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Analog Devices Inc. LTC3871HLXE-1#PBF
- Part No.:
- LTC3871HLXE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 48-LQFP Exposed Pad
- Datasheet:
-
LTC3871HLXE-1#PBF.pdf
- Description:
- BI-DIR PP SYNC BUCK OR BOOST CN
- Quantity:
- Payment:
- Shipping:
Inventory:4,509
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Product details
Overview
LTC3871HLXE-1#PBF from Analog Devices is a high-performance bidirectional polyphase synchronous buck/boost controller for automotive 48V/12V dual-battery systems. It regulates power flow from VHIGH (5–100V) to VLOW (1.2–30V) in buck mode or reverse in boost mode, supports up to 12-phase operation, and delivers ±1% voltage regulation accuracy over –40°C to 150°C junction temperature.
For engineers reviewing the LTC3871HLXE-1#PBF datasheet, LTC3871HLXE-1#PBF pinout, LTC3871HLXE-1#PBF application, or LTC3871HLXE-1#PBF equivalent, key selection considerations include bidirectional current programming, independent buck/boost loop compensation, programmable current sense thresholds (10–58.5 mV), phase-lockable 60–460 kHz frequency, and AEC-Q100 qualification for automotive use.
Technical Context
The LTC3871HLXE-1#PBF implements a proprietary constant-frequency current-mode architecture with separate peak-current (buck) and valley-current (boost) control loops. It features dual-channel interleaved operation with selectable 180° or 120° phasing via PHSMD pin and integrated PLL-based synchronization across multiple ICs via SYNC/CLKOUT pins.
It supports both DCR- and RSENSE-based current sensing with dedicated SNSA+/SNSD+ inputs per channel, enabling low-noise operation with <10 mV sense thresholds. Independent OV/UV monitors for VHIGH and VLOW (programmable thresholds), accurate IMON output proportional to average inductor current, and thermally enhanced 48-lead LQFP package ensure robust operation in harsh automotive environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VHIGH Range | 5 V to 100 V - supports wide-input 48V battery rail including transients up to 100V. |
| VLOW Range | 1.2 V to 30 V - enables regulation of 12V system or auxiliary rails down to low-voltage logic supplies. |
| Switching Frequency | 60 kHz to 460 kHz - programmable via FREQ pin resistor; synchronizable externally for EMI reduction. |
| Current Sense Threshold | 10 mV to 58.5 mV - adjustable in 10 mV steps via ILIM pin; supports ultra-low-DCR inductors or precision RSENSE. |
| Regulation Accuracy | ±1% over temperature - ensures stable VHIGH/VLOW feedback at 1.200 V reference with <0.2% load/line regulation. |
| Junction Temp Range | –40°C to +150°C - H-grade qualification enables under-hood deployment without derating. |
| Package | 48-lead 7 mm × 7 mm LQFP with exposed GND pad - θJA = 36°C/W; requires soldered thermal pad for rated performance. |
Pinout & Package
Package: 48-lead plastic LQFP (7 mm × 7 mm), exposed pad (Pin 49) connected to GND. Thermal pad must be soldered to PCB ground plane for rated 150°C operation and optimal thermal resistance (θJA = 36°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SS (1) | Soft-start ramp input | 1.25 µA internal pull-up sets controlled VLOW/VHIGH ramp rate; capacitor-to-ground enables inrush limiting. |
| VFBLOW (2), VFBHIGH (5) | Inverting error amplifier inputs | Connect to resistive dividers from VLOW/VHIGH; 1.200 V internal reference enables precise regulation. |
| ITHLOW/ITHHIGH (3,4) | Current limit threshold & EA compensation | Set max current per direction; external RC network stabilizes buck/boost loops independently. |
| BUCK (16) | Mode select control | Float or tie to V5 for buck (VHIGH→VLOW); ground for boost (VLOW→VHIGH) - defines primary regulation path. |
| SETCUR (12) | Initial current limit programming | Sources 7.5 µA - sets initial average inductor current limit before ITH loop takes over. |
| IMON (11) | Current monitoring output | 1.25 V = zero average current; gain varies with ILIM state (19–38 V/V) - enables real-time bidirectional current telemetry. |
| TG1/TG2 (22,39), BG1/BG2 (25,36) | Top/bottom gate drivers | DRVCC-referenced outputs drive external N-MOSFETs; 5 Ω pull-up / 2.5 Ω pull-down ensures fast switching (60 ns rise/fall). |
