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Analog Devices Inc. LT8708EUHG#PBF
- Part No.:
- LT8708EUHG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LT8708EUHG#PBF.pdf
- Description:
- 80V SYNCHRONOUS 4-SWITCH BUCK-BO
- Quantity:
- Payment:
- Shipping:
Inventory:223
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Product details
Overview
LT8708EUHG#PBF from Analog Devices is a high-performance 80V synchronous 4-switch buck-boost DC/DC controller with bidirectional power capability. It regulates input/output voltage (1.3V–80V) and forward/reverse current on both sides, supports six independent regulation modes (VIN/VOUT voltage, IIN/IOUT in both directions), and operates in DCM/CCM/HCM/Burst Mode. Used in automotive 48V systems and dual-battery energy transfer.
For engineers reviewing the LT8708EUHG#PBF datasheet, LT8708EUHG#PBF pinout, LT8708EUHG#PBF application, or LT8708EUHG#PBF equivalent, key selection factors include its 40-lead QFN package with high-voltage pin spacing, ±100mV differential current-sense range, 100–400kHz adjustable switching frequency, and AEC-Q100 qualification for automotive-grade reliability.
Technical Context
The LT8708EUHG#PBF implements a synchronous 4-switch topology with independent control of TG1/BG1/SW1/BOOST1 and TG2/BG2/SW2/BOOST2 to enable seamless buck, boost, and buck-boost operation across VIN ≅ VOUT transitions. Its bidirectional logic uses DIR and MODE pins to configure unidirectional (FWD/RVS) or hybrid conduction modes without interrupting switching.
It integrates four error amplifiers (EA1–EA6) for simultaneous regulation of FBIN, FBOUT, IMON_INP/INN, and IMON_OP/ON, enabling precise current limiting at 72–110mV sense thresholds per direction and region. Internal gate drivers deliver 20ns rise/fall times with 80–90ns dead-time control for NMOS switches.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 80V VINCHIP; supports 12V, 24V, 48V, and 60V battery systems without external regulators. |
| Output Voltage Range | 1.3V to 80V; enables single-inductor conversion where output may be above, below, or equal to input. |
| Switching Frequency | 100–400kHz via RT resistor or SYNC pin; allows optimization of efficiency vs. size in high-power designs. |
| Current Sense Threshold | 72–110mV (buck/boost, forward/reverse); sets precise overcurrent protection using external sense resistors. |
| Operating Temperature | –40°C to +125°C junction; qualified per AEC-Q100 Grade E for under-hood automotive applications. |
| Package | 40-lead 5mm × 8mm QFN with exposed GND pad; provides thermal performance (θJC = 3.8°C/W) and HV pin spacing. |
| Regulation Modes | Six independent loops: VIN voltage, VOUT voltage, IIN forward/reverse, IOUT forward/reverse. |
Pinout & Package
LT8708EUHG#PBF is housed in a 40-lead (5mm × 8mm) plastic QFN package with exposed GND pad (Pin 41), rated for TJMAX = 150°C and θJA = 36°C/W. High-voltage pin spacing ensures robust isolation 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 during reverse recovery. |
| TG1, TG2 | Top-gate drive outputs | Drive gate of high-side NMOS; 20ns rise/fall, 90ns off-to-on delay prevents shoot-through. |
| BG1, BG2 | Bottom-gate drive outputs | Drive gate of low-side NMOS; 20ns rise/fall, 80ns off-to-on delay ensures safe commutation. |
| CSPIN/CSNIN | Input-side current sense inputs | Differential pair for monitoring IIN; common-mode range 0–80V, ±100mV differential range. |
| CSPOUT/CSNOUT | Output-side current sense inputs | Differential pair for monitoring IOUT; identical specs to CSPIN/CSNIN for bidirectional symmetry. |
| DIR | Direction control input | Logic-high (>1.6V) enables VIN→VOUT; logic-low (<1.2V) enables VOUT→VIN power flow. |
| MODE | Conduction mode select | 0.4V = CCM; 0.8–1.2V = HCM; 1.6–2.0V = DCM; ≥2.4V = Burst Mode for light-load efficiency. |
