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Analog Devices Inc. LTC7871ILWE#PBF
- Part No.:
- LTC7871ILWE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 64-LQFP Exposed Pad
- Datasheet:
-
LTC7871ILWE#PBF.pdf
- Description:
- 6-PHASE BIDIRECTIONAL BUCK/BOOST
- Quantity:
- Payment:
- Shipping:
Inventory:143
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Product details
Overview
LTC7871ILWE#PBF from Analog Devices is a six-phase, synchronous bidirectional buck/boost controller designed for 48V/12V dual-battery automotive systems. It regulates in buck mode (VHIGH→VLOW) or boost mode (VLOW→VHIGH) based on the BUCK pin state, supports up to 100V VHIGH and 60V VLOW input ranges, delivers ±1% voltage regulation accuracy over temperature, and features SPI interface, phase-lockable 60kHz–750kHz switching frequency, and accurate bidirectional current programming.
For engineers reviewing the LTC7871ILWE#PBF datasheet, LTC7871ILWE#PBF pinout, LTC7871ILWE#PBF application, or LTC7871ILWE#PBF equivalent, key selection considerations include its bidirectional control architecture, six-phase interleaved operation with precise per-phase current matching, independent buck/boost loop compensation, programmable current limit via SETCUR pin and SPI, and AEC-Q100 qualification status for automotive deployment.
Technical Context
The LTC7871ILWE#PBF implements a proprietary constant-frequency current-mode control architecture with separate transconductance amplifiers for buck (gm–buck = 2 mmho) and boost (gm–boost = 1 mmho) modes, enabling dynamic regulation of input/output voltage or current. Its six PWM outputs are phased at 0°, 60°, 120°, 180°, 240°, and 300° relative to Phase 1, supporting up to 24-phase multi-IC synchronization via CLKOUT.
It integrates dual error amplifiers (EA_VHIGH and EA_VLOW), independent ITHHIGH/ITHLOW compensation nodes, programmable OV/UV monitors for both rails, and a 20µA FREQ pin current source for resistor-based frequency setting. The device uses AC-coupled (SNSA+) and DC-coupled (SNSD+) current sense inputs per phase, with configurable gain (4–40 V/V) depending on DCR/RSENSE configuration and ILIM pin voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VHIGH Range | 6V to 100V - supports primary rail in 48V automotive systems with headroom for transients. |
| VLOW Range | 1.2V to 60V - enables regulation of 12V auxiliary bus or backup power systems. |
| Voltage Regulation Accuracy | ±1% over –40°C to 125°C - ensures stable output under full automotive temperature range without recalibration. |
| Switching Frequency | 60kHz to 750kHz, phase-lockable - allows EMI optimization and multi-IC synchronization across up to 24 phases. |
| Current Sense Threshold Range | 6.5mV to 70mV (RSENSE config) - sets max per-phase inductor current from ~2A to ~23A with 3mΩ sense resistor. |
| SETCUR Pin Current | 16.0µA typical - provides precise, temperature-stable current limit programming via external resistor or SPI DAC. |
| Operating Junction Temp | –40°C to 125°C - rated for under-hood automotive environments with thermal derating above 125°C. |
Pinout & Package
The LTC7871ILWE#PBF is housed in a thermally enhanced 64-lead (10mm × 10mm) plastic LQFP package (LWE), with exposed pad (Pin 65) connected to SGND and required to be soldered to PCB ground for thermal performance (θJA = 17°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VHIGH (Pin 48) | Main high-side supply input | Accepts 6–100V input; powers internal circuitry and gate drivers via internal LDO; requires local 0.1–1µF bypass. |
| VFBHIGH (Pin 7) / VFBLOW (Pin 3) | Feedback inputs for high/low rail regulation | Connect to resistor dividers from VHIGH/VLOW; enable ±1% regulation accuracy with <±40nA input bias current. |
| ITHHIGH (Pin 6) / ITHLOW (Pin 4) | Buck/boost current threshold and compensation nodes | Set peak current limit and provide loop compensation; support independent Type II/III networks per mode. |
| PWM1–PWM6 (Pins 29,31,32,33,34,36) | Phase-gated top-driver outputs | Three-state compatible signals driving external gate drivers; phased at 0°, 60°, 120°, 180°, 240°, 300° for interleaving. |
| BUCK (Pin 54) | Mode selection control | Ground = boost mode (VLOW→VHIGH); float or tied to V5 = buck mode (VHIGH→VLOW); no internal pull-up/down. |
| SNSA1+–SNSA6+ (Pins 17,22,23,58,59,64) SNSD1+–SNSD6+ (Pins 19,20,25,56,61,62) SNS1––SNS6– (Pins 18,21,24,57,60,63) |
