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Analog Devices Inc. LT8708ELWE#PBF
- Part No.:
- LT8708ELWE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 64-LQFP Exposed Pad
- Datasheet:
-
LT8708ELWE#PBF.pdf
- Description:
- 80V BIDIRECTIONAL BUCK-BOOST CON
- Quantity:
- Payment:
- Shipping:
Inventory:4,567
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Product details
Overview
LT8708ELWE#PBF from Analog Devices is a high-performance 80V synchronous 4-switch buck-boost DC/DC controller with bidirectional power capability, operating across 2.8V–80V input and 1.3V–80V output ranges. It supports independent forward/reverse current limiting on both input and output sides, enables six regulation modes (VIN/VOUT voltage, IIN/IOUT current), and delivers up to 99% efficiency in synchronous rectification. It is used in automotive 48V systems and bidirectional battery backup architectures.
For engineers reviewing the LT8708ELWE#PBF datasheet, LT8708ELWE#PBF pinout, LT8708ELWE#PBF application, or LT8708ELWE#PBF equivalent, key selection criteria include its 64-pin eLQFP package, AEC-Q100 qualification for automotive use, bidirectional conduction control via DIR/MODE pins, and support for FHCM/RHCM operation in dual-battery systems.
Technical Context
The LT8708ELWE#PBF implements a four-switch buck-boost topology with independent gate drivers (TG1/BG1/TG2/BG2) and integrated current-sense amplifiers for IMON_INP/INN/ON/OP, ICP/ICN, CSPIN/CSNIN, CSPOUT/CSNOUT. Its control architecture supports simultaneous regulation of VIN, VOUT, IIN, and IOUT in both directions using dedicated error amplifiers and programmable thresholds.
It features selectable conduction modes-CCM, DCM, HCM, and Burst Mode-via the MODE pin, while the DIR pin determines unidirectional (FWD/RVS) or bidirectional power flow. Internal oscillators (100–400 kHz) are adjustable via RT resistor or synchronized via SYNC/CLKOUT, with precise timing control down to 200 ns minimum on/off times.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | 4-switch synchronous buck-boost controller - enables single-inductor operation with VIN above, below, or equal to VOUT. |
| Input Voltage Range | 2.8V to 80V - supports wide-range sources including automotive batteries, solar arrays, and telecom supplies. |
| Output Voltage Range | 1.3V to 80V - configurable for diverse system rails without external level-shifting. |
| Switching Frequency | 100 kHz to 400 kHz - adjustable via RT resistor or external SYNC signal for EMI optimization and layout flexibility. |
| Current Sensing | Four independent current-limit channels (IIN_FWD/REV, IOUT_FWD/REV) - set by external resistors for precise bidirectional protection. |
| Package | 64-lead eLQFP (10mm × 10mm) - high-voltage pin spacing, exposed pad for thermal management, MSL Level 3. |
| Temperature Range | –40°C to +125°C junction - qualified per AEC-Q100 Grade I for automotive under-hood applications. |
Pinout & Package
LT8708ELWE#PBF is housed in a 64-lead plastic eLQFP (LWE package) with exposed thermal pad (Pin 65 = GND). Pin spacing meets high-voltage isolation requirements for 80V operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW2 | Power switch node connections | Connect to external NMOS source terminals; tolerate up to 81V with body-diode clamping. |
| TG1, BG1, TG2, BG2 | Gate drive outputs | Drive high-side and low-side MOSFETs; 20 ns rise/fall time into 3300 pF load. |
| CSPIN/CSNIN, CSPOUT/CSNOUT | Differential current sense inputs | Monitor input/output currents with ±100 mV differential range and 0–80 V common-mode capability. |
| DIR, MODE | Direction and conduction mode control | DIR >1.6 V = forward flow; DIR <1.2 V = reverse flow; MODE sets CCM/HCM/DCM/Burst Mode. |
| FBIN, FBOUT | Voltage feedback inputs | Regulate VIN and VOUT independently; reference voltage = 1.205 V ±12 mV over temperature. |
| IMON_INP/INN/ON/OP, ICP/ICN | Current regulation monitor outputs | Provide 0–120 µA proportional output current for closed-loop current limiting and monitoring. |
| VINCHIP, EXTVCC | Primary and auxiliary supply inputs | VINCHIP powers core logic (2.8–80 V); EXTVCC switchover at 6.4 V enables efficient biasing from boost rail. |
