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Analog Devices Inc. LT8708ILWE-1#PBF
- Part No.:
- LT8708ILWE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 64-LQFP Exposed Pad
- Datasheet:
-
LT8708ILWE-1#PBF.pdf
- Description:
- 80V BIDIRECTIONAL BUCK-BOOST SLA
- Quantity:
- Payment:
- Shipping:
Inventory:4,608
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Product details
Overview
LT8708ILWE-1#PBF from Analog Devices is a high-voltage synchronous 4-switch buck-boost DC/DC slave controller designed to parallel with the LT8708 master in multiphase systems. It operates exclusively as a slave, supports bidirectional conduction (forward/reverse VIN current), delivers up to 80V input/output capability, and enables scalable power delivery in automotive 48V and dual-battery systems.
For engineers reviewing the LT8708ILWE-1#PBF datasheet, LT8708ILWE-1#PBF pinout, LT8708ILWE-1#PBF application, or LT8708ILWE-1#PBF equivalent, key selection considerations include its 64-lead eLQFP package, AEC-Q100 qualification for automotive use, 100kHz–400kHz programmable switching frequency, slave-specific current monitoring (IMON_INP/IMON_INN), and precise synchronization via CLKOUT/SYNC pins.
Technical Context
The LT8708ILWE-1#PBF implements a dedicated slave control architecture synchronized to an LT8708 master via four interconnect signals (SYNC, DIR, ICN, ICP), enforcing identical conduction modes (CCM/HCM/DCM/Burst) and voltage/current limits set by the master. Its dual current-sense monitor paths independently regulate forward and reverse VIN current using IMON_INP and IMON_INN pins with 20µA base offset plus proportional current output.
It integrates two independent gate drivers (TG1/BG1 and TG2/BG2) with 20ns rise/fall times, 80–90ns dead-time control, and 200ns minimum on/off times for M2/M3 switches. The VC error amplifier output drives external compensation, while FBIN/FBOUT pins interface with master-controlled voltage regulation loops.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Synchronous 4-switch buck-boost slave controller - requires LT8708 master for full system operation. |
| Input Voltage Range | Up to 80V - supports high-voltage automotive and industrial battery systems including 48V architectures. |
| Switching Frequency | 100kHz to 400kHz - adjustable via RT resistor; synchronized via SYNC/CLKOUT for phase interleaving. |
| Current Monitoring | IMON_INP/IMON_INN pins provide 20µA + proportional current output - enables independent forward/reverse VIN current limiting. |
| Package | 64-lead (10mm × 10mm) eLQFP - exposed pad grounded, MSL Level 3, rated for –40°C to 125°C junction temperature. |
| AEC-Q100 Grade | Grade I - qualified for automotive applications per AEC-Q100 Rev H, ensuring reliability in harsh environments. |
| Efficiency | Up to 98% - achieved via synchronous rectification and optimized gate drive timing with <200ns minimum switch times. |
Pinout & Package
LT8708ILWE-1#PBF is housed in a 64-lead (10mm × 10mm) plastic eLQFP package with exposed thermal pad (Pin 65 = GND). Pin spacing complies with high-voltage isolation requirements for 80V operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CLKOUT (Pin 63) | Clock output | Provides 180° out-of-phase oscillator signal for synchronization; also serves as linear junction temperature monitor via duty cycle variation. |
| SYNC (Pin 14) | External clock input | Accepts 1.3V–5.5V logic-level clock to lock switching frequency; used to phase-align with master LT8708 CLKOUT. |
| DIR (Pin 7) | Power direction control | Determines energy flow direction (VIN→VOUT or VOUT→VIN) in DCM/HCM modes; driven by master's DIR signal. |
| ICN / ICP (Pins 6 / 15) | Slave current command inputs | Set negative/positive VIN current targets; connected directly to master LT8708's corresponding outputs for matched regulation. |
| IMON_INP / IMON_INN (Pins 11 / 12) | VIN current monitor outputs | Deliver 20µA + k·IVIN current - used to limit forward/reverse input current independently via external resistors. |
| VC (Pin 10) | Error amplifier output | Drives external compensation network; sets current/voltage regulation loop gain and stability for slave phase. |
