My Inquiry
My Account
Analog Devices Inc. LTC3859AIUHF#PBF
- Part No.:
- LTC3859AIUHF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 38-WFQFN Exposed Pad
- Datasheet:
-
LTC3859AIUHF#PBF.pdf
- Description:
- IC REG CTRLR MULT TOPOLOGY 38QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,519
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LTC3859AIUHF#PBF from Analog Devices is a 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/boost outputs, and phase-lockable switching frequency up to 850kHz - enabling high-efficiency multi-rail power in automotive cold-crank and battery-powered systems.
For engineers reviewing the LTC3859AIUHF#PBF datasheet, LTC3859AIUHF#PBF pinout, LTC3859AIUHF#PBF application, or LTC3859AIUHF#PBF equivalent, key selection considerations include its triple-output topology with independent RUN control, Burst Mode® optimization for boost stage at high VIN, OPTI-LOOP compensation, and QFN-38 (5mm × 7mm) thermal performance (θJA = 34.7°C/W).
Technical Context
The LTC3859AIUHF#PBF implements 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 MOSFET duty cycle in Burst Mode®, and up to 60V output capability. Its PLLIN/MODE pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction across all channels.
It supports RSENSE or DCR current sensing per channel, features separate ITH pins for loop compensation, and integrates gate drivers with matched rise/fall times (TG: 25ns/16ns; BG: 28ns/13ns) and low on-resistance (TG3/BG3: 1.2Ω/1.0Ω). The device operates from 4.5V–38V VBIAS or down to 2.5V post-startup when biased from boost output or auxiliary supply.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Buck/Buck/Boost triple-output synchronous controller - enables compact multi-rail generation without external driver ICs. |
| Input Voltage Range | 4.5V to 38V VBIAS; supports cold-crank operation down to 2.5V when biased from boost output or auxiliary rail. |
| Quiescent Current | 55μA (one channel active in Sleep Mode) - extends runtime in always-on battery systems like automotive telematics. |
| Switching Frequency | 75kHz–850kHz phase-lockable; programmable 50kHz–900kHz via FREQ pin resistor - allows EMI tuning and inductor size optimization. |
| Feedback References | 0.8V ±1.2% (buck), 1.2V ±1.2% (boost) - ensures tight output regulation across temperature and load. |
| Gate Driver Strength | TG3/BG3: 1.2Ω pull-up / 1.0Ω pull-down - drives high-side/lower-side N-MOSFETs with fast transitions (≤28ns) and minimal shoot-through risk. |
| Package & Thermal | 38-pin 5mm × 7mm QFN with exposed PGND pad; θJA = 34.7°C/W - delivers robust thermal performance in space-constrained industrial PCBs. |
Pinout & Package
Package: 38-lead plastic QFN (5mm × 7mm), exposed PGND pad (Pin 39) requiring solder connection to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FREQ (Pin 1) | Oscillator frequency programming input | Resistor-to-GND sets 50kHz–900kHz; GND = 350kHz, INTVCC = 535kHz - enables precise EMI control and layout-driven frequency selection. |
| PLLIN/MODE (Pin 2) | Sync input / light-load mode selector | Accepts external clock for synchronization; voltage level selects Burst Mode® (GND), pulse-skipping (1.2V–INTVCC−1.3V), or forced CCM (INTVCC). |
| RUN1, RUN2, RUN3 (Pins 9,10,11) | Independent enable/disable controls | Each pin shuts down its respective channel below 1.17V (buck) or 1.20V (boost); all <0.7V enters full shutdown (14μA IQ). |
| VFB1, VFB2, VFB3 (Pins 36,14,6) | Feedback inputs | Monitor output voltage via resistive divider; regulate to 0.8V (buck) or 1.2V (boost) - supports remote sensing and accurate multi-output tracking. |
| TG1/TG2/TG3 & BG1/BG2/BG3 (Pins 32/18/27, 29/21/25) | Top/bottom gate drivers | Drive N-MOSFET gates with rail-to-rail swing; TG3/BG3 optimized for boost stage with 1.2Ω/1.0Ω on-resistance and 120ns min on-time. |
| PGOOD1 (Pin 33) | Power-good indicator | Open-drain output asserting when VFB1 deviates >±10% - provides system-level sequencing and fault signaling for primary buck rail. |
| OV3 (Pin 17) | Boost overvoltage flag | Open-drain output pulled low when VFB3 exceeds +10% of setpoint - enables secondary protection for high-voltage boost outputs. |
