Allegro A8284SLB, A8284SB Datasheet

8284

Data Sheet

27448.1

ADVANCE INFORMATION

(Subject to change without notice)

December 22, 2000

A8284SLB

OSEL

OLF

VBULK

LNBB

NC

GND

GND

SENSE

LNBA

LX

VIN

TCAP

1

2

3

4

5

6

7

8

9

9

10

BUCK

11

12

REG.

24

23

22

21

PUMP

CHARGE

20

19

18

17

16

15

14

VOLTAGE

CONTROL

13

EXTM

VINT

PUMPX

VPUMP

CPUMP

GND

GND

ENT

EN

VSEL0

VSEL1

LLC

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 compen­sate 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.

Dwg. PP-072-1A

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, VIN.......................... 47 V

Output Current, IO.... Internally Limited

Logic Input Voltage Range,

VI................................... -0.5 V to +7 V

Flag Output Voltage, V

Operating Temperature Range,

TA............................... -20°C to +85°C

Storage Temperature Range,

TS............................. -40°C to +150°C

CONTACT FACTORY

.................. 7 V

OLF

FEATURES

■ 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™ (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 .

8284

TWO-OUTPUT LNB SUPPLY AND
CONTROL-VOLTAGE REGULATOR

FUNCTIONAL BLOCK DIAGRAM

VINT

ENT

OLF

VBULK

150 mV

RS

SENSE

LNBB

1

0

EXTM

LNBA

OSEL

Dwg. FP-051

47 V
MAX

VPUMP

CHARGE

TSD

CPUMP

PUMP

176 kHz

OVER-CURRENT

PUMPX

VOLTAGE

REG.

EN

5 V

VIN

BOOST VOLTAGE

–

+

÷2

÷8

&

WAVESHAPING

7 V

352 kHz

BUCK

CONV.

22 kHz TONE

VREF

VSEL0

VSEL1

LX

–

OVER-

CURRENT

+

800 mV

TCAP

–

+

25 kΩ

LLC

–

+

1 kΩ

+

+

–

5 kΩ

5 kΩ

OSEL VSEL0 VSEL1 LLC V

LNBA(typ)VLNBB(typ)

LLLL13 VLow
L L L H 14 V Low

L L H L 18 V Low
L L H H 19 V Low
L H L L 12 V Low
L H L H 13 V Low
L H H L 20 V Low

LHHH21 VLow
HLLLLow13 V
H L L H Low 14 V
H L H L Low 18 V
H L H H Low 19 V
H H L L Low 12 V
H H L H Low 13 V
H H H L Low 20 V
HHHHLow21 V

2

115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 [phone]
Copyright © 2000, Allegro MicroSystems, Inc.

Output Voltage Select Table

8284

TWO-OUTPUT LNB SUPPLY AND

CONTROL-VOLTAGE REGULATOR

ELECTRICAL CHARACTERISTICS at TA = 25°C, OSEL = H for LNBB, OSEL = L for LNBA (each
output tested separately), ENT = L, EN = H, LLC = L, V
noted).

Characteristic Symbol Test Conditions Min. Typ. Max. Units

= 24 V, IO = 50 mA (unless otherwise

IN

Limits

Supply Voltage V

Output Voltage V

Line Regulation ∆V

Load Regulation ∆V

Current-Limiting Threshold V

Tone Frequency f

Tone Amplitude V

OM(th)

tone

tone(PP)

Tone Duty Cycle dc

Tone Rise or Fall Time tr, t

External Modulation Gain G

External Modulation V

mod

mod(PP)

Input Voltage

IN

O

O

O

tone

IO = 600 mA, VSEL0 = L, VSEL1 = L, LLC = L

IO = 600 mA, VSEL0 = L, VSEL1 = L, LLC = L

IO = 600 mA, VSEL0 = L, VSEL1 = L, LLC = H

IO = 600 mA, VSEL0 = L, VSEL1 = H, LLC = L

IO = 600 mA, VSEL0 = L, VSEL1 = H, LLC = H

IO = 600 mA, VSEL0 = H, VSEL1 = L, LLC = L

IO = 600 mA, VSEL0 = H, VSEL1 = L, LLC = H

IO = 600 mA, VSEL0 = H, VSEL1 = H, LLC = L

IO = 600 mA, VSEL0 = H, VSEL1 = H, LLC = H

—

3.3 + ∆V

BUCK

47 V

12.5 13 13.5 V

13.4 14 14.6 V

17.3 18 18.7 V

18.2 19 19.8 V

11.5 12 12.5 V

12.5 13 13.5 V

19.2 20 20.8 V

20.2 21 21.8 V

VO = 13 V, VI = 16 to 40 V — 4.0 40 mV

VO = 18 V, VI = 21 to 40 V — 4.0 40 mV

VO = 13 or 18 V, IO = 50 to 600 mA — 80 180 mV

125 135 145 mV

ENT = H 20 22 24 kHz

ENT = H 550 680 800 mV

ENT = H 40 50 60 %

f

ENT = H 5.0 10 15 µs

∆VO/∆V

, f = 10 Hz to 40 kHz — 5.0 — V/V

mod

AC coupling — — 160 mV

External Modulation Z
Impedance

www.allegromicro.com

mod

f = 10 Hz to 40 kHz — 5.0 — kΩ

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