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Analog Devices Inc. LT8708HUHG#TRPBF
- Part No.:
- LT8708HUHG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT8708HUHG#TRPBF.pdf
- Description:
- 80V SYNCHRONOUS 4-SWITCH BUCK-BO
- Quantity:
- Payment:
- Shipping:
Inventory:4,948
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Product details
Overview
LT8708HUHG#TRPBF from Analog Devices is a high-voltage synchronous 4-switch buck-boost DC/DC controller with bidirectional power flow capability, operating from 2.8V to 80V input and regulating output from 1.3V to 80V. 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 dual-battery systems requiring seamless power transfer between battery banks.
For engineers reviewing the LT8708HUHG#TRPBF datasheet, LT8708HUHG#TRPBF pinout, LT8708HUHG#TRPBF application, or LT8708HUHG#TRPBF equivalent, this page provides verified technical context, validated pin functions, confirmed bidirectional conduction modes (CCM/HCM/DCM/Burst), exact thermal rating (–40°C to 150°C), and real-world efficiency data across buck/boost/buck-boost regions.
Technical Context
The LT8708HUHG#TRPBF implements a four-switch topology with independent gate drivers (TG1/BG1/TG2/BG2) and dual current-sense amplifiers for input/output current monitoring. Its MODE and DIR pins configure conduction mode (CCM, HCM, DCM, Burst Mode) and unidirectional/bidirectional operation without interrupting switching.
It integrates six regulation loops: VIN voltage, VOUT voltage, forward/reverse input current, and forward/reverse output current - each with dedicated error amplifiers (EA1–EA6), programmable thresholds, and temperature-stable reference voltages (1.205V typical). The VC pin serves as a unified control node coordinating all loops via gain-controlled current sense thresholds.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 80V - supports wide-range sources including automotive batteries (12V/48V), solar arrays, and industrial rails without external pre-regulation. |
| Output Voltage Range | 1.3V to 80V - enables single-inductor buck-boost conversion where VIN may be above, below, or equal to VOUT. |
| Operating Junction Temp | –40°C to 150°C - qualified per AEC-Q100 Grade H, suitable for under-hood automotive environments and high-temperature industrial enclosures. |
| Switching Frequency | 100kHz to 400kHz - adjustable via RT resistor; supports high-efficiency operation while minimizing magnetics size and EMI. |
| Current Sense Threshold | 72–110mV (buck/boost modes) - precise, temperature-compensated thresholds enable accurate ±1% current limiting at high side and low side. |
| Efficiency | Up to 99% - achieved via synchronous rectification, low-loss gate drivers (20ns rise/fall), and optimized dead-time control. |
| Package | 40-lead 5mm × 8mm QFN with high-voltage pin spacing - supports 80V operation with creepage/clearance compliance for safety-critical designs. |
Pinout & Package
LT8708HUHG#TRPBF uses the UHG package: 40-lead (5mm × 8mm) plastic QFN with exposed thermal pad (Pin 41 = GND). Pin spacing meets high-voltage isolation requirements for 80V operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW2 | Power switch nodes | Connect to external NMOS FET source terminals; rated for 81V max, tolerate negative swing via body diodes. |
| TG1, BG1, TG2, BG2 | Gate drivers | Drive high-side and low-side NMOS gates; 20ns rise/fall time, 80–90ns cross-conduction delay prevents shoot-through. |
| CSPIN/CSNIN, CSPOUT/CSNOUT | Differential current sense inputs | Monitor input-side (CSPIN/CSNIN) and output-side (CSPOUT/CSNOUT) currents with ±100mV common-mode range up to 80V. |
| DIR, MODE | Function configuration | DIR selects forward (≥1.6V) or reverse (≤1.2V) power flow; MODE sets CCM (≤0.4V), HCM (0.8–1.2V), DCM (1.6–2.0V), or Burst Mode (≥2.4V). |
| FBIN, FBOUT | Voltage feedback inputs | FBIN regulates VIN (1.205V ref); FBOUT regulates VOUT (1.207V ref); both support remote sensing and resistive divider scaling. |
| VC | Unified control node | Summing point for all regulation loops; controls current sense thresholds via ±135mV/V gain in buck/boost modes. |
| INTVCC, EXTVCC, GATEVCC | Supply rails | INTVCC (6.3V regulated) powers internal circuitry; EXTVCC switchover at 6.4V reduces dissipation; GATEVCC supplies gate drivers. |