| FBIN / FBOUT (Pins 8 / 9) | Voltage feedback inputs | Interface with master's EA3/EA4 amplifiers; typically tied to LDO33/GND to disable local regulation and follow master control. |
| TG1/BG1/TG2/BG2 (Pins 19/20/21/22) | NMOS gate drivers | Drive high-side (TG) and low-side (BG) MOSFET gates with 20ns transitions and controlled dead time to prevent shoot-through. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional slave operation | Enables reversible power transfer in dual-battery systems without requiring separate master/slave firmware or control logic. |
| Independent VIN current limiting | IMON_INP and IMON_INN pins allow separate forward and reverse input current thresholds - critical for regenerative braking and battery charging. |
| Phase-synchronized clocking | CLKOUT/SYNC interface ensures precise 180° phase shift between master and slave - reduces input/output ripple and improves EMI performance. |
| High-voltage robustness | CSNIN/CSPIN/CSPOUT/CSNOUT pins rated to 80V common-mode - supports direct sensing across high-side current shunts in 48V+ systems. |
| AEC-Q100 automotive qualification | Guaranteed operation from –40°C to 125°C junction temperature with validated reliability testing - suitable for under-hood deployment. |
Applications
| Automotive Dual-Battery Systems | 48V Mild Hybrid Power Management |
|---|---|
Use Scenario: Bidirectional power transfer between 12V starter battery and 48V traction battery during engine start-stop and regenerative braking. IC Role / Device Role / Timing Role: Slave controller managing second phase of buck-boost conversion, synchronized to master LT8708 for coordinated voltage/current regulation. Use Value: Enables scalable 30A+ output current with matched phase current sharing and reduced thermal stress versus single-phase solutions. | Use Scenario: Efficient step-up from 48V bus to 14V auxiliary supply and step-down for 48V motor drives in mild hybrid vehicles. IC Role / Device Role / Timing Role: Slave phase extending power capacity of LT8708-based converter, operating in same CCM/HCM modes as master under shared control. Use Value: Achieves >97% efficiency at 20A load in buck-boost region while maintaining tight output voltage regulation via master-slave VC loop coupling. |
| Industrial Energy Storage Systems | Bidirectional DC Fast Charging Interfaces |
Use Scenario: Reversible DC-DC stage connecting lithium-ion battery banks to grid-tied inverters for peak shaving and backup power. IC Role / Device Role / Timing Role: Slave controller handling one leg of paralleled multiphase topology, enforcing master-set voltage limits and direction commands via DIR/ICN pins. Use Value: Supports 80V input range and independent reverse-current limiting - essential for safe battery discharge into grid during islanding events. | Use Scenario: High-power bidirectional interface between EV charger and vehicle battery pack during V2G (vehicle-to-grid) operation. IC Role / Device Role / Timing Role: Slave phase delivering additional current headroom beyond master LT8708, with synchronized switching to minimize EMI in compact charging modules. Use Value: Enables 5kW+ bidirectional power delivery using two-phase interleaved design, reducing input capacitor RMS current by ~30% versus single-phase. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost slave controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8708ELWE-1#PBF | Same functionality and pinout; rated for 0°C to 125°C junction temperature (vs. –40°C to 125°C for LT8708ILWE-1#PBF). | Not qualified for extended cold-start automotive environments below 0°C ambient. | Select when industrial temperature range suffices and AEC-Q100 is not required. |
| LT8708HUHG-1#PBF | 40-lead QFN package (5mm × 8mm); rated for –40°C to 150°C junction temperature; different pin count and layout. | Requires PCB redesign due to package and pinout incompatibility; suited for space-constrained high-temp applications. | Choose only if thermal margin exceeds 125°C and board area is limited - not a drop-in replacement. |
Compared with LT8708ELWE-1#PBF, the LT8708ILWE-1#PBF adds guaranteed –40°C startup and AEC-Q100 compliance for automotive use; compared with LT8708HUHG-1#PBF, it offers larger eLQFP package with better thermal dissipation at lower cost but requires more PCB area.