Per-phase AC/DC current sense inputs | SNSA+ captures ripple for fast transient response; SNSD+ and SNS– form DC path for average current regulation and protection. |
| CSB/SCLK/SDI/SDO (Pins 37–40) | SPI interface signals | 4-wire serial interface (5MHz max) for real-time register read/write, fault reporting, and margining control. |
Key Features
| Feature | Design Value |
|---|---|
| Six-phase interleaved bidirectional control | Enables >180A total output with reduced input/output ripple, lower EMI, and improved thermal distribution vs. single-phase designs. |
| Independent buck and boost loop compensation | Allows optimized stability and transient response for both power flow directions without compromise or re-tuning. |
| Programmable current limit via SETCUR pin and SPI | 16µA precision current source + 32-step SPI DAC enables fine-grained, temperature-stable current regulation from system MCU. |
| Accurate inductor current monitoring (IMON) | 1.25V zero-current reference with ±10% accuracy enables real-time load monitoring and predictive diagnostics for battery health. |
| Spread spectrum modulation (SSFM) | Configurable ±12% frequency dithering reduces peak EMI by spreading energy across bandwidth-critical for automotive EMC compliance. |
| AEC-Q100 qualification in progress | Meets stress test requirements for automotive Grade 1 (–40°C to 125°C) operation, supporting functional safety–aware designs. |
Applications
| Automotive 48V/12V Dual Battery Systems | Backup Power Systems |
|---|---|
Use Scenario: Seamless power transfer between 48V main traction battery and 12V auxiliary network during engine start-stop, regenerative braking, or load shedding. IC Role / Device Role / Timing Role: Bidirectional six-phase controller managing energy flow direction, voltage regulation, and per-phase current limiting in real time. Use Value: Enables >95% efficiency in both buck and boost modes, reducing thermal load and extending battery life while meeting ISO 16750 transient immunity. |
Use Scenario: Uninterruptible power delivery from secondary battery to critical ECUs during primary rail failure or cold-cranking events. IC Role / Device Role / Timing Role: Fast-switching bidirectional regulator maintaining stable 12V output despite VHIGH sagging below 30V. Use Value: Achieves <40µs fault-to-shutdown response via dedicated FAULT pin and OV/UV comparators, ensuring fail-safe operation. |
| High-Density Server PSU Modules | Industrial Energy Storage Interfaces |
Use Scenario: High-efficiency 48V-to-12V intermediate bus conversion in AI accelerator racks requiring >200A aggregate current. IC Role / Device Role / Timing Role: Six-phase controller synchronized across multiple LTC7871ICs via CLKOUT to scale output capacity without phase skew. Use Value: Delivers >97% peak efficiency at 100A with <1% current mismatch between phases, minimizing derating and heatsink size. |
Use Scenario: Bi-directional power management between lithium-ion storage bank and DC microgrid in smart factory UPS systems. IC Role / Device Role / Timing Role: Programmable current regulation and SPI-monitored IMON output enable closed-loop state-of-charge estimation. Use Value: Supports ±10% current accuracy over temperature, enabling precise charge/discharge cycle control and predictive maintenance. |
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 |
|---|---|---|---|
| LTC7872ILWE#PBF | Eight-phase version with identical pinout, same 60kHz–750kHz frequency range, but adds integrated MOSFET drivers and higher current capability per phase. | Targeted at >250A systems where board space permits larger gate drive integration; not drop-in due to different driver architecture and thermal profile. | Select when scaling beyond six-phase current capacity is required and external drivers are undesirable. |
| MPQ8971-AEC1 from Monolithic Power Systems | Single-phase, 48V/12V bidirectional controller with integrated 100V/60A GaN drivers; lacks multi-phase interleaving, SPI interface, and independent buck/boost compensation. | Suitable for low-power (<30A) auxiliary loads; cannot replace LTC7871ILWE#PBF in high-current or synchronized multi-IC architectures. | Consider only for cost-sensitive, space-constrained applications where six-phase performance and diagnostics are unnecessary. |
Compared with LTC7872ILWE#PBF, the LTC7871ILWE#PBF offers proven six-phase interleaving with minimal layout complexity and full diagnostic visibility via SPI, while MPQ8971-AEC1 trades flexibility and scalability for integration and BOM reduction in simpler systems.