| PGND (Pin 39) | Power ground reference | Exposed pad tied to source nodes of bottom MOSFETs and CIN(–); mandatory solder connection for thermal dissipation and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent RUN control | Enables staggered startup, dynamic rail disabling, and partial-system power gating - reduces inrush and improves system-level power management. |
| OPTI-LOOP™ compensation | Allows stable loop response across wide range of output capacitor ESR and capacitance values - eliminates need for custom compensation per design. |
| 100% duty cycle in Boost Burst Mode® | Maintains regulation during ultra-low load even with VIN > VOUT - critical for maintaining backup rail integrity in automotive start-stop systems. |
| Low dropout operation (99% duty cycle) | Supports buck operation with minimal headroom - enables efficient 5V→3.3V or 12V→5V conversion under brownout conditions. |
| Programmable soft-start & tracking | TRACK/SS1/SS2/SS3 pins support coordinated ramp-up and voltage sequencing - prevents back-powering and latch-up in multi-IC systems. |
| Wide bias input range (4.5V–38V) | Eliminates need for pre-regulator in 12V/24V automotive or industrial bus applications - simplifies front-end architecture. |
Applications
| Automotive Start-Stop Systems | Industrial Multi-Rail Power Supplies |
|---|---|
Use Scenario: Powering infotainment, ADAS sensors, and CAN transceivers during engine cranking where battery drops to 2.5V. IC Role / Device Role / Timing Role: Triple-output controller generating 5V (infotainment), 8.5V (camera sensor bias), and regulated 10V (CAN PHY) from 2.5V–16V battery. Use Value: Maintains all rails in regulation during cold crank thanks to 2.5V startup capability and 99% buck dropout - avoids system reset. |
Use Scenario: Providing isolated 3.3V, 5V, and 12V rails for PLC I/O modules, fieldbus interfaces, and microcontrollers in factory automation. IC Role / Device Role / Timing Role: Central synchronous controller managing buck-buck-boost topology with independent RUN sequencing and PGOOD monitoring. Use Value: Reduces BOM count by eliminating discrete drivers and regulators; OPTI-LOOP ensures stability across varying load profiles and temperature. |
| Battery-Powered Test Equipment | Distributed Telecom Power |
Use Scenario: Portable oscilloscopes and signal analyzers requiring low-noise analog rails and efficient digital core supplies from Li-ion battery (3.0V–4.2V). IC Role / Device Role / Timing Role: Generates 1.2V (FPGA core), 3.3V (ADC/DAC interface), and 5V (USB host) using boost-first architecture with EXTVCC bias. Use Value: 55μA Sleep Mode IQ extends battery life; programmable Burst Mode minimizes light-load ripple without sacrificing transient response. |
Use Scenario: Remote radio units (RRUs) needing 5V (baseband), 12V (PA bias), and 28V (antenna tuning) from -48V telecom bus. IC Role / Device Role / Timing Role: High-voltage boost stage (up to 60V) combined with dual bucks to generate intermediate rails with precise tracking. Use Value: 60V boost capability and 38V VBIAS rating allow direct derivation from -48V bus with minimal front-end components - improves efficiency and reliability. |
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#PBF | Same electrical specs and pinout; rated for –40°C to 125°C junction (vs. LTC3859AIUHF#PBF's –40°C to 125°C grade with tighter initial VFB tolerance). | Valid for commercial/industrial ambient environments; not qualified for extended automotive AEC-Q100 stress testing. | Select when full automotive-grade validation is unnecessary and cost sensitivity is higher. |
| LTC3859AHUHF#PBF | Identical functionality; rated for –40°C to 150°C junction temperature - includes enhanced HTOL screening and wider VFB drift spec over temperature. | Suitable for under-hood automotive or high-ambient industrial deployments where sustained 125°C+ case temperatures occur. | Select when operating junction temperature may exceed 125°C and long-term reliability under thermal stress is critical. |
Compared with LTC3859AEUHF#PBF, the LTC3859AIUHF#PBF offers tighter initial feedback voltage accuracy (±0.8% vs. ±1.0%) and guaranteed performance over –40°C to 125°C, while LTC3859AHUHF#PBF adds high-temperature qualification for harsher thermal environments - enabling tiered selection based on reliability requirements and ambient constraints.
