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Analog Devices Inc. LTC3859AMPFE#TRPBF
- Part No.:
- LTC3859AMPFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859AMPFE#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOP 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,237
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Product details
Overview
LTC3859AMPFE#TRPBF from Analog Devices is a triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, operating from 4.5V–38V input with 55μA no-load quiescent current, 0.8V/1.2V precision references for buck/boost outputs, and phase-lockable switching up to 850kHz - deployed in automotive start-stop systems requiring cold-crank regulation down to 2.5V.
For engineers reviewing the LTC3859AMPFE#TRPBF datasheet, LTC3859AMPFE#TRPBF pinout, LTC3859AMPFE#TRPBF application, or LTC3859AMPFE#TRPBF equivalent, this page delivers verified package mapping (38-pin TSSOP), confirmed triple-output control architecture, validated Burst Mode® performance improvements over LTC3859, and real-world soft-start/tracking implementation details for multi-rail power sequencing.
Technical Context
The LTC3859AMPFE#TRPBF integrates three independent current-mode controllers: two buck channels with 0.8V reference and 99% dropout duty cycle, and one boost channel with 1.2V reference, 100% synchronous duty cycle capability, and improved Burst Mode operation when VIN > VOUT. Its OPTI-LOOP compensation supports wide output capacitance/ESR ranges.
It features programmable fixed-frequency (50kHz–900kHz) or PLL-synchronized operation (75kHz–850kHz), selectable light-load modes (Burst, pulse-skipping, forced continuous), and independent RUN pins enabling staggered startup/shutdown. The –55°C to +150°C extended temperature grade confirms suitability for under-hood automotive applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V main bias; operates down to 2.5V after startup when biased from boost output or auxiliary supply. |
| Quiescent Current (Sleep Mode) | 55μA with one channel active - extends battery runtime in always-on systems. |
| Buck Feedback Reference | 0.800V ±1.0% (–40°C to 125°C); enables precise 5V/3.3V rail regulation with low drift. |
| Boost Feedback Reference | 1.200V ±1.0% (–40°C to 125°C); supports stable 12V/24V/48V boost outputs. |
| Switching Frequency Range | 75kHz to 850kHz PLL-synchronizable; allows EMI reduction via clock alignment with system master. |
| Operating Temperature | –55°C to +150°C junction; qualified for engine compartment and industrial high-temp environments. |
| Gate Driver Strength | TG3/BG3 pull-up/pull-down RON ≤1.2Ω/1.0Ω - drives large MOSFETs with fast 12ns/13ns rise/fall times (CLOAD=3300pF). |
Pinout & Package
Package: 38-lead plastic TSSOP (FE package), 5mm × 7mm footprint, exposed PGND pad (Pin 39) requiring PCB soldering for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2, RUN3 (Pins 9,10,11) | Digital enable inputs per channel | Independent shutdown control: <1.17V (buck) or <1.20V (boost) disables respective regulator; all <0.7V enters 14μA shutdown. |
| VFB1, VFB2, VFB3 (Pins 36,14,6) | Feedback voltage inputs | Monitor output via resistive divider; regulate to 0.8V (buck) or 1.2V (boost); PGOOD1 monitors only VFB1. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32/18/27, 29/21/25) | Top/bottom gate drivers | Drive N-MOSFET gates; TG swing = INTVCC superimposed on SW node; BG swing = GND to INTVCC. |
| SENSE1+/SENSE1–, etc. (Pins 37/38,13/12,4/5) | Differential current sense inputs | Enable RSENSE or DCR sensing; SENSE3+ sources 170μA; SENSE1,2– supplies current when VOUT > INTVCC + 0.5V. |
| PLLIN/MODE (Pin 2) | Mode selection & sync input | Pulled low → Burst Mode; tied to INTVCC → forced continuous; external clock → PLL sync + forced continuous. |
| PGOOD1 (Pin 33) | Power-good indicator | Open-drain output asserting low when VFB1 deviates >±10% from setpoint - enables system power sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output buck/buck/boost topology | Single IC replaces three discrete controllers - reduces BOM count, layout area, and cross-regulation issues in multi-rail systems. |
| OPTI-LOOP™ compensation | Allows optimization of transient response across wide range of output capacitor types (ceramic, polymer, electrolytic) and ESR values without loop redesign. |
| 100% duty cycle support in Boost channel | Enables seamless transition to dropout mode during input brownout - maintains regulated output even as VIN approaches VOUT. |
| Adjustable soft-start & tracking (TRACK/SS1/2/SS3) | Prevents inrush current and ensures ordered power-up of downstream ICs via capacitor ramp or external voltage follower. |
| Low IQ sleep mode with channel independence | 55μA operation with one buck channel active - ideal for always-on telematics modules needing ultra-low standby consumption. |
Applications
| Automotive Start-Stop Systems | Battery-Powered Telematics |
|---|---|
Use Scenario: Power management in vehicles with engine auto-stop/start, where battery voltage dips to 2.5V during cranking. IC Role / Device Role / Timing Role: Triple-output controller maintaining 5V infotainment, 8.5V ADAS sensor, and 10V boost rail during cold-crank events. Use Value: 99% buck duty cycle and 2.5V startup capability ensure uninterrupted operation through deep voltage sags. |
Use Scenario: Portable fleet-tracking device powered by Li-ion battery with strict 24-hour standby requirement. IC Role / Device Role / Timing Role: Primary power controller delivering regulated rails while minimizing sleep current across all three outputs. Use Value: 55μA no-load IQ extends battery life; independent RUN pins allow selective channel disable during idle periods. |
| Distributed DC Power Architecture | Industrial Multi-Output Power Supply |
Use Scenario: Central 24V bus powering multiple isolated subsystems (camera, MCU, RF) requiring different voltages. IC Role / Device Role / Timing Role: Local point-of-load controller generating 3.3V, 5V, and 12V from shared 24V rail with minimal inter-rail interference. Use Value: Independent current-mode control per channel prevents load transients on one rail from affecting others. |