Availability
LTC7871ILWE#PBF is available at Aetrix Electronics and suitable for automotive 48V/12V dual battery systems, industrial backup power interfaces, and high-density server intermediate bus converters requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.
Supply support for LTC7871ILWE#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, sensing, and timing solutions.
The LTC7871ILWE#PBF belongs to Analog Devices' Power by Linear™ controller family, engineered specifically for high-efficiency, high-reliability bidirectional DC/DC conversion in next-generation automotive electrification and energy infrastructure applications.
FAQ
What is the operating temperature range for the LTC7871ILWE#PBF?
The LTC7871ILWE#PBF is specified for operation from –40°C to +125°C junction temperature. This rating aligns with automotive Grade I requirements and is validated across the full range for parameters including voltage regulation accuracy (±1%), current sense threshold, and oscillator frequency stability. Thermal design must account for θJA = 17°C/W and mandatory soldering of the exposed pad (Pin 65) to PCB ground.
How does the LTC7871ILWE#PBF handle bidirectional mode switching?
The LTC7871ILWE#PBF switches between buck and boost modes based solely on the logic state of the BUCK pin: grounding it enables boost (VLOW→VHIGH), while floating or tying it to V5 enables buck (VHIGH→VLOW). No software or SPI command is required-the transition is hardware-controlled and occurs within microseconds, supported by independent loop compensation networks for each mode.
Can the LTC7871ILWE#PBF be synchronized with other controllers?
Yes, the LTC7871ILWE#PBF supports multi-IC synchronization via its CLKOUT pin (Pin 50), which outputs a buffered clock signal phased at 30° relative to Phase 1. When used with the SYNC pin (Pin 52), it accepts external clocks from 60kHz to 750kHz, enabling precise phase alignment across up to 24 phases using multiple LTC7871ICs-critical for EMI reduction and current sharing in high-power systems.
What current sense configurations does the LTC7871ILWE#PBF support?
The LTC7871ILWE#PBF supports both DCR-based and RSENSE-based current sensing per phase, using separate SNSA+ (AC) and SNSD+/SNS– (DC) inputs. Gain is configurable from 4 V/V (RSENSE) to 40 V/V (DCR) depending on ILIM pin voltage. Maximum sense threshold ranges from 6.5mV to 70mV, allowing accurate current regulation from ~2A to >20A per phase with standard sense resistors or integrated inductor DCR.
Is the LTC7871ILWE#PBF pin-compatible with other members of the LTC787x family?
No, the LTC7871ILWE#PBF is not pin-compatible with LTC7872 or LTC7873 variants. While all share the 64-pin LWE package and many signal names, pin assignments differ significantly-for example, LTC7872 relocates several current sense and SPI pins to accommodate integrated drivers. Board redesign is required for substitution; refer to respective pin configuration diagrams before migration.
LTC7871ILWE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 64-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:
- 6
- Output Phases:
- 6
- Voltage - Supply (Vcc/Vdd):
- 6V ~ 100V
- Frequency - Switching:
- 60kHz ~ 750kHz
- Duty Cycle (Max):
- 98%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- SPI
- Control Features:
- Enable, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 64-LQFP-EP (10x10)
LTC7871ILWE#PBF FAQ
1.How can I place an order for LTC7871ILWE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7871ILWE#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 LTC7871ILWE#PBF reliable?
The price and inventory of LTC7871ILWE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7871ILWE#PBF is usually 5 days.
3.What payment methods are accepted for LTC7871ILWE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7871ILWE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7871ILWE#PBF?
LTC7871ILWE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7871ILWE#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 LTC7871ILWE#PBF?
For technical support, including LTC7871ILWE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7871ILWE#PBF requirements.
6.How does Aetrix verify that LTC7871ILWE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC7871ILWE#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 LTC7871ILWE#PBF meets industry standards.
7.What is the process for return or replacement of LTC7871ILWE#PBF?
All LTC7871ILWE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7871ILWE#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 LTC7871ILWE#PBF part is unused and in its original packaging.
Return procedure for LTC7871ILWE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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