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Analog Devices Inc. LTC3868EUH#PBF
- Part No.:
- LTC3868EUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3868EUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:146
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Product details
Overview
LTC3868EUH#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 a 4V–24V input, features 170µA quiescent current in single-channel sleep mode, 0.8V reference accuracy (±12mV), and out-of-phase operation to reduce input ripple. It is used in notebook computers and battery-powered digital systems requiring high efficiency and low standby power.
For engineers reviewing the LTC3868EUH#PBF datasheet, LTC3868EUH#PBF pinout, LTC3868EUH#PBF application, or LTC3868EUH#PBF equivalent, key selection criteria include dual-channel phase control, RSENSE/DCR current sensing flexibility, OPTI-LOOP® compensation for wide COUT/ESR tolerance, programmable frequency (50kHz–900kHz), and integrated short-circuit latchoff with adjustable soft-start timing.
Technical Context
The LTC3868EUH#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 an error amplifier (gm = 2 mmho) comparing VFB to a precision 0.8V reference, with ITH voltage modulating peak inductor current via differential current sense inputs (SENSE+/SENSE−).
It integrates dual gate drivers (TG/BG) with <30ns transition times, internal 5.1V LDO (INTVCC) powered from VIN or EXTVCC (switchover at 4.7V), and robust protection including output overvoltage detection (±10% trip), undervoltage lockout (3.6V–4.2V), and foldback current limiting activated below 72% nominal VOUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 24V - supports wide-input intermediate bus and multi-cell Li-ion/battery chemistries without external pre-regulation. |
| VOUT Range | 0.8V to 14V - enables generation of standard logic rails (1.2V, 1.8V, 3.3V, 5V, 8.5V, 12V) with ±12mV reference accuracy. |
| IQ (Sleep, 1 ch) | 170µA typical - extends battery runtime in portable instruments and palmtop computers during light-load standby. |
| Frequency Range | 50kHz to 900kHz programmable - allows optimization of size (high f) vs. efficiency (low f) and EMI filtering requirements. |
| Duty Cycle Max | 99.4% - supports ultra-low dropout operation down to VOUT ≈ VIN − 0.2V, critical for high-VIN-to-low-VOUT conversion. |
| Current Sense | RSENSE or DCR sensing - eliminates need for dedicated shunt resistors in high-current applications, reducing power loss. |
| Protection | Output OVP (±10%), short-circuit latchoff, foldback current limit, UVLO, PGOOD monitoring - enables autonomous fault recovery and system-level safety compliance. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND), rated for –40°C to +85°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1– / SENSE2– (1, 9) | Differential current sense (–) input | Supplies bias current when > INTVCC – 0.5V; sets common-mode range for accurate DCR/RSENSE sensing. |
| FREQ (2) | VCO frequency programming | 20µA pull-up enables resistor-based frequency setting (50–900kHz); GND = 350kHz, INTVCC = 535kHz. |
| PHASMD (3) | Phase relationship selector | Configures TG2/CLKOUT phase offset relative to TG1 (180°/60°, 240°/120°, or 180°/90°) for PolyPhase™ synchronization. |
| CLKOUT (4) | Master clock output | INTVCC-rail-swing signal for daisy-chaining additional controllers; enables precise multi-phase timing alignment. |
| PLLIN/MODE (5) | Synchronization & light-load mode control | Accepts external clock (75–850kHz) or selects Burst Mode® (GND), pulse-skipping (1.2–3.7V), or forced continuous (INTVCC). |
| SGND (6, 33) | Small-signal ground reference | Must be isolated from PGND; exposed pad soldering required for thermal performance (θJA = 34°C/W). |
| RUN1 / RUN2 (7, 8) | Independent channel enable | 1.26V threshold per channel; both < 0.7V forces full shutdown (IQ = 8µA). |
| TG1 / TG2 (26, 15) | Top N-MOSFET gate drive | Floating driver with 2.5Ω pull-up / 1.5Ω pull-down; supports bootstrapped operation up to VIN + INTVCC. |
| BG1 / BG2 (23, 18) | Bottom N-MOSFET gate drive | Ground-referenced driver with 2.4Ω pull-up / 1.1Ω pull-down; optimized for synchronous rectification. |
| VFB1 / VFB2 (31, 11) | Feedback voltage input | Compares remote-sensed output to 0.8V reference; ±50nA input bias minimizes divider error. |
