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Analog Devices Inc. LT8708IUHG#TRPBF
- Part No.:
- LT8708IUHG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT8708IUHG#TRPBF.pdf
- Description:
- 80V SYNCHRONOUS 4-SWITCH BUCK-BO
- Quantity:
- Payment:
- Shipping:
Inventory:3,748
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Product details
Overview
LT8708IUHG#TRPBF from Analog Devices is a high-performance 80V synchronous 4-switch buck-boost DC/DC controller with bidirectional power 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, operates in DCM/CCM/HCM/Burst Mode®, and delivers up to 99% efficiency in synchronous rectification. It is used in automotive 48V systems and dual-battery energy transfer applications.
For engineers reviewing the LT8708IUHG#TRPBF datasheet, LT8708IUHG#TRPBF pinout, LT8708IUHG#TRPBF application, or LT8708IUHG#TRPBF equivalent, key selection considerations include its 40-lead QFN (5mm × 8mm) high-voltage pin spacing package, AEC-Q100 qualification for automotive use, independent four-quadrant current regulation, and support for real-time MODE/DIR pin reconfiguration during switching.
Technical Context
The LT8708IUHG#TRPBF implements a true 4-switch buck-boost topology with separate gate drivers (TG1/BG1/TG2/BG2) for two synchronous half-bridges, enabling seamless transition between buck, boost, and buck-boost regions without external diodes. Its control architecture integrates six independent regulation loops: VIN voltage, VOUT voltage, forward/reverse input current, and forward/reverse output current - all configurable via dedicated pins (FBIN/FBOUT/IMON_INP/IMON_INN/IMON_OP/IMON_ON).
It features programmable conduction modes (DCM/CCM/HCM/Burst) selected via the MODE pin and unidirectional/bidirectional operation set by the DIR pin. The IC includes integrated current-sense amplifiers with ±100mV differential input range, precision 1.2V reference error amplifiers (±1.5mV max offset), and robust protection including thermal shutdown, UVLO on INTVCC/GATEVCC/LDO33, and overvoltage lockouts on VINHIMON/VOUTLOMON.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 80V - supports wide-range sources including automotive batteries (12V/24V/48V), solar arrays, and industrial rails. |
| Output Voltage Range | 1.3V to 80V - enables flexible system-level voltage translation in bidirectional energy storage interfaces. |
| Switching Frequency | 100kHz to 400kHz - adjustable via RT resistor; allows optimization of size vs. efficiency in high-power converters. |
| Current Sense Threshold | 72–110mV (buck/boost modes) - sets precise current limits with minimal sensing loss and high noise immunity. |
| Operating Temp Range | –40°C to +125°C - qualified for industrial and automotive under-hood environments per AEC-Q100 Grade I. |
| Package | 40-lead QFN (5mm × 8mm) with exposed GND pad - provides low thermal resistance (θJC = 3.8°C/W) and HV pin spacing for >80V operation. |
| Efficiency | Up to 99% - achieved via synchronous rectification and low RDS(on) MOSFET drive capability (20ns rise/fall times). |
Pinout & Package
LT8708IUHG#TRPBF is housed in a 40-lead (5mm × 8mm) plastic QFN package with exposed thermal pad (Pin 41 = GND). Pin spacing meets high-voltage isolation requirements for ≥80V operation. The package is RoHS-compliant and moisture-sensitive level 3 (MSL 3).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW2 | Switch node outputs | Connect to external NMOS source terminals; rated to 81V; tolerate negative swing via body diode or Schottky clamp. |
| TG1, BG1, TG2, BG2 | Gate drivers | Drive high-side (TG) and low-side (BG) NMOS FETs; 20ns rise/fall time into 3300pF load; dead-time controlled internally. |
| CSPIN/CSNIN, CSPOUT/CSNOUT | Current sense inputs | Differential inputs for input-side (CSPIN/CSNIN) and output-side (CSPOUT/CSNOUT) current monitoring; ±100mV common-mode range up to 80V. |
| FBIN/FBOUT | Voltage feedback inputs | High-impedance (≤15nA bias) inputs for VIN and VOUT regulation; referenced to internal 1.2V precision bandgap. |
| MODE/DIR | Operation mode control | MODE selects CCM/DCM/HCM/Burst; DIR selects forward (VIN→VOUT) or reverse (VOUT→VIN) power flow; both functional during switching. |
| IMON_INP/INN/OP/ON | Current limit set points | Analog inputs setting forward/reverse input/output current limits independently via external resistors; 1.2V reference-based threshold. |
