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Analog Devices Inc. LT8708HUHG-1#TRPBF
- Part No.:
- LT8708HUHG-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT8708HUHG-1#TRPBF.pdf
- Description:
- 80V SYNCHRONOUS 4-SWITCH BUCK-BO
- Quantity:
- Payment:
- Shipping:
Inventory:4,575
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Product details
Overview
LT8708HUHG-1#TRPBF from Analog Devices is a high-voltage synchronous 4-switch buck-boost 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, maintains identical conduction modes (CCM/HCM/DCM/Burst) with the master, and targets automotive 48V systems and bidirectional battery charging applications.
For engineers reviewing the LT8708HUHG-1#TRPBF datasheet, LT8708HUHG-1#TRPBF pinout, LT8708HUHG-1#TRPBF application, or LT8708HUHG-1#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification for 150°C junction operation, 40-pin QFN package with high-voltage pin spacing, four-wire parallel interface (SYNC, CLKOUT, DIR, MODE), and independent forward/reverse VIN current limiting via IMON_INP/IMON_INN pins.
Technical Context
The LT8708HUHG-1#TRPBF implements a slave-only control architecture synchronized to an LT8708 master via CLKOUT/SYNC signals, enforcing identical voltage regulation (FBIN/FBOUT) and current sharing behavior. Its dual current monitor inputs-IMON_INP (positive VIN current) and IMON_INN (negative VIN current)-enable independent setting of forward and reverse input current limits, while DIR and MODE pins configure bidirectional power flow and conduction mode selection (CCM/HCM/DCM/Burst).
It integrates gate drivers for four external NMOS switches (TG1/BG1/TG2/BG2), supports 100kHz–400kHz switching frequency via RT resistor or external SYNC, and features integrated LDO33 (3.3V/22mA) and INTVCC (6.3V/165mA) regulators. The device uses CSPIN/CSNIN and CSPOUT/CSNOUT differential sense pairs for accurate current monitoring across ±100mV differential range and 0–80V common-mode voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Operating Voltage Range | VINCHIP: 5.5V–80V; supports wide-input industrial and automotive battery systems including 12V, 24V, 48V, and dual-battery architectures. |
| Switching Frequency | 100kHz–400kHz; adjustable via RT resistor or external SYNC signal, enabling EMI optimization and inductor size reduction. |
| Current Sense Range | ±100mV differential input on CSPIN/CSNIN and CSPOUT/CSNOUT; enables precise high-side and low-side current sensing with external shunts. |
| Junction Temperature Range | –40°C to +150°C; qualified per AEC-Q100 Grade H, suitable for under-hood automotive environments and high-reliability industrial power systems. |
| Package | 40-lead (5mm × 8mm) plastic QFN with exposed thermal pad; provides high-voltage pin spacing and low θJA = 36°C/W for thermally demanding applications. |
| Integrated Regulators | INTVCC (6.3V/165mA) and LDO33 (3.295V/22mA); powers internal circuitry and external logic without requiring auxiliary supplies. |
| Bidirectional Control | DIR pin selects forward (VIN→VOUT) or reverse (VOUT→VIN) power flow; IMON_INP/IMON_INN independently limit positive/negative VIN current. |
Pinout & Package
LT8708HUHG-1#TRPBF is housed in a 40-lead (5mm × 8mm) plastic QFN package with exposed GND pad (Pin 41), rated for 150°C maximum junction temperature and optimized for high-voltage isolation and thermal performance.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (CLKOUT) | Clock output | 180° out-of-phase oscillator/SYNC output; used to synchronize slave phases or monitor die temperature via duty cycle variation. |
| 2 (SS) | Soft-start timing | Connects to capacitor for controlled ramp-up of VC voltage; ensures coordinated start-up with master LT8708. |
| 3 (SHDN) | Shutdown control | Logic-high enables operation; logic-low reduces quiescent current to ≤1µA for system-level power gating. |
| 4 (CSN), 5 (CSP) | Inductor current sense (−)/(+) | Differential inputs for primary current sensing; set inductor peak current threshold in conjunction with VC and RSENSE. |
| 6 (ICN) | Negative VOUT current command | Connected to master ICN to enforce current matching; sets negative output current regulation target for bidirectional operation. |
| 7 (DIR) | Power direction control | High = forward (VIN→VOUT); low = reverse (VOUT→VIN); active only in DCM/HCM modes per MODE pin configuration. |
| 8 (FBIN), 9 (FBOUT) | VIN/VOUT feedback inputs | Connect to GND or LDO33 to disable respective error amplifiers; master controls overall voltage regulation. |
