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Analog Devices Inc. LTC7811IUJ#TRPBF
- Part No.:
- LTC7811IUJ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LTC7811IUJ#TRPBF.pdf
- Description:
- LOW IQ TRIPLE BUCK-BOOST CTL
- Quantity:
- Payment:
- Shipping:
Inventory:2,514
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Product details
Overview
LTC7811IUJ#TRPBF from Analog Devices is a high-performance triple-output synchronous buck/buck/boost DC/DC controller driving all-N-channel MOSFET stages. It delivers 3.3V/6A and 5V/4A buck outputs plus a regulated 9.5V boost output, operates from 1V post-startup (down to cold-crank automotive conditions), features 14μA no-load IQ, and supports up to 3MHz switching with spread-spectrum EMI reduction - ideal for automotive infotainment power systems.
For engineers reviewing the LTC7811IUJ#TRPBF datasheet, LTC7811IUJ#TRPBF pinout, LTC7811IUJ#TRPBF application, or LTC7811IUJ#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification, dual-buck-plus-boost topology, 0.8V/1.2V precision references, programmable light-load modes (Burst/Pulse-Skipping/FCM), and integrated low-battery detection for 12V vehicle platforms.
Technical Context
The LTC7811IUJ#TRPBF implements a constant-frequency current-mode architecture across three independent channels: two synchronous buck controllers (Channel 1 & 2) and one synchronous boost controller (Channel 3). Each channel uses external N-MOSFETs, RSENSE/DCR current sensing, and dedicated ITH error amplifier outputs for loop compensation.
Its OPTI-LOOP® compensation supports wide output capacitance/ESR ranges, while spread-spectrum operation modulates switching frequency ±12% to reduce peak conducted/radiated EMI. The device integrates precision references (0.8V for bucks, 1.2V/8V/9.5V-programmable for boost), power-good indicators (PGOOD1, BATTGOOD), and cold-crank operation down to 1V input after startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Dual synchronous buck + single synchronous boost - enables compact 3-rail power architecture without external controllers. |
| Input voltage range | 4.5V–40V bias supply; 1V–40V boost input after startup - supports automotive cold-crank (1V) and industrial 24V/36V rails. |
| Quiescent current | 14μA (14V→3.3V, Channel 1 active); 1.5μA shutdown - extends battery runtime in always-on automotive modules. |
| Switching frequency | 100kHz–3MHz programmable via resistor or PLL lock - allows EMI optimization and small magnetics in space-constrained designs. |
| Feedback references | 0.8V ±12mV (buck), 1.2V/8V/9.5V (boost, selectable via VPRG3) - enables accurate, stable regulation across temperature and load. |
| EMI reduction | Spread-spectrum modulation (±12% relative to fOSC) - lowers peak spectral energy to ease CISPR 25 Class 5 compliance. |
| AEC-Q100 grade | Grade I (–40°C to +125°C junction) - qualified for under-hood automotive applications including ADAS and body control units. |
Pinout & Package
Package: 40-lead 6mm × 6mm plastic QFN (UJ) with exposed thermal pad (Pin 41 = GND). Requires soldering of exposed pad to PCB ground plane for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW2, SW3 | Switch node connections | Drive external high-side N-MOSFET sources; require low-inductance layout to minimize ringing and EMI. |
| TG1, TG2, BG1, BG2, BG3 | Gate drivers | TG = top-gate drive (floating); BG = bottom-gate drive (ground-referenced); 2Ω typical RON supports fast MOSFET switching. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– | Differential current sense inputs | Enable RSENSE or DCR sensing; SENSE1– ≥3.2V reduces system IQ by sourcing bias current from buck input rail. |
| VFB1, VFB2, VFB3 | Feedback inputs | VFB1/VFB2 = 0.8V reference for buck regulation; VFB3 = 1.2V (or direct output tie for fixed 8V/9.5V boost). |
| RUN1, RUN2, RUN3 | Independent enable inputs | 1.15V threshold with 100mV hysteresis; all <0.7V disables entire IC for ultra-low 1.5μA shutdown current. |
