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Analog Devices Inc. LTC3859AHUHF#TRPBF
- Part No.:
- LTC3859AHUHF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859AHUHF#TRPBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,204
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Product details
Overview
LTC3859AHUHF#TRPBF from Analog Devices is a high-performance triple-output synchronous DC/DC controller (buck/buck/boost) driving all-N-channel MOSFET stages, featuring 55μA no-load quiescent current, 0.8V/1.2V precision references for buck and boost outputs respectively, and phase-lockable switching frequency up to 850kHz - enabling efficient multi-rail power in automotive start-stop and battery-powered digital systems.
For engineers reviewing the LTC3859AHUHF#TRPBF datasheet, LTC3859AHUHF#TRPBF pinout, LTC3859AHUHF#TRPBF application, or LTC3859AHUHF#TRPBF equivalent, this page delivers verified technical context, package-specific pin functions, real-world application cards, and two validated alternative parts with documented functional and application-level differences.
Technical Context
The LTC3859AHUHF#TRPBF implements three independent current-mode control loops - two buck channels with 0.8V reference and one boost channel with 1.2V reference - each with dedicated ITH error amplifier outputs, SENSE± differential current sensing, and RUN enable inputs. Its OPTI-LOOP compensation supports wide output capacitance/ESR ranges, while the PLLIN/MODE pin selects Burst Mode®, pulse-skipping, or forced continuous conduction across all channels.
It integrates gate drivers with <1.2Ω pull-down resistance for TG3/BG3, supports RSENSE or DCR sensing, enables 100% duty cycle in boost synchronous operation even during Burst Mode®, and features dual soft-start/tracking inputs (TRACK/SS1,2) plus independent SS3 for the boost channel - all operating from a 4.5V–38V VBIAS supply or down to 2.5V post-startup via auxiliary bias.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Triple-output synchronous controller: two buck + one boost, all-N-channel MOSFET drive |
| Input Voltage Range | 4.5V–38V VBIAS; operates down to 2.5V after startup when biased from boost output or auxiliary rail |
| Quiescent Current | 55μA in Sleep Mode (one channel active), enabling extended battery runtime in always-on systems |
| Reference Voltages | 0.8V ±12mV (buck channels), 1.2V ±18mV (boost channel) - tight tolerance ensures accurate output regulation |
| Switching Frequency | Programmable 50kHz–900kHz or phase-lockable 75kHz–850kHz - supports EMI optimization and inductor size reduction |
| Max Output Voltage | Buck: ≤24V; Boost: up to 60V - suitable for high-side LED strings, industrial sensors, and isolated bias rails |
| Operating Temperature | –40°C to +150°C junction (H-grade) - qualified for under-hood automotive and harsh industrial environments |
Pinout & Package
Package: 38-lead (5mm × 7mm) plastic QFN (UHF); exposed thermal pad (Pin 39) must be soldered to PGND for thermal and electrical performance. θJA = 34.7°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming input | Resistor-to-GND sets 50kHz–900kHz; tied to GND/INTVCC for fixed 350kHz/535kHz - enables EMI spread-spectrum tuning |
| PLLIN/MODE (Pin 2) | Sync input / light-load mode selector | Accepts external clock for synchronization; configures Burst Mode® (GND), pulse-skipping (1.2V–INTVCC–1.3V), or forced CCM (INTVCC) |
| TRACK/SS1, TRACK/SS2 (Pins 34, 16) | Buck soft-start and tracking input | Regulates VFB1/VFB2 to min(0.8V, applied voltage); supports power sequencing and voltage ramp control |
| SS3 (Pin 3) | Boost soft-start input | Regulates VFB3 to min(1.2V, applied voltage); enables controlled ramp-up of high-voltage boost output |
| VFB1, VFB2, VFB3 (Pins 36, 14, 6) | Feedback voltage inputs | Monitor output via resistive divider; trip PGOOD1 (Pin 33) if VFB1 deviates >±10% from 0.8V setpoint |
| TG1/TG2/TG3, BG1/BG2/BG3 (Pins 32/18/27, 29/21/25) | Top/bottom gate drivers | Drive N-MOSFET gates with fast transition times (13–28ns); TG3/BG3 optimized for 100% duty-cycle boost operation |
| PGND (Pin 39) | Power ground reference | Exposed pad - must be solidly connected to PCB ground plane to ensure thermal dissipation and low-noise gate drive return path |
Key Features
| Feature | Design Value |
|---|---|
| Low IQ Sleep Mode | 55μA (one channel active) extends battery life in always-on telematics and ADAS modules |
| OPTI-LOOP Compensation | Allows stable loop response across wide range of ceramic/low-ESR output capacitors without external compensation redesign |
| 100% Duty Cycle Boost | Enables seamless regulation even when VIN ≥ VOUT - critical for cold-crank scenarios where input dips to 2.5V |
| Independent RUN Controls | RUN1/RUN2/RUN3 pins allow per-channel enable/disable for dynamic power rail management in multi-core SoCs |
| Boost Overvoltage Protection | OV3 open-drain output asserts when VFB3 exceeds 110% setpoint - provides fail-safe shutdown for sensitive loads |
| EXTVCC Switchover | Automatically switches INTVCC supply from VBIAS to EXTVCC when >4.7V - improves efficiency in systems with auxiliary 5V/12V rails |
Applications
| Automotive Start-Stop Systems | Battery-Powered Digital Devices |
|---|---|
Use Scenario: Power management during engine cranking where battery voltage drops to 2.5V for 100ms–1s. IC Role / Device Role / Timing Role: Triple-output controller maintains 5V/8.5V/10V rails for infotainment, ADAS camera, and CAN transceivers despite input collapse. Use Value: 99% buck dropout duty cycle and 2.5V minimum operating voltage ensure uninterrupted operation through cold crank. |
Use Scenario: Portable medical monitor requiring long runtime on single Li-ion cell with multiple regulated rails. IC Role / Device Role / Timing Role: Generates 3.3V (buck1), 5V (buck2), and 12V (boost) from 3.0–4.2V battery input using ultra-low IQ sleep mode. Use Value: 55μA quiescent current extends standby time beyond 30 days without compromising fast wake-up response. |
| Distributed DC Power Systems | Multioutput Buck-Boost Applications |
Use Scenario: Industrial IoT gateway with isolated sensor interfaces, wireless modem, and microcontroller - each requiring different voltages. IC Role / Device Role / Timing Role: Provides tightly regulated 3.3V (MCU), 5V (USB interface), and 15V (RS-485 transceiver) from 12V or 24V backplane. Use Value: Independent TRACK/SS inputs enable synchronized soft-start across all rails, preventing inrush current conflicts. |
Use Scenario: Test equipment needing both step-down (for logic) and step-up (for analog front-end bias) from shared 5V input. IC Role / Device Role / Timing Role: Simultaneously regulates 3.3V buck output and 24V boost output with shared current sensing and thermal monitoring. Use Value: Single-chip integration eliminates discrete boost controller, reducing BOM count and PCB area by >40% vs dual-controller solution. |
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 |
|---|---|---|---|
| LTC3859AEUHF#TRPBF | Same architecture and pinout; rated for –40°C to +125°C junction (E-grade), not 150°C | Suitable for commercial/industrial ambient environments but not under-hood automotive | Select when full H-grade temperature range is unnecessary and cost optimization is prioritized |
| LTC3859AIUHF#TRPBF | Identical electrical specs and package; guaranteed over –40°C to +125°C (I-grade) with production test coverage | Validated for extended temperature industrial use (e.g., factory automation controllers) with tighter test correlation | Choose for applications requiring production-tested 125°C operation without H-grade premium |
Compared with LTC3859AHUHF#TRPBF, the E- and I-grade variants offer identical functionality and layout compatibility but differ in temperature qualification scope and test assurance - making them drop-in alternatives only where 150°C junction operation is not required.
Availability
LTC3859AHUHF#TRPBF is available at Aetrix Electronics and suitable for automotive start-stop systems, battery-powered portable electronics, and distributed industrial power supplies requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.
Supply support for LTC3859AHUHF#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 product line delivers high-efficiency, low-quiescent-current multi-output controllers designed specifically for demanding automotive and battery-critical applications where input voltage collapse and thermal robustness are primary constraints.
FAQ
What is the minimum input voltage for LTC3859AHUHF#TRPBF after startup?
The LTC3859AHUHF#TRPBF can operate from as low as 2.5V after startup when biased from the boost converter output or an auxiliary supply - a key feature for automotive cold-crank resilience. This is distinct from its 4.5V–38V main VBIAS operating range and requires proper external bias routing per the datasheet's EXTVCC section.
Does LTC3859AHUHF#TRPBF support phase synchronization with external clocks?
Yes, the LTC3859AHUHF#TRPBF supports external synchronization via the PLLIN/MODE pin (Pin 2). When an external clock is applied, the phase-locked loop aligns the rising edge of TG1 with the external clock's rising edge, enabling noise-sensitive systems to avoid beat frequencies and meet strict EMI requirements.
How does the OPTI-LOOP compensation in LTC3859AHUHF#TRPBF simplify design?
The OPTI-LOOP compensation in LTC3859AHUHF#TRPBF allows designers to optimize transient response across a wide range of output capacitor types and ESR values without changing external compensation components. It uses internal scaling to maintain stability whether using ceramic, polymer, or electrolytic capacitors - reducing prototype iterations.
Can LTC3859AHUHF#TRPBF drive both buck and boost channels simultaneously?
Yes, the LTC3859AHUHF#TRPBF is designed for concurrent operation of all three channels - two buck and one boost - with independent RUN pins (RUN1, RUN2, RUN3) allowing individual enable/disable. Its integrated gate drivers and shared INTVCC regulator support full simultaneous regulation without performance degradation.
What is the purpose of the OV3 pin on LTC3859AHUHF#TRPBF?
The OV3 pin on LTC3859AHUHF#TRPBF is an open-drain overvoltage indicator for the boost channel. It pulls low when VFB3 is within ±10% of its 1.2V setpoint and goes high-impedance when VFB3 exceeds 110% - providing a hardware fault signal to trigger system-level shutdown or alert before damage occurs to downstream 60V-tolerant loads.
LTC3859AHUHF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN 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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 38-QFN (5x7)
LTC3859AHUHF#TRPBF FAQ
1.How can I place an order for LTC3859AHUHF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AHUHF#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 LTC3859AHUHF#TRPBF reliable?
The price and inventory of LTC3859AHUHF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AHUHF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3859AHUHF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AHUHF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AHUHF#TRPBF?
LTC3859AHUHF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AHUHF#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 LTC3859AHUHF#TRPBF?
For technical support, including LTC3859AHUHF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AHUHF#TRPBF requirements.
6.How does Aetrix verify that LTC3859AHUHF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AHUHF#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 LTC3859AHUHF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3859AHUHF#TRPBF?
All LTC3859AHUHF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AHUHF#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 LTC3859AHUHF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3859AHUHF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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