| PGOOD1 / PGOOD2 (27, 14) | Open-drain power-good indicator | Asserts low when VFB deviates >±10% from setpoint; 25µs fault reporting delay ensures noise immunity. |
| SS1 / SS2 (29, 13) | Soft-start & short-circuit timer | 1µA internal pull-up charges external capacitor; 2V arming / 1.5V latchoff thresholds enable configurable timeout. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Minimizes required output capacitance by enabling stable loop response across wide COUT/ESR ranges - reduces BOM count and board area. |
| Out-of-Phase Dual Control | 180° phase shift between channels cuts input ripple current by ~70%, allowing smaller, lower-cost input capacitors and reduced EMI. |
| Programmable Light-Load Modes | Selectable Burst Mode®, pulse-skipping, or forced continuous operation - balances efficiency (Burst), noise (FCM), and transient response (pulse-skip). |
| Integrated Short-Circuit Protection | Adjustable latchoff timeout (via SS capacitor) + foldback current limiting - prevents thermal runaway while maintaining safe fault current (<1A typical). |
| Flexible Power Supply Options | Auto-switching between VIN- and EXTVCC-powered INTVCC (switchover at 4.7V) - enables efficient self-biasing from regulated output rails. |
Applications
| Notebook Computers | Portable Instruments |
|---|---|
|
Use Scenario: Dual-rail power supply for CPU core (3.3V/5A) and peripheral I/O (8.5V/3.5A) in space-constrained clamshell designs. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent voltage domains with coordinated soft-start and phase interleaving. Use Value: 170µA IQ extends battery life during suspend; out-of-phase operation reduces input capacitor count by 2× versus single-phase solutions. |
Use Scenario: Battery-powered handheld oscilloscope requiring clean, low-noise 3.3V analog front-end and 8.5V display backlight supplies. IC Role / Device Role / Timing Role: High-PSRR, low-ripple dual-output controller with Burst Mode® for extended idle time and fast wake-up response. Use Value: OPTI-LOOP® ensures stability with ceramic output caps; PGOOD outputs enable microcontroller-controlled rail sequencing and fault logging. |
| Battery-Operated Digital Devices | Distributed DC Power Systems |
|
Use Scenario: Power management for FPGA-based edge sensor node with variable load profiles (deep sleep → burst processing). IC Role / Device Role / Timing Role: Adaptive dual-channel controller switching between Burst Mode® (sleep) and forced continuous (active) based on real-time load demand. Use Value: Programmable frequency avoids sensitive EMI bands; ILIM pin configures current limits per rail to match FPGA I/O and core domain requirements. |
Use Scenario: Intermediate bus converter in industrial IoT gateway distributing 3.3V and 8.5V to multiple daughterboards over backplane traces. IC Role / Device Role / Timing Role: Robust, thermally efficient controller with EXTVCC support enabling local regulation from upstream 12V rail to minimize distribution losses. Use Value: 99.4% max duty cycle maintains regulation under brownout; CLKOUT synchronizes downstream converters to eliminate beat frequencies. |
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 600kHz frequency; lacks PLLIN/MODE programmability and OPTI-LOOP®. | Targeted at cost-sensitive consumer electronics where layout simplicity outweighs fine-grained light-load optimization. | Choose MP2918GL-Z when board space is critical and fixed-frequency operation suffices; avoid if EXTVCC biasing or adaptive light-load modes are required. |
| ISL95836IRZ-T | Intel VR12.5-compliant dual-phase controller; supports SVID interface, dynamic VID scaling, and telemetry; higher IQ (350µA sleep); no Burst Mode®. | Designed for CPU voltage regulation in client platforms with strict Intel compliance and telemetry needs. | Choose ISL95836IRZ-T only for Intel-compatible systems requiring SVID communication; not suitable for general-purpose dual-rail applications. |
Compared with MP2918GL-Z and ISL95836IRZ-T, the LTC3868EUH#PBF uniquely combines ultra-low IQ, flexible frequency/phase control, EXTVCC support, and OPTI-LOOP® - making it optimal for battery life–critical, thermally constrained, and multi-rail industrial/portable designs where programmability and protection granularity matter.
