My Inquiry
My Account
Analog Devices Inc. LT8705AIFE#TRPBF
- Part No.:
- LT8705AIFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) 31 Leads, Exposed Pad
- Datasheet:
-
LT8705AIFE#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK-BOOST 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,644
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT8705AIFE#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous 4-switch buck-boost DC/DC controller IC designed for high-voltage industrial and automotive power conversion. It supports 2.8V–80V input and 1.3V–80V output, integrates quad N-channel gate drivers, and features four independent feedback loops (input/output voltage and current). It enables single-inductor buck-boost operation in telecom voltage stabilizers and solar charge controllers.
For engineers reviewing the LT8705AIFE#TRPBF datasheet, LT8705AIFE#TRPBF pinout, LT8705AIFE#TRPBF application, or LT8705AIFE#TRPBF equivalent, key selection criteria include its 100kHz–400kHz synchronizable switching frequency, integrated 3.3V/12mA LDO, MODE pin selectable light-load operation (Burst Mode®/DCM/FCM), and dual current-sense monitoring capability for input and output rails.
Technical Context
The LT8705AIFE#TRPBF implements a proprietary current-mode control architecture with diode-ANDed error amplifiers driving the VC pin to regulate output voltage while maintaining stability across buck, boost, and buck-boost regions. Its four independent feedback loops-FBIN, FBOUT, IMON_IN, and IMON_OUT-enable precise input current limiting, output current regulation, and bidirectional power flow management without external op-amps.
It uses synchronous rectification with dedicated TG1/BG1 and TG2/BG2 gate drivers supporting fast 20ns rise/fall times and programmable dead-time control via internal timing logic. The controller's MODE pin selects among forced continuous conduction mode (FCM), discontinuous conduction mode (DCM), or Burst Mode® operation-each with distinct efficiency vs. noise trade-offs at light loads.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.8V to 80V - supports wide-input systems including 24V/48V industrial buses and 60V+ solar arrays. |
| VOUT Range | 1.3V to 80V - enables regulated output above or below input, critical for battery charging and voltage stabilization. |
| Switching Frequency | 100kHz to 400kHz - adjustable via RT resistor; synchronizable to external clock for EMI reduction in multi-rail systems. |
| Gate Drivers | Quad N-channel drivers (TG1/BG1/TG2/BG2) - drives external MOSFETs with 20ns rise/fall times and built-in shoot-through protection. |
| LDO Output | 3.3V/12mA - powers auxiliary circuitry (e.g., sensors, level shifters) without external regulator. |
| Feedback Loops | Input voltage (FBIN), output voltage (FBOUT), input current (IMON_IN), output current (IMON_OUT) - enables full system-level power management. |
| Operating Temp | –40°C to +125°C - qualified for under-hood automotive and industrial ambient environments. |
Pinout & Package
LT8705AIFE#TRPBF is housed in a 38-lead plastic TSSOP package (FE38 variant) with exposed thermal pad (Pin 39 = GND). The package measures 12.5mm × 6.1mm and supports θJA = 25°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SHDN (Pin 4) | Shutdown control input | Logic-high (>1.184V) enables device; logic-low disables switching and reduces quiescent current to ≤1µA. |
| FBIN (Pin 8) | Input voltage feedback input | Connects to resistor divider from VIN; regulates input voltage during source-limited operation (e.g., solar MPPT). |
| FBOUT (Pin 9) | Output voltage feedback input | Connects to resistor divider from VOUT; sets regulated output voltage with ±1.2% accuracy over temperature. |
| IMON_IN (Pin 3) | Input current monitor output | Sinks current proportional to input current (1µA/mA typical); used for input current limiting or telemetry. |
| IMON_OUT (Pin 10) | Output current monitor output | Sinks current proportional to output current (1µA/mA typical); enables constant-current output or load protection. |
| MODE (Pin 2) | Light-load operating mode select | 0.4V = FCM; floating = Burst Mode®; >2.3V = DCM - directly controls efficiency/noise behavior at light loads. |
| SYNC (Pin 14) | External clock synchronization input | Accepts 0.5V–5.5V logic clock; enables phase-aligned operation with other regulators to reduce conducted EMI. |
| CLKOUT (Pin 13) | Internal oscillator clock output | 180° out-of-phase with internal switching; duty cycle varies linearly with die temperature for thermal monitoring. |
| TG1/BG1 (Pins 26/17) | Top/bottom gate drive for switch node 1 | Drives M1/M2 MOSFETs; BOOST1 supplies floating bias for TG1; GATEVCC powers BG1. |
| TG2/BG2 (Pins 21/19) | Top/bottom gate drive for switch node 2 | Drives M3/M4 MOSFETs; BOOST2 supplies floating bias for TG2; GATEVCC powers BG2. |
