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Analog Devices Inc. LTC3858IUFD-1#TRPBF
- Part No.:
- LTC3858IUFD-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3858IUFD-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,121
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Product details
Overview
LTC3858IUFD-1#TRPBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down DC/DC controller IC designed for high-efficiency, low-quiescent-current power conversion in battery- and intermediate-bus-powered systems. It delivers two independent outputs (e.g., 3.3V/5A and 8.5V/3.5A), supports 4V–38V input, features 170μA no-load IQ (one channel active), and operates out-of-phase to reduce input ripple and EMI.
For engineers reviewing the LTC3858IUFD-1#TRPBF datasheet, LTC3858IUFD-1#TRPBF pinout, LTC3858IUFD-1#TRPBF application, or LTC3858IUFD-1#TRPBF equivalent, key selection considerations include its dual-channel current-mode architecture, OPTI-LOOP® compensation, programmable 50kHz–900kHz switching frequency, selectable light-load modes (Burst Mode®, pulse-skipping, forced continuous), and integrated short-circuit latchoff with independent soft-start.
Technical Context
The LTC3858IUFD-1#TRPBF implements a constant-frequency, current-mode control architecture with two independent 180° out-of-phase controllers driving external N-channel MOSFETs. Each channel uses a transconductance error amplifier (gm = 2 mmho), precision 0.800V reference (±12 mV over –40°C to 125°C), and differential current sensing via SENSE+/- pins supporting both RSENSE and DCR methods.
Its internal 5.1V INTVCC LDO can be powered from VIN or an external EXTVCC supply ≥4.7V, enabling efficient self-biasing from output rails. The device integrates phase-lockable synchronization (75kHz–850kHz), adjustable current limit via ITH voltage, and robust protection including output overvoltage detection (±10% VFB trip), PGOOD1 monitoring, and short-circuit latchoff triggered by SS pin discharge.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide-range industrial, automotive, and battery chemistries (e.g., 12V/24V bus, Li-ion, lead-acid). |
| Quiescent Current (One Channel On) | 170μA typical - extends runtime in always-on battery-powered digital devices. |
| Feedback Reference Voltage | 0.800V ±12mV (–40°C to 125°C) - enables precise output regulation down to 0.8V with minimal drift. |
| Switching Frequency Range | 50kHz to 900kHz (programmable) - balances efficiency, size, and EMI; supports synchronization to external clock. |
| Output Phase Relationship | 180° out-of-phase operation - halves required input capacitance and reduces RMS input ripple current. |
| Shutdown Current | 8μA maximum - ensures ultra-low standby power when both RUN pins are pulled low. |
| Package | 28-lead 4mm × 5mm QFN - thermally enhanced surface-mount package with exposed SGND pad (θJA = 43°C/W). |
Pinout & Package
Package: 28-lead plastic QFN (4mm × 5mm), exposed thermal pad (Pin 29) connected to SGND. Requires soldering of exposed pad for rated thermal performance (TJMAX = 125°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1+, SENSE2+ | Differential current sense (+) inputs | Connect to DCR network or RSENSE to set per-channel peak current limit; enable accurate current-mode control. |
| SENSE1–, SENSE2– | Differential current sense (–) inputs | Reference return for current sensing; bias current varies with common-mode voltage (e.g., –550μA at VOUT < INTVCC – 0.5V). |
| TG1, TG2 | Top gate drivers | Drive external high-side N-MOSFET gates with 2.5Ω pull-up / 1.5Ω pull-down; voltage swing = INTVCC – 0.5V superimposed on SW node. |
| BG1, BG2 | Bottom gate drivers | Drive external low-side N-MOSFET gates with 2.4Ω pull-up / 1.1Ω pull-down; rail-to-rail swing (0V to INTVCC). |
| VFB1, VFB2 | Feedback inputs | Monitor regulated output voltage via resistive divider; comparator trips at ±10% deviation for PGOOD1 assertion. |
| SS1, SS2 | Soft-start / latchoff timer inputs | Internal 1μA pull-up charges external capacitor for controlled ramp-up; also discharges at 9μA during short-circuit to trigger latchoff at 1.5V. |
| ITH1, ITH2 | Error amplifier outputs | Set per-channel current limit threshold; voltage range 0V–1.2V directly scales peak inductor current. |
| PLLIN/MODE | Sync input / light-load mode select | Pull to GND → Burst Mode®; to INTVCC → forced continuous; to 1.2V–(INTVCC–1.3V) → pulse-skipping. |
