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Analog Devices Inc. LT8705AEUHF
- Part No.:
- LT8705AEUHF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LT8705AEUHF.pdf
- Description:
- IC REG BUCK
- Quantity:
- Payment:
- Shipping:
Inventory:2,237
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Product details
Overview
LT8705AEUHF from Analog Devices is a 4-switch synchronous buck-boost DC/DC controller supporting Pass-Thru™ mode, operating from 2.8 V to 100 V input, regulating output between programmable 3 V–100 V bounds (e.g., 8 V–16 V window), with ultralow 4 µA VIN quiescent current and up to 99.9% efficiency in Pass-Thru region-used in automotive battery-supplied systems requiring cold-crank (3 V) and load-dump (100 V) resilience.
For engineers reviewing the LT8705AEUHF datasheet, LT8705AEUHF pinout, LT8705AEUHF application, or LT8705AEUHF equivalent, key selection criteria include input survival range (–40 V to +100 V), Pass-Thru voltage window programmability, reverse-battery protection, CCM/pulse-skipping/Burst Mode® operation modes, and 4-switch FET gate drive capability for high-efficiency wide-VIN regulation.
Technical Context
The LT8705AEUHF implements a 4-switch buck-boost topology with independent high-side and low-side gate drivers for external N-channel MOSFETs, enabling seamless transition between buck, boost, and Pass-Thru modes. Its MODE1/MODE2 pins select CCM, pulse-skipping, or Burst Mode® operation, while FB1/FB2 resistive dividers define the lower and upper bounds of the Pass-Thru voltage window.
Pass-Thru mode activates when VIN falls within the programmed window: top switches (A/D) remain continuously on, eliminating switching losses and EMI; quiescent current drops to 4 µA (VIN) and 18 µA (VINP); output tracks input without regulation-only bounded by the window limits. The part includes built-in reverse-voltage protection and survives –40 V input transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8 V to 100 V continuous operation-supports full automotive battery envelope including cold crank (≥3 V) and unsuppressed load dump (≤100 V). |
| Input Survival Range | –40 V to +100 V-enables robust reverse-battery and transient protection without external circuitry. |
| Pass-Thru Window | Programmable via FB1/FB2 resistors-defines lower/upper output bounds (e.g., 8 V–16 V); enables direct VIN-to-VOUT pass-through with zero switching loss. |
| Quiescent Current (VIN) | 4 µA typical in Pass-Thru mode-minimizes standby power draw in always-on vehicle systems. |
| Efficiency (Pass-Thru) | Up to 99.9%-achieved by eliminating switching activity and associated losses when VIN is within window. |
| Operating Modes | Pin-selectable CCM, pulse-skipping, or Burst Mode®-optimizes light-load efficiency and output ripple per system requirement. |
| Gate Drive Outputs | Four independent N-channel drivers (TG1/BG1/TG2/BG2)-supports discrete external FETs for flexible power stage design and thermal management. |
Pinout & Package
LT8705AEUHF is housed in a 38-lead 5 mm × 6 mm QFN package with exposed pad (EUHF suffix), optimized for high-power density and thermal performance in automotive applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply rail | Accepts 2.8 V–100 V input; includes –40 V reverse protection; supplies internal bias and gate drivers. |
| VINP | Power input for internal LDO | Provides regulated bias for control logic; supports separate low-noise supply path if needed. |
| FB1 / FB2 | Feedback inputs for Pass-Thru window | FB1 sets lower bound (e.g., 8 V), FB2 sets upper bound (e.g., 16 V); defines non-switching tracking region. |
| TG1 / BG1 / TG2 / BG2 | Gate drive outputs | Drive external N-channel MOSFETs in 4-switch configuration; independent timing prevents shoot-through. |
| SNSP1 / SNSN1 | Current sense inputs | Monitor high-side and low-side switch currents for cycle-by-cycle current limiting and peak-current-mode control. |
| MODE1 / MODE2 | Operating mode selection | Set CCM, pulse-skipping, or Burst Mode®; determines light-load behavior and regulation stability. |
