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A8283SLB Schematic ( PDF Datasheet ) - Allegro MicroSystems

Teilenummer A8283SLB
Beschreibung LNB SUPPLY AND CONTROL-VOLTAGE REGULATOR
Hersteller Allegro MicroSystems
Logo Allegro MicroSystems Logo 




Gesamt 8 Seiten
A8283SLB Datasheet, Funktion
8283
PRELIMINARY INFORMATION
(Subject to change without notice)
November 21, 2000
A8283SLB
OSEL 1
OLF 2
VBULK 3
MIOUT 4
MI 5
GND 6
GND 7
SENSE 8
LNB 99
LX 10
VIN 11
TCAP 12
BUCK
REG.
24 EXTM
23 VINT
22 PUMPX
21 VPUMP
20 CPUMP
19 GND
18 GND
17 ENT
16 EN
15 VSEL0
14 VSEL1
13 LLC
Dwg. PP-072A
Note that the A8283SB (dual in-line package)
and A8283SLB (small-outline IC package) are
electrically identical and share a common
terminal number assignment.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VIN .......................... 47 V
Output Current, IO .... Internally Limited
Logic Input Voltage Range,
VI ................................... -0.5 V to +7 V
Bypass Switch Current,
ISW ........................ Internally Limited
Flag Output Voltage, VOLF .................. 7 V
Operating Temperature Range,
TA ............................... -20°C to +85°C
Storage Temperature Range,
TS ............................. -40°C to +150°C
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 down
converter via the coaxial cable. If the device is in stand-by mode (EN terminal
LOW), the regulator output is disabled, allowing the antenna downconverters to
be supplied or controlled by other satellite receivers sharing the same coaxial
cable. Similar two-output LNB supply and control voltage regulators are the
A8284SB/SLB.
For slave operation in single-dish dual-receiver systems, the bypass
function is implemented by an electronic switch between the master input
terminal (MI) and the LNB terminal, leaving all LNB power and control
functions to the master receiver. This electronic switch is closed if the device
is powered, EN is HIGH, and OSEL is LOW.
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 regulator.
Logic inputs (VSEL0, VSEL1, and LLC) select the desired output voltage. A
tracking current-mode buck converter provides the linear regulator with an
input voltage that is set to the output voltage plus typically 0.8 V. This main-
tains constant voltage drop across the linear regulator while permitting ad-
equate voltage range for tone injection.
The device is supplied in a 24-pin plastic DIP with batwing tabs
(A8283SB), or a 24-lead SOIC power-tab package (A8283SLB). In both cases,
the power tab is at ground potential and needs no electrical isolation.
FEATURES
I Short-Circuit Protected Bypass Function for Slave Operation
I LNB Selection and Stand-By Function
I Built-In Tone Oscillator Factory Trimmed to 22 kHz, Facilitates
DiSEqC™ (a trademark of EUTELSAT) Encoding
I Full Modulation With No Load
I Tracking Switch-Mode Power Converter for Lowest Dissipation
I Externally Adjustable Short-Circuit Protection
I LNB Short-Circuit Protection and Diagnostics
I Auxiliary Modulation Input
I Cable Length Compensation
I Internal Over-Temperature Protection
This device incorporates features that have patents pending.
Always order by complete part number, e.g., A8283SLB .






A8283SLB Datasheet, Funktion
8283
LNB SUPPLY AND
CONTROL-VOLTAGE REGULATOR
TerminalConfiguration
Symbol
OSEL
Terminal
1
OLF
VBULK
MIOUT
MI
GND
SENSE
LNB
LX
VIN
TCAP
LLC
VSEL1
VSEL0
EN
ENT
GND
CPUMP
VPUMP
PUMPX
VINT
EXTM
2
3
4
5
6, 7
8
9
10
11
12
13
14
15
16
17
18, 19
20
21
22
23
24
Function
Logic input: selects between LNB on (when high) and
bypass switch closed (when low)
Overload flag output: low when IO > IOM or IO > ISWM or
TJ > 165°C, high when IO < IOM and IO < ISWM and TJ < 130°C
Tracking supply voltage to linear regulators
Output voltage from MI (connect to terminal 9)
Master input
Ground
Current limit setup resistor
Output voltage to LNB (connect to terminal 4)
Inductor drive point
Supply input voltage (minimum, VLNB + 2.5 V)
Capacitor for setting the rise and fall time of the outputs
Logic input: when high, increases output voltage by 1 V
for line length compensation
Logic input: output voltage select
Logic input: output voltage select
Logic input: when high, enables device
Logic input: when high, enables internal 22 kHz
modulation
Ground
High side of charge-pump capacitor
Gate supply voltage for high-side drivers
Charge-pump drive
Bypass capacitor for internal voltage reference
External modulation input
115 Northeast Cutoff, Box 15036
6 Worcester, Massachusetts 01615-0036 (508) 853-5000

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