7
8