| FBIN/FBOUT | VIN and VOUT feedback inputs | High-impedance (10–15nA bias) inputs referenced to 1.205V internal bandgap for precision regulation. |
| INTVCC/GATEVCC | Internal regulator outputs | 6.3V regulated supply (±2%) for gate drivers and internal circuitry; UVLO at 4.65V with 170mV hysteresis. |
| LDO33 | 3.3V auxiliary regulator | 3.295V output (±0.5%), 22mA max; powers external logic or level-shifters without extra LDO. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional power control | Hardware-based DIR pin enables deterministic forward/reverse flow without firmware intervention or timing risk. |
| Four independent current limits | Separate resistors set IIN-FWD, IIN-RVS, IOUT-FWD, IOUT-RVS thresholds-no shared scaling or compromise. |
| Synchronous rectification support | Integrated dual NMOS gate drivers eliminate external driver ICs and reduce BOM count in 4-switch designs. |
| Hybrid Conduction Mode (HCM) | Smoothly transitions between DCM and CCM at light-to-moderate loads, maintaining >95% efficiency across 1–15A range. |
| AEC-Q100 Grade E qualification | Validated for automotive use including temperature cycling, HTOL, and ESD; supports functional safety analysis. |
Applications
| Automotive Dual-Battery System | 48V–12V Bidirectional Converter |
|---|---|
Use Scenario: Seamless power transfer between 48V starter-generator rail and 12V legacy system during engine start/stop cycles. IC Role / Device Role / Timing Role: Primary buck-boost controller managing bidirectional energy flow, voltage regulation, and current limiting on both rails. Use Value: Eliminates need for separate buck and boost controllers; maintains <1.2V output regulation tolerance and <100μs transient response under 10A load steps. | Use Scenario: Regenerative braking energy capture from 48V bus into 12V battery during deceleration. IC Role / Device Role / Timing Role: Reverse-mode controller enforcing strict IOUT-RVS limit and VOUT undervoltage lockout to protect 12V battery. Use Value: Enables >97% peak efficiency at 15A reverse current while meeting ISO 16750-2 pulse load requirements. |
| Solar Charge Controller | Industrial UPS Backup System |
Use Scenario: MPPT-enabled charging of 48V battery bank from variable PV array (20–80V VOC). IC Role / Device Role / Timing Role: Input-voltage-regulated buck-boost controller with VINHIMON overvoltage protection and FBIN feedback loop. Use Value: Supports wide-input solar arrays without pre-regulator; achieves <±0.5% line regulation over full VIN range. | Use Scenario: Bidirectional DC-DC stage between supercapacitor bank and 24V system rail in factory automation UPS. IC Role / Device Role / Timing Role: Fast-response bidirectional controller with RVSOFF-controlled reverse shutdown and IMON_ON monitoring. Use Value: Delivers <50μs fault response to overcurrent events and supports hot-plug capacitor bank connection per IEC 61000-4-5. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3780EFE#PBF | 4-switch synchronous controller with 4–36V input, no bidirectional support, fixed 100–600kHz fSW. | Unidirectional only; lacks DIR pin, reverse current sensing, and RVS regulation loops. | Select when bidirectionality is unnecessary and cost sensitivity outweighs feature set. |
| MPQ4420AGL-AEC1-Z | Monolithic 4-switch buck-boost IC (3.3–40V), integrated MOSFETs, 2A max, no current-sense flexibility. | Lower voltage/current rating; no independent IIN/IOUT limiting; not AEC-Q100 qualified. | Select for space-constrained 12V/24V systems requiring integrated FETs and simplified layout. |
Compared with LTC3780EFE#PBF and MPQ4420AGL-AEC1-Z, the LT8708EUHG#PBF uniquely delivers full bidirectional regulation with independent current limits, AEC-Q100 qualification, and 80V operation-making it the only option for high-voltage automotive and industrial energy-transfer systems requiring reverse power flow integrity.
