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Analog Devices Inc. LTC3868IUH#PBF
- Part No.:
- LTC3868IUH#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3868IUH#PBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:145
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Product details
Overview
LTC3868IUH#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 for high-efficiency power conversion. It delivers 0.8V–14V output voltage range per channel, supports 4V–24V input, operates with 170µA quiescent current (one channel active), and features out-of-phase operation to reduce input ripple-used in battery-powered portable instruments and distributed DC power systems.
For engineers reviewing the LTC3868IUH#PBF datasheet, LTC3868IUH#PBF pinout, LTC3868IUH#PBF application, or LTC3868IUH#PBF equivalent, key selection criteria include its dual-channel phase control, OPTI-LOOP® compensation, programmable switching frequency (50kHz–900kHz), RSENSE/DCR current sensing, and integrated short-circuit latchoff protection with adjustable soft-start.
Technical Context
The LTC3868IUH#PBF implements a constant-frequency current-mode architecture with two independent controllers operating 180° out of phase to minimize input capacitor RMS current and system noise. Each channel uses an error amplifier (EA) with transconductance gm = 2 mmho and a precision 0.8V reference (±1.5% over temperature) to regulate output voltage via VFB1/VFB2 feedback.
It integrates dual gate drivers (TG1/TG2, BG1/BG2) with 2.5Ω pull-up / 1.5Ω pull-down on top-side and 2.4Ω/1.1Ω on bottom-side drivers, supports external synchronization via PLLIN/MODE (75kHz–850kHz), and includes dedicated ITH1/ITH2 compensation nodes and SENSE+/SENSE− differential current sense inputs for accurate peak-current limiting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 24V - accommodates wide intermediate bus voltages and Li-ion/Li-poly battery chemistries without external pre-regulation. |
| Output Voltage Range | 0.8V to 14V per channel - enables generation of core logic, I/O, and analog supply rails from single controller. |
| Quiescent Current | 170µA (one channel active) - extends runtime in always-on portable instrumentation and low-power edge sensors. |
| Switching Frequency | 50kHz to 900kHz (programmable) - allows optimization of size (higher fSW → smaller inductors/caps) vs. efficiency (lower fSW → reduced switching loss). |
| Current Sense Threshold | 22mV to 86mV (selectable via ILIM pin) - supports precise overcurrent protection across RSENSE or DCR sensing networks. |
| Duty Cycle Max | 99.4% - enables ultra-low dropout operation near VIN = VOUT, critical for high-voltage-input, low-output-voltage applications. |
| Reference Voltage Accuracy | ±1.5% (0.788V–0.812V at 25°C) - ensures tight output regulation under varying load and line conditions. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND). Requires soldering of exposed pad to PCB for rated thermal performance (θJA = 34°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1−, SENSE2− (Pins 1, 9) | Differential current sense (−) input | Supplies bias current above INTVCC − 0.5V; enables accurate current measurement with RSENSE or DCR networks. |
| FREQ (Pin 2) | VCO frequency programming | 20µA internal pull-up sets oscillator frequency; resistor-to-GND selects 50kHz–900kHz range. |
| PHASMD (Pin 3) | Phase relationship selector | Configures TG2/CLKOUT phase offset relative to TG1 (180°/240°/floating default = 180°). |
| PLLIN/MODE (Pin 5) | Synchronization & light-load mode control | Accepts external clock (75–850kHz) or selects Burst Mode®/pulse-skipping/forced continuous operation. |
| RUN1, RUN2 (Pins 7, 8) | Independent channel enable | Logic-level shutdown: <1.26V disables one channel; both <0.7V reduces IQ to 8µA globally. |
| PGOOD1, PGOOD2 (Pins 14, 27) | Open-drain power-good indicator | Asserts low when VFB deviates >±10% from 0.8V setpoint - enables system sequencing and fault reporting. |
| SS1, SS2 (Pins 13, 29) | Soft-start & short-circuit latchoff timer | Internal 1µA pull-up charges external capacitor for controlled ramp; voltage threshold triggers latchoff during sustained overcurrent. |
| ITH1, ITH2 (Pins 12, 30) | Error amplifier output & compensation node | Directly controls peak current limit; connects to RC network for loop stability across wide COUT/ESR ranges. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Enables stable transient response across 10µF–1000µF output capacitance and 1mΩ–100mΩ ESR without redesigning compensation network. |
| Out-of-Phase Dual Control | Reduces required input bulk capacitance by ~50% and lowers conducted EMI by canceling input ripple harmonics. |
| Programmable Light-Load Operation | Three selectable modes (Burst Mode®, pulse-skipping, forced continuous) optimize efficiency across 10µA–5A load range. |
| Short-Circuit Latchoff Protection | Independent per-channel timeout circuit using SS pin voltage decay (2V arming → 1.5V latchoff) prevents thermal runaway during faults. |
| Integrated INTVCC/EXTVCC LDO | Auto-switches between VIN- and EXTVCC-derived 5.1V supply - enables efficient self-biasing from regulated output rails. |
Applications
| Portable Instrumentation | Battery-Powered Digital Devices |
|---|---|
|
Use Scenario: Handheld multimeter with dual rail (3.3V logic + 8.5V analog front-end) powered by 2-cell Li-ion battery (6–8.4V). IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller generating isolated, tightly regulated outputs with minimal input ripple and extended battery life. Use Value: 170µA IQ preserves battery capacity during standby; out-of-phase operation reduces input cap count and board area by 30%. |
Use Scenario: Portable medical sensor node requiring 3.3V microcontroller supply and 5V USB charging interface from single 7.4V battery pack. IC Role / Device Role / Timing Role: Dual-channel DC/DC controller delivering independent, soft-started outputs with PGOOD sequencing for safe boot and fault isolation. Use Value: Adjustable soft-start (SS1/SS2) prevents inrush current; latchoff protection avoids thermal damage during accidental short-circuit during field use. |
| Distributed DC Power Systems | Notebook & Palmtop Computers |
|
