 |
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
|
| If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
|
| Datasheet File OCR Text: |
| Product Preview, July 19, 99 (Subject to Change Without Notice) page 1 of 7 8283 Interim Data Sheet 21-50 V IN BUCK REGULATOR Vout + 0.8V LNB LNB Supply and Control Voltage Regulator * * * * * * * * * * * Short-circuit protected bypass function for slave operation 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 MI VOLTAGE CONTROL 3 DATA IN 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. If the device is in stand-by mode (EN terminal LOW), the regulator output is disabled. This is to allow the antenna downconverters to be supplied/controlled by other satellite receivers sharing the same coaxial cable. In this mode the device will limit reverse current to 3 mA. For slave operation in single-dish dual-receiver systems, the bypass function is implemented by an electronic switch between the Master Input terminal (MI) and the LNB terminal, thus leaving all LNB power and control functions to the Master Receiver. This electronic switch is closed if the device is powered and EN terminal is LOW. 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... ABSOLUTE MAXIMUM RATINGS DC Input voltage.......................................50 V Output Current .........................Internally limited Logic Input Voltage.......................... -0.5 to 7 V Bypass Switch current................ Internally limited Storage temperature range...................-40 to 150C Operating Junction Temperature Range...-40 to 150C Product Preview, July 19, 99 (Subject to Change Without Notice) page 2 of 7 8283 The LNBR is a combination of a tracking switching regulator and low-noise linear regulator. Logic inputs (VSEL0, VSEL1 and LLC) select the desired output voltage. A tracking current-mode buck converter provides the linear regulator an input voltage that is set to the output voltage plus typically 0.8 volt. This maintains constant voltage drop across the linear regulator 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 time, 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 regulator 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 7 8283 *DiSEqCTM is a trademark of EUTELSAT. Product Preview, July 19, 99 (Subject to Change Without Notice) page 4 of 7 8283 Terminal Configuration Symbol VINT CPUMP EN ENT EXTM GND VBULK LLC Vo MI LX SENSE OLF 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 tabs Tracking supply voltage to linear regulators Logic input: increases output voltage by 1 V for line length Output voltage to LNB Master input Inductor drive point Current limit setup resistor Overload flag output 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 7 8283 Truth Tables Control I/O OUT IN IN Terminal Name OLF EN ENT L Iout > Iomax or Tj > 165C Bypass switch closed 22 kHz tone OFF H Iout < Iomax and LNB ON 22 kHz tone ON Tj < 130C VSEL0 L L L L H H H H VSEL1 L H L H L H L H LLC L L H H L L H H VLNB (TYP.) 13 V 18 V 14 V 19 V 12 V 20 V 13 V 21 V Product Preview, July 19, 99 (Subject to Change Without Notice) page 6 of 7 8283 Electrical Characteristics for LNBR Series (TA = 25C, ENT=L, EN=H, LLC=L, VIN=24 V, Iout=50 mA (unless otherwise specified). Symbol Parameter Test Conditions Min. Typ. Max Unit VIN VCC1 Supply Voltage IO=600 mA,VSEL0=L,VSEL1=L, LLC=L 2.5+V 47 V O VO1 VO2 VO1 VO2 VO VO SVR IMAX fTONE aTONE dcTONE t R, t F gEXTM VEXTM ZEXTM VOL IOZ VIL VIH IIH ICC ICC IOBK TSHDN VBUCK fO VswIl VSW Output Voltage IO=600 mA,VSEL0=L,VSEL1=H, LLC=L Io=600 mA, SEL0=L,VSEL1=H, LLC=H Output Voltage IO=600 mA, VSEL0=L,VSEL1=L LLC=L IO=600 mA, VSEL0=L,VSEL1=L, LLC=H Output Voltage IO=600 mA,VSEL0=H,VSEL1=H, LLC=L Io=600 mA, SEL0=H,VSEL1=H, LLC=H Output Voltage IO=600 mA, VSEL0=H,VSEL1=L, LLC=L IO=600 mA, VSEL0=H,VSEL1=L, LLC=H Line Regulation VO=13 V, VIN =16 to 40 V VO=18 V, VIN =21 to 40 V Load Regulation VO=13 or 18 V, IO=50 to 600 mA Supply Voltage Rejection fAC=100 Hz Output Current Limiting Rsense=0.22 ohm Tone Frequency ENT=H Tone Amplitude ENT=H Tone duty cycle ENT=H Tone rise or fall time ENT=H External modulation gain VOUT/VEXTM, f=10 Hz to 40 kHz External modulation input AC coupling voltage External modulation f=10 Hz to 40 kHz impedance Overload flag terminal logic IOL=8 mA low Overload flag terminal OFF VOH=6 V state leakage current Control input terminal logic low Control input terminal logic high Control terminals input current VIH=5 V Supply current Outputs disabled (EN=L) Supply current ENT=H, IOUT=600 mA, VO=13 Output reverse current EN=L, VLNBA=VLNBB=18 V VIN1=VIN2=22 V or floating Thermal shutdown threshold Linear regulator voltage drop VBULK -VO Switching frequency fTONE * 16 Bypass switch current limit EN=L Bypass switch voltage drop EN=L, ISW=300 mA, (MI to LNB) 17.3 12.5 630 20 0.55 40 5.0 18 19 13 14 20 21 12 13 4.0 4.0 80 45 680 22 0.68 50 10 1.0 18.7 13.5 40 40 180 730 24 0.8 60 15 0.8 V V V V V V V V mV mV mV dB mA kHz Vpp % s V/V Vpp k V a 5.0 0.28 < 1.0 0.8 2.0 < 1.0 .5 382 1.0 165 0.8 352 700 0.15 V V A mA mA mA C V kHz mA V 320 630 384 Product Preview, July 19, 99 (Subject to Change Without Notice) page 7 of 7 8283 |
Price & Availability of 8283
 |
|
|
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
| [Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
|
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |