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A8292 Schematic ( PDF Datasheet ) - Allegro MicroSystems

Teilenummer A8292
Beschreibung Dual LNB Supply and Control Voltage Regulator
Hersteller Allegro MicroSystems
Logo Allegro MicroSystems Logo 




Gesamt 19 Seiten
A8292 Datasheet, Funktion
A8292
Dual LNB Supply and Control Voltage Regulator
Features and Benefits
Description
2-wire serial I2C™ -compatible interface: control (write) and Intended for analog and digital satellite receivers, this dual
status (read)
low-noise block converter regulator (LNBR) is a monolithic
LNB voltages (16 programmable levels) compatible with linear and switching voltage regulator, specifically designed to
all common standards
provide the power and the interface signals to two LNB down
Tracking switch-mode power converter for lowest dissipation converters via coaxial cables. TheA8292 requires few external
Integrated converter switches and current sensing
components, with the boost switches and compensation circuitry
Provides up to 500 mA per channel and 750 mA total
integrated inside of the device. A high switching frequency is
Static current limit circuit allows full current at startup and chosen to minimize the size of the passive filtering components,
1318V output transition; reliably starts wide load range further assisting in cost reduction. The high level of component
Push-pull output stage minimizes 1318V and 1813V
integration ensures extremely low noise and ripple figures.
output transition times for highly capacitive loads
Adjustable rise/fall time via external timing capacitor
Built-in tone oscillator, factory-trimmed to 22 kHz
facilitates DiSEqC™ tone encoding, even at no-load
Four methods of 22 kHz tone generation, via I2C™ data
bits and/or external pin
The A8292 has been designed for high efficiency, utilizing
the Allegro® advanced BCD process. The integrated boost
switches have been optimized to minimize both switching and
static losses. To further enhance efficiency, the voltage drop
across the tracking regulators has been minimized.
22 kHz tone detector facilitates DiSEqC™ 2.0 decoding The A8292 has integrated tone detection capability, to support
Auxiliary modulation input
full two-way DiSEqC™ communications. Several schemes
LNB overcurrent with timer
are available for generating tone signals, all the way down
Diagnostics for output voltage level, input supply UVLO, to no-load, and using either the internal clock or an external
and DiSEqC™ tone output
Cable disconnect diagnostic
timewww.DataSheet4U.com source.
Package:
28 pin 5 mm × 5mm MLP/QFN
(suffix ET)
Continued on the next page…
Functional Block Diagram
VS
VDD
C2
100 μF
A
Channel 1
L1
33 μH
L3
D1 1 MH
A8292
VIN
C1
100 nF
VREG
C3
220 nF
Regulator
R3
R2
R1
SDA
SCL
I2 C
Compatible
Interface
IRQ
C5
100 μF
C6
1 μF
R4 R5
C4
100 nF
TDO1 EXTM1 LX1
GNDLX1 BOOST1 VCP1
Boost
Converter
Charge
Pump
C12 D
TMode1
EXTM1
Fsw
DAC
LNB
Voltage
Control
Wave
Shape
TCAP1
TGate1
Fault Monitor
OCP1
OCP2
PNG1
PNG2
TSD
VUV
Fsw
Clock
Divider 22 kHz
Oscillator
PAD
GND
VPump
Linear
Stage
TDO1
Tone
Detect
R6
157
LNB1
C8
D2 220 nF
L2
220 μH
R8
30 7
C9
220 nF
D
TCAP1
C7
10 nF
C11
0.68 μF
B
TDI1
R7
100 7
C10
10 nF
C13
10 nF
D3
C
VOUT1
D4
C
A Channel 1 of 2 channels shown.
B R8-C11 network is needed only when high
inductive load is applied, such as ProBrand LNB.
C D3 and D4 are used for surge protection.
D Either C12 or C9 should be used, but not both.
8292-DS, Rev. 3






A8292 Datasheet, Funktion
A8292
Dual LNB Supply and Control Voltage Regulator
ELECTRICAL CHARACTERISTICS (continued) at TA = 25°C, VIN = 8 to 16 V, unless noted otherwise1
Characteristics
Symbol
Test Conditions
Min.
I2C™ Address Setting
ADD Voltage for Address 0001,000
Address1
0
ADD Voltage for Address 0001,001
Address2
1.3
ADD Voltage for Address 0001,010
ADD Voltage for Address 0001,011
Address3
Address4
2.3
3.3
1Operation at 16 V may be limited by power loss in the linear regulator.
2Guaranteed by design.
Typ. Max. Units
– 0.7 V
– 1.7 V
– 2.7 V
– 5.0 V
tSU:STA tHD:STA
I2C™ Interface Timing Diagram
tSU:DAT
tHD:DAT
tSU:STO
tBUF
SDA
SCL
tLOW
tHIGH
Allegro MicroSystems, Inc.
6
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com

6 Page









A8292 pdf, datenblatt
A8292
Dual LNB Supply and Control Voltage Regulator
Control Registers (I2C™-Compatible Write Register)
All main functions of the A8292 are controlled through the
I2C™-compatible interface via the 8-bit Control registers. As the
A8292 contains numerous control options, as well as featuring
two channels, it is necessary to have four Control registers. Each
register contains up to 6 bits of data (bit 0 to bit 5), followed by 2
bits for the register address (bit 6 and bit 7). The power-up states
for the control functions are all 0s.
The following tables define the control bits for each address
and the settings for output voltage:
Table 2. Control Registers with Address (I1, I0) = 00 and 01
Name
Channel 1
Channel 2
Bit (Address: I1, I0 = 00) (Address: I1, I0 = 01)
Setting
0 VSEL01
1 VSEL11
2 VSEL21
3 VSEL31
VSEL02
VSEL12
VSEL22
VSEL32
See table 4, Output Voltage
Amplitude Selection
0: LNBx = Low range
1: LNBx = High range
4 ODT1
ODT2
0: Overcurrent disable time off
1: Overcurrent disable time on
5 ENB1
ENB2
0: Disable LNBx Output
1: Enable LNBx Output
6 I0
Address Bit
I0 Channel 1: 0
Channel 2: 1
7 I1
Address Bit
I1 Channel 1: 0
Channel 2: 0
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
VSEL0x
VSEL1x
VSEL2x
VSEL3x
ODTx
ENBx
I0
I1
These three bits provide incremental control over the voltage on the LNBx output.
The available voltages provide the necessary levels for all the common standards
plus the ability to add line compensation in increments of 333 mV. The voltage levels are
defined in table 4, Output Voltage Amplitude Selection.
Switches between the low level and high level output voltages on the LNBx output. 0 selects
the low level voltage and 1 selects the high level. The low-level center voltage is 12.709 V
nominal and the high level is 18.042 V nominal. These may be increased in steps of 333 mV
using the VSEL2x, VSEL1x and VSEL0x control register bits.
Enables the overcurrent disable timer. When set to 1, and an overcurrent occurs for longer
than the detection time, the LNBx ouput on the channel is disabled. When set to 0, and an
overcurrent occurs, the LNBx output will operate in current limit indefinitely. It is highly
recommended that the ODT function be enabled at all times.
Enables the LNBx output. When set to 1 the LNBx output is switched on. When set to 0,
the LNBx output is disabled.
Address
Address
Allegro MicroSystems, Inc.
12
115 Northeast Cutoff, Box 15036
Worcester, Massachusetts 01615-0036 (508) 853-5000
www.allegromicro.com

12 Page





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