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Analog Devices Inc. LTC3858IGN-1#PBF
- Part No.:
- LTC3858IGN-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3858IGN-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,607
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Product details
Overview
LTC3858IGN-1#PBF 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 distributed systems. It supports independent 0.8V–24V outputs, operates from 4V–38V input, delivers up to 99% duty cycle, and features RSENSE or DCR current sensing - enabling robust 8.5V/3.3V dual-rail supplies in automotive and battery-powered digital devices.
For engineers reviewing the LTC3858IGN-1#PBF datasheet, LTC3858IGN-1#PBF pinout, LTC3858IGN-1#PBF application, or LTC3858IGN-1#PBF equivalent, key selection criteria include its 170μA no-load IQ, out-of-phase dual-channel operation reducing input ripple, OPTI-LOOP® compensation, phase-lockable 75kHz–850kHz frequency range, and latchoff protection during short-circuit conditions.
Technical Context
The LTC3858IGN-1#PBF implements a constant-frequency current-mode architecture with two independent controllers operating 180° out of phase to minimize input capacitor ESR losses and power supply noise. Each channel uses an error amplifier (EA) comparing VFB to a precision 0.800V reference, with ITH voltage controlling peak inductor current via differential current sensing at SENSE+ and SENSE− pins.
It integrates dual gate drivers (TG/BG) supporting N-channel MOSFETs, internal LDOs powering INTVCC from VIN or EXTVCC, programmable soft-start via SS1/SS2, and output overvoltage/short-circuit protection with independent latchoff timers. The PLLIN/MODE pin selects light-load operation modes: Burst Mode®, pulse-skipping, or forced continuous conduction.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide intermediate bus voltages and battery chemistries including 12V, 24V, and 36V systems. |
| Quiescent Current (One Channel On) | 170μA - extends runtime in battery-operated applications such as portable instrumentation and IoT edge nodes. |
| Feedback Reference Voltage | 0.800V ±12mV (–40°C to 125°C) - enables precise output regulation across temperature with minimal external resistor tolerance impact. |
| Switching Frequency Range | 75kHz to 850kHz (phase-lockable) - allows EMI optimization and compact magnetics design while maintaining stability under load transients. |
| Max Duty Cycle | 99.4% - supports ultra-low dropout operation in high-input-to-low-output voltage conversions (e.g., 5V→3.3V or 12V→3.3V). |
| Current Sense Threshold | 43mV to 57mV - sets accurate overcurrent trip point using RSENSE or DCR sensing networks without external amplification. |
| Shutdown IQ | 8μA - ensures minimal standby power draw when both RUN1 and RUN2 are pulled below 0.7V. |
Pinout & Package
Package: 28-Lead Plastic SSOP (0.150" width), –40°C to 125°C operating junction temperature, θJA = 90°C/W.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1+, SENSE2+ | Differential current sense (+) inputs | Connect to DCR network or current-sense resistor; set peak current limit with ITH voltage and offset calibration. |
| SENSE1–, SENSE2– | Differential current sense (–) inputs | Reference node for current comparator; supplies bias current above INTVCC – 0.5V to enable accurate high-side sensing. |
| FREQ | Oscillator frequency control | Resistor-to-GND sets 50kHz–900kHz; tied to GND/INTVCC for fixed 350kHz/535kHz; internal 20μA pull-up enables programming. |
| PLLIN/MODE | Sync input / light-load mode select | Accepts external clock for synchronization; logic level selects Burst Mode® (GND), pulse-skipping (1.2V–INTVCC–1.3V), or forced continuous (INTVCC). |
| RUN1, RUN2 | Independent channel enable | Pull <1.23V to disable one channel; pull both <0.7V for full shutdown with 8μA IQ; internal clamp protects against >8V overvoltage. |
| SS1, SS2 | Soft-start and latchoff timer | Internal 1μA pull-up charges external capacitor for linear VOUT ramp; voltage >2V arms short-circuit timeout; falling below 1.5V triggers latchoff. |
| VFB1, VFB2 | Output voltage feedback inputs | Compare to 0.800V reference; regulate VOUT via external resistor divider; PGOOD1 monitors VFB1 within ±10%. |
