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Analog Devices Inc. LTC3871ILXE-1#PBF
- Part No.:
- LTC3871ILXE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
LTC3871ILXE-1#PBF.pdf
- Description:
- IC BUCK/BOOST CONTROLLER
- Quantity:
- Payment:
- Shipping:
Inventory:200
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Product details
Overview
LTC3871ILXE-1#PBF from Analog Devices is a bidirectional polyphase synchronous buck/boost controller for dual-battery automotive systems, supporting 48V↔12V energy transfer with ±1% voltage regulation accuracy, programmable current limits (10–50mV sense threshold), and phase-lockable 60–460kHz operation in thermally enhanced 48-lead LQFP package.
For engineers reviewing the LTC3871ILXE-1#PBF datasheet, LTC3871ILXE-1#PBF pinout, LTC3871ILXE-1#PBF application, or LTC3871ILXE-1#PBF equivalent, key selection considerations include bidirectional current programming, independent buck/boost loop compensation, VHIGH/VLOW OV/UV monitoring thresholds, DCR/RSENSE sensing flexibility, and AEC-Q100 qualification for automotive 48V/12V systems.
Technical Context
The LTC3871ILXE-1#PBF implements proprietary constant-frequency current mode control with separate peak-current (buck) and valley-current (boost) modulation schemes, enabling seamless bidirectional power flow between VHIGH (5–100V) and VLOW (1.2–30V) rails. Its dual-channel architecture supports 180° or 120° interleaved operation up to 12 phases.
It integrates two independent error amplifiers (EA_VHIGH, EA_VLOW), dual current sense paths (SNSA+/SNSD+ per channel), programmable transconductance (gm-buck = 2 mmho, gm-boost = 1 mmho), and dedicated ITHHIGH/ITHLOW pins for real-time current limit adjustment in each direction-critical for dynamic load sharing in backup power and regenerative braking systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VHIGH Range | 5V to 100V input - supports wide-range 48V battery systems including transient overvoltage conditions. |
| VLOW Range | 1.2V to 30V output - enables direct regulation of 12V auxiliary bus or low-voltage backup supplies. |
| Voltage Regulation Accuracy | ±1% over temperature - ensures stable rail control under thermal stress in engine bay environments. |
| Switching Frequency | 60kHz to 460kHz (synchronizable) - allows EMI optimization and multi-phase interleaving for reduced ripple. |
| Current Sense Threshold | 10mV to 50mV (programmable via ILIM) - supports high-efficiency DCR sensing with minimal conduction loss. |
| Operating Junction Temp | –40°C to 125°C - meets automotive Grade I requirements for under-hood deployment. |
| AEC-Q100 Qualification | Qualified per AEC-Q100 Rev H - validated for automotive reliability including HTOL, TC, and ESD testing. |
Pinout & Package
Package: 48-lead (7mm × 7mm) plastic LQFP with exposed GND pad (Pin 49), θJA = 36°C/W. Requires soldering of exposed pad to PCB ground for thermal performance and noise immunity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1/SW2 (Pins 23, 38) | Switch Node Outputs | Drive external high-side MOSFETs; swing from Schottky drop below PGND to VHIGH - defines power path topology. |
| TG1/TG2 (Pins 22, 39) | Top Gate Drivers | Floating outputs referenced to SW nodes; supply gate drive for N-channel high-side switches via bootstrap capacitors. |
| BG1/BG2 (Pins 25, 36) | Bottom Gate Drivers | Ground-referenced drivers for synchronous rectifier MOSFETs - enable >97% efficiency in both buck and boost modes. |
| VFBHIGH/VFBLOW (Pins 5, 2) | Voltage Feedback Inputs | Inverting inputs to dual error amplifiers - set regulated output voltages at 1.200V ±12mV reference point. |
| ITHHIGH/ITHLOW (Pins 4, 3) | Current Limit Control | Analog inputs setting peak (buck) or valley (boost) current thresholds - enable precise bidirectional current regulation. |
| BUCK (Pin 16) | Mode Selection | Logic-controlled pin: float/V5 = buck mode (VHIGH→VLOW), GND = boost mode (VLOW→VHIGH) - determines power flow direction. |
| DRVCC (Pin 29) | Gate Driver Supply | Adjustable 6–10V LDO output - optimizes MOSFET RDS(on) and switching loss across operating conditions. |
