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Analog Devices Inc. LTC3871ELXE-1#PBF
- Part No.:
- LTC3871ELXE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
LTC3871ELXE-1#PBF.pdf
- Description:
- BI-DIR PP SYNC BUCK OR BOOST CN
- Quantity:
- Payment:
- Shipping:
Inventory:221
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Product details
Overview
LTC3871ELXE-1#PBF from Analog Devices is a bidirectional polyphase synchronous buck/boost controller for automotive 48V/12V dual-battery systems, supporting VHIGH up to 100V and VLOW up to 30V, ±1% voltage regulation accuracy, and programmable current limits from 10mV to 50mV in buck or boost mode.
For engineers reviewing the LTC3871ELXE-1#PBF datasheet, LTC3871ELXE-1#PBF pinout, LTC3871ELXE-1#PBF application, or LTC3871ELXE-1#PBF equivalent, this page delivers verified technical context, real-world operating parameters, package-specific layout guidance, and validated alternative options for dual-rail power conversion design.
Technical Context
The LTC3871ELXE-1#PBF implements proprietary constant-frequency current-mode control with independent buck and boost loop compensation, enabling seamless bidirectional energy transfer between high- and low-voltage rails. It supports both DCR- and RSENSE-based current sensing with selectable CCM/DCM operation and phase-lockable frequency from 60kHz to 460kHz.
Its architecture includes two independent current control loops (ITHHIGH/ITHLOW), dual voltage feedback paths (VFBHIGH/VFBLOW), and dedicated OV/UV monitors for both VHIGH and VLOW rails. The device features thermally enhanced 48-lead LQFP packaging with exposed GND pad and AEC-Q100 qualification for automotive use.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VHIGH Range | 5V to 100V - supports input from automotive 48V bus or industrial HV rail without external level-shifting. |
| VLOW Range | 1.2V to 30V - enables regulation of 12V auxiliary systems, backup supplies, or intermediate bus converters. |
| Regulation Accuracy | ±1% over temperature - ensures stable output under thermal stress in engine bay or under-hood environments. |
| Switching Frequency | 60kHz–460kHz (synchronizable) - allows EMI optimization and multi-phase interleaving up to 12 phases. |
| Current Sense Threshold | 10mV–58.5mV (programmable via ILIM) - supports ultra-low-loss DCR sensing or precision RSENSE configurations. |
| Package | 48-lead 7mm × 7mm LQFP with exposed GND pad - provides θJA = 36°C/W and mandatory PCB soldering for thermal integrity. |
| AEC-Q100 Grade | Grade I (–40°C to +125°C junction) - certified for automotive powertrain and chassis applications. |
Pinout & Package
Package: 48-lead plastic LQFP (7mm × 7mm), exposed GND pad (Pin 49), RoHS-compliant lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SS (1) | Soft-start ramp input | 1.25µA internal pull-up sets controlled VLOW/VHIGH ramp rate; capacitor-to-ground defines soft-start time. |
| VFBLOW (2), VFBHIGH (5) | Inverting inputs of error amplifiers | Compare sensed VLOW/VHIGH against 1.200V reference; enable precise regulation of either rail as source or sink. |
| ITHLOW (3), ITHHIGH (4) | Current threshold programming nodes | Set peak/valley current limits independently for buck (VHIGH→VLOW) and boost (VLOW→VHIGH) modes. |
| BUCK (16) | Mode selection control | Float or tie to V5 for buck operation; ground for boost - determines direction of power flow and control loop activation. |
| TG1/TG2 (22,39), BG1/BG2 (25,36) | Top/bottom gate drivers | Drive external N-channel MOSFETs with 5Ω pull-up / 2.5Ω pull-down resistance; support synchronous rectification. |
| DRVCC (29), EXTVCC (27) | Gate driver supply rails | DRVCC outputs 6–10V (set by DRVSET); EXTVCC bypasses VHIGH LDO when > (DRVCC – 0.5V), improving efficiency. |
| GND (49) | Exposed thermal pad | Mandatory solder connection to PCB ground plane - required for thermal performance and signal integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional power flow control | Single IC manages energy transfer from VHIGH→VLOW (buck) or VLOW→VHIGH (boost) based on BUCK pin state - eliminates need for separate controllers. |
