A8285SLBTR-T Datasheet, PDF (1/18 Pages) Allegro MicroSystems – LNB Supply and Control Voltage Regulator

A8285 and A8287
LNB Supply and Control Voltage Regulator
Features and Benefits
• LNB selection and standby function
• Provides up to 500 mA load current
• Two-wire serial I²C interface
• Built-in tone oscillator, factory-trimmed to 22 kHz;
facilitates DiSEqC™ 2.0 encoding
• Auxiliary modulation input
• 22 kHz tone detector facilitates DiSEqC™ decoding
(A8287 only)
• Tracking switch-mode power converter for lowest
dissipation
• LNB overcurrent protection and diagnostics
• Internal overtemperature protection
• LNB voltages (16 possible levels) compatible with all
common standards
Packages
16-pin SOIC
(A8285)
24-pin SOIC
(A8287)
Description
Intended for analog and digital satellite receivers, the LNB
(low noise block) converter regulator is a monolithic linear and
switching voltage regulator, specifically 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 I²C (Inter-C bus) standard, that operates
up to 400 kHz.
The A8285 is supplied in a 16-lead plastic power SOIC with
internally fused leads for thermal dissipation. The A8287 is
supplied in a 24-lead plastic power SOIC with internally fused
leads. Both devices are also available in lead (Pb) free versions,
with 100% matte tine leadframe plating.
V _IN C10
100 nF
Functional Block Diagram
C1
33 µF
L1
33 µH
D1
C5
100 nF
C2
C4
100 nF 100 µF
VREG
C3 _{220 nF}
EXTM
R3 R4 R5
V_DD
SDA
SCL
ADD
IRQ
VIN
Internal
Regulator
BOOST
Feedback
OSC In
Boost Converter
LX
VCP
Charge
Pump
VPUMP
Overcurrent
BOOST
OSC
Clock
Divider
22 kHz
Tone
Generator
Output
Voltage
Select
Fault Monitor
Overcurrent
TSD
Undervoltage
Overcurrent
100 mV
DISABLE
Tracking
Regulator
GM
22 kHz Tone
Detector
R1
15 Ω
LNB
D2
L2
33 µH
1.5 µF
C7
220 nF
C6
TCAP
6.8 nF
C8
TOUT
220 Ω R2
10 nF
TDI
C9
TDO
R6 ^VDD
A8285-DS, Rev. F