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A8286 Dataheets PDF



Part Number A8286
Manufacturers Allegro MicroSystems
Logo Allegro MicroSystems
Description Dual LNB Supply and Control Voltage Regulator
Datasheet A8286 DatasheetA8286 Datasheet (PDF)

A8286 Dual LNB Supply and Control Voltage Regulator Features and Benefits ▪ 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 ▪ Output current limit of 900 mA typical, with 48 ms timer ▪ Static current limit circuit allows full current at startup and 13→18 V output transition; rel.

  A8286   A8286


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A8286 Dual LNB Supply and Control Voltage Regulator Features and Benefits ▪ 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 ▪ Output current limit of 900 mA typical, with 48 ms timer ▪ Static current limit circuit allows full current at startup and 13→18 V output transition; reliably starts wide load range ▪ Push-pull output stage minimizes 13→18 V and 18→13 V 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 ▪ 22 kHz tone detector facilitates DiSEqC™ 2.0 decoding ▪ Diagnostics for output voltage level, input supply UVLO, and DiSEqC™ tone output ▪ Cable disconnect diagnostic ▪ Auxiliary modulation input ▪ LNB overcurrent with timer Package: 28-pin QFN (suffix ET) Description Intended for analog and digital satellite receivers, this dual 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 two LNB down converters via coaxial cables. The A8286 requires few external components, with the boost switches 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 level of component integration ensures extremely low noise and ripple figures. The A8286 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. The A8286 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 time source. Continued on the next page… 5 mm × 5 mm (Not to scale) VS VDD 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. Functional Block Diagram C2 100 µF A Channel 1 L1 33 µH L3 D1 1 µH A8286 C5 100 µF C6 1 µF R4 R5 C4 100 nF TDO1 EXTM1 LX1 GNDLX1 BOOST1 VCP1 VIN C1 100 nF VREG C3 220 nF Regulator R3 R2 R1 SDA SCL I2 C− Compatible Interface IRQ 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 15 Ω LNB1 C8 D2 220 nF L2 220 µH R8 30 Ω C9 220 nF D TCAP1 C7 22 nF C11 0.68 µF B TDI1 R7 100 Ω C10 10 nF D3 C VOUT1 C13 D4 10 nF C 8286-DS, Rev. 22 MCO-0000208 January 27, 2020 A8286 Dual LNB Supply and Control Voltage Regulator Description (continued) A comprehensive set of fault registers are provided which, comply with all the common standards, including: overcurrent, thermal shutdown, undervoltage, cable disconnect, power not good, and tone detect. The device uses a 2-wire bidirectional serial interface, compatible with the I2C™ standard, that operates up to 400 kHz. The A8286 is supplied in a lead (Pb) free 28-lead MLP/QFN with 100% matte tin leadframe. Absolute Maximum Ratings Characteristic Symbol Conditions Rating Units Load Supply Voltage, VIN pin VIN Output Current1 IOUT 30 V Internally Limited A Output Voltage, BOOST pin  Output Voltage, LNB pin  Output Voltage, LX pin  Output Voltage, VCP pin Logic Input Voltage, EXTM pin Surge2 VCP –0.3 to 33 V –1 to 33 V –0.3 to 30 V –0.3 to 41 V –0.3 to 5 V Logic Input Voltage, other pins –0.3 to 7 V Logic Output Voltage –0.3 to 7 V Operating Ambient Temperature TA  –20 to 85 °C Junction Temperature TJ(max) 150 °C Storage Temperature Tstg –55 to 150 °C 1Output current rating may be limited by duty cycle, ambient temperature, and heat sinking. Under any set of conditions, do not exceed the specified current ratings, or a junction temperature, TJ, of 150°C. 2Use Allegro recommended Application circuit. Package Thermal Characteristics* Package RθJA (°C/W) PCB ET 32 4-layer * Additional information is available on the Allegro website. Ordering Information Use the following complete part numbers when ordering: Part Number Packinga A8286SETTR-Tb 7-in. reel.


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