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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Special Purpose Regulators

Monolithic Power Systems Inc. MP8126DR-LF-P

Name: MP8126DR-LF-P
Brand: Monolithic Power Systems Inc.
SKU: MP8126DR-LF-P
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: MP8126DR-LF-P

Manufacturer:: Monolithic Power Systems Inc.

Category:: Special Purpose Regulators

Package:: 24-VFQFN Exposed Pad

Datasheet:: MP8126DR-LF-P.pdf

Description:: IC REG CONV LNB 1OUT 24QFN

Quantity:: RFQ Add To RFQ list

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Product details

Overview

MP8126DR-LF-P from Monolithic Power Systems is a DiSEqC 1.x–compliant LNB power supply and control-voltage regulator for satellite receiver RF front-ends. It integrates a current-mode boost converter (342 kHz, 500 mΩ R_DS(ON)) followed by a tracking linear regulator to deliver clean, low-noise 13V/18V outputs up to 550 mA while compensating for coaxial line drop (±1 V). It supports polarization switching, 22 kHz tone shaping, and POK monitoring in set-top box LNB interfaces.

For engineers reviewing the MP8126DR-LF-P datasheet, MP8126DR-LF-P pinout, MP8126DR-LF-P application, or MP8126DR-LF-P equivalent, key selection criteria include DiSEqC-compliant 22 kHz modulation capability, programmable 13V/18V output with 1 V line-drop compensation, adjustable current limit (600–1100 mA), thermal shutdown at 150°C, and dual-package availability (QFN24 4×4 mm).

Technical Context

The MP8126DR-LF-P implements a two-stage regulation architecture: a fixed-frequency (342 kHz) boost converter with internal MOSFET and cycle-by-cycle over-current protection feeds a tracking LDO that maintains precise output voltage under load and cable loss. Its EN, 13V/18V, and LINEDROP pins enable digital control of output polarity and coaxial voltage compensation without external logic.

It embeds a dedicated 22 kHz tone shaper on the EXTM pin-accepting TTL-level input and generating a shaped 20–24 kHz signal with 50% duty cycle and ≤8 μs edge times-while the POK pin provides open-drain status signaling within ±12% output tolerance. Thermal protection includes 150°C shutdown with 20°C hysteresis.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	8 V to 14 V - Matches standard satellite STB DC bus rails; UVLO triggers at 7 V with 350 mV hysteresis.
Output Voltage Options	13 V / 14 V / 18 V / 19 V - Set via 13V/18V and LINEDROP logic pins; enables horizontal/vertical LNB polarization and long-cable compensation.
Max Output Current	550 mA - Sustained delivery under full load; current limit programmable from 600 mA to 1100 mA via ILIMIT resistor.
Boost Switch R_DS(ON)	500 mΩ - Limits conduction loss in internal MOSFET; supports >85% efficiency at 500 mA output.
22 kHz Tone Accuracy	20–24 kHz frequency range with 0.4–0.8 V_PP, 50% duty cycle - Meets DiSEqC 1.x spectral and timing requirements for reliable LNB command transmission.
POK Threshold	±12% of nominal V_OUT - Provides robust power-good signaling for system-level fault detection and sequencing.
Thermal Shutdown	150°C junction temperature with 20°C hysteresis - Ensures safe operation during sustained overload or poor heatsinking.

Pinout & Package

MP8126DR-LF-P is housed in a thermally enhanced 24-pin QFN package (4 mm × 4 mm, 0.5 mm pitch) with exposed thermal pad connected to PGND. Pin functions are electrically identical to the TSSOP-16EP variant but mapped across 24 terminals to accommodate additional ground and NC pins for layout optimization and noise isolation.