| TG1/TG2, BG1/BG2 | Top/bottom N-MOSFET gate drivers | TG swing = SW + (INTVCC – 0.5V); BG swing = 0V to INTVCC; 2.5Ω/1.5Ω pull-up/pull-down resistances drive typical 10nC gates at 850kHz. |
Key Features
| Feature | Design Value |
|---|---|
| Out-of-phase dual-channel operation | Reduces RMS input current by ~30% and cuts required input capacitance by half versus in-phase controllers. |
| OPTI-LOOP® compensation | Enables stable loop response across wide COUT/ESR variations (e.g., ceramic + polymer caps), eliminating need for iterative tuning. |
| Programmable light-load modes | Burst Mode® achieves >85% efficiency at 1mA load; pulse-skipping maintains fixed frequency; forced continuous avoids audible noise. |
| Independent short-circuit latchoff | Each channel discharges SS capacitor at 9μA upon VOUT drop <70%; latches off at 1.5V threshold - prevents thermal runaway without system reset. |
| EXTVCC switchover LDO | Automatically switches INTVCC sourcing from VIN to EXTVCC >4.7V, enabling efficient self-biasing from regulated output rails. |
Applications
| Automotive Infotainment Power Supply | Industrial PLC Dual-Rail Converter |
|---|---|
|
Use Scenario: Powering SoC, DDR memory, and display interfaces in head units requiring isolated 3.3V and 8.5V rails from 12V battery with cold-crank immunity. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent output regulation, phase interleaving, and fault recovery. Use Value: 170μA IQ preserves battery life during sleep; 99.4% max duty cycle sustains 3.3V output during 6V cold-crank; latchoff prevents MOSFET failure during wiring shorts. |
Use Scenario: Generating 3.3V FPGA core and 8.5V I/O rails from 24V industrial bus in programmable logic controllers with strict EMI limits. IC Role / Device Role / Timing Role: High-efficiency, phase-locked dual controller minimizing input ripple and enabling spread-spectrum-compatible clock synchronization. Use Value: Out-of-phase operation reduces input cap size by 50%; phase-lockable 75kHz–850kHz range avoids critical EMI bands; OPTI-LOOP® ensures stability with mixed-ceramic output caps. |
| Battery-Powered Test Equipment | Distributed Telecom DC-DC System |
|
Use Scenario: Portable oscilloscope or spectrum analyzer needing ultra-low-noise 3.3V analog and 8.5V ADC supplies from Li-ion battery (3.0–4.2V per cell). IC Role / Device Role / Timing Role: Low-IQ dual controller with Burst Mode® operation extending runtime while maintaining fast transient response. Use Value: 170μA IQ doubles battery life vs. standard controllers; adjustable soft-start prevents inrush into sensitive analog circuitry; PGOOD1 enables sequenced power-up. |
Use Scenario: Intermediate bus converter in 48V telecom shelf supplying multiple 3.3V/8.5V point-of-load regulators with high reliability and thermal margin. IC Role / Device Role / Timing Role: Robust dual-channel controller with EXTVCC self-biasing, overvoltage protection, and thermal-aware shutdown. Use Value: EXTVCC input allows INTVCC to be powered from local 5V rail - improving overall system efficiency; 125°C junction rating supports high-density PCB layouts. |
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 | Fixed 600kHz frequency; no phase-lock capability; lower IQ (120μA); integrated MOSFETs (not controller-only); 12V max VIN. | Suitable for space-constrained, cost-sensitive designs where input voltage ≤12V and fixed frequency suffices. | Select MP2918GL-Z only if board area and BOM count are prioritized over input voltage range and frequency flexibility. |
| LTC3858EUFD-1#PBF | Same die, 28-lead 4mm×5mm QFN package; θJA = 43°C/W (vs. 90°C/W for SSOP); exposed pad requires PCB thermal relief. | Better thermal performance in high-power density applications; preferred for >5A/channel designs with limited airflow. | Choose LTC3858EUFD-1#PBF when thermal management is critical and PCB layout accommodates QFN soldering requirements. |
Compared with MP2918GL-Z, LTC3858IGN-1#PBF offers wider VIN (4–38V vs. 4–12V), programmable frequency, and true controller flexibility; compared with LTC3858EUFD-1#PBF, it trades thermal performance for SSOP compatibility in legacy footprints and easier reworkability.
