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Analog Devices Inc. LTC3858EUH#PBF
- Part No.:
- LTC3858EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3858EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:185
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Product details
Overview
LTC3858EUH#PBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down DC/DC controller IC driving two independent N-channel MOSFET stages. It delivers 3.3V/5A and 8.5V/3.5A outputs from 4V–38V input, features 170μA quiescent current in single-channel sleep mode, 0.8V reference accuracy, and out-of-phase operation to reduce input ripple. It is used in battery-powered digital systems requiring high-efficiency dual-rail power conversion.
For engineers reviewing the LTC3858EUH#PBF datasheet, LTC3858EUH#PBF pinout, LTC3858EUH#PBF application, or LTC3858EUH#PBF equivalent, key selection criteria include its dual-channel phase control, RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation, programmable 50kHz–900kHz switching frequency, and latch-off protection during short-circuit events.
Technical Context
The LTC3858EUH#PBF implements a constant-frequency current-mode architecture with two independent controllers operating 180° out of phase-reducing input capacitor RMS current and system noise. Each channel uses a transconductance error amplifier (gm = 2 mmho), precision 0.800V ±1.2% feedback reference, and adjustable current limit via ILIM pin selection (GND/FLOAT/INTVCC).
Its dual-loop control supports selectable light-load modes: Burst Mode® (for ultra-low IQ), pulse-skipping (for low-noise intermittent operation), or forced continuous conduction (for minimal output ripple). The internal 5.1V INTVCC LDO can be powered from VIN or an external EXTVCC supply ≥4.7V, enabling efficient self-biasing from one of its own output rails.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 38V - supports wide-input industrial, automotive, and battery-based systems including 12V/24V buses and Li-ion/LiFePO₄ packs. |
| IQ (Sleep, 1 ch) | 170μA typical - extends runtime in always-on battery-powered applications such as portable instrumentation or remote sensors. |
| VFB Accuracy | ±1.2% over –40°C to 125°C - ensures stable output regulation across temperature without external trimming. |
| fSW Range | 50kHz to 900kHz programmable - enables optimization of size (high-f) vs. efficiency (low-f) and EMI compliance. |
| Duty Cycle Max | 99.4% - supports ultra-low dropout operation (e.g., 3.3V out from 3.6V input), critical for battery end-of-discharge scenarios. |
| Current Sense | RSENSE or DCR sensing - eliminates need for dedicated sense resistors in high-current designs, reducing power loss and BOM cost. |
| PGOOD Threshold | ±10% VFB window with 2.5% hysteresis - provides reliable power-good signaling for FPGA/CPU sequencing and fault detection. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND), rated for –40°C to 125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1– / SENSE2– (1, 9) | Differential current sense (–) input | Supplies bias current when > INTVCC – 0.5V; enables accurate DCR/RSENSE sensing with offset cancellation. |
| FREQ (2) | Oscillator frequency programming | 20μA internal pull-up sets VCO frequency; resistor-to-GND selects 50–900kHz; GND/INTVCC forces fixed 350/535kHz. |
| PHASMD (3) | Phase relationship selector | Configures TG2/CLKOUT phase offset relative to TG1: 180°/60° (GND), 240°/120° (INTVCC), or 180°/90° (floating). |
| PLLIN/MODE (5) | Synchronization & light-load mode control | Accepts external clock for PLL sync; GND = Burst Mode®, INTVCC = forced CCM, mid-voltage = pulse-skip. |
| RUN1 / RUN2 (7, 8) | Independent channel enable | Logic-level shutdown: <1.23V disables channel; both <0.7V shuts down entire IC (IQ = 8μA). |
| ILIM (28) | Current limit threshold select | Three levels (GND/FLOAT/INTVCC) set max sense voltage to 22/43/64mV - scales current limit without changing RSENSE. |
| SS1 / SS2 (29, 13) | Soft-start & short-circuit timer | 1μA internal pull-up charges external cap for linear VOUT ramp; also discharges at 9μA during fault to trigger latch-off at 1.5V. |
