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Analog Devices Inc. LTC3868IUH#TRPBF
- Part No.:
- LTC3868IUH#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 32-WFQFN Exposed Pad
- Datasheet:
-
LTC3868IUH#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 32QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,738
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Product details
Overview
LTC3868IUH#TRPBF 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 battery-powered portable instruments requiring high efficiency and low-noise power conversion.
For engineers reviewing the LTC3868IUH#TRPBF datasheet, LTC3868IUH#TRPBF pinout, LTC3868IUH#TRPBF application, or LTC3868IUH#TRPBF equivalent, key selection criteria include dual-phase current-mode control, OPTI-LOOP® compensation for wide output capacitor ESR tolerance, phase-lockable 75kHz–850kHz switching frequency, RSENSE/DCR sensing flexibility, and independent soft-start with short-circuit latchoff protection.
Technical Context
The LTC3868IUH#TRPBF implements a constant-frequency current-mode architecture with two fully independent controllers operating 180° out of phase-reducing input capacitance requirements and minimizing supply-induced noise. Each channel features dedicated ITH, SS, VFB, SENSE+, SENSE−, PGOOD, and RUN pins, enabling asymmetric output configurations and independent fault management.
Its internal 5.1V INTVCC LDO can be powered from VIN or an external EXTVCC source ≥4.7V, improving system efficiency. The device supports three light-load modes-Burst Mode®, pulse-skipping, and forced continuous-selected via the PLLIN/MODE pin, and includes precision overvoltage protection (±10% trip at VFB), 99.4% max duty cycle for ultra-low dropout, and no current foldback during startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 24V - supports wide-input industrial and battery-based systems including 12V intermediate bus and multi-cell Li-ion packs. |
| VOUT Range | 0.8V to 14V - programmable via external resistor divider; enables generation of standard logic rails (1.2V, 1.8V, 3.3V, 5V, 8.5V, etc.) with ±12mV reference accuracy. |
| IQ (Sleep, 1 ch) | 170µA typical - extends runtime in always-on portable instrumentation and low-power embedded systems. |
| fSW Range | 75kHz to 850kHz (phase-lockable); 50kHz–900kHz (programmable) - allows optimization of size vs. efficiency and EMI compliance across diverse PCB layouts. |
| Current Sensing | RSENSE or DCR - eliminates need for dedicated sense resistors in high-current applications, reducing conduction loss and board space. |
| Protection Features | Output OVP (±10%), short-circuit latchoff, foldback limiting, UVLO (3.6V–4.2V), and PGOOD monitoring - ensures robust operation under fault conditions without external supervision. |
| Package | 32-lead 5mm × 5mm QFN with exposed thermal pad (Pin 33 = SGND) - provides low thermal resistance (θJA = 34°C/W) for high-power density designs. |
Pinout & Package
Package: 32-lead (5mm × 5mm) plastic QFN with exposed thermal pad (Pin 33 = SGND). Must be soldered to PCB for rated thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SENSE1−, SENSE2− (1, 9) | Differential current comparator (−) input | Supplies bias current when > INTVCC − 0.5V; sets current-sense common-mode range for accurate DCR/RSENSE measurement. |
| FREQ (2) | VCO frequency control | Resistor-to-GND sets fSW from 50kHz–900kHz; GND = 350kHz, INTVCC = 535kHz - enables precise EMI tuning and layout optimization. |
| PHASMD (3) | Phase relationship selector | Configures TG2/CLKOUT phase offset vs. TG1 (180°/60°, 240°/120°, or 180°/90°) - critical for multiphase interleaving and noise cancellation. |
| CLKOUT (4) | Synchronization clock output | Drives daisy-chained controllers; swing = INTVCC to GND - enables scalable multi-phase designs beyond dual-channel. |
| PLLIN/MODE (5) | Sync input / light-load mode select | Accepts external clock (75–850kHz) or selects Burst Mode® (GND), pulse-skipping (1.2–3.7V), or forced CCM (INTVCC). |
| SGND (6, 33) | Small-signal ground reference | Must be routed separately from PGND; exposed pad (33) is SGND - prevents noise coupling into feedback and current-sense paths. |
| RUN1, RUN2 (7, 8) | Independent channel enable | <1.26V disables one channel; both <0.7V enters 8µA shutdown - supports dynamic power sequencing and rail isolation. |
| BOOST1, BOOST2 (17, 24) | Top-gate bootstrap supplies | Voltage swing = INTVCC to (VIN + INTVCC); requires external Schottky diode and capacitor - enables high-side N-MOSFET drive. |
| TG1, TG2 (15, 26) | Top N-MOSFET gate drivers | Floating outputs with 25ns rise/16ns fall time (3300pF load); drives gate charge efficiently up to 850kHz - minimizes switching loss. |
| BG1, BG2 (18, 23) | Bottom N-MOSFET gate drivers | Pull-up/down RON = 2.4Ω/1.1Ω; fast transition (28ns/13ns) - ensures low conduction loss and tight dead-time control. |
