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Analog Devices Inc. LTC3858EGN-1#PBF
- Part No.:
- LTC3858EGN-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3858EGN-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,691
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Product details
Overview
LTC3858EGN-1#PBF from Analog Devices (formerly Linear Technology) is a dual-phase, synchronous step-down DC/DC controller IC designed for high-efficiency intermediate bus conversion. It delivers two independent output voltages (e.g., 3.3V/5A and 8.5V/3.5A), supports 4V–38V input, features 170μA no-load quiescent current, and operates out-of-phase to reduce input ripple. It is used in battery-powered digital systems requiring low IQ and robust short-circuit protection.
For engineers reviewing the LTC3858EGN-1#PBF datasheet, LTC3858EGN-1#PBF pinout, LTC3858EGN-1#PBF application, or LTC3858EGN-1#PBF equivalent, key selection criteria include its dual-channel phase-shifted operation, OPTI-LOOP® compensation, selectable light-load modes (Burst Mode®, pulse-skipping, forced continuous), 0.8V reference accuracy, and latchoff protection during output short circuits.
Technical Context
The LTC3858EGN-1#PBF implements a constant-frequency current-mode architecture with two independent 180° out-of-phase controllers, minimizing input capacitor ESR stress and power supply noise. Each channel uses an error amplifier (EA) driving ITH to regulate peak inductor current via differential current sensing (RSENSE or DCR).
It integrates dual gate drivers (TG/BG) with 2.5Ω pull-up and 1.5Ω pull-down on TG, internal 5.1V INTVCC LDO powered from VIN or EXTVCC (≥4.7V), precision 0.8V feedback reference (±1.5% over temperature), and programmable soft-start with independent SS1/SS2 pins enabling controlled ramp-up and short-circuit latchoff timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide-range industrial and automotive battery inputs and intermediate bus rails. |
| Quiescent Current (One Channel On) | 170μA - extends runtime in battery-operated systems without compromising regulation. |
| Feedback Reference Voltage | 0.800V ±1.5% - enables accurate output voltage setting down to 0.8V with minimal external divider error. |
| Switching Frequency Range | 75kHz–850kHz (phase-lockable) or 50kHz–900kHz (programmable) - allows EMI optimization and inductor size trade-offs. |
| Max Duty Cycle | 99.4% - supports ultra-low dropout operation (e.g., 12V→11.5V) without losing regulation. |
| Output Overvoltage Protection | ±10% trip threshold on VFB - provides hardware-level safeguard against regulator failure or feedback fault. |
| Shutdown Current | 8μA - ensures near-zero power draw when both RUN pins are pulled below 0.7V. |
Pinout & Package
Package: 28-Lead Plastic SSOP (0.150" width), RoHS-compliant, operating junction temperature range –40°C to 125°C, θJA = 90°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1+, SENSE2+ | Differential current sense (+) inputs | Connect to DCR network or RSENSE to set per-channel current limit; referenced to SENSE–. |
| SENSE1–, SENSE2– | Differential current sense (–) inputs | Provide common-mode bias point; source current > INTVCC – 0.5V to enable comparator. |
| TG1, TG2 | Top N-MOSFET gate drivers | Floating outputs swinging at SW + (INTVCC – 0.5V); drive external high-side FETs. |
| BG1, BG2 | Bottom N-MOSFET gate drivers | Ground-referenced outputs (0V to INTVCC); drive synchronous rectifiers. |
| VFB1, VFB2 | Feedback voltage inputs | Compare output divider voltage to 0.8V reference; determine regulated output level. |
| SS1, SS2 | Soft-start / latchoff timer inputs | Internal 1μA pull-up sets ramp time; voltage >2V arms short-circuit timeout; <1.5V triggers latchoff. |
| RUN1, RUN2 | Channel enable/disable controls | Digital logic inputs: <1.26V disables channel; both <0.7V forces full shutdown (8μA IQ). |
| PGOOD1 | Open-drain power-good indicator | Asserts low when VFB1 deviates >±10% from target - signals valid regulation for downstream sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Enables stable transient response across wide ranges of output capacitance (e.g., 10μF–1000μF) and ESR without loop re-tuning. |
| Out-of-Phase Dual Control | Reduces RMS input ripple current by ~70% vs. in-phase operation - cuts required CIN volume and lowers EMI. |
| Selectable Light-Load Modes | Burst Mode® (highest efficiency at μA loads), pulse-skipping (low-noise), or forced continuous (lowest output ripple). |
| Independent Short-Circuit Latchoff | Each channel has dedicated SS-based timeout circuit - prevents thermal runaway during sustained overload without affecting other rail. |
| EXTVCC Switchover | Automatically switches INTVCC supply from VIN LDO to external 4.7–14V source - improves system efficiency when powering INTVCC from a regulated output rail. |
Applications
| Telecom Intermediate Bus Converter | Industrial PLC Power Supply |
|---|---|
Use Scenario: Converting 24V or 48V backplane to isolated 12V/5V/3.3V rails for FPGA, DSP, and I/O modules. IC Role / Device Role / Timing Role: Dual-phase controller managing two independent buck stages with synchronized but phase-shifted switching to minimize input filter size. Use Value: Reduces input capacitor count by 40% versus single-phase design while maintaining <10mVpp ripple on each output. | Use Scenario: Providing tightly regulated 5V and 3.3V supplies for microcontroller, analog sensors, and communication interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Primary DC/DC controller with latchoff protection and wide input range tolerance for unregulated 24VDC industrial power. Use Value: Survives 40V load-dump transients and maintains regulation during brownouts due to 38V max VIN and 99.4% duty cycle capability. |
| Battery-Powered Test Equipment | Automotive Infotainment Head Unit |
