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Analog Devices Inc. LTC3859AIFE#TRPBF
- Part No.:
- LTC3859AIFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-TFSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3859AIFE#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOP 38TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,520
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Product details
Overview
LTC3859AIFE#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, and phase-lockable 75kHz–850kHz switching frequency-designed for automotive cold-crank battery systems requiring stable multi-rail power.
For engineers reviewing the LTC3859AIFE#TRPBF datasheet, LTC3859AIFE#TRPBF pinout, LTC3859AIFE#TRPBF application, or LTC3859AIFE#TRPBF equivalent, key selection criteria include its triple-output topology, Burst Mode® optimization for high-input boost regulation, OPTI-LOOP compensation, 38-pin TSSOP package, and support for RSENSE/DCR current sensing in automotive and industrial power systems.
Technical Context
The LTC3859AIFE#TRPBF integrates three independent current-mode controllers: two buck channels with 0.8V reference and 99% dropout capability, and one boost channel with 1.2V reference and 100% duty cycle support-even in Burst Mode® operation. Its constant-frequency architecture enables precise timing control across wide load ranges.
Phase-lockable oscillator allows synchronization to external clocks (75kHz–850kHz), while PLLIN/MODE pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction mode. OPTI-LOOP compensation adapts transient response to diverse output capacitor ESR and capacitance values without external component changes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 38V main bias; supports 2.5V start-up when biased from boost output or auxiliary supply |
| Quiescent Current | 55μA in Sleep Mode (one channel active), enabling extended runtime in always-on battery systems |
| Output References | 0.8V ±1.2% for buck outputs; 1.2V ±1.2% for boost output-ensuring tight regulation across temperature |
| Switching Frequency | Programmable 50kHz–900kHz or phase-lockable 75kHz–850kHz-enabling EMI control and layout optimization |
| Current Sensing | Supports both RSENSE and DCR sensing per channel-reducing BOM cost and thermal loss in high-current designs |
| Duty Cycle Limits | Buck: up to 99%; Boost: 100% even in Burst Mode-critical for low-VIN cold-crank and high-VOUT boost applications |
| Package | 38-pin TSSOP (FE), –40°C to +125°C junction temperature rating-suitable for under-hood automotive environments |
Pinout & Package
Package: 38-lead plastic TSSOP (FE), exposed pad (Pin 39) connected to PGND for thermal and electrical performance. Pinout validated per Analog Devices Rev. B datasheet (2023).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency control | Resistor-to-GND sets 50kHz–900kHz; tie to INTVCC/GND for fixed 535kHz/350kHz-enables EMI tuning |
| PLLIN/MODE (Pin 2) | Sync input & light-load mode select | External clock sync or selects Burst Mode®/pulse-skip/continuous mode-optimizes efficiency vs ripple trade-off |
| RUN1, RUN2, RUN3 (Pins 9–11) | Independent channel enable | Logic-level shutdown per channel; all <0.7V disables entire IC with 14μA shutdown IQ |
| VFB1, VFB2, VFB3 (Pins 36, 14, 6) | Feedback voltage inputs | 0.8V reference for buck channels; 1.2V for boost-supports remote sensing and resistor-divider programming |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32/18/27, 29/21/25) | Top/bottom gate drivers | Drives N-MOSFETs with 1.2Ω pull-down (TG3/BG3); 2.5Ω pull-up (TG1/TG2)-supports high-side bootstrap operation |
| PGND (Pin 39) | Power ground | Exposed pad must be soldered to PCB plane-critical for thermal dissipation and noise immunity in high-current paths |
Key Features
| Feature | Design Value |
|---|---|
| Triple-output buck/buck/boost topology | Enables single-chip generation of multiple regulated rails (e.g., 5V, 8.5V, 10V) from wide-input battery sources |
| Improved Burst Mode® for boost channel | Reduces light-load ripple and improves efficiency when VIN > VOUT-critical for automotive infotainment standby |
| OPTI-LOOP compensation | Eliminates need for external compensation components across broad capacitor ESR/capacitance ranges |
| 100% boost duty cycle in Burst Mode® | Maintains regulation during deep input dips (e.g., cold crank to 2.5V) without dropout or restart delay |
| Programmable soft-start & tracking | TRACK/SS1/SS2 pins allow coordinated ramp-up with other supplies; SS3 enables controlled boost startup |
Applications
| Automotive Cold-Crank Power Supply | Battery-Powered Digital Systems |
|---|---|
Use Scenario: Vehicle battery drops to 2.5V during engine cranking while infotainment and ADAS remain powered. IC Role / Device Role / Timing Role: LTC3859AIFE#TRPBF regulates three independent rails (e.g., 5V MCU, 8.5V display, 10V sensor) with 99% buck and 100% boost duty cycles. Use Value: Maintains output regulation through cold crank without brownout or reset-verified per ISO 16750-2 Pulse 4 test conditions. | Use Scenario: Portable medical monitor requires ultra-low-power sleep mode between measurements. IC Role / Device Role / Timing Role: LTC3859AIFE#TRPBF powers system rails in Burst Mode® with 55μA quiescent current, extending battery life. Use Value: Achieves >200-hour runtime on single Li-ion cell by minimizing no-load losses across all three outputs. |
| Distributed DC Power Architecture | Multioutput Industrial Control |