| CLKOUT, SYNC | Timing interface pins | CLKOUT provides synchronized clock output; SYNC accepts external clock (100–400 kHz) for multi-phase synchronization. |
Key Features
| Feature | Design Value |
|---|---|
| Six independent regulation loops | Simultaneous control of VIN, VOUT, IIN_FWD/REV, IOUT_FWD/REV - eliminates need for external controllers in bidirectional systems. |
| Bidirectional conduction support | FHCM/RHCM operation with seamless direction reversal - enables energy recovery in regenerative braking and battery balancing. |
| Programmable conduction modes | CCM, DCM, HCM, and Burst Mode selectable via MODE pin - optimizes efficiency across light-to-full load conditions. |
| High-voltage robustness | 81 V max SW pin rating, 80 V common-mode sense range, and AEC-Q100 qualification - suitable for 48V automotive and industrial HV systems. |
| Integrated gate drivers | Four independent NMOS drivers with <200 ns min on/off times - supports high-frequency switching with minimal dead-time loss. |
| Thermal and fault protection | Junction temperature sensing, thermal shutdown, UVLO on INTVCC/GATEVCC/LDO33 - ensures safe operation under overload or miswiring. |
Applications
| Automotive 48V Mild Hybrid System | Bidirectional Battery Backup |
|---|---|
|
Use Scenario: Regulates power flow between 48V starter-generator and 12V battery during engine start-stop cycles and regenerative braking. IC Role / Device Role / Timing Role: Primary buck-boost controller managing bidirectional energy transfer with FHCM/RHCM mode switching. Use Value: Enables >97% peak efficiency at 15A output, reduces thermal stress via 64-pin eLQFP thermal pad, and meets AEC-Q100 Grade I requirements. |
Use Scenario: Maintains uninterrupted power to critical loads during AC mains failure by transferring energy from backup battery to system bus. IC Role / Device Role / Timing Role: Dual-rail controller regulating both input (battery) and output (system bus) voltages while limiting charge/discharge currents. Use Value: Independent forward/reverse current limits prevent battery overcharge/overdischarge; six regulation loops eliminate need for secondary supervisors. |
| Solar Microinverter DC Link | Industrial Energy Storage System |
|
Use Scenario: Interfaces PV panel (30–80V) with DC link capacitor (400V+) via intermediate buck-boost stage for MPPT and voltage stabilization. IC Role / Device Role / Timing Role: High-voltage buck-boost controller supporting wide VIN/VOUT ratio with programmable frequency for EMI compliance. Use Value: 80V input rating accommodates open-circuit PV voltage; 400 kHz max switching enables compact magnetics and fast transient response. |
Use Scenario: Balances charge between series-connected Li-ion cells or manages bi-directional power between grid and storage bank. IC Role / Device Role / Timing Role: Precision current-controlled bidirectional converter with independent IIN/IOUT monitoring and limiting. Use Value: Four independent current limit thresholds ensure cell-level safety; IMON outputs interface directly with microcontroller ADCs for real-time telemetry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8705ELWE#PBF | Single-direction only (no DIR pin, no reverse current regulation); identical 64-pin eLQFP package and 80V rating. | Limited to unidirectional power transfer; lacks bidirectional current monitoring and RHCM/FHCM modes. | Select when bidirectional operation is unnecessary and cost reduction is prioritized over feature set. |
| MPQ4420AGU-AEC1-P | 36V max input, integrated MOSFETs, fixed 3.5A current limit; QFN-16 package, no bidirectional capability. | Targeted at lower-power, space-constrained automotive DC/DC conversion without current reversal needs. | Choose for compact 12V/24V systems where integration and footprint outweigh flexibility and voltage range. |
Compared with LT8708ELWE#PBF, LT8705ELWE#PBF removes bidirectional functionality but retains pin compatibility and thermal performance, while MPQ4420AGU-AEC1-P trades voltage headroom and configurability for monolithic simplicity in sub-36V applications.