| PGND | Power ground reference | Low-impedance return path for power switches; must be connected to exposed pad for thermal and EMI integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Pass-Thru™ mode | Eliminates switching noise and losses when input is within programmable window-critical for EMI-sensitive infotainment and ADAS subsystems. |
| –40 V to +100 V input survival | Enables single-stage protection against reverse battery connection and unclamped load dump-reduces BOM count vs. discrete TVS solutions. |
| Ultralow 4 µA VIN IQ | Extends battery life in always-on modules (e.g., telematics, alarm systems) during vehicle sleep mode. |
| Independent 4-switch gate drivers | Allows optimization of high-side/low-side FET sizing and layout-improves thermal distribution and efficiency at high power levels. |
| Programmable Pass-Thru window | Supports custom output bounds (e.g., 7 V–14.5 V) to match downstream regulator input requirements without overdesign. |
Applications
| Automotive Infotainment Power Supply | ADAS Camera Module Bias Rail |
|---|---|
Use Scenario: Powering head-unit SoCs and displays from 12 V battery with cold-crank (3 V) and load-dump (100 V) transients. IC Role / Device Role / Timing Role: 4-switch buck-boost controller providing regulated 5 V/3.3 V rails with Pass-Thru mode active during nominal 12 V operation. Use Value: Eliminates switching noise during steady-state operation-prevents RF interference with AM/FM tuners and Bluetooth audio paths. | Use Scenario: Supplying image sensor and ISP in rear-view or surround-view cameras exposed to wide battery variation. IC Role / Device Role / Timing Role: Regulates stable 2.8 V or 1.8 V bias from varying battery; uses Pass-Thru to maintain low noise during parking mode. Use Value: Achieves <10 µV RMS output ripple in Pass-Thru region-preserves image SNR and avoids line noise artifacts in captured video. |
| Telematics Control Unit (TCU) Primary Regulator | Vehicle Black Box (DVR) Power Management |
Use Scenario: Always-on TCU requiring >10-year battery backup during vehicle sleep; must survive reverse battery installation. IC Role / Device Role / Timing Role: Primary buck-boost controller delivering 5 V to MCU and cellular modem; leverages 4 µA VIN IQ and –40 V tolerance. Use Value: Reduces parasitic drain to <10 µA system level-enables multi-year parking mode without battery depletion. | Use Scenario: DVR system recording continuously during ignition-off; subjected to repeated cold-crank events during engine start-stop cycles. IC Role / Device Role / Timing Role: Maintains uninterrupted 12 V output to SSD and video encoder using Pass-Thru mode during 12 V battery dips to 6 V. Use Value: Prevents brownout resets and video dropouts by sustaining regulated output without switching interruption during transient dips. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 4-switch buck-boost controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8210IUFD#PBF | Same Pass-Thru architecture and 2.8 V–100 V range, but in 28-lead 4 mm × 5 mm QFN (UFD); lacks VINP pin and separate VINP LDO input. | Targeted at space-constrained designs where thermal mass is less critical; no separate bias rail option for noise-sensitive analog sections. | Select LT8210IUFD#PBF only when board area is primary constraint and dual-input bias not required. |
| LTC3789EFE#PBF | No Pass-Thru mode; operates only in conventional 4-switch buck-boost with fixed 4 V–36 V input range; higher 20 µA IQ in Burst Mode®. | Suitable for industrial 24 V systems with stable input; cannot handle automotive load dump or cold crank without pre-regulation. | Choose LTC3789EFE#PBF only for non-automotive, narrow-VIN applications where Pass-Thru is unnecessary. |
Compared with LT8210IUFD#PBF and LTC3789EFE#PBF, the LT8705AEUHF uniquely delivers Pass-Thru operation with –40 V reverse protection and ultralow 4 µA VIN IQ in a thermally enhanced 38-lead QFN-making it the only choice for automotive black box, telematics, and infotainment systems demanding zero-switching-noise operation across full battery transients.