| SHDN, SWEN | Enable/control logic | SHDN (1.22V threshold) disables IC with <1μA quiescent current; SWEN enables/disables switching with internal pull-down release at 0.8V. |
Key Features
| Feature | Design Value |
|---|---|
| Six independent regulation loops | Simultaneous control of VIN voltage, VOUT voltage, forward/reverse input current, and forward/reverse output current - eliminates need for external controllers in bidirectional battery systems. |
| Bidirectional conduction modes | Supports CCM, HCM, DCM, and Burst Mode in both directions; MODE/DIR pin changes allowed during active switching without fault or restart. |
| High-voltage robustness | SW1/SW2 pins rated to 81V; CSPIN/CSNIN/CSPOUT/CSNOUT tolerate 0–80V common-mode; QFN package features high-voltage pin spacing per safety standards. |
| Integrated gate drivers | Four matched NMOS drivers (TG1/BG1/TG2/BG2) with 20ns switching transitions and programmable dead time - enables >99% efficiency with discrete FETs. |
| AEC-Q100 Grade H qualification | Validated for –40°C to 150°C junction operation; includes thermal shutdown, overvoltage lockouts, and current-limit hysteresis for automotive reliability. |
Applications
| Automotive 48V Dual-Battery System | Industrial Energy Storage Backup |
|---|---|
Use Scenario: Seamless power transfer between 48V starter battery and 12V auxiliary battery during engine start-stop cycles and regenerative braking. IC Role / Device Role / Timing Role: Primary buck-boost controller managing bidirectional energy flow, voltage regulation, and current limiting on both sides. Use Value: Eliminates need for separate boost and buck converters; achieves >97% efficiency at 15A output with FHCM/RHCM operation per design example. |
Use Scenario: Maintaining uninterrupted power to critical PLC I/O modules during AC mains failure using supercapacitor or Li-ion backup bank. IC Role / Device Role / Timing Role: Bidirectional regulator controlling charge (VOUT→VIN) and discharge (VIN→VOUT) with independent current limits and voltage windows. Use Value: Enables precise ±2% current regulation in both directions using four external sense resistors - ensures safe capacitor charging and load hold-up. |
| Solar Microinverter DC Link | Telecom 48V/54V Battery Switchover |
Use Scenario: Stabilizing variable PV panel output (25–60V) to fixed 400V DC link for inverter stage, with reverse-current blocking during night-time. IC Role / Device Role / Timing Role: High-voltage buck-boost controller with reverse-input current limit (ICN) and VOUTLOMON undervoltage protection. Use Value: Supports discontinuous conduction mode (DCM) for light-load efficiency; 80V input rating accommodates open-circuit PV voltage spikes. |
Use Scenario: Automatic switchover between primary 48V telecom battery and secondary 54V backup bank during brownout or maintenance. IC Role / Device Role / Timing Role: Voltage- and current-regulated bidirectional interface with fast direction reversal (<100μs) via DIR pin control. Use Value: Prevents bus collapse during transition using synchronized soft-start (SS pin) and independent VIN/VOUT regulation loops. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3780 | Single-direction only; no reverse current regulation; max 60V input; no DIR/MODE pins for bidirectional control. | Suitable for unidirectional solar charge or DC-DC conversion but cannot replace LT8708HUHG#TRPBF in battery-to-battery energy transfer. | Select LTC3780 only when bidirectional operation and independent reverse current limiting are not required. |
| MPQ4323-AEC1 | Integrated power stage (4 MOSFETs); lower voltage rating (36V); no independent input/output current sensing; no HCM/DCM mode selection. | Targeted at compact 12V/24V automotive DC-DC modules; lacks the precision current monitoring and wide 80V range of LT8708HUHG#TRPBF. | Choose MPQ4323-AEC1 for space-constrained, cost-sensitive 24V systems where full bidirectional control and 80V tolerance are unnecessary. |
Compared with LTC3780 and MPQ4323-AEC1, the LT8708HUHG#TRPBF uniquely delivers six independent regulation loops, AEC-Q100 Grade H qualification, and true hardware-enforced bidirectional current limiting - making it the only option for automotive 48V dual-battery architectures requiring certified reliability and deterministic power flow control.
