Document
8283
PRELIMINARY INFORMATION
(Subject to change without notice) November 21, 2000
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
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
I I I I I I I I I I Short-Circuit Protected Bypass Function for Slave Operation LNB Selection and Stand-By Function Built-In Tone Oscillator Factory Trimmed to 22 kHz, Facilitates DiSEqC™ (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 .... Internally Limited 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
VBULK SENSE
CPUMP
PUMPX
VPUMP
47 V MAX
VIN LX
+
MI VINT VOLTAGE REG. BOOST VOLTAGE MIOUT 0 1 – 5V 176 kHz + 352 kHz 25 kΩ – + 7V VREF BUCK CONV. – + OVERCURRENT – + 800 mV + 150 mV
CHARGE PUMP
EN
÷2 ENT
÷8 & WAVESHAPING
22 kHz TONE
TSD OLF OVERCURRENT
1 kΩ
VSEL1
VSEL0
OSEL
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
2
115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 2000, Allegro MicroSystems, Inc.
– LNB 5 kΩ EXTM 5 kΩ 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, IO = 50 mA (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 Line Regulation ∆VO ∆VO VOM(th) ftone Vtone(PP) dctone t r, t f Gmod Vmod(PP) Zmod ENT = H ENT = H ENT = H ENT = H ∆VO/∆Vmod, f = 10 Hz to 40 kHz AC coupling VO = 13 V, VI = 16 to 40 V VO = 18 V, VI = 21 to 40 V Load Regulation Current-Limiting Threshold Tone Frequency Tone Amplitude Tone.