| PGOOD1 / PGOOD2 (27, 14) | Open-drain power-good indicator | Asserts low when VFB deviates >±10% from 0.8V; includes 25μs delay and hysteresis for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by optimizing transient response across wide range of COUT/ESR values - reduces solution size and cost. |
| Out-of-Phase Dual Control | 180° phase shift between channels cuts input ripple current by ~70%, allowing smaller input bulk capacitors and lower EMI. |
| Programmable Light-Load Mode | Selectable Burst Mode®, pulse-skipping, or forced CCM - balances efficiency, noise, and output ripple per application requirement. |
| Short-Circuit Latch-Off Protection | Independent SS-pin-based timeout per channel - latches off after fault persists long enough to discharge SS from >2V to <1.5V, preventing thermal runaway. |
| Internal 5.1V LDO with EXTVCC Switchover | Auto-selects between VIN- and EXTVCC-derived INTVCC - enables efficient self-powering from regulated output rails, improving overall system efficiency. |
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 interface (8.5V backlight) in head-unit under varying 9–16V battery input. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent 3.3V/5A and 8.5V/3.5A rails with phase interleaving and precise soft-start sequencing. Use Value: 170μA sleep IQ extends standby time; 99.4% duty cycle sustains 3.3V output during cold-crank (6.5V battery); latch-off prevents damage during connector short. | Use Scenario: Distributed 24V-to-5V/3.3V conversion for isolated analog input channels and microcontroller in modular automation controller. IC Role / Device Role / Timing Role: High-reliability dual-output controller with RSENSE/DCR flexibility, PGOOD monitoring, and robust overvoltage/short-circuit protection. Use Value: Wide 4–38V input accommodates 24V bus derating and surge; ±10% PGOOD enables safe FPGA configuration; OPTI-LOOP allows use of low-cost bulk electrolytics. |
| Battery-Powered Test Equipment | Telecom Remote Radio Unit (RRU) |
Use Scenario: Portable oscilloscope or signal analyzer requiring clean, low-noise 3.3V logic and 8.5V analog supply from Li-ion pack (3.0–4.2V/cell). IC Role / Device Role / Timing Role: Dual-channel step-down controller with Burst Mode® for <100μA system standby and forced CCM for low-noise ADC/DAC operation. Use Value: 8μA shutdown IQ preserves battery life; programmable fSW avoids sensitive RF bands; independent RUN pins allow dynamic rail enable/disable. | Use Scenario: Base station RRU converting 48V intermediate bus to 3.3V FPGA core and 8.5V RF front-end bias in thermally constrained outdoor enclosure. IC Role / Device Role / Timing Role: High-efficiency dual-phase controller with EXTVCC option to self-power INTVCC from 3.3V rail, reducing heat generation in sealed housing. Use Value: 5mm × 5mm QFN fits tight layout; 125°C rating supports extended ambient; phase-lockable fSW enables synchronized switching with other system clocks. |
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 |
|---|---|---|---|
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers only; no EXTVCC option; fixed 0.6V reference; no Burst Mode®. | Targeted at cost-sensitive consumer power supplies; lacks latch-off protection and wide VIN range. | Choose MP2918GL-Z only if integrated drivers suffice and 4–38V input/short-circuit latch-off are not required. |
| TPS546D24RQFT | Single-chip dual-phase controller with PMBus interface, 0.5V reference, and digital loop compensation; supports telemetry but higher IQ (2.5mA). | Designed for server VR13/VR14 compliance; requires digital configuration; no analog soft-start or OPTI-LOOP. | Choose TPS546D24RQFT only when digital monitoring, telemetry, and strict VR standards outweigh need for ultra-low IQ and analog design simplicity. |
Compared with MP2918GL-Z and TPS546D24RQFT, the LTC3858EUH#PBF offers superior low-IQ performance (170μA vs. >2mA), wider input range (4–38V vs. ≤20V), analog flexibility (RSENSE/DCR, OPTI-LOOP, Burst Mode®), and robust fault protection - making it optimal for ruggedized, battery-aware, or thermally constrained industrial and automotive designs.