| CSNIN/CSPIN (Pins 36/37) | Input current sense differential inputs | Measure voltage across RSENSE1 to enable input current regulation or limiting. |
| CSNOUT/CSPOUT (Pins 32/34) | Output current sense differential inputs | Measure voltage across RSENSE2 to enable output current regulation or limiting. |
| INTVCC (Pin 1) | Internal 6.35V regulator output | Powers gate drivers and internal circuitry; sourced from VIN or EXTVCC depending on voltage level. |
| GATEVCC (Pin 18) | Gate driver supply rail | Must be tied directly to INTVCC; provides bias for all four gate drivers. |
| EXTVCC (Pin 30) | External bias input | When >6.4V, powers INTVCC and reduces VIN supply current; improves efficiency in high-VIN applications. |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor buck-boost topology | Eliminates need for separate buck and boost stages; reduces BOM count and board area in wide-input-range systems. |
| Four independent feedback loops | Enables simultaneous regulation of input voltage, output voltage, input current, and output current - essential for battery charging and renewable energy interfaces. |
| Programmable light-load mode | MODE pin selects Burst Mode® (low IQ), DCM (moderate ripple), or FCM (lowest noise) - no external components required. |
| Integrated 3.3V/12mA LDO | Powers external analog circuitry (e.g., ADC references, current-sense amps) without adding discrete regulators or LDOs. |
| CLKOUT-based die temperature monitor | CLKOUT duty cycle shifts linearly with junction temperature - enables real-time thermal telemetry without external sensor. |
| Robust gate driver timing | 20ns rise/fall times with 80–100ns dead-time control prevent shoot-through in high-frequency, high-power designs. |
Applications
| Solar Charge Controller | Automotive 12V/48V Bidirectional Converter |
|---|---|
Use Scenario: Regulates variable PV array voltage (30–80V) to charge 48V battery bank while enforcing maximum input current limit. IC Role / Device Role / Timing Role: Primary buck-boost controller managing both input MPPT and output constant-voltage/constant-current charging profiles. Use Value: Enables single-stage conversion with up to 98% peak efficiency and seamless transition between buck/boost modes as battery state-of-charge changes. | Use Scenario: Interfaces 12V starter battery with 48V mild-hybrid system, supporting regenerative braking energy recovery and engine start assist. IC Role / Device Role / Timing Role: Bidirectional power controller using synchronous rectification and dual current-sense loops to manage forward/reverse power flow. Use Value: Achieves >95% efficiency in both directions with precise input/output current limiting to protect battery cells and meet ISO 16750-2 transient requirements. |
| Telecom Voltage Stabilizer | Industrial 24V/48V Power Supply |
Use Scenario: Stabilizes fluctuating -48V telecom rectifier output (–36V to –72V) to deliver clean +48V for base station equipment. IC Role / Device Role / Timing Role: High-reliability buck-boost controller operating in reverse polarity configuration with input/output overvoltage/overcurrent protection. Use Value: Maintains regulated output during brownouts and surges while providing real-time current telemetry via IMON_IN/IMON_OUT pins. | Use Scenario: Powers industrial PLC I/O modules from unregulated 24V or 48V DC bus with tight output regulation and fault reporting. IC Role / Device Role / Timing Role: Programmable power controller supporting multiple output voltages (3.3V, 5V, 12V) via secondary DC/DC stages, with primary stage regulating bulk bus. Use Value: Simplifies system design by integrating input current limiting, output voltage regulation, and thermal monitoring into one controller IC. |
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 | Same 4-switch architecture but fixed 100kHz–600kHz frequency range; lacks IMON_IN/IMON_OUT pins and CLKOUT thermal monitor. | Supports lower minimum output voltage (0.8V) but no integrated input current regulation loop. | Select when cost sensitivity outweighs need for dual current monitoring or thermal telemetry. |
| MPQ4332GJ-AEC1-Z | Automotive-grade 4-switch buck-boost controller with integrated MOSFETs (60V); no external gate drivers or independent IMON pins. | Targeted for space-constrained automotive modules; limited to 3.5A output and lacks programmable light-load modes. | Select for AEC-Q100-compliant designs where integration and qualification supersede flexibility. |
Compared with LTC3780EFE#PBF and MPQ4332GJ-AEC1-Z, LT8705AIFE#TRPBF offers superior system-level control with four independent feedback loops, programmable light-load behavior, and real-time thermal monitoring - making it optimal for high-performance industrial and telecom power systems requiring full telemetry and protection.