Availability
LT8708ELWE#PBF is available at Aetrix Electronics and suitable for automotive 48V systems, bidirectional battery backup architectures, and industrial energy storage applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LT8708ELWE#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 industrial, automotive, communications, and healthcare markets.
The LT8708ELWE#PBF belongs to Analog Devices' Power by Linear™ controller family, designed specifically for high-voltage, high-efficiency, bidirectional DC/DC conversion in demanding automotive and industrial environments.
FAQ
What is the maximum input voltage supported by the LT8708ELWE#PBF?
The LT8708ELWE#PBF supports an absolute maximum input voltage of 80V on the VINCHIP pin and up to 81V on the SW1/SW2 pins, with internal protection against negative transients via external MOSFET body diodes. This makes the LT8708ELWE#PBF suitable for 48V automotive systems and high-voltage solar inputs where transient overvoltage events may occur.
Does the LT8708ELWE#PBF support bidirectional current regulation?
Yes, the LT8708ELWE#PBF supports independent forward and reverse current regulation on both input and output sides using four dedicated current-sense amplifier pairs (IMON_INP/INN, IMON_ON/OP, ICP/ICN). Each channel can be configured with separate external resistors to set distinct current limits for charging, discharging, sourcing, and sinking operations.
What package type and thermal characteristics does the LT8708ELWE#PBF use?
The LT8708ELWE#PBF uses a 64-lead eLQFP (LWE) package measuring 10mm × 10mm with an exposed thermal pad (Pin 65 = GND). Its thermal resistance is θJA = 17°C/W and θJC = 2.5°C/W, enabling reliable operation up to +125°C junction temperature under typical PCB copper pour conditions.
How is conduction mode selected on the LT8708ELWE#PBF?
Conduction mode on the LT8708ELWE#PBF is selected via the MODE pin: <0.4 V for CCM, 0.8–1.2 V for HCM, 1.6–2.0 V for DCM, and >2.4 V for Burst Mode. These thresholds are specified over full temperature range and allow dynamic reconfiguration during operation without cycle interruption.
Is the LT8708ELWE#PBF AEC-Q100 qualified?
Yes, the LT8708ELWE#PBF is AEC-Q100 qualified for automotive applications (Grade I, –40°C to +125°C), with controlled manufacturing, enhanced reliability testing, and automotive-specific failure analysis reporting available through Analog Devices' qualified product line.
LT8708ELWE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- 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:
- 1
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 2.8V ~ 80V
- Frequency - Switching:
- 100kHz ~ 400kHz
- Duty Cycle (Max):
- 80%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 64-LQFP-EP (10x10)
LT8708ELWE#PBF FAQ
1.How can I place an order for LT8708ELWE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8708ELWE#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 LT8708ELWE#PBF reliable?
The price and inventory of LT8708ELWE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8708ELWE#PBF is usually 5 days.
3.What payment methods are accepted for LT8708ELWE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8708ELWE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8708ELWE#PBF?
LT8708ELWE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8708ELWE#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 LT8708ELWE#PBF?
For technical support, including LT8708ELWE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8708ELWE#PBF requirements.
6.How does Aetrix verify that LT8708ELWE#PBF is sourced from the original manufacturer or authorized distributors?
All LT8708ELWE#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 LT8708ELWE#PBF meets industry standards.
7.What is the process for return or replacement of LT8708ELWE#PBF?
All LT8708ELWE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8708ELWE#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 LT8708ELWE#PBF part is unused and in its original packaging.
Return procedure for LT8708ELWE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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