Availability
LTC3858IGN-1#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, and battery-powered test equipment requiring stable component supply with long-term lifecycle support.
Supply support for LTC3858IGN-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 acquired Linear Technology in 2017 and maintains its high-performance power management portfolio with rigorous automotive-grade qualification and long-term product support.
The LTC3858 family targets high-efficiency, low-IQ dual-phase DC/DC controllers for demanding applications including automotive, industrial, and portable instrumentation where reliability, thermal resilience, and precise regulation are critical.
FAQ
What is the maximum input voltage rating for the LTC3858IGN-1#PBF?
The LTC3858IGN-1#PBF has an absolute maximum input supply voltage (VIN) of 40V, with a recommended operating range of 4V to 38V. This allows safe operation across automotive battery transients (e.g., load dump up to 36V) and industrial 24V/36V bus systems. Exceeding 40V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3858IGN-1#PBF support phase synchronization with external clocks?
Yes, the LTC3858IGN-1#PBF supports external 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 rising edge of that clock, enabling deterministic timing across multiple converters. The supported sync frequency range is 75kHz to 850kHz.
How does the short-circuit latchoff function work on the LTC3858IGN-1#PBF?
The LTC3858IGN-1#PBF implements independent latchoff per channel using the SS1/SS2 pins. Once the SS voltage exceeds 2V (arming threshold), a 9μA discharge current pulls SS down if VOUT drops below 70% of regulation. If SS falls below 1.5V, the channel shuts down permanently until VIN or RUN is cycled - protecting MOSFETs and inductors during sustained faults.
Can the LTC3858IGN-1#PBF operate with only one output active?
Yes, the LTC3858IGN-1#PBF supports independent channel control. Pulling RUN1 high and RUN2 low disables Channel 2 while Channel 1 remains fully operational with 170μA quiescent current. Both channels can be enabled or disabled dynamically, enabling flexible power sequencing and partial-system sleep modes in multi-rail systems.
What is the purpose of the EXTVCC pin on the LTC3858IGN-1#PBF?
The EXTVCC pin on the LTC3858IGN-1#PBF provides an alternative power source for the internal INTVCC LDO. When EXTVCC exceeds 4.7V, the device automatically switches from VIN-based to EXTVCC-based regulation, delivering 5.1V to INTVCC. This enables efficient self-biasing from a clean, regulated output rail - reducing heat and improving overall system efficiency.
LTC3858IGN-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
LTC3858IGN-1#PBF FAQ
1.How can I place an order for LTC3858IGN-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3858IGN-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 LTC3858IGN-1#PBF reliable?
The price and inventory of LTC3858IGN-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 LTC3858IGN-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3858IGN-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3858IGN-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3858IGN-1#PBF?
LTC3858IGN-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3858IGN-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 LTC3858IGN-1#PBF?
For technical support, including LTC3858IGN-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3858IGN-1#PBF requirements.
6.How does Aetrix verify that LTC3858IGN-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3858IGN-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 LTC3858IGN-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3858IGN-1#PBF?
All LTC3858IGN-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3858IGN-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 LTC3858IGN-1#PBF part is unused and in its original packaging.
Return procedure for LTC3858IGN-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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