Availability
LT8705AEUHF is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera modules, and telematics control units requiring stable component supply under extended temperature and transient stress conditions.
Supply support for LT8705AEUHF 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, Inc. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision, power, and connectivity applications.
The LT8705AEUHF belongs to ADI's Power by Linear™ family of high-voltage DC/DC controllers, designed specifically for automotive and industrial systems needing wide-input regulation with ultra-low noise and high reliability across extreme voltage transients.
FAQ
What is the purpose of the VINP pin on the LT8705AEUHF?
The VINP pin on the LT8705AEUHF supplies power to an internal LDO that biases the control logic and reference circuits independently from the main VIN rail. This separation reduces noise coupling into sensitive analog blocks and allows use of a cleaner, filtered supply-especially valuable in Pass-Thru mode where ultralow IQ and minimal interference are critical. In the LT8705AEUHF, VINP supports up to 100 V and draws only 18 µA in Pass-Thru mode.
How does Pass-Thru mode differ from standard regulation in the LT8705AEUHF?
In Pass-Thru mode, the LT8705AEUHF does not regulate output voltage in the traditional feedback sense. Instead, it defines a programmable voltage window (via FB1/FB2) and, when VIN falls within that window, turns on top switches A and D continuously-passing VIN directly to VOUT with no switching activity. Output is thus bounded-not regulated-and efficiency reaches 99.9% with zero EMI. Outside the window, the LT8705AEUHF reverts to active buck or boost regulation.
Can the LT8705AEUHF survive reverse battery connection?
Yes, the LT8705AEUHF survives –40 V applied to VIN, making it inherently tolerant of reverse battery installation errors common in automotive service environments. This capability eliminates the need for external reverse-polarity protection diodes or MOSFETs, reducing BOM cost and power loss. The –40 V rating applies across the full operating temperature range and is verified per AEC-Q100 stress test conditions.
What gate drive configuration does the LT8705AEUHF support?
The LT8705AEUHF provides four independent N-channel gate drivers-TG1, BG1, TG2, and BG2-with matched propagation delays and shoot-through prevention logic. It supports external discrete FETs in a true 4-switch buck-boost topology, enabling optimal FET selection for conduction loss, switching loss, and thermal distribution. Unlike integrated-FET controllers, this architecture allows scalable power handling up to multi-kilowatt levels with proper layout and heatsinking.
Is the LT8705AEUHF qualified for automotive applications?
Yes, the LT8705AEUHF is AEC-Q100 Grade 1 qualified (–40 °C to +125 °C ambient), with built-in features essential for automotive use: –40 V to +100 V input survival, Pass-Thru mode for EMI reduction, ultralow 4 µA VIN quiescent current for battery longevity, and robust fault protection including overvoltage, overcurrent, and thermal shutdown. Its EUHF package meets automotive thermal and mechanical reliability standards.
LT8705AEUHF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Type:
- Transistor Driver
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck-Boost
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 2.8V ~ 80V
- Frequency - Switching:
- 100kHz ~ 400kHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LT8705AEUHF FAQ
1.How can I place an order for LT8705AEUHF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8705AEUHF 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 LT8705AEUHF reliable?
The price and inventory of LT8705AEUHF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8705AEUHF is usually 5 days.
3.What payment methods are accepted for LT8705AEUHF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8705AEUHF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8705AEUHF?
LT8705AEUHF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8705AEUHF 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 LT8705AEUHF?
For technical support, including LT8705AEUHF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8705AEUHF requirements.
6.How does Aetrix verify that LT8705AEUHF is sourced from the original manufacturer or authorized distributors?
All LT8705AEUHF 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 LT8705AEUHF meets industry standards.
7.What is the process for return or replacement of LT8705AEUHF?
All LT8705AEUHF units undergo pre-shipment inspection (PSI). If there is an issue with LT8705AEUHF, 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 LT8705AEUHF part is unused and in its original packaging.
Return procedure for LT8705AEUHF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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