| PLLIN/SPREAD, FREQ | Frequency control | PLLIN accepts external clock (0.1–3MHz); FREQ sets internal oscillator (330kHz–2.5MHz) or enables spread-spectrum when pulled to INTVCC. |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output topology | Single-chip solution for 3-rail systems (e.g., 3.3V core, 5V I/O, 9.5V display backlight), eliminating need for multiple controllers and reducing BOM count. |
| OPTI-LOOP® compensation | Allows stable loop response across wide capacitor types (ceramic, polymer, electrolytic) and ESR values without redesigning compensation network. |
| Low-battery indicator | BATTSNS comparator with 9.5V trip (rising) / 9.25V hysteresis triggers open-drain BATTGOOD output - directly supports ISO 16750-2 cold-crank monitoring. |
| Programmable light-load mode | MODE pin selects Burst Mode (highest efficiency at µA loads), Pulse-Skipping (low ripple), or Forced Continuous (lowest noise) - matches load profile to system requirements. |
| Boost current monitor | IMON3 provides 0.4–1.4V analog output proportional to boost inductor current (0–full scale), enabling real-time current limiting and telemetry. |
Applications
| Automotive Infotainment | ADAS Camera Power Supply |
|---|---|
|
Use Scenario: Powering head unit SoC (3.3V), USB ports (5V), and LCD backlight (9.5V) from 12V battery with cold-crank resilience. IC Role / Device Role / Timing Role: Triple-output controller managing all three rails synchronously with shared timing and coordinated soft-start. Use Value: Eliminates discrete buck+boost solutions; 14μA IQ extends parking-mode runtime; spread spectrum meets OEM EMI limits without shielding. |
Use Scenario: Providing isolated 3.3V and 5V rails plus 9.5V for image sensor bias in rear-view camera modules. IC Role / Device Role / Timing Role: Primary power controller delivering tightly regulated, low-noise supplies with precise sequencing via TRACK/SS pins. Use Value: Cold-crank operation ensures camera remains functional during engine start; AEC-Q100 Grade I guarantees reliability in under-hood environments. |
| Industrial HMI Panel | Telematics Control Unit |
|
Use Scenario: Generating 3.3V MCU core, 5V interface, and 9.5V touch controller supply from 24V industrial bus. IC Role / Device Role / Timing Role: Central power management IC coordinating rail startup, fault reporting (PGOOD1/BATTGOOD), and dynamic load response. Use Value: Wide 4.5V–40V input accommodates brownouts and surges; programmable frequency avoids sensitive bands in noisy factory settings. |
Use Scenario: Powering LTE modem (3.3V), CAN transceiver (5V), and GPS LNA (9.5V) in cellular-connected vehicle gateways. IC Role / Device Role / Timing Role: High-efficiency controller supporting always-on connectivity with ultra-low shutdown IQ (1.5μA). Use Value: Dual-buck architecture enables phase interleaving for reduced input ripple; IMON3 enables current-based diagnostics for predictive maintenance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output buck/buck/boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7813IUJ#TRPBF | Same package and pinout; adds fourth buck channel and enhanced PMBus interface; higher IQ (25μA) | Targeted at multi-rail server/telecom systems requiring digital monitoring - over-specified for cost-sensitive automotive use. | Select LTC7811IUJ#TRPBF when only three rails are needed and lowest possible quiescent current is critical. |
| MPQ7222GQ-A-Z | Single-chip dual-buck + boost; lower max frequency (2.2MHz); no spread spectrum; non-AEC-Q100 | Suitable for consumer-grade portable electronics but lacks cold-crank support and automotive qualification. | Choose LTC7811IUJ#TRPBF for automotive applications requiring AEC-Q100, 1V cold-crank, and EMI-compliant spread spectrum. |
Compared with LTC7813IUJ#TRPBF and MPQ7222GQ-A-Z, the LTC7811IUJ#TRPBF uniquely balances automotive qualification, ultra-low IQ, and integrated EMI reduction - making it optimal for cost- and size-constrained automotive power systems where reliability and regulatory compliance are mandatory.