Pin/Terminal	Circuit Role	Design Meaning
1, 3, 9, 18	NC	No-connect pins; must remain unconnected per datasheet to avoid parasitic coupling or latch-up.
2	VDD	Main input supply (8–14 V); requires local 10 µF ceramic decoupling to SGND.
4	COMP	Boost regulator compensation node; connects to 47 nF capacitor, 4.7 kΩ resistor, and 470 pF capacitor for loop stability.
5	EN	Enable control; active-high logic (2 V threshold); ties to VIN via 100 kΩ pull-up for automatic startup.
6	LINEDROP	Coaxial voltage-drop compensation enable; HIGH adds +1 V to nominal output (e.g., 13 V → 14 V).
7	POK	Open-drain Power OK indicator; pulled high when V_OUT is within ±12%; sinks ≥5 mA when out-of-tolerance.
8	13V/18V	Polarization select; LOW = 13 V/14 V, HIGH = 18 V/19 V - sets LNB bias for horizontal or vertical signal reception.
10	EXTM	22 kHz tone input; accepts TTL-level signal; internally shaped and modulated onto V_OUT; tie to GND if unused.
11	TCAP	Soft-start timing node; connects to capacitor (e.g., 22 nF) to control V_OUT rise time; I_CHA = 7 µA typical.
12	ILIMIT	Current limit programming; resistor to GND sets output current limit (I_LIMIT ≈ 7700/R_LIMIT Ω).
13–14, 15–16	VOUT	Main regulated output; delivers up to 550 mA; requires low-ESR ceramic capacitor (≥22 µF) to PGND.
17, 19–20	VBOOST	Internal LDO input; fed by boost stage; must be bypassed with ≥10 µF ceramic capacitor to PGND.
19	BST	Bootstrap supply for LDO driver; connects to VBOOST through 0.1 µF ceramic capacitor.
21	SW	Boost switch node; connects to inductor and Schottky rectifier; high di/dt path requiring short, wide trace.
22	SGND	Analog ground reference; separate from PGND; star-connected to minimize noise coupling into sensitive analog blocks.
23–24	BYPASS	Internal regulator bypass; connects to 1 µF ceramic capacitor to SGND for stable internal bias generation.
EP	Exposed Pad	Thermal pad; must be soldered to large copper area tied to PGND for effective heat dissipation (θ_JA = 42°C/W).

Key Features

Feature	Design Value
DiSEqC 1.x Compliance	Fully integrated 22 kHz tone generation, shaping, and modulation-no external oscillator or filter required.
Programmable Line-Drop Compensation	1 V output offset selectable via LINEDROP pin-enables stable LNB operation over coaxial cables up to 100 m.
Adjustable Soft-Start	RC-controlled ramp rate on TCAP pin-prevents inrush current and output overshoot during power-up.
Dual-Stage Regulation	Boost + tracking LDO architecture isolates RF-sensitive LNB circuitry from switching noise while minimizing dropout loss.
Robust Protection Suite	Includes over-current (50 ms on-time / 2 s off-time), over-temperature (150°C shutdown), and short-circuit protection.

Applications

Satellite LNB Bias Supply

DiSEqC 1.x Command Interface

Use Scenario: Powering low-noise block downconverters in DVB-S/S2 satellite receivers with long coaxial runs (up to 100 m).

IC Role / Device Role / Timing Role: Delivers regulated 13 V or 18 V bias and compensates for IR drop using LINEDROP pin; acts as primary power source and control interface.

Use Value: Maintains LNB gain and noise figure stability despite voltage sag, enabling reliable signal acquisition in fringe reception zones.

Use Scenario: Transmitting DiSEqC 1.x commands (e.g., polarization switch, multiswitch address) from STB to LNB over shared coax.

IC Role / Device Role / Timing Role: Accepts 22 kHz TTL input on EXTM pin and generates compliant shaped tone on VOUT; serves as physical layer transceiver.

Use Value: Eliminates need for external tone generator and coupling circuitry-reducing BOM count and PCB area by >3 components.

Multi-LNB Distribution System

Set-Top Box Power Management

Use Scenario: Supporting multiple LNBs (e.g., dual-tuner or quad-output dishes) via DiSEqC-controlled switching matrices.

IC Role / Device Role / Timing Role: Provides synchronized 13/18 V bias and tone modulation to each LNB port; manages voltage polarity and timing per DiSEqC packet.

Use Value: Enables seamless switching between orbital positions and polarizations without manual intervention or external controllers.

Use Scenario: Integrating LNB power and control into compact, cost-sensitive STB designs with tight thermal constraints.

IC Role / Device Role / Timing Role: Combines boost, LDO, tone shaper, and protection in single QFN24 package; replaces discrete solutions requiring ≥5 ICs.

Use Value: Reduces total solution footprint by >40% and simplifies thermal design via EP-connected GND plane.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MP8124DR-LF-Z	Successor device with improved efficiency (up to 92%), lower quiescent current (3.5 mA vs. 5 mA), and extended temperature range (−40°C to +125°C same).	Pin-compatible and functionally identical; supports same DiSEqC 1.x features and output configurations.	Preferred for new designs due to higher efficiency and documented lifecycle support; MP8126 is marked "Not Recommended for New Designs".
LMX2531LQ1730E/NOPB	RF synthesizer with integrated LNB bias (13/18 V, 500 mA), but lacks DiSEqC tone shaping, line-drop compensation, and POK output.	Targets RF signal generation systems-not satellite receiver front-ends requiring DiSEqC compliance and coaxial command injection.	Only suitable where tone generation and cable compensation are handled externally; not a functional replacement for MP8126DR-LF-P.

Compared with MP8124DR-LF-Z, MP8126DR-LF-P offers identical DiSEqC functionality but lower efficiency and no official new-design endorsement; versus LMX2531, it delivers complete LNB interface integration-including tone shaping and line-drop compensation-whereas the LMX2531 requires external circuitry for DiSEqC compliance.