| 10 (VC) | Error amplifier output | Compensation node for voltage/current loops; ties to external RC network to stabilize closed-loop response. |
| 11 (IMON_INP), 12 (IMON_INN) | Positive/negative VIN current monitor | Output current proportional to average VIN current; used for independent forward/reverse input current limiting and monitoring. |
| 13 (RT) | Frequency setting | Resistor-to-ground sets switching frequency; matched to master RT ensures phase-aligned operation in multiphase systems. |
| 14 (SYNC) | External clock input | Accepts 100kHz–400kHz clock; when tied to master CLKOUT, enforces 180° phase shift between master and slave phases. |
| 16 (BG1), 18 (BG2) | Bottom gate drivers | Drive gates of low-side NMOS switches (M1/M2); rail-to-rail output swing referenced to GATEVCC (6.3V). |
| 17 (GATEVCC) | Gate driver supply | Must be connected to INTVCC; powers BG1/BG2 drivers and requires local 1µF ceramic bypass to GND. |
| 20 (TG1), 22 (TG2) | Top gate drivers | Drive gates of high-side NMOS switches (M3/M4); bootstrap operation enabled via BOOST1/BOOST2 pins. |
| 21 (INTVCC) | Internal regulator output | 6.3V regulated supply for internal logic and gate drivers; max 165mA load capacity shared with LDO33. |
| 23 (VINCHIP) | Main chip supply | Primary power input (5.5V–80V); powers internal circuitry and charges INTVCC/LDO33 when EXTVCC is inactive. |
| 24 (GND) | Ground reference | Analog/digital ground; must be connected to exposed pad (Pin 41) for optimal thermal and noise performance. |
| 25 (BG1) | Bottom gate 1 driver | Same function as Pin 16; duplicate listing reflects dual-driver topology for two switch legs. |
| 26 (GATEVCC) | Gate driver supply | Same function as Pin 17; duplicate listing reflects shared supply requirement for all gate drivers. |
| 27 (BG2) | Bottom gate 2 driver | Same function as Pin 18; drives second low-side MOSFET in 4-switch buck-boost topology. |
| 28 (BOOST2) | Bootstrap capacitor connection | Connects to bootstrap capacitor for TG2 high-side driver; enables floating gate drive above SW2 potential. |
| 29 (TG2) | Top gate 2 driver | Drives gate of high-side NMOS M4; operates in bootstrap mode using BOOST2 and SW2 nodes. |
| 30 (LDO33) | 3.3V regulator output | Stable 3.3V/22mA supply for external logic, ADC references, or level-shifting circuits; internally regulated from VINCHIP or EXTVCC. |
| 31 (IMON_ON) | Output current monitor | Current output proportional to average VOUT current; used for output current limiting and telemetry in slave-controlled systems. |
| 32 (IMON_OP) | Output current monitor | Complementary output to IMON_ON; provides differential current monitoring capability for enhanced accuracy. |
| 33 (MODE) | Conduction mode select | Voltage thresholds define CCM (≤0.4V), HCM (0.8–1.2V), DCM (1.6–2.0V), Burst (>2.4V); matches master MODE setting for consistent behavior. |
| 34 (SWEN) | Switch enable | Active-high control for enabling/disabling switching operation; synchronizes with master SWEN for coordinated start/stop. |
| 35 (VINHIMON) | VIN high-voltage monitor | Input for overvoltage lockout; triggers shutdown if VIN exceeds 1.23V threshold (corresponding to ~80V at divider ratio). |
| 36 (VOUTLOMON) | VOUT low-voltage monitor | Input for undervoltage lockout; disables regulation if VOUT falls below 1.225V threshold (e.g., <12V at typical divider). |
| 37 (RVSOFF) | Reverse VIN shutdown | Open-drain output indicating reverse VIN fault condition; pulls low when reverse current exceeds programmed limit. |
| 38 (BOOST1) | Bootstrap capacitor connection | Connects to bootstrap capacitor for TG1 high-side driver; enables floating gate drive above SW1 potential. |
| 39 (TG1) | Top gate 1 driver | Drives gate of high-side NMOS M3; operates in bootstrap mode using BOOST1 and SW1 nodes. |
| 40 (SW1) | Switch node 1 | Connection point for high-side NMOS drain and low-side NMOS source (M1/M3); handles full switching waveform up to 81V. |
| 41 (GND) | Exposed thermal pad | Must be soldered to PCB copper pour for thermal dissipation and EMI reduction; electrically connected to internal GND plane. |
Key Features
| Feature | Design Value |
|---|---|
| AEC-Q100 Grade H qualification | Rated for –40°C to +150°C junction operation, enabling use in automotive engine compartments and industrial high-temp environments. |
| Four-wire parallel interface | SYNC, CLKOUT, DIR, and MODE pins allow seamless synchronization and bidirectional coordination with LT8708 master without additional logic. |