| Programmable current limit foldback | LTC3871-1 variant uses distinct ITHHIGH/VILIM mapping vs. LTC3871 - enables optimized overcurrent protection for asymmetric load profiles. |
| Low-DCR current sensing | Dual-path sensing (SNSA+/SNSD+) achieves 5× SNR improvement - supports <1mΩ inductor DCR without external op-amps or filtering complexity. |
| Independent OV/UV monitoring | Separate OVHIGH/UVHIGH and OVLOW pins with 1.2V trip thresholds and 5µA hysteresis current - enables robust fault detection on both rails. |
| Multi-phase synchronization | CLKOUT and SYNC pins support master-slave phasing across up to 12 phases - reduces input/output ripple and improves thermal distribution. |
Applications
| Automotive Dual-Battery System | Backup Power Supply |
|---|---|
|
Use Scenario: Seamless power sharing between 48V mild-hybrid starter-generator and 12V legacy vehicle network during start-stop, regenerative braking, or load shedding. IC Role / Device Role / Timing Role: Bidirectional controller regulating VHIGH (48V) and VLOW (12V) simultaneously, switching at 200kHz with 180° interleave between channels. Use Value: Enables >97% efficiency at 10A load using synchronous MOSFETs and eliminates discrete DC/DC converter stacking. |
Use Scenario: Maintaining critical 12V loads (ECUs, sensors, infotainment) during main battery failure or deep discharge in commercial vehicles. IC Role / Device Role / Timing Role: Boost-mode regulator drawing from 48V auxiliary battery to sustain 12V rail; UVHIGH/UVLOW comparators trigger graceful shutdown before brownout. Use Value: Programmable current limit prevents overload during fault recovery; IMON pin provides real-time average current telemetry for system diagnostics. |
| High-Efficiency Charger | Industrial Dual-Rail Converter |
|
Use Scenario: Bidirectional charging of 48V traction battery from 12V auxiliary source during maintenance or emergency top-up. IC Role / Device Role / Timing Role: Reversible buck-boost controller operating in boost mode (VLOW→VHIGH) with accurate current regulation via SETCUR and ILIM pins. Use Value: ±10% IMON accuracy enables closed-loop charge current control without external shunt amplifier; FREQ pin adjusts switching to optimize magnetics size. |
Use Scenario: Powering mixed-voltage FPGA/ASIC subsystems requiring isolated 12V and 48V rails from a common HV DC bus in telecom or server PSUs. IC Role / Device Role / Timing Role: Primary controller managing VHIGH (HV bus) to VLOW (12V logic rail) conversion while monitoring both rails for overvoltage events. Use Value: Independent loop compensation per rail ensures stability across wide load transients; PHSMD pin configures 120° or 180° channel phasing to minimize input capacitor stress. |
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 |
|---|---|---|---|
| LTC3871ELXE#PBF | LTC3871-1 variant has different current limit foldback characteristics vs. LTC3871 - specifically optimized for boost-mode current limiting in high-VLOW scenarios. | Preferred for applications where VLOW-side current limiting dominates design requirements (e.g., 12V→48V boost charging). | Select LTC3871ELXE-1#PBF when boost-mode current regulation linearity and foldback behavior are critical; verify ITHHIGH vs. VILIM curve matches your DCR/RSENSE configuration. |
| MP2960GQ-Z | Monolithic dual-output controller with integrated MOSFETs; fixed 300kHz frequency; no programmable current sense threshold or phase synchronization. | Suitable for space-constrained, lower-power (<15A) 48V/12V interfaces where external FETs are undesirable. | Choose MP2960GQ-Z only if board area and BOM count outweigh need for programmability, thermal headroom, and multi-phase scalability. |
Compared with LTC3871ELXE#PBF and MP2960GQ-Z, the LTC3871ELXE-1#PBF offers superior current-sense flexibility, AEC-Q100 qualification, and scalable multi-phase operation - making it the only option qualified for automotive-grade bidirectional power conversion with full parameter control.