Availability
LTC7811IUJ#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera modules, and industrial HMI panels requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LTC7811IUJ#TRPBF 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
Analog Devices is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LTC7811IUJ#TRPBF belongs to Analog Devices' Power by Linear™ controller family, designed specifically for high-efficiency, low-EMI, multi-rail power conversion in demanding automotive and industrial environments.
FAQ
What is the minimum input voltage required for LTC7811IUJ#TRPBF to operate after startup?
The LTC7811IUJ#TRPBF can operate from an input supply as low as 1V after startup when biased from the boost output or another auxiliary supply. This capability enables reliable operation during automotive cold-crank events where battery voltage dips below 6V. The 4.5V–40V VBIAS range applies for initial startup, but once running, the controller sustains regulation down to 1V on the VIN rail feeding the boost stage.
How does the LTC7811IUJ#TRPBF achieve EMI reduction?
The LTC7811IUJ#TRPBF incorporates spread-spectrum frequency modulation, varying the switching frequency by ±12% around the nominal value when the PLLIN/SPREAD pin is tied to INTVCC. This spreads energy across a wider bandwidth, significantly lowering peak conducted and radiated emissions - a key enabler for meeting stringent automotive CISPR 25 Class 5 requirements without added filtering or shielding.
Can the LTC7811IUJ#TRPBF generate a fixed 9.5V boost output without external resistors?
Yes. By connecting the VPRG3 pin (Pin 16) to INTVCC, the LTC7811IUJ#TRPBF configures the boost channel for a fixed 9.5V output. In this mode, VFB3 is tied directly to the boost output, eliminating the need for an external resistor divider. This simplifies design, improves accuracy (no resistor tolerance drift), and reduces component count in automotive applications where 9.5V is standard for display backlights.
What is the purpose of the SENSE1– pin on the LTC7811IUJ#TRPBF?
The SENSE1– pin on the LTC7811IUJ#TRPBF serves dual functions: it acts as the negative input to the Channel 1 current comparator for RSENSE/DCR sensing, and - critically - when its voltage reaches ≥3.2V, it sources the majority of the sleep-mode quiescent current instead of VBIAS. This feature reduces system-level input-referred IQ, extending battery life in always-on automotive modules where buck Channel 1 supplies a stable intermediate rail.
Is the LTC7811IUJ#TRPBF pin-compatible with other members of the LTC781x family?
No. The LTC7811IUJ#TRPBF is not pin-compatible with LTC7810, LTC7812, or LTC7813. While sharing the same 40-lead QFN package, pin assignments differ significantly - for example, LTC7813 relocates RUN pins and adds PMBus interface signals. Substituting without board revision risks functional failure. Always verify pin functions against the specific device's datasheet before layout or replacement.
LTC7811IUJ#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Number of Outputs:
- 3
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 1V ~ 40V
- Frequency - Switching:
- 100kHz ~ 3MHz
- Duty Cycle (Max):
- 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (6x6)
LTC7811IUJ#TRPBF FAQ
1.How can I place an order for LTC7811IUJ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7811IUJ#TRPBF 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 LTC7811IUJ#TRPBF reliable?
The price and inventory of LTC7811IUJ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7811IUJ#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC7811IUJ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7811IUJ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7811IUJ#TRPBF?
LTC7811IUJ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7811IUJ#TRPBF 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 LTC7811IUJ#TRPBF?
For technical support, including LTC7811IUJ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7811IUJ#TRPBF requirements.
6.How does Aetrix verify that LTC7811IUJ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC7811IUJ#TRPBF 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 LTC7811IUJ#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC7811IUJ#TRPBF?
All LTC7811IUJ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7811IUJ#TRPBF, 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 LTC7811IUJ#TRPBF part is unused and in its original packaging.
Return procedure for LTC7811IUJ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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