Use Scenario: Portable oscilloscope or signal generator using Li-ion (8.4V–12.6V) battery to power mixed-signal subsystems. IC Role / Device Role / Timing Role: Low-IQ dual controller delivering 3.3V for logic and 8.5V for analog front-end amplifiers with independent soft-start sequencing. Use Value: 170μA quiescent current extends battery life >30% versus comparable controllers; Burst Mode® maintains >85% efficiency at 100μA load. | Use Scenario: Converting vehicle battery (9V–16V) to stable 5V USB and 3.3V MCU rails inside head unit with CAN/LIN interface. IC Role / Device Role / Timing Role: Dual-output buck controller with AEC-Q200-compatible package (SSOP), UVLO hysteresis, and short-circuit latchoff for safety-critical power domains. Use Value: Meets automotive cold-crank (4.5V min) and hot-crank (38V max) requirements; PGOOD1 enables safe processor reset sequencing. |
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 |
|---|---|---|---|
| LTC3858IGU-1#PBF | Same functionality, but in 28-lead 4mm × 5mm QFN package (θJA = 43°C/W vs. 90°C/W); includes clock-out and phase modulation pins not present on SSOP. | Preferred for space-constrained PCBs needing better thermal performance; unsuitable where SSOP footprint or lead pitch is required. | Select when board layout allows QFN and thermal management demands lower junction rise. |
| MP8765GL-Z | Single-chip dual-phase controller with integrated MOSFETs (30V/12A); no external gate drivers; fixed 500kHz frequency; lacks phase-locking and EXTVCC switchover. | Used in cost-sensitive, low-to-mid power (<100W) applications where integration reduces BOM count; not suitable for high-input-voltage or thermally demanding designs. | Choose for simplified design with lower component count where 38V VIN and discrete FET flexibility are unnecessary. |
Compared with LTC3858IGU-1#PBF, the LTC3858EGN-1#PBF offers identical control features in a legacy SSOP package suited for through-hole rework or legacy assembly lines, while MP8765GL-Z trades configurability for integration - making it viable only where input voltage stays below 30V and thermal headroom exceeds 25°C/W.
Availability
LTC3858EGN-1#PBF is available at Aetrix Electronics and suitable for telecom intermediate bus converters, industrial PLC power supplies, and battery-powered test equipment requiring stable component supply, long-term lifecycle support, and guaranteed RoHS compliance.
Supply support for LTC3858EGN-1#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. (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 product line was designed specifically for high-efficiency, dual-output, wide-input-voltage DC/DC conversion in space- and power-constrained systems - emphasizing low IQ, robust protection, and flexible light-load operation.
FAQ
What is the maximum input voltage rating for the LTC3858EGN-1#PBF?
The LTC3858EGN-1#PBF has an absolute maximum input supply voltage (VIN) rating of 40V, with recommended operating range from 4V to 38V. Exceeding 40V may cause permanent damage. The device's 99.4% maximum duty cycle and undervoltage lockout (UVLO) with 4.0V turn-on hysteresis ensure reliable startup and dropout operation across automotive and industrial input profiles.
Does the LTC3858EGN-1#PBF support synchronization to an external clock?
Yes, the LTC3858EGN-1#PBF supports external clock synchronization via the PLLIN/MODE pin. When an external clock signal is applied, the internal phase-locked loop aligns the rising edge of TG1 with the external clock's rising edge. This feature enables noise reduction in multi-rail systems and EMI compliance in sensitive applications - a capability confirmed in the functional diagram and oscillator specifications section of the datasheet.
How does the short-circuit latchoff function work on the LTC3858EGN-1#PBF?
The LTC3858EGN-1#PBF implements independent short-circuit latchoff per channel using the SS1/SS2 pins. Once the SS voltage rises above 2.0V (arming threshold), a 9μA discharge current pulls SS down if VFB drops below 70% of regulation. If SS falls below 1.5V, the channel latches off until VIN or RUN is cycled. This behavior is explicitly defined in the "Short-Circuit Latch-Off" section and verified in Figure 1 of the datasheet.
Can the LTC3858EGN-1#PBF operate with only one output enabled?
Yes, the LTC3858EGN-1#PBF supports independent channel control: pulling RUN1 low disables only Channel 1 while Channel 2 remains active, and vice versa. In single-channel operation, quiescent current drops to 170μA (typical), and the unused channel's gate drivers, current sense, and feedback circuitry are fully disabled - preserving efficiency and reducing noise coupling, as specified in the Electrical Characteristics table under IQ conditions.
What is the purpose of the EXTVCC pin on the LTC3858EGN-1#PBF?
The EXTVCC pin on the LTC3858EGN-1#PBF allows the internal 5.1V INTVCC LDO to be powered from an external regulated source (4.7V–14V) instead of VIN. When EXTVCC exceeds 4.7V, the VIN LDO shuts off and the EXTVCC LDO activates - improving overall system efficiency, especially when powering INTVCC from a clean, high-efficiency output rail like the 3.3V or 5V buck stage itself.
LTC3858EGN-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- 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:
- Enable, Frequency Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC3858EGN-1#PBF FAQ
1.How can I place an order for LTC3858EGN-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3858EGN-1#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 LTC3858EGN-1#PBF reliable?
The price and inventory of LTC3858EGN-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3858EGN-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3858EGN-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3858EGN-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3858EGN-1#PBF?
LTC3858EGN-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3858EGN-1#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 LTC3858EGN-1#PBF?
For technical support, including LTC3858EGN-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3858EGN-1#PBF requirements.
6.How does Aetrix verify that LTC3858EGN-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3858EGN-1#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 LTC3858EGN-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3858EGN-1#PBF?
All LTC3858EGN-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3858EGN-1#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 LTC3858EGN-1#PBF part is unused and in its original packaging.
Return procedure for LTC3858EGN-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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