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Part: A8283SLB
Category:
Description: LNB Supply And Control-voltage Regulator
Company: Allegro Micro Systems, Inc.
Datasheet: Download A8283SLB datasheet File size : 227 kB
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Datasheet text preview:
8283
PRELIMINARY INFORMATION
(Subject to change without notice) October 9, 2001
LNB SUPPLY AND CONTROL-VOLTAGE REGULATOR
Intended for analog and digital satellite receivers, the low-noise block converter regulator (LNBR) is a monolithic linear and switching voltage regulator designed to provide power and interface signals to the LNB down converter via the coaxial cable. If the device is in stand-by mode (EN terminal LOW), the regulator output is disabled, allowing the antenna downconverters to be supplied or controlled by other satellite receivers sharing the same coaxial cable. Similar two-output LNB supply and control voltage regulators are the A8284SB/SLB. 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, leaving all LNB power and control functions to the master receiver. This electronic switch is closed if the device is powered, EN is HIGH, and OSEL is LOW. The regulator outputs are set to 12, 13, 18, or 20 V by the VSEL terminals. Additionally, it is possible to increase the selected voltage by 1 V to compensate for the voltage drop in the coaxial cable (LLC terminal HIGH). The LNBR combines 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 with an input voltage that is set to the output voltage plus typically 0.8 V. This maintains constant voltage drop across the linear regulator while permitting adequate voltage range for tone injection. The device is supplied in a 24-pin plastic DIP with batwing tabs (A8283SB), or a 24-lead SOIC power-tab package (A8283SLB). In both cases, the power tab is at ground potential and needs no electrical isolation.
Data Sheet 27448.1
A8283SLB
OSEL OLF VBULK MIOUT MI GND GND SENSE LNB LX VIN TCAP 1 2 3 24 23 22 EXTM VINT PUMPX VPUMP CPUMP GND GND ENT EN VSEL0 VSEL1 LLC
4 5 6 7 8 9 9 10 11 12 BUCK REG.
CHARGE PUMP VOLTAGE CONTROL
21 20 19 18 17 16 15 14 13
Dwg. PP-072A
Note that the A8283SB (dual in-line package) and A8283SLB (small-outline IC package) are electrically identical and share a common terminal number assignment.
FEATURES
s s s s s s s s s s 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 (a trademark of EUTELSAT) 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
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VIN .. 47 V Output Current, IO .... 1.0 A Logic Input Voltage Range, VI .. -0.5 V to +7 V Bypass Switch Current, ISW ...... Internally Limited Flag Output Voltage, VOLF ......... 7 V Operating Temperature Range, TA ....... -20°C to +85°C Storage Temperature Range, TS ..... -40°C to +150°C
This device incorporates features that have patents pending.
Always order by complete part number, e.g., A8283SLB .
8283 LNB SUPPLY AND CONTROL-VOLTAGE REGULATOR
FUNCTIONAL BLOCK DIAGRAM
RS
SENSE VBULK
PUMPX
CPUMP
VPUMP
47 V MAX
VIN LX
+
MI VINT VOLTAGE REG. BOOST VOLTAGE MIOUT 0 1 5V 176 kHz + 352 kHz 25 k + 7V VREF BUCK CONV. + OVERCURRENT + 800 mV + 150 mV
CHARGE PUMP
EN
÷2 ENT
÷8 & WAVESHAPING
22 kHz TONE
TSD OLF OVERCURRENT 5 k 1 k REXTM
OSEL
VSEL0
VSEL1
LLC
TCAP
Output Voltage Select Table
VSEL0 L L L L H H H H VSEL1 L L H H L L H H LLC L H L H L H L H VLNB(typ) 13 V 14 V 18 V 19 V 12 V 13 V 20 V 21 V
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 2001 Allegro MicroSystems, Inc.
LNB 5 k EXTM Dwg. FP-051-1
8283 LNB SUPPLY AND CONTROL-VOLTAGE REGULATOR
ELECTRICAL CHARACTERISTICS at TA = 25°C, ENT = L, EN = H, OSEL = H, LLC = L, VIN = 24 V, VO = 13 V or 18 V, IO = 50 mA, REXTM = open (unless otherwise noted).