| PGATE (33) | Input short protection driver | Drives external PMOS high during UVHIGH fault - disconnects VHIGH rail to prevent damage from low-input conditions. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional power flow control | Single IC manages energy transfer both from 48V to 12V (buck) and 12V to 48V (boost) on demand - eliminates need for separate converters. |
| Independent buck/boost loop compensation | Dual ITH pins (ITHLOW/ITHHIGH) allow optimized stability margins for each operating mode - avoids compromise tuning. |
| Programmable current sense thresholds | ILIM pin selects 6 discrete thresholds (10–58.5 mV) - supports DCR sensing down to 0.2 mΩ or RSENSE as low as 1 mΩ. |
| Phase-lockable multi-IC operation | SYNC/CLKOUT pins enable precise phasing of up to 12 phases across multiple LTC3871HLXE-1#PBF units - reduces input/output ripple and thermal stress. |
| AEC-Q100 qualified H-grade | Rated for –40°C to +150°C junction temperature with full electrical specs guaranteed - meets automotive under-hood reliability requirements. |
Applications
| Automotive 48V/12V Dual Battery System | High-Efficiency Bidirectional Charger |
|---|---|
|
Use Scenario: Power management between primary 48V traction battery and secondary 12V auxiliary system in mild-hybrid vehicles. IC Role / Device Role / Timing Role: Bidirectional controller regulating VLOW (12V) from VHIGH (48V) during acceleration, and VHIGH from VLOW during regenerative braking or idle stop-start. Use Value: Enables >97% efficiency in both directions using synchronous rectification, reducing heat generation and extending battery life. |
Use Scenario: Onboard charger that accepts AC input to charge 48V battery while simultaneously powering 12V loads, or discharges 48V to recharge 12V battery during maintenance. IC Role / Device Role / Timing Role: Core controller managing bidirectional DC-DC conversion with programmable current limits and independent voltage regulation loops. Use Value: Eliminates need for two separate chargers; single-chip solution reduces BOM cost and PCB area by >40% versus discrete implementations. |
| Backup Power System for ADAS | Industrial Energy Storage Interface |
|
Use Scenario: Seamless switchover between main 48V supply and backup 12V battery during transient faults or brownouts in autonomous driving ECUs. IC Role / Device Role / Timing Role: Fast-response bidirectional regulator maintaining stable 12V rail while monitoring current direction and magnitude via IMON output. Use Value: Sub-100 µs fault response time prevents ADAS processor reset; OV/UV monitors on both rails ensure safe operation during grid instability. |
Use Scenario: Interfacing lithium-titanate (LTO) 24V storage bank with 48V industrial bus in factory automation equipment. IC Role / Device Role / Timing Role: High-efficiency bidirectional DC-DC stage enabling charge/discharge cycles with precise current control and thermal derating up to 150°C. Use Value: Programmable VHIGH/VLOW OV/UV thresholds adapt to varying cell chemistries; DCR sensing minimizes power loss in high-current charging paths. |
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 |
|---|---|---|---|
| MPQ8875A-AEC1 | Single-channel, fixed 48V→12V only; no boost capability; lower max VHIGH (65V); no IMON output. | Restricted to unidirectional 48V/12V step-down; unsuitable for regenerative energy recovery or backup power reversal. | Select when only buck operation is required and cost sensitivity outweighs bidirectional flexibility. |
| LTC3871HLXE#PBF | Same pinout and feature set but uses LTC3871 (not -1) current foldback profile; different ITHHIGH vs ITHLOW scaling. | Delivers identical bidirectional functionality but exhibits distinct current-limit behavior during overload - may require re-tuning compensation networks. | Choose when legacy design compatibility or specific foldback response is needed; verify current-limit hysteresis matches system safety requirements. |
Compared with MPQ8875A-AEC1 and LTC3871HLXE#PBF, the LTC3871HLXE-1#PBF uniquely supports true bidirectional power flow with independent current programming per direction, making it the only option suitable for applications requiring energy recovery, seamless rail switchover, or dual-battery charge balancing.