| FREQ | Oscillator frequency control | Resistor-to-GND sets frequency (50kHz–900kHz); internal 20μA current source enables simple programming. |
| RUN1, RUN2 | Channel enable/disable controls | <1.26V disables individual channel; <0.7V shuts down entire IC (IQ = 8μA). |
| PGOOD1 | Power-good indicator | Open-drain output asserting low when VFB1 deviates >±10% from 0.8V; supports system sequencing and fault reporting. |
| VIN, PGND, SGND | Main input, power ground, signal ground | VIN powers internal LDO; PGND connects to MOSFET sources; SGND is isolated analog ground for sensitive feedback paths. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance and enables stable loop response across wide COUT/ESR variations without external compensation redesign. |
| Out-of-Phase Dual Control | Reduces RMS input ripple current by ~30% and cuts peak input capacitor stress, allowing smaller, lower-cost bulk capacitors. |
| Independent Soft-Start & Short-Circuit Latchoff | Each channel ramps output voltage separately; SS pin serves dual role-soft-start timing and autonomous short-circuit timeout (no external logic needed). |
| Low-Dropout Operation (99% Duty Cycle) | Enables regulation with VIN as low as VOUT + 0.2V (e.g., 3.5V IN → 3.3V OUT), critical for battery end-of-life operation. |
| EXTVCC Bias Option | Accepts external 4.7V–14V supply to power INTVCC, eliminating LDO losses and enabling high-efficiency self-bias from converter outputs. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Dual-rail power for SoC (core 1.1V, I/O 3.3V) and display backlight (8.5V) in head-unit under varying 9V–16V battery input. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent 3.3V/5A and 8.5V/3.5A outputs with out-of-phase switching to suppress conducted EMI. Use Value: 170μA quiescent current preserves battery during sleep mode; 4V–38V input range accommodates cold-crank and load-dump transients. |
Use Scenario: Distributed 5V and 24V rails powering analog sensor front-ends and digital logic in modular automation hardware. IC Role / Device Role / Timing Role: Dual-output controller generating isolated 5V (for microcontroller) and 24V (for solenoid drivers) from 24V intermediate bus. Use Value: Independent RUN pins allow dynamic rail shutdown; short-circuit latchoff protects against field-wiring faults without system-level intervention. |
| Portable Medical Diagnostic Device | Telecom Remote Radio Unit (RRU) |
|
Use Scenario: Battery-powered ultrasound imager requiring quiet, long-life 3.3V digital and 5V analog supplies from single-cell Li-ion (3.0V–4.2V). IC Role / Device Role / Timing Role: High-efficiency dual buck controller operating in Burst Mode® below 100mA to maintain >85% efficiency at microamp loads. Use Value: Ultra-low 170μA IQ extends battery life; OPTI-LOOP® ensures stability with ceramic output caps; 0.8V reference enables precise low-voltage regulation. |
Use Scenario: Outdoor base station RRU converting 48V backplane to 12V FPGA core and 5V auxiliary rails in thermally constrained enclosure. IC Role / Device Role / Timing Role: Dual-phase controller synchronized to system clock (via PLLIN/MODE) to avoid beat frequencies with RF subsystems. Use Value: Phase-lockable 75kHz–850kHz frequency avoids interference bands; EXTVCC option allows biasing from 12V rail to improve overall system efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3858EUFD-1#TRPBF | Same silicon, –40°C to 85°C temperature grade (vs. –40°C to 125°C for LTC3858IUFD-1#TRPBF); identical electrical specs and pinout. | Suitable for commercial/industrial ambient environments only; not qualified for extended junction temperature operation. | Select when full automotive or extended industrial temperature range is not required; lower cost alternative with identical functionality. |
| MP2918GL-Z | Monolithic dual buck (integrated MOSFETs); 4.5V–18V input; fixed 500kHz frequency; no EXTVCC or OPTI-LOOP®; 1.2V reference. | Targets space-constrained, lower-power (<10A total) applications where integration outweighs flexibility; lacks out-of-phase noise reduction. | Choose for simplified BOM and layout in <15W applications; avoid when input >18V, need >125°C operation, or require adaptive compensation. |
Compared with LTC3858EUFD-1#TRPBF, the LTC3858IUFD-1#TRPBF offers guaranteed operation up to 125°C junction temperature-critical for under-hood or sealed industrial enclosures-while MP2918GL-Z trades configurability and voltage range for monolithic simplicity and reduced external component count.
