Data Sheet
27448.003c
A8285/A8287
LNB Supply and Control Voltage Regulator
Intended for analog and digital satellite receivers, the LNB (low noise
block) converter regulator is a monolithic linear and switching voltage
regulator, specifi cally designed to provide power and interface signals
to an LNB downconverter, via coaxial cable.
The device uses a 2-wire bidirectional serial interface, compatible with
the I
2
C (Inter-C bus) standard, that operates up to 400 kHz.
The A8285 is supplied in a 16-lead plastic power SOIC with copper
batwing tabs (suffi x LB). The A8287 is supplied in a 24-lead plastic
power SOIC with copper batwing tabs (part number suffi x LB).
null LNB selection and standby function
null Provides up to 500 mA load current
null Two-wire serial I
2
C interface
null Built-in tone oscillator, factory-trimmed to 22 kHz; facilitates
DiSEqC™ 2.0 encoding
null Auxiliary modulation input
null 22 kHz tone detector facilitates DiSEqC™ decoding

(A8287 only)
null Tracking switch-mode power converter for lowest dissipation
null LNB overcurrent protection and diagnostics
null Internal overtemperature protection
null LNB voltages (16 possible levels) compatible with all common
standards
Use the following complete part numbers when ordering:
Preliminary Data Sheet
Subject to Change without Notice
January 21, 2004
AB SO LUTE MAX I MUM RAT INGS
8ADD
4GND
7EXTM
3IRQ
6VIN
2SDA
5VREG
9 NC
13 GND
10 TCAP
14 LX
11 TOUT
15 BOOST
12 LNB
16 VCP1SCL
A8287SlB
SOIC
Part Number Package Description
A8287SLB 24-pin, batwing SOIC All features
A8285SLB 16-pin, batwing SOIC Tone detect not provided
Load Supply Voltage, V
IN
....................................16 V
Output Current, I
OUT
..................Internally Limited*
Output Voltage
LNB, BOOST .....................–0.3 V to 28 V
TOUT................................. –0.3 V to 22 V
Logic Input
EXTM ...................................–0.3 V to 5 V
Other .................................... –0.3 V to 7 V
Logic Output ........................................ –0.3 V to 7 V
Package Power Dissipation ………..See power dis si-
pation information in the Application Information section
Operating Temperature
Ambient, T
A
.......................–20°C to +85°C
Junction, T
J
.......................–20°C to +150°C
Storage,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 specifi ed current
rating or a junction temperature of +150°C.
13 TDI
14 NC
TCAP15
16 TOUT
17 LNB
21 GND
18 GND
22 GND
19 GND
23 BOOST
20 LX
24 VCP
12TDO
11ADD
10EXTM
9VIN
8VREG
4GND
7GND
3IRQ
6GND
2SDA
5GND
1SCL
A8285SlB
SOIC
FEATURES
Scale 1:1
Scale 1:1