Availability
LTC3871HLXE-1#PBF is available at Aetrix Electronics and suitable for automotive 48V/12V systems, bidirectional onboard chargers, and industrial energy storage interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3871HLXE-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 with precision power, timing, and interface solutions.
The LTC3871 family was designed specifically for high-reliability bidirectional DC-DC conversion in automotive dual-battery architectures, emphasizing thermal robustness, noise-immune current sensing, and seamless mode transition without voltage droop.
FAQ
What distinguishes LTC3871HLXE-1#PBF from the standard LTC3871HLXE#PBF?
The LTC3871HLXE-1#PBF implements a different current limit foldback characteristic compared to the LTC3871HLXE#PBF, specifically optimized for boost-mode overload protection. This affects how the device responds to overcurrent events when operating in VLOW-to-VHIGH direction - the -1 variant provides steeper foldback to limit power dissipation during sustained faults. Both share identical pinout, temperature rating (–40°C to 150°C), and core bidirectional functionality.
How does the LTC3871HLXE-1#PBF achieve accurate current sensing with very low DCR inductors?
The LTC3871HLXE-1#PBF uses dual-path current sensing: SNSA+ captures the AC component and SNSD+ captures the DC component of the inductor current waveform. Internal signal processing combines them to emulate a high-SNR DCR sense signal - achieving effective signal-to-noise ratio improvements of 14 dB. This allows reliable operation with DCR values as low as 0.2 mΩ while maintaining 10 mV minimum sense threshold accuracy.
Can LTC3871HLXE-1#PBF synchronize with external clock sources?
Yes, the LTC3871HLXE-1#PBF supports full synchronization via its SYNC pin, accepting external clock signals from 60 kHz to 460 kHz. Its integrated PLL locks to the incoming clock and aligns internal oscillator phase - enabling precise multi-phase interleaving across multiple LTC3871HLXE-1#PBF units without external timing components. CLKOUT provides a buffered copy of the synchronized clock for daisy-chaining.
What is the role of the PGATE pin on LTC3871HLXE-1#PBF, and how is it used?
The PGATE pin on LTC3871HLXE-1#PBF drives the gate of an external PMOS transistor placed in series with the VHIGH input rail. When a UVHIGH fault is detected (e.g., VHIGH drops below programmed threshold), PGATE pulls high to turn off the PMOS, disconnecting the faulty input source. Its output swings from VHIGH down to VHIGH –15 V - ensuring full enhancement of common-source PMOS devices without level-shifting circuitry.
Does LTC3871HLXE-1#PBF support both continuous and discontinuous conduction modes?
Yes, the LTC3871HLXE-1#PBF supports selectable CCM/DCM operation via the MODE pin. Tying MODE to SGND forces continuous conduction in both buck and boost modes; floating MODE enables DCM in buck and forced CCM in boost; tying MODE to V5 enables DCM in buck and non-synchronous operation in boost. This flexibility optimizes efficiency across light-load and heavy-load conditions.
LTC3871HLXE-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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 48-eLQFP (7x7)
LTC3871HLXE-1#PBF FAQ
1.How can I place an order for LTC3871HLXE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3871HLXE-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 LTC3871HLXE-1#PBF reliable?
The price and inventory of LTC3871HLXE-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 LTC3871HLXE-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3871HLXE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3871HLXE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3871HLXE-1#PBF?
LTC3871HLXE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3871HLXE-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 LTC3871HLXE-1#PBF?
For technical support, including LTC3871HLXE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3871HLXE-1#PBF requirements.
6.How does Aetrix verify that LTC3871HLXE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3871HLXE-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 LTC3871HLXE-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3871HLXE-1#PBF?
All LTC3871HLXE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3871HLXE-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 LTC3871HLXE-1#PBF part is unused and in its original packaging.
Return procedure for LTC3871HLXE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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