Availability
LT8708HUHG#TRPBF is available at Aetrix Electronics and suitable for automotive 48V systems, industrial energy storage backup, solar microinverter DC links, and telecom battery switchover applications requiring stable component supply and long-term lifecycle support.
Supply support for LT8708HUHG#TRPBF 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, sensing, and timing solutions.
The LT8708HUHG#TRPBF belongs to Analog Devices' Power by Linear™ high-voltage controller family, designed specifically for efficient, reliable, and flexible bidirectional power conversion in demanding automotive and industrial battery systems.
FAQ
What is the maximum input voltage supported by the LT8708HUHG#TRPBF?
The LT8708HUHG#TRPBF supports an absolute maximum input voltage of 80V on the VINCHIP pin and up to 81V on the SW1/SW2 pins. Its CSPIN/CSNIN/CSPOUT/CSNOUT pins tolerate 0–80V common-mode voltage, enabling direct connection to high-voltage battery rails without level-shifting circuitry. This makes the LT8708HUHG#TRPBF suitable for 48V automotive systems and industrial 60V+ backup applications.
How does the LT8708HUHG#TRPBF achieve bidirectional power flow control?
The LT8708HUHG#TRPBF uses dedicated DIR and MODE pins to configure direction and conduction mode independently. When DIR ≥1.6V, power flows forward (VIN→VOUT); when DIR ≤1.2V, it flows reverse (VOUT→VIN). Combined with MODE pin settings (CCM/HCM/DCM/Burst), the LT8708HUHG#TRPBF executes precise current limiting and regulation in both directions using separate IMON_INP/IMON_INN (input) and IMON_OP/IMON_ON (output) sense paths.
What package type and thermal performance does the LT8708HUHG#TRPBF use?
The LT8708HUHG#TRPBF uses a 40-lead 5mm × 8mm plastic QFN (UHG package) with exposed thermal pad (Pin 41 = GND). It is rated for –40°C to 150°C junction temperature and has θJA = 36°C/W and θJC = 3.8°C/W. This AEC-Q100 Grade H qualification ensures reliable operation in under-hood automotive environments and high-temperature industrial enclosures where thermal margin is critical.
Can the LT8708HUHG#TRPBF regulate both input and output voltage simultaneously?
Yes - the LT8708HUHG#TRPBF integrates two independent voltage regulation loops: FBIN regulates VIN (1.205V reference) and FBOUT regulates VOUT (1.207V reference). Both loops operate concurrently with dedicated error amplifiers (EA3 and EA4), allowing simultaneous stabilization of input bus voltage (e.g., battery) and output rail (e.g., system load) - essential for maintaining stability during dynamic load or source transients.
What is the purpose of the VC pin on the LT8708HUHG#TRPBF?
VC is the unified control node that coordinates all six regulation loops (VIN/VOUT voltage, IIN/IOUT current). It sets the current sense thresholds via gain-controlled amplifiers (±135mV/V), determines loop priority during conflict, and serves as the summing point for error signals. In practice, VC voltage directly reflects the most demanding regulation requirement - making it critical for loop compensation and stability analysis in the LT8708HUHG#TRPBF design.
LT8708HUHG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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:
- -
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (5x8)
LT8708HUHG#TRPBF FAQ
1.How can I place an order for LT8708HUHG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8708HUHG#TRPBF 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 LT8708HUHG#TRPBF reliable?
The price and inventory of LT8708HUHG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8708HUHG#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8708HUHG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8708HUHG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8708HUHG#TRPBF?
LT8708HUHG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8708HUHG#TRPBF 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 LT8708HUHG#TRPBF?
For technical support, including LT8708HUHG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8708HUHG#TRPBF requirements.
6.How does Aetrix verify that LT8708HUHG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8708HUHG#TRPBF 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 LT8708HUHG#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8708HUHG#TRPBF?
All LT8708HUHG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8708HUHG#TRPBF, 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 LT8708HUHG#TRPBF part is unused and in its original packaging.
Return procedure for LT8708HUHG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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