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Home > Products > Integrated Circuits (ICs) > Interface > Specialized

STMicroelectronics LNBS21PD-TR

Name: LNBS21PD-TR
Brand: STMicroelectronics
SKU: LNBS21PD-TR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: LNBS21PD-TR

Manufacturer:: STMicroelectronics

Category:: Specialized

Package:: 20-SOIC (0.433", 11.00mm Width) Exposed Pad

Datasheet:: LNBS21PD-TR.pdf

Description:: IC INTFACE SPECIALIZED 20PWRSOIC

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Product details

Overview

LNBS21PD-TR from STMicroelectronics is a monolithic LNB supply and control IC with integrated step-up DC/DC controller, 22kHz tone oscillator/detector, I²C interface, and loop-through switch - designed for satellite STB receivers and multiswitch boxes. It delivers regulated 13V/18V outputs (±0.7V), supports DiSEqC 2.x bi-directional communication, provides pulsed current limiting (900ms off-time), and features internal overtemperature shutdown at 150°C.

For engineers reviewing the LNBS21PD-TR datasheet, LNBS21PD-TR pinout, LNBS21PD-TR application, or LNBS21PD-TR equivalent, this device is selected for analog/digital satellite receiver designs requiring precise LNB voltage selection, fast 22kHz tone start-up, cable-length compensation, short-circuit diagnostics, and I²C-configurable protection thresholds.

Technical Context

The LNBS21PD-TR integrates a current-mode step-up controller driving an external MOSFET to generate VUP (16–22V), feeding a linear post-regulator that delivers low-noise 13V/18V outputs with <200mV load regulation. Its I²C-controlled System Register configures voltage select (VSEL), tone enable (TEN), loop-through (EN), current limit mode (ISEL/PCL), and cable compensation (LLC).

Bi-directional DiSEqC 2.x support is implemented via dedicated DSQIN (PWK modulation input) and DETIN/DSQOUT (22kHz tone detection and demodulated data output), with AC-coupled detector input and open-drain DSQOUT. Internal 22kHz oscillator accuracy is factory-trimmed to ±10% (20–24kHz), with 40–60% duty cycle and <15µs rise/fall time.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	13V or 18V (typ.), selectable via I²C VSEL bit; ±1V adjustable via LLC bit for coaxial cable drop compensation
22kHz Tone Frequency	22kHz ±10% (20–24kHz), factory-trimmed oscillator enabling DiSEqC-compliant carrier generation
Current Limiting	Configurable static (750–1000mA) or pulsed mode (900ms off-time, 90ms on-time) with OLF flag reporting overload status
Thermal Protection	Shuts down step-up and linear regulators at 150°C (typ.), resumes at 140°C (15°C hysteresis), sets OTF flag
I²C Address Options	Four fixed addresses (0001000 to 0001011) set by ADDR pin voltage level (0–5V range)
Supply Range	8–15V DC input (VCC), supports single-supply operation in STB chassis with under-voltage lockout at 6.7V
Package	PowerSO-20, thermally enhanced exposed pad package with 2°C/W junction-to-case thermal resistance

Pinout & Package

LNBS21PD-TR is housed in PowerSO-20 package - a surface-mount, thermally optimized 20-pin power package with exposed copper pad for heatsinking. Pin 1 is located at top-left corner when notch is oriented upward; pin numbering follows standard counter-clockwise sequence.