Availability
LT8705AIFE#TRPBF is available at Aetrix Electronics and suitable for solar charge controllers, automotive bidirectional converters, and telecom voltage stabilizers requiring stable component supply, long-term lifecycle support, and guaranteed traceability.
Supply support for LT8705AIFE#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LT® portfolio.
The LT8705A belongs to Linear's high-voltage buck-boost controller family, engineered for demanding applications requiring wide input/output ranges, precise current regulation, and robust thermal performance in harsh environments.
FAQ
What is the maximum input voltage rating for LT8705AIFE#TRPBF?
The LT8705AIFE#TRPBF has an absolute maximum input voltage rating of 80V on the VIN pin. Operation is specified from 2.8V to 80V, with proper derating and thermal management required near the upper limit. Exceeding 80V risks permanent damage per Absolute Maximum Ratings.
Does LT8705AIFE#TRPBF support bidirectional power flow?
Yes, LT8705AIFE#TRPBF supports bidirectional power flow through its four-switch architecture and independent input/output current sensing (IMON_IN and IMON_OUT). When configured with appropriate external MOSFETs and control logic, it can regulate power in either direction - essential for regenerative braking and battery backup systems.
How does the MODE pin affect light-load efficiency in LT8705AIFE#TRPBF?
The MODE pin on LT8705AIFE#TRPBF selects among three light-load behaviors: <0.4V forces continuous conduction mode (FCM), floating enables Burst Mode® (lowest IQ), and >2.3V activates discontinuous conduction mode (DCM). Each setting trades off efficiency, output ripple, and EMI profile - allowing optimization for specific system requirements.
Can LT8705AIFE#TRPBF operate without an external microcontroller?
Yes, LT8705AIFE#TRPBF is a fully autonomous controller requiring no microcontroller. All regulation (voltage/current), protection (OVP/OCP), and mode selection (via MODE/SYNC/SHDN pins) are handled internally. External components include only passive elements (resistors, capacitors, inductors, MOSFETs) and optional telemetry resistors for IMON pins.
What is the purpose of the CLKOUT pin on LT8705AIFE#TRPBF?
The CLKOUT pin on LT8705AIFE#TRPBF outputs a square wave at the switching frequency, 180° out-of-phase with internal clock. Its duty cycle varies linearly with junction temperature - enabling real-time die temperature monitoring without external sensors. It also serves as a synchronization reference for other compatible regulators.
LT8705AIFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) 31 Leads, 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:
- 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-TSSOP-EP
LT8705AIFE#TRPBF FAQ
1.How can I place an order for LT8705AIFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8705AIFE#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 LT8705AIFE#TRPBF reliable?
The price and inventory of LT8705AIFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8705AIFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8705AIFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8705AIFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8705AIFE#TRPBF?
LT8705AIFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8705AIFE#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 LT8705AIFE#TRPBF?
For technical support, including LT8705AIFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8705AIFE#TRPBF requirements.
6.How does Aetrix verify that LT8705AIFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8705AIFE#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 LT8705AIFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8705AIFE#TRPBF?
All LT8705AIFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8705AIFE#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 LT8705AIFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8705AIFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT8705AIFE#TRPBF Tags
-
UCC28C45DR
Texas Instruments
-
UCC28C40DR
Texas Instruments
-
UCC28C43DR
Texas Instruments
-
ZXSC410E6TA
Diodes Incorporated
-
LM3524DMX/NOPB
Texas Instruments
-
LM3489MMX/NOPB
Texas Instruments
-
MIC2102YML-TR
Microchip Technology
-
LM5148RGYR
Texas Instruments
-
TL598CDR
Texas Instruments
-
LM5155DSSR
Texas Instruments
-
LM25085MYX/NOPB
Texas Instruments
-
UCC2813DTR-0
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
