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| Product Preview, July, 19, 99 (Subject to Change Without Notice) page 1 of 6 8284 Interim Data Sheet 21-50 V IN BUCK REGULATOR Vout + 0.8 V LNBA Two Output LNB Supply and Control Voltage Regulator * * * * * * * * * * * Complete interface for two LNBs remote supply and control LNB selection and stand-by function Built-in tone oscillator factory trimmed to 22 kHz facilitates DiSEqCTM encoding Full modulation with no load Tracking switch-mode power converter for lowest dissipation Externally adjustable short-circuit protection LNB short-circuit protection and diagnostics Auxiliary modulation input Cable length compensation Internal over temperature protection Reverse current protection LNBB VOLTAGE CONTROL 3 DATA IN ABSOLUTE MAXIMUM RATINGS DC Input voltage.......................................50 V Output Current .........................Internally limited Logic Input Voltage............................ -0.5 to 7 V Storage temperature range............... ...-40 to 150C Operating Junction Temperature Range...-40 to 150C Intended for analog and digital satellite receivers, the 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 the LNB downconverter via the coaxial cable. Because most satellite receivers have two antenna ports, the output voltage of the regulator is available at one of two logic-selectable output terminals (LNBA, LNBB). If the device is in stand-by mode (EN terminal LOW), both regulator outputs are disabled. This is to allow the antenna downconverters to be supplied and controlled by other satellite receivers sharing the same coaxial cable. In this mode the device will limit reverse current to 3 mA. The regulator outputs are set to 12, 13, 18, or 20 volts by the VSEL terminals. Additionally, it is possible to increase by 1 V the selected voltage to compensate the voltage drop in the coaxial cable (LLC terminal HIGH). Cont.... Product Preview, July, 19, 99 (Subject to Change Without Notice) page 2 of 6 8284 The LNBR is a combination of a tracking switching regulator and low-noise linear regulators. Logic inputs (VSEL0, VSEL1 and LLC) select the desired output voltage. A tracking current-mode buck converter provides the linear regulator input voltage that is set to the output voltage plus typically 0.8 volt. This maintains constant voltage drop across the linear regulators while permitting adequate voltage range for tone injection. The ENT (Tone Enable) terminal activates the internal tone signal modulating the dc output with a + 0.3 V, 22 kHz symmetrical waveform. The internal oscillator is factory trimmed to provide a tone of 22 kHz + 2 kHz. No further adjustment is required. The internal oscillator operates the buck converter at 16 times the tone frequency. Burst coding of the 22 kHz tone can be accomplished, due to the fast response of the ENT input and rapid tone response. This allows implementation of the DiSEqCTM protocols. To improve design flexibility and to allow implementation of proposed LNB remote control standards, an analog modulation input terminal is available (EXTM). An appropriate dc blocking capacitor must be used to couple the modulating signal source to the EXTM terminal. If external modulation is not used, the EXTM terminal can be left open. The output linear regulators will sink and source current. This feature allows full modulation capability into capacitive loads as high as 250 nF. The programmed output voltage rise and fall times can be set by an internal 50 k resister and an external capacitor located on the TCAP terminal. Although any value of capacitor is permitted, practical values are typically 1 nF to 20 nF. This feature only affects the turn on and programmed voltage rise and fall times. Modulation is unaffected by the choice of TCAP. This terminal can be left open if voltage rise and fall time control is not required. Two terminals are dedicated to the over current protection/monitoring: SENSE and OLF. The LNB output is current limited. The short-circuit protection threshold is set by the value of an external resistor, Rsense. Rsense = 0.15/Imax where Imax is the desired current limit. The minimum safe value for Rsense is 0.22 ohm In operation the short-circuit protection