Availability
LTC3868EUH#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instruments, and distributed DC power systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.
Supply support for LTC3868EUH#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 analog and power management portfolio. Linear Technology was renowned for precision, reliability, and innovation in power conversion ICs.
The LTC3868EUH#PBF belongs to Linear's high-efficiency synchronous controller family, designed specifically for dual-output, battery-sensitive, and thermally demanding applications in portable computing and instrumentation.
FAQ
What is the minimum input voltage supported by the LTC3868EUH#PBF?
The LTC3868EUH#PBF supports a minimum input voltage of 4V, enabling compatibility with fully discharged two-cell Li-ion batteries (≈4.2V nominal, down to ~3.6V per cell) and regulated 5V intermediate buses. Operation below 4V triggers undervoltage lockout (UVLO) at 3.6V (rising) to prevent unstable regulation.
How does the LTC3868EUH#PBF achieve ultra-low quiescent current?
The LTC3868EUH#PBF achieves 170µA typical IQ in single-channel sleep mode through a dedicated low-power bias network, selective circuit disabling, and optimized internal LDO design. Its shutdown IQ drops to 8µA when both RUN pins fall below 0.7V - verified across –40°C to +85°C per datasheet Figure G17/G18.
Can the LTC3868EUH#PBF synchronize to an external clock?
Yes - the LTC3868EUH#PBF accepts external synchronization via the PLLIN/MODE pin (Pin 5), supporting input clocks from 75kHz to 850kHz. When enabled, the phase-locked loop aligns the rising edge of TG1 to the external clock's rising edge, enabling deterministic timing across multi-controller systems.
What protection features does the LTC3868EUH#PBF provide against output short circuits?
The LTC3868EUH#PBF provides dual-layer short-circuit protection: (1) foldback current limiting activates when VOUT falls below 72% of nominal, progressively reducing peak current; and (2) short-circuit latchoff triggers after a user-configurable timeout (via SS capacitor) when VOUT drops below 70%, shutting down the channel until VIN or RUN is recycled.
Is the LTC3868EUH#PBF pin-compatible with the LTC3868-1 variant?
No - the LTC3868EUH#PBF is not pin-compatible with the LTC3868-1. The LTC3868-1 uses a 28-lead SSOP package, omits PHASMD and CLKOUT pins, has only one PGOOD output, and lacks phase modulation capability. Pin mapping, package footprint, and feature set differ significantly between the two variants.
LTC3868EUH#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 ~ 24V
- 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, Phase Control, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-QFN (5x5)
LTC3868EUH#PBF FAQ
1.How can I place an order for LTC3868EUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3868EUH#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 LTC3868EUH#PBF reliable?
The price and inventory of LTC3868EUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3868EUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3868EUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3868EUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3868EUH#PBF?
LTC3868EUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3868EUH#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 LTC3868EUH#PBF?
For technical support, including LTC3868EUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3868EUH#PBF requirements.
6.How does Aetrix verify that LTC3868EUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3868EUH#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 LTC3868EUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3868EUH#PBF?
All LTC3868EUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3868EUH#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 LTC3868EUH#PBF part is unused and in its original packaging.
Return procedure for LTC3868EUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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