Limits Characteristic Supply Voltage Output Voltage Symbol VIN VO Test Conditions IO = 600 mA, VSEL0 = L, VSEL1 = L, LLC = L IO = 600 mA, VSEL0 = L, VSEL1 = L, LLC = L IO = 600 mA, VSEL0 = L, VSEL1 = L, LLC = H IO = 600 mA, VSEL0 = L, VSEL1 = H, LLC = L IO = 600 mA, VSEL0 = L, VSEL1 = H, LLC = H IO = 600 mA, VSEL0 = H, VSEL1 = L, LLC = L IO = 600 mA, VSEL0 = H, VSEL1 = L, LLC = H IO = 600 mA, VSEL0 = H, VSEL1 = H, LLC = L IO = 600 mA, VSEL0 = H, VSEL1 = H, LLC = H Load Regulation Current-Limiting Threshold Tone Frequency Tone Amplitude External Modulation Output Tone Duty Cycle Tone Rise or Fall Time External Modulation Gain External Modulation Input Voltage External Modulation Impedance VO VOM(th) f tone V tone(PP) V mod(out) d c tone t r, t f Gm o d V mod(PP) Zm o d ENT = H ENT = H ENT = L, IO = 600 mA, REXTM = 200 k, Vmod(PP) = 130 mV, f = 22 kHz ENT = H ENT = H VO/Vmod, f = 22 kHz AC coupling 4.4 IO = 50 to 600 mA 125 20 550 400 Min. 4.5 + VO 12.5 13.4 17.3 18.2 11.5 12.5 19.2 20.2 13 14 18 19 12 13 20 21 80 135 22 680 Typ. Max. 47 13.8 14.9 18.7 19.8 12.8 13.8 20.8 21.8 220 160 24 800 800 Units V V V V V V V V V mV mV kHz mV mV
50 10 4.9 5.6 160
% µs V/V mV k
f = 22 kHz
5.0
continued next page ...
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8283 LNB SUPPLY AND CONTROL-VOLTAGE REGULATOR
ELECTRICAL CHARACTERISTICS at TA = 25°C, ENT = L, EN = H, OSEL = H, LLC = L, VIN = 24 V, VO = 13 V or 18 V, IO = 50 mA, REXTM = open (unless otherwise noted).
Limits Characteristic Overload Flag Logic Low Overload Flag Leakage Current Logic Input Voltage Symbol VOL I OZ V IL V IH Logic Input Current IIL I IH Supply Current I IN V IL = 0 V V IH = 5 V Outputs disabled (EN = L) ENT = H, IO = 600 mA, VO = 13 V Thermal Shutdown Temp. Linear Regulator Voltage Drop Switching Frequency Bypass Switch Current Limit Bypass Switch Voltage Drop (MI to LNB) TJ VBUCK fO I swM V sw V BULK -- V O 1 6 x ft o n e OSEL = L OSEL = L, Isw = 300 mA 320 400 2.0 <-1.0 <1.0 0.5 382 165 0.8 352 900 0.15 384 -10 10 Test Conditions IOL = 8 mA VOH = 5.5 V Min. Typ. 0.28 <1.0 Max. 0.8 10 0.8 Units V µA V V µA µA mA mA °C V kHz mA V
FUNCTIONAL DESCRIPTION
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. Applications that are required to deliver more than 400 mA and use the external modulation terminal should be rebiased to increase the voltage drop across the linear regulator. This will allow full modulation under all conditions.
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115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000
8283 LNB SUPPLY AND CONTROL-VOLTAGE REGULATOR
FUNCTIONAL DESCRIPTION (cont'd)
This can be accomplished by connecting a 200 k resistor from the external modulation terminal (24) to ground. This will reduce the LNB output voltage by typically 300 mV without effecting the VBULK voltage. The output voltage can be restored to the programmed value by connecting a 1 M resistor from the VINT terminal (23) to the TCAP terminal (12). This raises both VBULK and VO by typically 300 mV. The output linear regulator will sink and source current. This feature allows full modulation capability into capacitive loads as high as 0.25 µF. The programmed output voltage rise and fall times can be set by an internal 25 k resistor and an external capacitor located on the TCAP terminal. Although any value of capacitor is permitted, practical values are typically 0.001 µF to 0.02 µF. 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, RS, between terminals 3 and 8. RS = VOM(th)/IOM where VOM(th) is the current-limiting threshold voltage and IOM is the desired current limit value. The minimum recommended value for RS is 0.15 . 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 IOM. The tracking converter will maintain a constant voltage drop of 0.8 V across the linear regulator. This condition results in typically 550 mW dissipation (IOM x 0.8 V). Short-circuit or thermal-shutdown activation will cause the OLF terminal, an open-drain diagnostic output flag, to go LOW. Thermal resistance: DIP -- RJA = 40°C/W, RJT = 6°C/W, or SOIC -- RJA = 55°C/W, RJT = 6°C/W. The device junction temperature should be kept below 150°C. Thermal shut-down circuitry turns off the device if junction temperature exceeds +165°C typically.
The products described here are manufactured under one or more U.S. patents or U.S. patents pending. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. Before placing an order, the user is cautioned to verify that the information being relied upon is current. Allegro products are not authorized for use as critical components in life-support devices or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use.
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