Pin/Terminal	Circuit Role	Design Meaning
VCC	Primary supply input	8–15V DC input with UVLO at 6.7V; requires 220µF + 470nF bypass
GATE	Step-up converter gate drive	Drives external N-MOSFET (e.g., STN4NF03L); peak current ±400mA
SENSE	Current sense input	Monitors voltage across 0.1Ω sense resistor; triggers current limit at 200mV
Vup	Step-up output voltage feedback	Input to linear post-regulator; dynamically adjusted to minimize dropout loss
OUT	LNB output port	Delivers regulated 13/18V to LNB; includes short-circuit protection and diagnostic reporting
SDA/SCL	I²C bidirectional interface	Standard 500kHz I²C bus; supports 3.3V/5V µC logic; pull-up resistors required externally
DSQIN	DiSEqC encoding input	Accepts PWK data from µC; disabled when TEN=1 (continuous tone mode)
DETIN	Tone detector input	AC-coupled 22kHz input (0.2–1.5Vpp); 150kΩ impedance; enables bi-directional DiSEqC
DSQOUT	Tone detector output	Open-drain output reporting detected tone (LOW = present); compatible with 3.3V/5V µC inputs
LT1/LT2	Loop-through switch terminals	Internally shorted in standby (EN=0); rated for 900mA; used for slave STB cascading
EXTM	External modulation input	AC-coupled analog modulation path (6V gain); supports future LNB control standards
ADDR	I²C address configuration	Four discrete voltage levels (0/1.5/2.5/4V) select one of four I²C addresses

Key Features

Feature	Design Value
Integrated DiSEqC 2.x transceiver	Dedicated DSQIN/DETIN/DSQOUT pins enable full bi-directional protocol implementation without external tone generators or detectors
Dynamic pulsed current limiting	Reduces average power dissipation during sustained short circuits via 900ms OFF / 90ms ON cycling, while maintaining reliable startup
Cable-length voltage compensation	LLC bit adds +1V to selected output (13V→14V or 18V→19V) to offset coaxial voltage drop up to ~30m
I²C-configurable protection thresholds	ISEL and PCL bits allow runtime selection between two current limit ranges (650–900mA vs. 750–1000mA) and static vs. dynamic limiting modes
Thermal fault reporting	OTF bit in System Register indicates junction temperature >150°C; automatically resets at 140°C with 15°C hysteresis

Applications

Direct Satellite TV Receiver

Multi-LNB Multiswitch System

Use Scenario: Single-tuner STB receiving signals from one satellite position using a universal LNB.

IC Role / Device Role / Timing Role: Provides 13V/18V switching, 22kHz tone generation, and DiSEqC command transmission to select polarization and band.

Use Value: Eliminates need for discrete DC/DC, tone generator, and protection circuitry - reduces BOM count by ≥7 components and PCB area by >35%.

Use Scenario: Central multiswitch box distributing signals from 4+ LNBs to multiple STBs in apartment buildings.

IC Role / Device Role / Timing Role: Acts as master LNB controller per input port; manages voltage, tone, and DiSEqC commands for each connected LNB.

Use Value: Enables independent LNB control per port with shared I²C bus addressing (via ADDR pin), simplifying firmware and reducing interconnect complexity.

DiSEqC 2.x-Compatible Set-Top Box

PC-Based Satellite Tuner Card

Use Scenario: Dual-tuner STB supporting motorized dish positioning and multi-satellite reception via DiSEqC 2.x commands.

IC Role / Device Role / Timing Role: Generates precise 22kHz carrier with <15µs edge timing and decodes incoming DiSEqC responses via DSQOUT for closed-loop verification.

Use Value: Ensures reliable motor control and LNB switching with real-time diagnostic feedback (OLF/OTF flags), improving field failure rate by >40% vs. discrete solutions.

Use Scenario: Low-profile PCIe satellite tuner card for PC-based DVB-S2 reception with compact thermal envelope.

IC Role / Device Role / Timing Role: Delivers regulated LNB power with minimal heat generation using PowerSO-20's 2°C/W R_thj-case and dynamic current limiting.

Use Value: Maintains stable operation at 750mA load without external heatsink, enabling fanless PC tuner designs with <12W total system power.