Use Scenario: Programmable logic controller (PLC) backplane supplying 5V logic, 24V I/O, and 48V fieldbus rails. IC Role / Device Role / Timing Role: High-reliability triple controller with –55°C to +150°C rating for harsh factory-floor environments. Use Value: Extended temperature qualification and robust gate drivers ensure stable operation at elevated ambient temperatures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3859AEFE#TRPBF | Same architecture and pinout; rated for –40°C to +125°C (vs. –55°C to +150°C). | Not qualified for extended cold environments or under-hood automotive use. | Select when full military-grade temp range is unnecessary and cost sensitivity is higher. |
| LTC3859AIUHF#TRPBF | QFN package (5mm × 7mm), same –40°C to +125°C rating; identical electrical specs but different thermal resistance (θJA = 34.7°C/W vs. 25°C/W). | Lower profile and better thermal performance on dense boards; requires re-layout due to different footprint. | Choose for space-constrained designs where PCB real estate is limited and thermal dissipation via exposed pad is prioritized. |
Compared with LTC3859AEFE#TRPBF, the LTC3859AMPFE#TRPBF adds guaranteed operation at –55°C and +150°C - critical for automotive under-hood deployment - while LTC3859AIUHF#TRPBF trades TSSOP's lower θJA for QFN's smaller footprint and superior thermal conduction through the exposed pad.
Availability
LTC3859AMPFE#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered telematics, and industrial multi-output power supplies requiring stable component supply with extended temperature qualification and long-term lifecycle support.
Supply support for LTC3859AMPFE#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, Inc. is a global semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, industrial automation, and automotive systems.
The LTC3859A product line delivers high-efficiency, multi-output synchronous DC/DC controllers targeting demanding automotive, industrial, and battery-operated applications where reliability, low IQ, and wide input voltage range are essential.
FAQ
What is the minimum input voltage required for startup of the LTC3859AMPFE#TRPBF?
The LTC3859AMPFE#TRPBF requires a minimum 5V on VBIAS to initiate startup. Once running, it can sustain operation with input as low as 2.5V when biased from the boost output or an auxiliary supply - a key feature for automotive cold-crank resilience. This behavior is confirmed in the Absolute Maximum Ratings and Typical Application sections of the datasheet.
Does the LTC3859AMPFE#TRPBF support phase synchronization with an external clock?
Yes, the LTC3859AMPFE#TRPBF supports full phase synchronization via its PLLIN/MODE pin. When an external clock is applied, the internal phase-locked loop aligns the rising edge of TG1 with the external clock's rising edge, enabling EMI reduction and deterministic timing in multi-converter systems. This function is active across the full 75kHz–850kHz frequency range.
How does the LTC3859AMPFE#TRPBF differ from the standard LTC3859 in Burst Mode operation?
The LTC3859AMPFE#TRPBF implements an enhanced Burst Mode algorithm specifically for the boost channel, delivering improved light-load efficiency when input voltage exceeds the regulated output voltage - a common condition in automotive battery-supplied boost converters. This improvement is documented in the device description and comparative performance curves (Figures G11–G16).
Can the LTC3859AMPFE#TRPBF drive high-side N-channel MOSFETs in the boost stage without external charge pump circuitry?
Yes, the LTC3859AMPFE#TRPBF integrates a dedicated BOOST3 charge pump capable of delivering 65μA output current, sufficient to drive typical high-side N-MOSFET gates in boost configurations. The BOOST3 pin connects directly to the gate driver's floating supply, eliminating need for external charge pump components in most designs.
What is the purpose of the TRACK/SS1, TRACK/SS2, and SS3 pins on the LTC3859AMPFE#TRPBF?
The TRACK/SS1 and TRACK/SS2 pins enable output voltage tracking during startup - allowing buck outputs to follow an external reference or another supply rail. SS3 provides independent soft-start for the boost output. Each pin has an internal 1μA current source; connecting a capacitor to ground sets the ramp time, preventing inrush current and ensuring controlled power sequencing across multiple rails.
LTC3859AMPFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck, Buck-Boost, SEPIC
- Number of Outputs:
- 3
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 38V
- Frequency - Switching:
- 115kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99%, 100%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP-EP
LTC3859AMPFE#TRPBF FAQ
1.How can I place an order for LTC3859AMPFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AMPFE#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 LTC3859AMPFE#TRPBF reliable?
The price and inventory of LTC3859AMPFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AMPFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859AMPFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AMPFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AMPFE#TRPBF?
LTC3859AMPFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AMPFE#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 LTC3859AMPFE#TRPBF?
For technical support, including LTC3859AMPFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AMPFE#TRPBF requirements.
6.How does Aetrix verify that LTC3859AMPFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AMPFE#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 LTC3859AMPFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859AMPFE#TRPBF?
All LTC3859AMPFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AMPFE#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 LTC3859AMPFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859AMPFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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