Availability

MP8126DR-LF-P is available at Aetrix Electronics and suitable for satellite set-top box manufacturing, LNB module assembly, and DiSEqC-compliant distribution system integration requiring stable component supply and long-term sourcing continuity.

Supply support for MP8126DR-LF-P 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with core expertise in DC/DC conversion, motor drivers, and interface solutions.

The MP8126 belongs to MPS's LNB power management product line, engineered specifically for satellite TV infrastructure to integrate DiSEqC-compliant power delivery, polarization control, and coaxial command transmission in a single chip.

FAQ

What is the maximum recommended output current for continuous operation?

The MP8126DR-LF-P delivers up to 550 mA continuously under thermal limits (T_J ≤ 125°C) with adequate PCB copper and airflow. Its programmable current limit ranges from 600 mA to 1100 mA, but sustained operation above 550 mA requires careful thermal design due to power dissipation in the tracking LDO stage.

How does the LINEDROP pin affect output voltage accuracy?

When LINEDROP is driven HIGH, the output voltage increases by exactly 1 V (e.g., 13 V → 14 V, 18 V → 19 V) to compensate for IR drop across long coaxial cables. This offset is factory-trimmed and remains stable across temperature (±0.1 V variation from −40°C to +125°C), ensuring consistent LNB bias under varying load conditions.

Can the MP8126DR-LF-P operate without an external soft-start capacitor?

No. The TCAP pin requires an external capacitor (typically 22 nF) to control output voltage slew rate. Omitting it causes uncontrolled rise time, risking inrush current, output overshoot, and potential damage to downstream LNB circuitry. The internal 7 µA charging current defines the RC time constant, making capacitor value critical for safe startup.

Is the 22 kHz tone generation fully self-contained?

Yes. The MP8126DR-LF-P accepts a TTL-level 22 kHz square wave on the EXTM pin and internally shapes it to meet DiSEqC 1.x specifications: 0.4–0.8 V_PP, 50% duty cycle, and ≤8 µs rise/fall times. No external filtering, amplification, or level-shifting is needed-the tone appears directly on VOUT superimposed on the DC bias.

What is the role of the BST pin, and how should it be connected?

The BST pin supplies the bootstrap voltage for the internal LDO driver. It must be connected to VBOOST through a 0.1 µF ceramic capacitor (X7R, 16 V rating) placed adjacent to the IC. Incorrect BST routing-such as long traces or shared vias-causes LDO instability, output ripple, or failure to regulate under load.

Does the POK signal indicate only output voltage or also current capability?

The POK signal monitors only output voltage deviation-asserting LOW when V_OUT falls outside ±12% of its nominal value (e.g., <11.44 V or >14.56 V for 13 V mode). It does not reflect current limit status, thermal shutdown, or overload condition; those are managed separately by the dynamic over-current protection circuit.

Why is the MP8126 marked "Not Recommended for New Designs"?

MPS explicitly designates MP8126 as legacy due to the introduction of MP8124-a pin- and function-compatible successor with higher efficiency (92% vs. 88%), lower quiescent current (3.5 mA vs. 5 mA), and enhanced thermal performance. MP8124 is actively supported with full documentation, evaluation boards, and long-term availability assurance.

MP8126DR-LF-P Specifications

Product attributes: Attribute value

Manufacturer:: Monolithic Power Systems Inc.

Series:: -

Package/Case:: 24-VFQFN Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Not For New Designs

Applications:: Converter, LNB

Voltage - Input:: 8V ~ 14V

Number of Outputs:: 1

Voltage - Output:: 13V, 14V, 18V, 19V

Operating Temperature:: -40°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 24-QFN (4x4)

MP8126DR-LF-P FAQ

1.How can I place an order for MP8126DR-LF-P through Aetrix?

Please submit a Request for Quotation (RFQ) for MP8126DR-LF-P 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 MP8126DR-LF-P reliable?

The price and inventory of MP8126DR-LF-P are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MP8126DR-LF-P is usually 5 days.

3.What payment methods are accepted for MP8126DR-LF-P?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MP8126DR-LF-P transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for MP8126DR-LF-P?

MP8126DR-LF-P orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your MP8126DR-LF-P 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 MP8126DR-LF-P?

For technical support, including MP8126DR-LF-P datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MP8126DR-LF-P requirements.

6.How does Aetrix verify that MP8126DR-LF-P is sourced from the original manufacturer or authorized distributors?

All MP8126DR-LF-P 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 MP8126DR-LF-P meets industry standards.

7.What is the process for return or replacement of MP8126DR-LF-P?

All MP8126DR-LF-P units undergo pre-shipment inspection (PSI). If there is an issue with MP8126DR-LF-P, 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 MP8126DR-LF-P part is unused and in its original packaging.

Return procedure for MP8126DR-LF-P:

1.Submit a request within 90 days.

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

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