| Independent forward/reverse VIN current limiting | IMON_INP and IMON_INN pins provide separate analog current outputs for setting distinct positive and negative input current trip points. |
| Dual differential current sense inputs | CSPIN/CSNIN and CSPOUT/CSNOUT support ±100mV differential range and 0–80V common-mode voltage, enabling accurate shunt-based sensing in high-voltage rails. |
| Integrated 3.3V/22mA LDO | LDO33 supplies external logic, ADCs, or microcontrollers directly-eliminating need for discrete regulators in space-constrained designs. |
| 180° phase-shifted clock output | CLKOUT toggles at oscillator frequency but inverted relative to master CLKOUT, simplifying interleaved multiphase layout and reducing input ripple. |
Applications
| Automotive Dual-Battery Systems | 48V Mild Hybrid Power Conversion |
|---|---|
|
Use Scenario: Bidirectional energy transfer between 12V starter battery and 48V traction battery during regenerative braking and engine start-stop cycles. IC Role / Device Role / Timing Role: LT8708HUHG-1#TRPBF acts as slave controller in a two-phase LT8708/LT8708-1 system, regulating VOUT to match master-set voltage while independently limiting reverse VIN current during charge-back. Use Value: Enables >97% efficiency at 30A bidirectional transfer (VBAT2=13.5V), with precise current matching to master phase and AEC-Q100 reliability for under-hood deployment. |
Use Scenario: High-efficiency DC/DC conversion between 48V bus and 12V subsystems in mild hybrid vehicles, supporting ADAS sensors, infotainment, and lighting loads. IC Role / Device Role / Timing Role: LT8708HUHG-1#TRPBF serves as parallel slave to increase total system power handling beyond single-phase limits, maintaining synchronized switching and shared voltage regulation. Use Value: Doubles system current capability while retaining tight current sharing (<5% mismatch), reducing thermal stress on individual MOSFETs and extending lifetime in continuous 48V operation. |
| Industrial Bidirectional UPS | Renewable Energy Storage Interface |
|
Use Scenario: Seamless transition between grid-powered AC/DC conversion and battery-backed DC/DC inversion in telecom and datacenter uninterruptible power supplies. IC Role / Device Role / Timing Role: LT8708HUHG-1#TRPBF operates as slave in multiphase buck-boost stage, responding to master's DIR and MODE commands to reverse power flow during outage conditions. Use Value: Supports fast direction reversal (<100µs) with programmable forward/reverse current limits, ensuring stable bus voltage during switchover without capacitor oversizing. |
Use Scenario: Interfacing lithium-ion battery banks (24–58V) with solar charge controllers or grid-tied inverters requiring flexible voltage translation and bidirectional energy management. IC Role / Device Role / Timing Role: LT8708HUHG-1#TRPBF functions as scalable slave controller in modular battery management systems, allowing incremental power expansion by adding slave units to existing LT8708 master. Use Value: Enables plug-and-play scalability-each LT8708HUHG-1#TRPBF adds full-rated current capacity while maintaining master-enforced voltage accuracy and thermal derating coordination. |
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 |
|---|---|---|---|
| LT8708IUHG-1#TRPBF | Same functionality and pinout, but rated for –40°C to +125°C junction temperature (Grade I vs Grade H). | Not qualified for under-hood automotive use; suitable for industrial or commercial ambient environments where 150°C operation is unnecessary. | Select LT8708IUHG-1#TRPBF when thermal margin allows lower-cost qualification and extended temperature range is not required. |
| LT8708HUHG-1#WPBF | Identical electrical specs and thermal rating, but supplied in tray packaging (not tape-and-reel) and includes automotive-specific reliability documentation. | Designed for production lines requiring traceable automotive-grade documentation and controlled manufacturing flow. | Choose LT8708HUHG-1#WPBF for OEM automotive programs needing full PPAP support and AEC-Q100 test reports. |
Compared with LT8708IUHG-1#TRPBF, the LT8708HUHG-1#TRPBF provides guaranteed 150°C operation critical for engine bay placement, while LT8708HUHG-1#WPBF adds automotive traceability without altering electrical behavior-making the TRPBF variant optimal for high-volume automated assembly where reel packaging and thermal robustness are both essential.