produces current fold-back at the input due to the tracking converter. If the output is shorted the linear regulator will limit the output current to Imax. The tracking converter will maintain a constant voltage drop of 0.8 volts across the linear regulator. This condition results in (Imax)*(0.8 volts) or typically 550 mW dissipation. Short-circuit or thermal shutdown activation will cause the OLF terminal, an open-drain diagnostic output flag, to go LOW. The device is packaged in a 24 DIP or an SOIC power-tab package. Thermal resistance: DIP RJA=40C/W, RJT=6C/W,SOIC RJA=55C/W, RJT=6C/W Product Preview, July, 19, 99 (Subject to Change Without Notice) page 3 of 6 8284 DiSEqCTM is a trademark of EUTELSAT. Product Preview, July, 19, 99 (Subject to Change Without Notice) page 4 of 6 8284 Terminal Configuration Symbol VINT CPUMP EN ENT EXTM GND VBULK LLC Voa Vob LX SENSE OLF OSEL VIN or Vcc VPUMP PUMPX TCAP VSEL0 VSEL1 Terminal Function Bypass capacitor for internal voltage reference High side of charge-pump cap Logic input: enables switcher and outputs Logic input: enable internal modulation External modulation input Ground Tracking supply voltage to linear regulators Logic input: increases output voltage by 1 V for line length LNBA output voltage A LNBB output voltage B Inductor drive point Current limit setup resistor Overload flag output Logic input: selects between LNB, A or B Supply input voltage (range VLNB+2.5 V to 47 V) Gate supply voltage for high side drivers Charge-pump drive Capacitor for setting the rise and fall time of the outputs Logic input: output voltage select Logic input: output voltage select Product Preview, July 19, 99 (Subject to Change Without Notice) page 5 of 6 8284 Truth Tables Control I/O OUT IN Terminal Name OLF ENT L Iout > Iomax or Tj > 165C 22 kHz tone OFF H Iout < Iomax and 22 kHz tone ON Tj < 130C SEL L L L L H H H H L L L L H H H H VSEL0 L L L L L L L L H H H H H H H H VSEL1 L H L H L H L H L H L H L H L H LLC L L H H L L H H L L H H L L H H VLNBA (typ.) 13 V 18 V 14 V 19 V Low Low Low Low 12 V 20 V 13 V 21 V Low Low Low Low VLNBB (typ.) Low Low Low Low 13 V 18 V 14 V 19 V Low Low Low Low 12 V 20 V 13 V 21 V Product Preview, July 19, 99 (Subject to Change Without Notice) page 6 of 6 8284 Electrical Characteristics for LNBR Series (TA = 25C, ENT=L, EN=H, LLC=L, VIN=24 V, Iout=50 mA (unless otherwise specified). Symbol VIN VO1 VO2 VO1 VO2 Parameter VCC1 Supply Voltage Output Voltage Output Voltage Output Voltage Output Voltage Test Conditions IO=600 mA,VSEL0=L,VSEL1=L, LLC=L IO =600 mA,VSEL0=L,VSEL1=H, LLC=L Io=600 mA, SEL0=L,VSEL1=H, LLC=H IO=600 mA, VSEL0=L,VSEL1=L LLC=L IO=600 mA, VSEL0=L,VSEL1=L, LLC=H IO=600 mA,VSEL0=H,VSEL1=H, LLC=L Io=600 mA, SEL0=H,VSEL1=H, LLC=H IO=600 mA, VSEL0=H,VSEL1=L LLC=L IO=600 mA, VSEL0=H,VSEL1=L, LLC=H VO=13 V, VIN =16 to 40 V VO=18 V ,VIN =21 to 40 V VO=13 or 18 V IO=50 to 600 mA fAC=100 Hz Rsense=0.22 ohm ENT=H ENT=H ENT=H ENT=H VO/VEXTM, f=10 Hz to 40 kHz AC coupling f=10 Hz to 40 kHz IOL=8.0 mA VOH=6.0 V Min. 2.5+VO 17.3 12.5 18 19 13 14 20 21 12 13 4.0 4.0 80 45 680 22 0.68 50 10 1.0 40 40 180 730 24 0.8 60 15 0.8 5 0.28 < 1.0 0.8 2.0 VIH=5 V Outputs disabled (EN=L) ENT=H, IOUT=600 mA VO=13 EN=L, VLNBA=VLNBB=18 V VIN1=VIN2=22 V or floating VBULK -VO fTONE * 16 < 1.0 .5 382 1.0 165 0.8 352 Typ. Max 47 18.7 13.5 Unit V V V V V V V V V mV mV mV dB mA kHz Vpp % s V/V Vpp k V a V V A mA mA mA C V kHz VO VO SVR IMAX fTONE aTONE dTONE t R, t F gEXTM VEXTM ZEXTM VOL IOZ VIL VIH IIH ICC ICC IOBK TSHDN VBUCK fO Line Regulation Load Regulation Supply Voltage Rejection Output Current Limiting Tone Frequency Tone Amplitude Tone duty cycle Tone rise or fall time External modulation gain External modulation input voltage External modulation input impedance Overload flag terminal logic low Overload flag terminal OFF state leakage current Control input terminal logic low Control input terminal logic high Control terminals input current Supply current Supply current Output reverse current Thermal shutdown threshold Linear regulator voltage drop Switching frequency 630 20 0.55 40 5.0 320 384 Product Preview, July 19, 99 (Subject to Change Without Notice) page 7 of 6 8284 |
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