| VINCHIP/EXTVCC | Power supply inputs | VINCHIP powers core logic (2.8–80V); EXTVCC supplies gate drivers (6.15–6.6V switchover); reduces power loss at high VIN. |
| LDO33 | Integrated LDO | 3.3V/22mA regulated output; powers external circuitry or logic; includes UVLO (2.96–3.12V) and 1% load regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Six independent regulation loops | Simultaneous control of VIN, VOUT, IIN_FWD, IIN_REV, IOUT_FWD, IOUT_REV - eliminates need for external controllers in battery backup or regenerative systems. |
| Real-time MODE/DIR reconfiguration | Dynamic switching between conduction modes and power direction without cycle interruption - enables adaptive energy routing in vehicle start-stop or UPS systems. |
| Four-quadrant current limiting | Independent resistor-set thresholds for all four current directions - ensures safe bidirectional operation in capacitor charging, battery balancing, and motor drive interfaces. |
| AEC-Q100 Grade I qualification | Validated for automotive use across –40°C to +125°C junction temperature - supports deployment in 48V mild-hybrid architectures and ADAS power domains. |
| High-voltage QFN with HV pin spacing | 40-lead 5mm × 8mm package with creepage/clearance optimized for >80V operation - reduces PCB area vs. eLQFP while maintaining reliability in high-density layouts. |
Applications
| Automotive 48V Mild-Hybrid System | Industrial Dual-Battery Backup |
|---|---|
Use Scenario: Bidirectional power transfer between 48V starter-generator rail and 12V auxiliary network during engine start/stop cycles. IC Role / Device Role / Timing Role: Primary buck-boost controller managing voltage regulation, current limiting, and direction control between two battery domains. Use Value: Enables seamless energy recovery and delivery with <100ns gate driver timing control and 99% peak efficiency - reducing thermal stress and extending battery life. | Use Scenario: Seamless failover between primary and backup battery banks in telecom base stations or medical equipment. IC Role / Device Role / Timing Role: Central bidirectional regulator enforcing voltage/current boundaries during automatic switchover and charge balancing. Use Value: Prevents reverse current flow and overcharge via independent forward/reverse current limits - eliminating need for external OR-ing FETs or discrete protection circuits. |
| Solar Microinverter DC Link | Regenerative Motor Drive Interface |
Use Scenario: Interfacing PV panel output (30–80V) to variable DC link voltage (e.g., 400V) in single-stage microinverters. IC Role / Device Role / Timing Role: High-voltage buck-boost stage providing wide-input, high-efficiency DC-DC conversion before H-bridge inversion. Use Value: Supports MPPT tracking across full input range with <200ns minimum on-time and 400kHz max switching frequency - improving dynamic response and power density. | Use Scenario: Recovering braking energy from 24V/48V DC motors into onboard supercapacitor or secondary battery bank. IC Role / Device Role / Timing Role: Bidirectional converter regulating regenerated current into storage while maintaining stable bus voltage. Use Value: Uses IMON_INP/IMON_INN pins to enforce strict reverse-current limits during regeneration - preventing motor back-EMF damage and ensuring safe energy capture. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7821EFE#PBF | Fixed-ratio hybrid converter (no VOUT regulation); no bidirectional capability; requires external MOSFETs for all switches. | Optimized for high-efficiency fixed-ratio step-down only; unsuitable for battery charging or regenerative loads. | Select when only non-isolated, high-frequency (up to 3MHz), fixed-ratio conversion is needed - not for variable-output or bidirectional use. |
| MPQ4332GR-AEC1 | Monolithic 4-switch buck-boost IC (3.3–40V input); integrated 100V MOSFETs; no independent reverse current sensing or DIR pin. | Limited to lower voltage systems; lacks four-quadrant current regulation and real-time direction control. | Choose for cost-sensitive, space-constrained 12V/24V automotive modules where full 80V range and bidirectional flexibility are unnecessary. |
Compared with LTC7821EFE#PBF and MPQ4332GR-AEC1, the LT8708IUHG#TRPBF uniquely supports full 4-quadrant regulation, AEC-Q100 Grade I operation, and live MODE/DIR reconfiguration - making it the only option for high-voltage, safety-critical, dynamically reconfigurable bidirectional power systems.