Availability
LTC3858EUH#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC modules, and battery-powered test equipment requiring stable component supply, extended temperature operation, and long-term lifecycle support.
Supply support for LTC3858EUH#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, formed through the acquisition of Linear Technology in 2017.
The LTC3858EUH#PBF belongs to ADI's Power by Linear™ family of high-efficiency DC/DC controllers, designed specifically for demanding industrial, automotive, and telecom applications where reliability, wide input range, and ultra-low quiescent current are critical.
FAQ
What is the minimum input voltage supported by the LTC3858EUH#PBF?
The LTC3858EUH#PBF supports a minimum input voltage of 4V, enabling operation from partially discharged 2-cell Li-ion batteries (≈3.6V nominal) and 5V intermediate rails. This 4V lower limit is guaranteed across the full –40°C to 125°C operating junction temperature range, with undervoltage lockout releasing at 3.8V (typical) during VIN ramp-up.
How does the LTC3858EUH#PBF achieve ultra-low quiescent current in sleep mode?
The LTC3858EUH#PBF achieves 170μA typical quiescent current in single-channel sleep mode by disabling the unused channel's gate drivers, error amplifier, and oscillator while maintaining reference and bias circuits. Its proprietary low-power architecture minimizes leakage and dynamically scales bias currents - verified in production testing per Linear Technology specification LTC3858 datasheet Rev. F, page 3.
Can the LTC3858EUH#PBF be synchronized to an external clock source?
Yes, the LTC3858EUH#PBF supports external synchronization via the PLLIN/MODE pin (Pin 5), accepting clock inputs from 75kHz to 850kHz. When an external clock is applied, the internal phase-locked loop aligns the rising edge of TG1 with the rising edge of the external signal - enabling coherent switching across multi-phase or multi-rail systems to reduce beat frequencies and EMI peaks.
What protection features does the LTC3858EUH#PBF provide against output short circuits?
The LTC3858EUH#PBF provides dual-layer short-circuit protection: (1) foldback current limiting that progressively reduces peak current as VOUT drops below 70% of regulation, and (2) independent SS-pin-based latch-off that triggers after fault duration sufficient to discharge SS from >2V to <1.5V. Both mechanisms operate per channel and are confirmed in the Functional Diagram (page 10) and Short-Circuit Latch-Off section (page 12) of the LTC3858 datasheet.
Is the LTC3858EUH#PBF pin-compatible with the LTC3858-1 variant?
No, the LTC3858EUH#PBF is not pin-compatible with the LTC3858-1. The LTC3858-1 is offered in a 28-lead SSOP package with fixed current limit, only one PGOOD output, no phase modulation capability, and no CLKOUT pin - whereas the LTC3858EUH#PBF is a 32-lead QFN with full dual-PGOOD, PHASMD, CLKOUT, and programmable ILIM functionality. Pin counts, functions, and package footprints differ fundamentally.
LTC3858EUH#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tube
- 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:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3858EUH#PBF FAQ
1.How can I place an order for LTC3858EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3858EUH#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 LTC3858EUH#PBF reliable?
The price and inventory of LTC3858EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3858EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3858EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3858EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3858EUH#PBF?
LTC3858EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3858EUH#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 LTC3858EUH#PBF?
For technical support, including LTC3858EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3858EUH#PBF requirements.
6.How does Aetrix verify that LTC3858EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3858EUH#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 LTC3858EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3858EUH#PBF?
All LTC3858EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3858EUH#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 LTC3858EUH#PBF part is unused and in its original packaging.
Return procedure for LTC3858EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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