8281/8282
11/18/2002
Intended for analog and digital satellite receivers, the low noise block
converter regulator (LNBR) is a monolithic linear and switching voltage
regulator, specifically designed to provide the power and the interface
signals to the LNB downconverter via the coaxial cable.
If the device is in stand-by mode (EN terminal LOW), the regulator
output is disabled. This is to allow the antenna downconverters to be
supplied/controlled by other satellite receivers sharing the same coaxial
cable. In this mode the device will limit reverse current.
The A8281 is supplied in a 16-lead plastic SOIC with copper batwing
tab (suffix “LB”). The A8282 is supplied is a 24-lead plastic SOIC with
copper batwing tab (suffix “LB”). Operating temperature range is standard
classification (suffix "S").
The A8282 is available for improved power dissipation as well as
allowing direct replacement of Allegro’s first generation LNBR device, the
A8283SLB, with the exception of the bypass switch.
FEATURES
LNB selection and stand-by function
Built-in tone oscillator factory trimmed to 22 kHz facilitates DiSEqC
encoding
Tracking switch-mode power converter for lowest dissipation
Externally adjustable short-circuit protection
LNB short-circuit protection and diagnostics
Auxiliary modulation input
Internal over temperature protection
Reverse current protection
Cable Length Compensation (A8282 only)
This device incorporates features that have patents pending.
Always order by complete part number:
Part Number
A8282SLBTR
A8282SLB
A8281SLB
Package
24 Lead SOIC Tape/Reel
24 Lead SOIC
16 Lead SOIC
ABSOLUTE MAXIMUM RATINGS
at TA = +25
°
C
Load Supply Voltage, VIN ...........................4
7 V
Output Current, I
OUT
............
Internally Limited*
Output Voltage, V
OUT
........................
-1V to
22 V
Switching Node, LX .......................................
-1V
Logic Input .....................................
-0.3 V to 7 V
Package Power Dissipation (TA = +25
°
C), P
D
A8281SLB..........................
56
°
C/W**
A8282SLB..........................
50
°
C/W**
Operating Temperature Range,
T
A
................................
-20
°
C to +85
°
C
Junction Temperature, T
J
.........................
+150
°
C
Storage Temperature Range,
T
S
...............................
-55
°
C to +150
°
C
*
Output current rating may be limited by duty cycle,
ambient temperature, and heat sinking. Under any set of
conditions, do not exceed the specified current rating or a
junction temperature of 150
°
C.
** Measured on a PCB with 2 oz copper with ground area
of 1 square inch.
LNB SUPPLY AND CONTROL
VOLTAGE REGULATOR