Availability
LT8708IUHG#TRPBF is available at Aetrix Electronics and suitable for automotive 48V systems, industrial dual-battery backup, solar microinverter DC links, and regenerative motor drive interfaces requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for LT8708IUHG#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 industrial, automotive, communications, and healthcare markets.
The LT8708 product line was designed specifically for high-voltage, bidirectional, multi-loop regulated DC/DC conversion - targeting automotive energy recovery, battery backup, and wide-input renewable energy systems where traditional controllers lack current-direction agility and voltage range.
FAQ
What is the maximum input voltage rating for the LT8708IUHG#TRPBF?
The LT8708IUHG#TRPBF supports an absolute maximum input voltage of 80V on the VINCHIP pin and 81V on the SW1/SW2 switch nodes. Its CSPIN/CSNIN and CSPOUT/CSNOUT pins operate with common-mode voltages up to 80V, enabling direct connection to high-voltage battery rails without level-shifting circuitry. This makes the LT8708IUHG#TRPBF suitable for 48V automotive systems and industrial 60V+ applications.
Does the LT8708IUHG#TRPBF support bidirectional power flow with independent current limiting?
Yes, the LT8708IUHG#TRPBF supports full bidirectional power flow with four independent current limits: forward input, reverse input, forward output, and reverse output - each set via dedicated external resistors on IMON_INP/INN/OP/ON pins. The DIR pin configures direction, and the MODE pin selects conduction mode, all while maintaining regulation integrity. This capability is integral to the LT8708IUHG#TRPBF's architecture and verified across its full operating temperature range.
What package type and thermal characteristics does the LT8708IUHG#TRPBF use?
The LT8708IUHG#TRPBF uses a 40-lead plastic QFN package measuring 5mm × 8mm with an exposed thermal pad (Pin 41 = GND). It has a junction-to-case thermal resistance (θJC) of 3.8°C/W and junction-to-ambient (θJA) of 36°C/W. The package is MSL Level 3 and AEC-Q100 qualified for Grade I (–40°C to +125°C), ensuring reliable thermal performance in high-power automotive and industrial deployments of the LT8708IUHG#TRPBF.
Can the LT8708IUHG#TRPBF operate without an external EXTVCC supply?
Yes, the LT8708IUHG#TRPBF can operate using only VINCHIP (2.8V–80V) to power all internal circuitry, including gate drivers. However, when VINCHIP exceeds ~12V, connecting EXTVCC (6.15–6.6V) reduces power dissipation in the internal LDO and improves overall efficiency - especially critical in high-input-voltage applications like 48V automotive systems. The LT8708IUHG#TRPBF automatically switches between VINCHIP and EXTVCC based on voltage level and load.
How does the LT8708IUHG#TRPBF handle overvoltage and undervoltage protection?
The LT8708IUHG#TRPBF includes multiple integrated protections: INTVCC/GATEVCC UVLO (4.45–4.85V), LDO33 UVLO (2.96–3.12V), and programmable VINHIMON/VOUTLOMON thresholds (1.185–1.23V) with hysteresis. These monitor input and output rails and trigger shutdown or regulation adjustment. All protections are specified over the full –40°C to +125°C range and are part of the LT8708IUHG#TRPBF's AEC-Q100 qualification, ensuring robust fault handling in automotive environments.
LT8708IUHG#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 ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 40-QFN (5x8)
LT8708IUHG#TRPBF FAQ
1.How can I place an order for LT8708IUHG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8708IUHG#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 LT8708IUHG#TRPBF reliable?
The price and inventory of LT8708IUHG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8708IUHG#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8708IUHG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8708IUHG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8708IUHG#TRPBF?
LT8708IUHG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8708IUHG#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 LT8708IUHG#TRPBF?
For technical support, including LT8708IUHG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8708IUHG#TRPBF requirements.
6.How does Aetrix verify that LT8708IUHG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8708IUHG#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 LT8708IUHG#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8708IUHG#TRPBF?
All LT8708IUHG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8708IUHG#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 LT8708IUHG#TRPBF part is unused and in its original packaging.
Return procedure for LT8708IUHG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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