Availability
LT8708EUHG#PBF is available at Aetrix Electronics and suitable for automotive 48V systems, bidirectional battery chargers, and industrial UPS backup systems requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8708EUHG#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 LT8708EUHG#PBF belongs to Analog Devices' Power by Linear™ controller family, designed specifically for high-efficiency, high-voltage, bidirectional DC/DC conversion in next-generation automotive and energy-storage systems.
FAQ
What is the maximum input voltage supported by the LT8708EUHG#PBF?
The LT8708EUHG#PBF supports a VINCHIP input voltage range of 2.8V to 80V. Its SW1 and SW2 pins tolerate up to 81V, and CSPIN/CSNIN/CSPOUT/CSNOUT pins operate with 0–80V common-mode range. This enables direct interface with 48V automotive systems, telecom rectifiers, and high-voltage solar arrays without external clamping or pre-regulation.
Does the LT8708EUHG#PBF support true bidirectional power flow with independent regulation?
Yes, the LT8708EUHG#PBF supports full bidirectional power flow with independent regulation of VIN, VOUT, IIN (forward/reverse), and IOUT (forward/reverse). The DIR pin selects direction, and four dedicated current-sense amplifier pairs (IMON_INP/INN, IMON_OP/ON) allow setting distinct limits for each current path using discrete resistors-no software or external logic required.
What package type and thermal characteristics does the LT8708EUHG#PBF have?
The LT8708EUHG#PBF uses a 40-lead 5mm × 8mm plastic QFN package with exposed GND pad (Pin 41). It has θJC = 3.8°C/W and θJA = 36°C/W, supporting continuous operation up to +125°C junction temperature. The exposed pad must be soldered to PCB for thermal and electrical integrity per datasheet layout guidelines.
How is switching frequency configured on the LT8708EUHG#PBF?
Switching frequency on the LT8708EUHG#PBF is set either by an external RT resistor (100–400kHz range) or synchronized to an external clock via the SYNC pin. The RT pin draws 13–25μA soft-start current; typical values are RT = 365kΩ (120kHz), 215kΩ (202kHz), or 124kΩ (350kHz). SYNC accepts 1.3V high/0.5V low logic with 20–80% duty cycle tolerance.
Is the LT8708EUHG#PBF qualified for automotive applications?
Yes, the LT8708EUHG#PBF is AEC-Q100 qualified for Grade E (–40°C to +125°C). It undergoes stress testing including HTOL, temperature cycling, and ESD per automotive standards. The "E" suffix denotes this qualification, and the part is manufactured under controlled automotive processes-enabling use in engine control units, ADAS power supplies, and 48V mild-hybrid systems.
LT8708EUHG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tube
- 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)
LT8708EUHG#PBF FAQ
1.How can I place an order for LT8708EUHG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8708EUHG#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 LT8708EUHG#PBF reliable?
The price and inventory of LT8708EUHG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8708EUHG#PBF is usually 5 days.
3.What payment methods are accepted for LT8708EUHG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8708EUHG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8708EUHG#PBF?
LT8708EUHG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8708EUHG#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 LT8708EUHG#PBF?
For technical support, including LT8708EUHG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8708EUHG#PBF requirements.
6.How does Aetrix verify that LT8708EUHG#PBF is sourced from the original manufacturer or authorized distributors?
All LT8708EUHG#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 LT8708EUHG#PBF meets industry standards.
7.What is the process for return or replacement of LT8708EUHG#PBF?
All LT8708EUHG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8708EUHG#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 LT8708EUHG#PBF part is unused and in its original packaging.
Return procedure for LT8708EUHG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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