Use Scenario: Rack-mounted industrial IoT gateway with 12V backplane supplying 3.3V SoC core and 1.8V memory rails. IC Role / Device Role / Timing Role: High-efficiency dual-phase controller supporting wide 4–24V input range and phase-lockable frequency for EMI reduction in dense layouts. Use Value: 75–850kHz sync capability enables spread-spectrum alignment with other system clocks; DCR sensing eliminates current-sense resistor losses. |
Use Scenario: Ultrabook motherboard requiring compact, high-density 1.2V CPU core and 5V peripheral supplies from 19V adapter input. IC Role / Device Role / Timing Role: Dual-phase controller with 5mm × 5mm QFN package enabling high-power density; supports burst mode for silent operation during light loads. Use Value: 99.4% max duty cycle maintains regulation down to 1.2V output at 19V input; OPTI-LOOP® simplifies layout validation across multiple board revisions. |
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 |
|---|---|---|---|
| LTC3868EUH#PBF | Same silicon, rated for 0°C to 85°C ambient (vs. –40°C to 85°C for LTC3868IUH#PBF); identical pinout, specs, and functionality. | Suitable for commercial-grade portable devices without extended temperature requirements. | Select when full industrial temperature range is not required and cost sensitivity favors E-grade. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers but no EXTVCC option; fixed 0.6V reference; lacks OPTI-LOOP® and latchoff protection. | Targeted at cost-sensitive consumer electronics where simplified design outweighs advanced protection features. | Choose only if board space is extremely constrained and latchoff/soft-start flexibility is non-critical. |
Compared with LTC3868EUH#PBF, the LTC3868IUH#PBF guarantees full –40°C to 85°C operation without derating, while MP2918GL-Z trades robust fault handling and compensation flexibility for integration density-making LTC3868IUH#PBF preferred for mission-critical portable instrumentation and industrial edge devices.
Availability
LTC3868IUH#PBF is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered digital devices, and distributed DC power systems requiring stable component supply, long-term lifecycle support, and guaranteed industrial-temperature performance.
Supply support for LTC3868IUH#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 LTC3868IUH#PBF belongs to Linear's high-efficiency DC/DC controller product line, designed specifically for dual-phase, low-IQ, wide-input-voltage power conversion in space- and energy-constrained portable and embedded systems.
FAQ
What is the operating temperature range of the LTC3868IUH#PBF?
The LTC3868IUH#PBF is specified and guaranteed over the full –40°C to +85°C ambient temperature range. This industrial-grade rating ensures reliable startup, regulation, and protection functionality across extreme environmental conditions encountered in portable test equipment and outdoor edge devices - unlike the commercial-grade LTC3868EUH#PBF, which is only guaranteed from 0°C to 85°C.
How does the LTC3868IUH#PBF achieve low quiescent current in battery-powered applications?
The LTC3868IUH#PBF achieves 170µA quiescent current with one channel active through optimized biasing of internal references, error amplifiers, and gate drivers in sleep mode. Its 8µA shutdown current (both RUN pins <0.7V) further extends battery life. This low IQ is maintained across the full 4V–24V input range and enables multi-week operation in always-on sensor nodes without compromising regulation accuracy or transient response.
Can the LTC3868IUH#PBF synchronize to an external clock, and what is the supported frequency range?
Yes, the LTC3868IUH#PBF supports external synchronization via the PLLIN/MODE pin. When driven with a clean CMOS clock signal, it locks the rising edge of TG1 to the rising edge of the external clock across a 75kHz to 850kHz range. This capability enables EMI reduction through frequency alignment and facilitates multi-phase power supply coordination in complex systems - a feature not available in many competing dual controllers.
What protection features does the LTC3868IUH#PBF provide against output short circuits?
The LTC3868IUH#PBF provides dual-layer short-circuit protection: (1) foldback current limiting that progressively reduces peak current as output voltage drops below 72% of nominal, and (2) independent per-channel short-circuit latchoff triggered when SS pin voltage decays from ≥2V to ≤1.5V. This combination prevents thermal runaway while allowing safe restart after fault clearance - critical for unattended portable instrumentation.
Does the LTC3868IUH#PBF support DCR current sensing, and how is it configured?
Yes, the LTC3868IUH#PBF fully supports DCR current sensing via its differential SENSE+ and SENSE− inputs. The controller measures voltage across the inductor's DCR and compares it to a programmable threshold (22–86mV, set by ILIM pin). This eliminates the power loss and board area penalty of discrete current-sense resistors - especially valuable in high-current, high-efficiency applications like notebook CPU VRMs where thermal management is critical.
LTC3868IUH#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)
LTC3868IUH#PBF FAQ
1.How can I place an order for LTC3868IUH#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3868IUH#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 LTC3868IUH#PBF reliable?
The price and inventory of LTC3868IUH#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3868IUH#PBF is usually 5 days.
3.What payment methods are accepted for LTC3868IUH#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3868IUH#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3868IUH#PBF?
LTC3868IUH#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3868IUH#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 LTC3868IUH#PBF?
For technical support, including LTC3868IUH#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3868IUH#PBF requirements.
6.How does Aetrix verify that LTC3868IUH#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3868IUH#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 LTC3868IUH#PBF meets industry standards.
7.What is the process for return or replacement of LTC3868IUH#PBF?
All LTC3868IUH#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3868IUH#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 LTC3868IUH#PBF part is unused and in its original packaging.
Return procedure for LTC3868IUH#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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