Availability
LTC3858IUFD-1#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC I/O modules, and portable medical diagnostic devices requiring stable component supply, long-term lifecycle support, and guaranteed extended-temperature performance.
Supply support for LTC3858IUFD-1#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3858-1 belongs to Linear's high-efficiency power controller product line, engineered specifically for demanding dual-output DC/DC conversion in battery-backed, distributed, and thermally constrained systems where low IQ, precise regulation, and robust fault protection are essential.
FAQ
What is the maximum input voltage rating for the LTC3858IUFD-1#TRPBF?
The LTC3858IUFD-1#TRPBF has an absolute maximum input supply voltage (VIN) rating of 40V, with a recommended operating range of 4V to 38V. Exceeding 40V may cause permanent damage. This wide input range allows the LTC3858IUFD-1#TRPBF to accommodate 24V industrial buses, 12V automotive systems with load dump, and multi-cell battery packs.
How does the LTC3858IUFD-1#TRPBF achieve ultra-low quiescent current in battery-powered applications?
The LTC3858IUFD-1#TRPBF achieves 170μA typical quiescent current (one channel active) through optimized bias circuitry, sleep-mode gating of non-essential blocks, and a dedicated low-IQ architecture. In shutdown (both RUN pins <0.7V), it draws only 8μA. This enables multi-week operation in always-on portable medical or IoT devices using the LTC3858IUFD-1#TRPBF as primary power controller.
Can the LTC3858IUFD-1#TRPBF drive MOSFETs directly, and what are the gate driver specifications?
Yes, the LTC3858IUFD-1#TRPBF integrates high-current gate drivers: TG1/TG2 (top-side, 2.5Ω pull-up/1.5Ω pull-down) and BG1/BG2 (bottom-side, 2.4Ω pull-up/1.1Ω pull-down). Each driver supports 3300pF load with 13–28ns transition times. These drivers directly interface with standard N-channel MOSFETs, eliminating need for external drivers in most designs using the LTC3858IUFD-1#TRPBF.
What protection features are built into the LTC3858IUFD-1#TRPBF?
The LTC3858IUFD-1#TRPBF includes output overvoltage protection (±10% VFB trip), short-circuit latchoff (SS-pin-based autonomous shutdown), undervoltage lockout (3.6V–4.2V), and foldback current limiting. It also provides PGOOD1 monitoring and 99% duty-cycle dropout operation. These protections ensure robust operation in unattended systems using the LTC3858IUFD-1#TRPBF without external supervision circuits.
Is the LTC3858IUFD-1#TRPBF pin-compatible with other members of the LTC3858 family?
Yes, the LTC3858IUFD-1#TRPBF shares identical pinout and footprint with all 28-lead QFN variants of the LTC3858-1 family, including LTC3858EUFD-1#TRPBF and LTC3858HUFD-1#TRPBF. Differences are limited to temperature grade and ordering options-no PCB redesign is needed when upgrading from E-grade to I-grade, confirming direct replacement capability for the LTC3858IUFD-1#TRPBF.
LTC3858IUFD-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 38V
- Frequency - Switching:
- 105kHz ~ 835kHz, 350kHz ~ 535kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3858IUFD-1#TRPBF FAQ
1.How can I place an order for LTC3858IUFD-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3858IUFD-1#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 LTC3858IUFD-1#TRPBF reliable?
The price and inventory of LTC3858IUFD-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3858IUFD-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3858IUFD-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3858IUFD-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3858IUFD-1#TRPBF?
LTC3858IUFD-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3858IUFD-1#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 LTC3858IUFD-1#TRPBF?
For technical support, including LTC3858IUFD-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3858IUFD-1#TRPBF requirements.
6.How does Aetrix verify that LTC3858IUFD-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3858IUFD-1#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 LTC3858IUFD-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3858IUFD-1#TRPBF?
All LTC3858IUFD-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3858IUFD-1#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 LTC3858IUFD-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3858IUFD-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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