Availability
LT8708HUHG-1#TRPBF is available at Aetrix Electronics and suitable for automotive dual-battery systems, 48V mild hybrid converters, and industrial bidirectional UPS applications requiring stable component supply, AEC-Q100 compliance, and high-temperature reliability.
Supply support for LT8708HUHG-1#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 with precision power, sensing, and signal chain solutions.
The LT8708HUHG-1#TRPBF belongs to Analog Devices' Power by Linear™ family of high-voltage DC/DC controllers, engineered specifically for scalable, bidirectional, multiphase power conversion in next-generation automotive and industrial energy systems.
FAQ
What is the primary function of the LT8708HUHG-1#TRPBF in a power system?
The LT8708HUHG-1#TRPBF functions exclusively as a slave controller in multiphase buck-boost systems, paralleling with an LT8708 master to increase total power and current capability. It does not operate autonomously-it relies on the master for voltage regulation, timing, and mode control while contributing matched current output and independent forward/reverse input current limiting.
How does the LT8708HUHG-1#TRPBF achieve bidirectional power flow control?
The LT8708HUHG-1#TRPBF achieves bidirectional control through the DIR pin, which selects forward (VIN→VOUT) or reverse (VOUT→VIN) operation when MODE is configured for DCM or HCM. Independent current limiting is enforced via IMON_INP (positive VIN current) and IMON_INN (negative VIN current), allowing asymmetric forward/reverse current thresholds in the same LT8708HUHG-1#TRPBF design.
What package and thermal specifications apply to the LT8708HUHG-1#TRPBF?
The LT8708HUHG-1#TRPBF uses a 40-lead (5mm × 8mm) plastic QFN package with exposed GND pad (Pin 41), rated for –40°C to +150°C junction temperature and qualified per AEC-Q100 Grade H. Its thermal resistance is θJA = 36°C/W and θJC = 38°C/W, requiring direct soldering of the exposed pad to PCB copper for reliable high-power operation.
Can the LT8708HUHG-1#TRPBF operate without an LT8708 master?
No-the LT8708HUHG-1#TRPBF cannot operate independently. It lacks autonomous voltage regulation circuitry and requires continuous synchronization via CLKOUT/SYNC, shared MODE/DIR signals, and current command inputs (ICN/ICP/ICN) from an LT8708 master. Attempting standalone operation results in undefined behavior and failure to regulate output voltage or current.
What are the key differences between LT8708HUHG-1#TRPBF and LT8708HUHG-1#WPBF?
The LT8708HUHG-1#TRPBF and LT8708HUHG-1#WPBF share identical electrical specifications and thermal rating (–40°C to +150°C), but differ in packaging and compliance documentation. The #WPBF variant ships in trays and includes full AEC-Q100 automotive reliability reports and controlled manufacturing records, whereas the #TRPBF is tape-and-reel packaged for SMT automation without added automotive certification paperwork.
LT8708HUHG-1#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-1#TRPBF FAQ
1.How can I place an order for LT8708HUHG-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8708HUHG-1#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-1#TRPBF reliable?
The price and inventory of LT8708HUHG-1#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-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8708HUHG-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8708HUHG-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8708HUHG-1#TRPBF?
LT8708HUHG-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8708HUHG-1#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-1#TRPBF?
For technical support, including LT8708HUHG-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8708HUHG-1#TRPBF requirements.
6.How does Aetrix verify that LT8708HUHG-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8708HUHG-1#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-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8708HUHG-1#TRPBF?
All LT8708HUHG-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8708HUHG-1#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-1#TRPBF part is unused and in its original packaging.
Return procedure for LT8708HUHG-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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