Availability
LTC3871ELXE-1#PBF is available at Aetrix Electronics and suitable for automotive 48V/12V dual-battery systems, backup power supplies, and high-efficiency bidirectional chargers requiring stable component supply, long-term lifecycle assurance, and AEC-Q100 compliance.
Supply support for LTC3871ELXE-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LTC3871/LTC3871-1 product line was designed specifically for bidirectional power conversion in next-generation automotive electrical architectures, emphasizing reliability, efficiency, and seamless integration into 48V mild-hybrid systems.
FAQ
What distinguishes LTC3871ELXE-1#PBF from LTC3871ELXE#PBF?
The LTC3871ELXE-1#PBF implements a modified current limit foldback characteristic compared to the standard LTC3871ELXE#PBF, particularly in boost mode. This variant optimizes current regulation linearity and fault response when VLOW serves as the energy source - critical for 12V→48V charging applications. Both share identical pinout, package, and core functionality.
Does LTC3871ELXE-1#PBF support synchronous rectification?
Yes, LTC3871ELXE-1#PBF fully supports synchronous rectification via dedicated TG1/TG2 and BG1/BG2 gate drivers with matched 5Ω pull-up and 2.5Ω pull-down resistances. These drivers enable efficient control of external N-channel MOSFETs in both buck and boost modes, achieving up to 97% efficiency as documented in typical performance curves.
How is current sensing implemented on LTC3871ELXE-1#PBF?
LTC3871ELXE-1#PBF uses dual-path current sensing: SNSA+ captures high-bandwidth AC components, while SNSD+ processes low-bandwidth DC components. Together they emulate a high-SNR DCR sense signal - enabling accurate current measurement with inductor DCR values as low as 0.5mΩ. RSENSE-based sensing is also supported with appropriate filter design.
Can LTC3871ELXE-1#PBF operate in discontinuous conduction mode (DCM)?
Yes, LTC3871ELXE-1#PBF supports selectable DCM/CCM operation via the MODE pin. Floating MODE enables DCM in buck mode and forced CCM in boost mode; tying MODE to SGND forces CCM in both modes; tying to V5 enables DCM in buck and non-synchronous operation in boost - providing flexibility for light-load efficiency optimization.
Is LTC3871ELXE-1#PBF qualified for automotive applications?
Yes, LTC3871ELXE-1#PBF is AEC-Q100 qualified (Grade I, –40°C to +125°C junction temperature) and manufactured under controlled automotive processes. It meets stringent reliability, thermal, and EMI requirements for under-hood deployment in 48V mild-hybrid systems, including robust UV/OV protection and fault reporting via FAULT and PGATE pins.
LTC3871ELXE-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)
LTC3871ELXE-1#PBF FAQ
1.How can I place an order for LTC3871ELXE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3871ELXE-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 LTC3871ELXE-1#PBF reliable?
The price and inventory of LTC3871ELXE-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 LTC3871ELXE-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3871ELXE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3871ELXE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3871ELXE-1#PBF?
LTC3871ELXE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3871ELXE-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 LTC3871ELXE-1#PBF?
For technical support, including LTC3871ELXE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3871ELXE-1#PBF requirements.
6.How does Aetrix verify that LTC3871ELXE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3871ELXE-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 LTC3871ELXE-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3871ELXE-1#PBF?
All LTC3871ELXE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3871ELXE-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 LTC3871ELXE-1#PBF part is unused and in its original packaging.
Return procedure for LTC3871ELXE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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