A8291SETTR-T

A8291SETTR-T Datasheet

A8291 Single LNB Supply and Control Voltage Regulator

Part	Datasheet
A8291SETTR-T	A8291SETTR-T (pdf)

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A8291 Single LNB Supply and Control Voltage Regulator Last Time Buy These parts are in production but has been determined to be LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available. Date of status change December 5, 2016 Deadline for receipt of LAST TIME BUY orders August 30, 2017 Recommended Substitutions Generation 4 and 5 devices For existing customer transition, and for new customers or new applications, contact Allegro Sales. NOTE For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. A8291 Single LNB Supply and Control Voltage Regulator 2-wire serial I2C -compatible interface control write and status read LNB voltages 16 programmable levels compatible with all common standards Tracking switch-mode power converter for lowest dissipation Integrated converter switches and current sensing Provides up to 500 mA load current Static current limit circuit allows full current at startup and output transition reliably starts wide load range Push-pull output stage minimizes and 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 Filter bypass MOSFET minimizes losses during tone transmit 22 kHz tone detector facilitates DiSEqC decoding Auxiliary modulation input LNB overcurrent with timer Diagnostics for output voltage level, input supply UVLO, and DiSEqC tone output Cable disconnect diagnostic Package: 28 pin 5 mm x 5mm MLP/QFN suffix ET Intended for analog and digital satellite receivers, this single 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 an LNB down converter via coaxial cable. The A8291 requires few external components, with the boost switch and compensation circuitry integrated inside of the device. A high switching frequency is chosen to minimize the size of the passive filtering components, further assisting in cost reduction. The high levels of component integration ensure extremely low noise and ripple figures. The A8291 has been designed for high efficiency, utilizing the Allegro advanced BCD process. The integrated boost switch has been optimized to minimize both switching and static losses. To further enhance efficiency, the voltage drop across the tracking regulator has been minimized. The A8291 has integrated tone detection capability, to support full two-way DiSEqC communications. Several schemes are available for generating tone signals, all the way down to no-load, and using either the internal clock or an external Continued on the next VREG C3 220 nF VDD R1 R2 R3 R4 R5 R6 EXTM BFC TDO SDA SCL ADD IRQ C1 100 nF Regulator I2 C Compatible Interface Functional Block Diagram L1 33 µH D1 L3 1 µH C2 100 µF C5 100 µF LX GNDLX C6 1 µF C4 100 nF BOOST VCP Boost Converter Charge BFC Pump VPump LNB Voltage Control EXTM

PDF Datasheet Preview

A8291 Single LNB Supply and Control Voltage Regulator

Last Time Buy

These parts are in production but has been determined to be LAST TIME BUY. This classification indicates that the product is obsolete and notice has been given. Sale of this device is currently restricted to existing customer applications. The device should not be purchased for new design applications because of obsolescence in the near future. Samples are no longer available.

Date of status change December 5, 2016 Deadline for receipt of LAST TIME BUY orders August 30, 2017

Recommended Substitutions Generation 4 and 5 devices

For existing customer transition, and for new customers or new applications, contact Allegro Sales.

NOTE For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative.

A8291 Single LNB Supply and Control Voltage Regulator
2-wire serial I2C -compatible interface control write and status read

LNB voltages 16 programmable levels compatible with all common standards

Tracking switch-mode power converter for lowest dissipation Integrated converter switches and current sensing Provides up to 500 mA load current Static current limit circuit allows full current at startup and
output transition reliably starts wide load range Push-pull output stage minimizes and
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 Filter bypass MOSFET minimizes losses during tone transmit 22 kHz tone detector facilitates DiSEqC decoding Auxiliary modulation input LNB overcurrent with timer Diagnostics for output voltage level, input supply UVLO,
and DiSEqC tone output Cable disconnect diagnostic

Package:
28 pin 5 mm x 5mm MLP/QFN suffix ET

Intended for analog and digital satellite receivers, this single 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 an LNB down converter via coaxial cable. The A8291 requires few external components, with the boost switch and compensation circuitry integrated inside of the device. A high switching frequency is chosen to minimize the size of the passive filtering components, further assisting in cost reduction. The high levels of component integration ensure extremely low noise and ripple figures.

The A8291 has been designed for high efficiency, utilizing the Allegro advanced BCD process. The integrated boost switch has been optimized to minimize both switching and static losses. To further enhance efficiency, the voltage drop across the tracking regulator has been minimized.

The A8291 has integrated tone detection capability, to support full two-way DiSEqC communications. Several schemes are available for generating tone signals, all the way down to no-load, and using either the internal clock or an external

Continued on the next

VREG C3 220 nF VDD R1 R2 R3 R4 R5 R6

EXTM BFC TDO SDA SCL ADD IRQ

C1 100 nF

Regulator

I2 C Compatible

Interface

Functional Block Diagram

L1 33 µH D1

L3 1 µH

C2 100 µF

C5 100 µF LX GNDLX

C6 1 µF

C4 100 nF

BOOST VCP

Boost Converter

Charge BFC Pump

VPump

LNB Voltage Control

EXTM

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived A8291SETTR-T Datasheet file may be downloaded here without warranties.

Datasheet ID: A8291SETTR-T 516067