Availability
LT8708ILWE-1#PBF is available at Aetrix Electronics and suitable for automotive dual-battery systems, 48V mild hybrid power management, and industrial energy storage applications requiring stable component supply and long-term lifecycle support.
Supply support for LT8708ILWE-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 industrial, automotive, communications, and healthcare markets.
The LT8708 family is designed specifically for high-voltage, bidirectional, multiphase DC/DC conversion - enabling scalable, efficient power transfer in next-generation automotive and energy infrastructure systems.
FAQ
What is the primary function of the LT8708ILWE-1#PBF in a power system?
The LT8708ILWE-1#PBF functions exclusively as a slave controller that must be paired with an LT8708 master IC. It extends system power and current capability by adding a second phase in a synchronized, interleaved buck-boost configuration - enabling higher output current, reduced ripple, and improved thermal distribution without altering the master's control architecture.
Can the LT8708ILWE-1#PBF operate independently without an LT8708 master?
No, the LT8708ILWE-1#PBF cannot operate as a standalone controller. It lacks internal voltage regulation loops, oscillator autonomy, and startup sequencing logic. All critical functions - including FBIN/FBOUT regulation, VC loop control, and mode selection - depend on signals from the master LT8708. Attempting independent operation will result in undefined behavior or failure to switch.
How does the LT8708ILWE-1#PBF achieve bidirectional current control?
The LT8708ILWE-1#PBF achieves bidirectional current control through dedicated IMON_INP and IMON_INN pins, each providing a 20µA base current plus a proportional output tied to forward or reverse average VIN current. Combined with DIR pin logic and master-synchronized MODE settings, it enforces precise current limits in both directions - essential for battery charging and regenerative energy recovery.
What package and thermal characteristics define the LT8708ILWE-1#PBF?
The LT8708ILWE-1#PBF uses a 64-lead eLQFP package (10mm × 10mm) with exposed thermal pad (Pin 65 = GND). Its thermal resistance is θJA = 17°C/W and θJC = 2.5°C/W. Rated for –40°C to 125°C junction temperature, it meets AEC-Q100 Grade I requirements - making it suitable for under-hood automotive placement with appropriate PCB copper pour and airflow.
Which pins must be connected between the LT8708ILWE-1#PBF and LT8708 master for basic operation?
Four mandatory interconnect pins are required: SYNC (to master CLKOUT), DIR (to master DIR), ICN (to master ICN), and ICP (to master ICP). These establish phase synchronization, power direction, and current command sharing. Additional connections - such as RT, SS, and FBIN/FBOUT - should match the master's values to ensure consistent frequency, soft-start timing, and voltage regulation behavior across phases.
LT8708ILWE-1#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)
LT8708ILWE-1#PBF FAQ
1.How can I place an order for LT8708ILWE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8708ILWE-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 LT8708ILWE-1#PBF reliable?
The price and inventory of LT8708ILWE-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 LT8708ILWE-1#PBF is usually 5 days.
3.What payment methods are accepted for LT8708ILWE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8708ILWE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8708ILWE-1#PBF?
LT8708ILWE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8708ILWE-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 LT8708ILWE-1#PBF?
For technical support, including LT8708ILWE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8708ILWE-1#PBF requirements.
6.How does Aetrix verify that LT8708ILWE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT8708ILWE-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 LT8708ILWE-1#PBF meets industry standards.
7.What is the process for return or replacement of LT8708ILWE-1#PBF?
All LT8708ILWE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8708ILWE-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 LT8708ILWE-1#PBF part is unused and in its original packaging.
Return procedure for LT8708ILWE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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