| GND (Pin 49) | Exposed Thermal Pad | Primary thermal and signal return path - must be soldered to PCB ground plane for rated 150°C junction temp operation. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional Power Flow Control | Single IC manages energy transfer from VHIGH to VLOW (buck) and VLOW to VHIGH (boost) without external logic or mode switching circuitry. |
| Independent Buck/Boost Compensation | Dual EA loops with separate ITHHIGH/ITHLOW pins allow optimized stability margins and transient response for each power direction. |
| Low-DCR Current Sensing | Integrated SNSA+/SNSD+ differential sensing with 14dB SNR enhancement enables use of <1mΩ DCR inductors - reduces heat and improves efficiency. |
| Programmable OV/UV Monitoring | VHIGH/VLOW OV thresholds set via resistor dividers; UVHIGH controls PGATE for input short protection - enhances system safety in automotive environments. |
| Multiphase Scalability | CLKOUT and SYNC pins support synchronization of up to 12 phases across multiple LTC3871ILXE-1#PBF units - enables high-current (>100A) 48V/12V converters. |
Applications
| Automotive 48V/12V Dual Battery Systems | High-Efficiency Bidirectional Charger |
|---|---|
Use Scenario: Power management in mild-hybrid vehicles where 48V starter-generator supplies torque assist while 12V battery powers infotainment and lighting. IC Role / Device Role / Timing Role: Bidirectional controller regulating VHIGH (48V) ↔ VLOW (12V) with real-time current limiting and fault protection during regenerative braking or cold-cranking. Use Value: Enables seamless energy recovery and distribution without discrete DC/DC stages - reduces BOM count and improves system efficiency to >95%. |
Use Scenario: Onboard charger for electric commercial vehicles that must charge both traction and auxiliary batteries from a single AC source. IC Role / Device Role / Timing Role: Core controller managing bidirectional power conversion between AC-DC front-end and dual-battery storage, with programmable current limits per direction. Use Value: Eliminates need for separate buck and boost controllers - simplifies thermal design and enables shared magnetics and gate drivers. |
| Backup Power Systems | Industrial Energy Storage Interfaces |
Use Scenario: Telecom base station UPS where 48V battery bank backs up 12V control electronics during grid failure. IC Role / Device Role / Timing Role: Regulates bidirectional current flow between primary and backup rails using VHIGH/VLOW feedback and IMON-based current monitoring. Use Value: Provides accurate ±10% IMON current readback and fast OV/UV shutdown - ensures fail-safe switchover within 125µs fault delay. |
Use Scenario: Grid-tied energy storage system interfacing lithium-ion battery stack (48V) with 12V DC bus for HVAC and monitoring subsystems. IC Role / Device Role / Timing Role: High-reliability bidirectional regulator with AEC-Q100 qualification and –40°C to 125°C operation for outdoor cabinet deployment. Use Value: Supports continuous operation under wide ambient swings and voltage transients - validated for 1000+ thermal cycles per JEDEC JESD22-A104. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional buck/boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MPQ4269-AEC1 | Single-direction (buck-only) controller with integrated MOSFETs; no boost capability or bidirectional current programming. | Suitable only for unidirectional 48V→12V conversion; lacks VLOW-to-VHIGH energy recovery functionality. | Select when cost-sensitive, lower-power (<30A), and bidirectional operation is unnecessary. |
| LTC3871ILXE#PBF | Different current limit foldback behavior: LTC3871 has linear foldback, LTC3871-1 uses stepped foldback for tighter current regulation at light loads. | Preferred for applications requiring precise low-load current matching (e.g., battery balancing), whereas LTC3871-1 excels in high-dynamic-range charging. | Choose LTC3871ILXE#PBF if legacy design compatibility or linear foldback response is required; otherwise LTC3871ILXE-1#PBF offers superior light-load accuracy. |
Compared with MPQ4269-AEC1, LTC3871ILXE-1#PBF delivers true bidirectional control with independent loop compensation and programmable sensing - essential for regenerative systems. Versus LTC3871ILXE#PBF, the -1 variant provides improved current regulation linearity below 20% load, critical for battery state-of-charge fidelity.