Availability
LTC3859AIUHF#PBF is available at Aetrix Electronics and suitable for automotive start-stop systems, industrial multi-rail power supplies, and battery-powered test equipment requiring stable component supply, long lifecycle assurance, and traceable sourcing.
Supply support for LTC3859AIUHF#PBF 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 DC/DC controllers for demanding power architectures - designed specifically for automotive cold-crank resilience, battery longevity, and industrial thermal robustness.
FAQ
What is the minimum input voltage required for startup of the LTC3859AIUHF#PBF?
The LTC3859AIUHF#PBF requires a minimum 5V on VBIAS to initiate startup. Once running, it can sustain operation down to 2.5V if biased from the boost output or an auxiliary supply - enabling uninterrupted regulation during automotive cold-crank events where battery voltage dips below 5V.
How does the LTC3859AIUHF#PBF achieve 100% duty cycle in Boost Burst Mode®?
The LTC3859AIUHF#PBF achieves 100% synchronous MOSFET duty cycle in Boost Burst Mode® by disabling the top-side switch only when necessary for regulation - unlike conventional controllers that force discontinuous operation. This maintains output voltage stability even when input exceeds regulated output, critical for backup rail integrity.
Can the LTC3859AIUHF#PBF drive external MOSFETs with gate charges exceeding 50nC?
Yes - the LTC3859AIUHF#PBF's TG3/BG3 drivers deliver 1.2Ω/1.0Ω on-resistance and support ≤28ns transition times into 3300pF loads. For MOSFETs with >50nC gate charge, ensure gate resistance and layout minimize ringing; the 120ns minimum on-time for boost channel also constrains lowest practical switching frequency.
What is the purpose of the EXTVCC pin on the LTC3859AIUHF#PBF?
The EXTVCC pin on the LTC3859AIUHF#PBF accepts an external 4.7V–14V supply to power the internal INTVCC LDO, bypassing the VBIAS-fed regulator. This reduces power loss and heat generation when a clean, efficient auxiliary rail (e.g., from a pre-regulator) is available - improving overall system efficiency.
Does the LTC3859AIUHF#PBF support output voltage tracking between buck and boost channels?
No - the LTC3859AIUHF#PBF supports tracking only between the two buck channels (via TRACK/SS1 and TRACK/SS2) and independent soft-start for the boost channel (via SS3). The boost output regulates to 1.2V reference or SS3 voltage, but cannot be directly tracked to either buck output due to separate error amplifier structures.
LTC3859AIUHF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 38-WFQFN Exposed Pad
- Packaging:
- Tube
- 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-QFN (5x7)
LTC3859AIUHF#PBF FAQ
1.How can I place an order for LTC3859AIUHF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3859AIUHF#PBF 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 LTC3859AIUHF#PBF reliable?
The price and inventory of LTC3859AIUHF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3859AIUHF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3859AIUHF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3859AIUHF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3859AIUHF#PBF?
LTC3859AIUHF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3859AIUHF#PBF 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 LTC3859AIUHF#PBF?
For technical support, including LTC3859AIUHF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3859AIUHF#PBF requirements.
6.How does Aetrix verify that LTC3859AIUHF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3859AIUHF#PBF 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 LTC3859AIUHF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3859AIUHF#PBF?
All LTC3859AIUHF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3859AIUHF#PBF, 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 LTC3859AIUHF#PBF part is unused and in its original packaging.
Return procedure for LTC3859AIUHF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LTC3859AIUHF#PBF 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…