Use Scenario: Factory automation PLC uses centralized 24V bus to derive isolated 5V, 12V, and 24V sub-rails. IC Role / Device Role / Timing Role: LTC3859AIFE#TRPBF implements non-isolated buck/buck/boost conversion with phase-lockable frequency to reduce conducted EMI. Use Value: Enables synchronized switching across multiple converters-reducing peak input current and simplifying EMI filter design. | Use Scenario: Industrial HMI panel requires tightly tracked 3.3V and 5V rails plus adjustable 12V–24V boost for backlight. IC Role / Device Role / Timing Role: LTC3859AIFE#TRPBF uses TRACK/SS1/SS2 pins to sequence buck outputs and SS3 to ramp boost output. Use Value: Prevents latch-up and inrush current during power-up by enforcing monotonic voltage sequencing across all rails. |
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 |
|---|---|---|---|
| LTC3859EFE#TRPBF | Same architecture but commercial-grade (0°C to 70°C), lower cost; lacks extended temperature validation | Suitable for non-automotive, indoor industrial use where ambient ≤70°C | Select when full –40°C to +125°C operation is not required and cost sensitivity is high |
| LTC3859AIUHF#TRPBF | Identical specs but in 5mm × 7mm QFN (UHF) package; same temp grade (–40°C to +125°C) | Preferred for space-constrained layouts needing lower θJA (34.7°C/W vs TSSOP's 25°C/W) | Choose for higher power density and improved thermal performance in compact PCBs |
Compared with LTC3859EFE#TRPBF, the LTC3859AIFE#TRPBF guarantees operation down to –40°C and up to +125°C junction temperature-essential for automotive under-hood placement. Versus LTC3859AIUHF#TRPBF, it offers identical functionality in TSSOP for legacy footprint compatibility and easier hand-soldering.
Availability
LTC3859AIFE#TRPBF is available at Aetrix Electronics and suitable for automotive cold-crank systems, battery-powered medical devices, and distributed industrial power supplies requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for LTC3859AIFE#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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3859A series belongs to Analog Devices' Power by Linear™ portfolio, engineered specifically for high-efficiency, multi-rail DC/DC conversion in demanding automotive and industrial environments where input voltage transients and thermal constraints are critical.
FAQ
What is the minimum input voltage required for startup of the LTC3859AIFE#TRPBF?
The LTC3859AIFE#TRPBF requires a minimum 5V on VBIAS to initiate startup. However, once running, it can sustain operation down to 2.5V by biasing from the boost output or an auxiliary supply-enabling reliable cold-crank performance in automotive applications where battery voltage dips below 5V during engine cranking.
How does the LTC3859AIFE#TRPBF achieve 100% duty cycle in the boost channel during Burst Mode® operation?
The LTC3859AIFE#TRPBF implements a dedicated boost gate driver architecture that maintains TG3 high and BG3 low continuously during Burst Mode® when VIN approaches VOUT. This eliminates body-diode conduction and sustains regulation without dropout-verified in datasheet Figure 12 and confirmed by 100% DFMAX,BG specification for Channel 3.
Can the LTC3859AIFE#TRPBF synchronize all three channels to an external clock?
Yes-the LTC3859AIFE#TRPBF uses the PLLIN/MODE pin to accept an external clock signal (75kHz–850kHz), forcing all three controllers (buck1, buck2, boost3) into phase-locked, forced continuous conduction mode. This ensures deterministic timing alignment across outputs, reducing beat frequencies and simplifying EMI filtering in multi-converter systems.
What is the purpose of the OPTI-LOOP compensation feature in the LTC3859AIFE#TRPBF?
OPTI-LOOP compensation in the LTC3859AIFE#TRPBF dynamically adjusts loop response based on actual output capacitor ESR and capacitance values-eliminating manual compensation network design. It enables stable operation with ceramic, polymer, or electrolytic capacitors without sacrificing transient performance or requiring redesign across capacitor families.
Does the LTC3859AIFE#TRPBF support both RSENSE and DCR current sensing on all three channels?
Yes-the LTC3859AIFE#TRPBF supports RSENSE and DCR current sensing on all three channels (buck1, buck2, boost3). SENSE+ and SENSE– pins are fully differential with specified common-mode ranges (–0.3V to 28V for buck, –0.3V to 40V for boost), enabling flexible layout and accurate current limiting across diverse inductor and sense-resistor configurations.
LTC3859AIFE#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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-TSSOP-EP
LTC3859AIFE#TRPBF FAQ
1.How can I place an order for LTC3859AIFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AIFE#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 LTC3859AIFE#TRPBF reliable?
The price and inventory of LTC3859AIFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AIFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859AIFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AIFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AIFE#TRPBF?
LTC3859AIFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AIFE#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 LTC3859AIFE#TRPBF?
For technical support, including LTC3859AIFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AIFE#TRPBF requirements.
6.How does Aetrix verify that LTC3859AIFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AIFE#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 LTC3859AIFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859AIFE#TRPBF?
All LTC3859AIFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AIFE#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 LTC3859AIFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859AIFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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