Equivalent & Alternatives

The following parts are listed as comparable options for similar LNB supply and control applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
MAX2181AETL+	Single-chip LNB controller with integrated MOSFET driver; no external FET required; 22kHz tone accuracy ±5% (tighter than LNBS21PD-TR)	Lacks loop-through function and EXTM modulation input; supports only unidirectional DiSEqC 1.x	Select for space-constrained designs where integrated FET eliminates board area but DiSEqC 2.x is not needed
SP8001D	Higher output current (1.2A), wider input range (6–20V), and built-in ESD protection (±8kV HBM); uses SO-24 package instead of PowerSO-20	Does not support DiSEqC tone detection (no DETIN/DSQOUT); requires external tone generator for DiSEqC 2.x	Select when higher current headroom and robustness against ESD are critical, and DiSEqC 2.x receive capability is optional

Compared with MAX2181AETL+ and SP8001D, the LNBS21PD-TR uniquely combines DiSEqC 2.x bi-directional support, loop-through switching, and cable compensation in a thermally optimized PowerSO-20 package - making it optimal for cost-sensitive, feature-complete satellite receiver platforms requiring field-proven interoperability.

Availability

LNBS21PD-TR is available at Aetrix Electronics and suitable for satellite STB receivers, multiswitch distribution systems, and PC-based DVB-S2 tuner cards requiring stable component supply, long-term lifecycle continuity, and DiSEqC 2.x compliance.

Supply support for LNBS21PD-TR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, power, microcontroller, and sensor solutions for automotive, industrial, and consumer markets.

The LNBS21 series belongs to ST's broadcast power management product line, engineered specifically for satellite receiver power and control subsystems - emphasizing integration, DiSEqC protocol fidelity, thermal resilience, and minimal external component count.

FAQ

What is the purpose of the EXTM pin on the LNBS21PD-TR?

The EXTM pin is an AC-coupled analog modulation input that allows external signal sources (e.g., future LNB control protocols) to directly modulate the LNB output voltage. It provides 6V gain over 10Hz–40kHz bandwidth with 260Ω input impedance. When unused, it may be left floating - no pull-up/down is required.

How does the pulsed current limiting (PCL) mode operate during a short circuit?

In PCL mode (PCL=0), the LNBS21PD-TR cycles its output with 900ms OFF time and 90ms ON time when overload is detected. The OLF bit is set HIGH during OFF periods and cleared only after a full ON period with no overload. This reduces average power dissipation by >70% compared to static limiting, preventing thermal runaway.

Can the LNBS21PD-TR support both DiSEqC 1.x and 2.x protocols?

Yes - DiSEqC 1.x (unidirectional) is supported by enabling continuous 22kHz tone (TEN=1) and using DSQIN for command transmission. DiSEqC 2.x (bi-directional) requires TEN=0, DSQIN for encoding, and DETIN/DSQOUT for tone detection and response decoding - all natively implemented without external components.

What is the maximum recommended coaxial cable length when using LLC compensation?

With LLC=1, the +1V compensation offsets typical coaxial voltage drop of ~0.033V/m at 750mA. This supports up to ~30 meters of RG-6 cable (0.033V/m × 30m ≈ 1V drop). Beyond this, excessive dropout may cause LNB malfunction - verify with actual cable resistance and load current in final design.

LNBS21PD-TR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 20-SOIC (0.433", 11.00mm Width) Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Applications:: Power Supplies, Converters, Controllers

Interface:: SMBus (2-Wire/I2C)

Voltage - Supply:: 8V ~ 15V

Supplier Device Package:: PowerSO-20

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

LNBS21PD-TR FAQ

1.How can I place an order for LNBS21PD-TR through Aetrix?

Please submit a Request for Quotation (RFQ) for LNBS21PD-TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for LNBS21PD-TR reliable?

The price and inventory of LNBS21PD-TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LNBS21PD-TR is usually 5 days.

3.What payment methods are accepted for LNBS21PD-TR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LNBS21PD-TR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for LNBS21PD-TR?

LNBS21PD-TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your LNBS21PD-TR order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for LNBS21PD-TR?

For technical support, including LNBS21PD-TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LNBS21PD-TR requirements.

6.How does Aetrix verify that LNBS21PD-TR is sourced from the original manufacturer or authorized distributors?

All LNBS21PD-TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LNBS21PD-TR meets industry standards.

7.What is the process for return or replacement of LNBS21PD-TR?

All LNBS21PD-TR units undergo pre-shipment inspection (PSI). If there is an issue with LNBS21PD-TR, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The LNBS21PD-TR part is unused and in its original packaging.

Return procedure for LNBS21PD-TR:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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