Availability
LTC3871ILXE-1#PBF is available at Aetrix Electronics and suitable for automotive 48V/12V dual battery systems, high-efficiency bidirectional chargers, and backup power systems requiring stable component supply with full AEC-Q100 compliance and long-term industrial availability.
Supply support for LTC3871ILXE-1#PBF 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets with precision power management solutions.
The LTC3871 family was designed specifically for automotive-grade bidirectional DC/DC conversion in dual-voltage battery architectures, emphasizing robustness, thermal efficiency, and seamless transition between buck and boost modes without external supervision.
FAQ
What is the key functional difference between LTC3871ILXE-1#PBF and LTC3871ILXE#PBF?
The LTC3871ILXE-1#PBF implements a stepped current limit foldback characteristic, providing tighter current regulation accuracy at light loads (below 20% full scale), while the LTC3871ILXE#PBF uses linear foldback. This makes LTC3871ILXE-1#PBF preferable for battery balancing and precision charging applications where low-load fidelity matters. Both share identical pinout, package, and core architecture.
How does LTC3871ILXE-1#PBF achieve bidirectional operation without external logic?
The LTC3871ILXE-1#PBF uses its BUCK pin (Pin 16) as a hardware mode selector: floating or tied to V5 configures buck mode (VHIGH→VLOW), while grounding it enables boost mode (VLOW→VHIGH). Internal logic automatically reconfigures the current sense path, error amplifier reference, and PWM timing - eliminating need for external microcontrollers or level shifters in basic implementations.
Can LTC3871ILXE-1#PBF support DCR current sensing with very low inductor DCR values?
Yes - LTC3871ILXE-1#PBF features dual-path current sensing (SNSA+/SNSD+) with internal filtering optimized for low-DCR inductors. It achieves 14dB SNR enhancement, enabling accurate current measurement with DCR as low as 0.2mΩ. The SNSD+ filter time constant must match L/DCR, while SNSA+ bandwidth is set five times higher for optimal noise rejection.
What thermal management requirements apply to LTC3871ILXE-1#PBF in automotive applications?
LTC3871ILXE-1#PBF requires soldering of its exposed GND pad (Pin 49) to a minimum 250mm² copper area on the PCB for thermal performance. With θJA = 36°C/W, maintaining TJ ≤125°C demands ≤2.5W dissipation at 85°C ambient - achievable using 4-layer board with inner ground/power planes and thermal vias under the pad.
Does LTC3871ILXE-1#PBF provide real-time current monitoring for system diagnostics?
Yes - the IMON pin (Pin 11) outputs a voltage directly proportional to average inductor current across both channels: 1.25V = zero current, with ±10% accuracy over temperature. This enables closed-loop battery charge control, fault detection, and telemetry without external ADCs - critical for ISO 26262-compliant automotive diagnostics.
LTC3871ILXE-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 48-LQFP Exposed Pad
- Packaging:
- Tray
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Up, Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Boost
- Number of Outputs:
- 2
- Output Phases:
- 12
- Voltage - Supply (Vcc/Vdd):
- 1.2V ~ 100V
- Frequency - Switching:
- 60kHz ~ 460kHz
- Duty Cycle (Max):
- 98%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Phase Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 48-eLQFP (7x7)
LTC3871ILXE-1#PBF FAQ
1.How can I place an order for LTC3871ILXE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3871ILXE-1#PBF 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 LTC3871ILXE-1#PBF reliable?
The price and inventory of LTC3871ILXE-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3871ILXE-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3871ILXE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3871ILXE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3871ILXE-1#PBF?
LTC3871ILXE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3871ILXE-1#PBF 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 LTC3871ILXE-1#PBF?
For technical support, including LTC3871ILXE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3871ILXE-1#PBF requirements.
6.How does Aetrix verify that LTC3871ILXE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3871ILXE-1#PBF 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 LTC3871ILXE-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3871ILXE-1#PBF?
All LTC3871ILXE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3871ILXE-1#PBF, 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 LTC3871ILXE-1#PBF part is unused and in its original packaging.
Return procedure for LTC3871ILXE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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