| VIN (22) | Main input supply | Accepts 4V–24V; powers internal LDO and logic - serves as primary power source unless EXTVCC is active. |
| EXTVCC (20) | External INTVCC supply input | Enables INTVCC sourcing from efficient secondary rail (e.g., 5V output) when ≥4.7V - improves overall system efficiency by bypassing VIN LDO. |
| PGOOD1, PGOOD2 (14, 27) | Open-drain power-good indicators | Assert low when VFB deviates >±10% from 0.8V; 25µs fault delay - provides reliable rail monitoring for FPGA/CPU sequencing. |
| SS1, SS2 (13, 29) | Soft-start and short-circuit timer | Internal 1µA pull-up charges external capacitor; voltage ramp controls VOUT rise; >2V arms latchoff, <1.5V triggers shutdown - integrates startup control and fault response. |
| ITH1, ITH2 (12, 30) | Error amplifier output / current limit control | Voltage sets peak inductor current threshold; direct interface to compensation network - enables OPTI-LOOP® transient optimization. |
| VFB1, VFB2 (11, 31) | Feedback voltage inputs | Compare output divider voltage to 0.8V reference; ±50nA input bias - supports high-impedance dividers for low quiescent current. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop response across wide range of output capacitor values and ESR - eliminates need for iterative compensation redesign when changing bulk capacitance. |
| Out-of-Phase Dual Control | 180° phase shift between channels cuts input ripple current by ~70% - reduces required input capacitance and lowers EMI emissions. |
| Independent Soft-Start & Fault Management | Separate SS1/SS2 pins enable staggered rail ramp-up and per-channel short-circuit latchoff - prevents cascading failures in multi-rail systems. |
| Low-IQ Sleep Mode | 170µA IQ with one channel active - extends battery life in handheld test equipment and portable medical sensors without sacrificing responsiveness. |
| Programmable Light-Load Operation | Burst Mode®, pulse-skipping, or forced CCM selectable per design needs - balances efficiency, output ripple, and acoustic noise in sensitive applications. |
| Robust Protection Suite | Includes OVP, UVLO, short-circuit latchoff, foldback limiting, and PGOOD - enables unattended operation in industrial edge nodes and remote data loggers. |
Applications
| Portable Instrumentation | Notebook Power Systems |
|---|---|
|
Use Scenario: Handheld oscilloscopes and multimeters requiring isolated 3.3V digital and 8.5V analog rails from a single Li-ion battery pack. IC Role / Device Role / Timing Role: Dual-phase controller generating tightly regulated, low-noise outputs with independent sequencing and fault containment. Use Value: 170µA sleep IQ extends battery runtime; out-of-phase operation minimizes conducted EMI on shared input bus; PGOOD signals enable safe MCU wake-up. |
Use Scenario: Embedded controller power in ultrabooks needing 3.3V for SoC I/O and 8.5V for display backlight, supplied from 12V main rail. IC Role / Device Role / Timing Role: High-efficiency dual buck controller with programmable fSW and OPTI-LOOP® for rapid load transients. Use Value: 99.4% max duty cycle maintains regulation during brownout; phase-lockable fSW simplifies EMI filtering; EXTVCC option improves overall system efficiency. |
| Battery-Powered Digital Devices | Distributed DC Power Systems |
|
Use Scenario: Portable ultrasound probes using 3.3V for FPGA and 8.5V for analog front-end, powered by 2S Li-ion (6–8.4V). IC Role / Device Role / Timing Role: Low-IQ dual controller supporting burst-mode operation to maintain µA-level standby current. Use Value: 8µA shutdown current enables long-term storage; independent RUN pins allow selective rail disable during sleep states; RSENSE/DCR flexibility reduces BOM cost. |
Use Scenario: Industrial IoT gateway with distributed 3.3V sensor interface and 8.5V RF module rails fed from 24V PoE-derived bus. IC Role / Device Role / Timing Role: Wide-VIN dual controller providing fault-isolated, high-reliability power with latchoff protection against field wiring faults. Use Value: 4V–24V input range accommodates PoE voltage drop and line transients; short-circuit latchoff prevents thermal runaway; CLKOUT enables synchronized multi-board timing. |
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 500kHz fSW; no phase modulation or CLKOUT; integrated MOSFET drivers only (no external FET support) | Targeted at compact, cost-sensitive consumer power; lacks independent channel control and programmable light-load modes | Select MP2918GL-Z only for space-constrained, single-rail applications where external FET flexibility and dual-phase synchronization are unnecessary. |
| LTC3855IUHF#PBF | Single-channel, 4-phase capable; supports up to 4-phase interleaving but no second independent output; higher IQ (250µA) | Optimized for high-current single-output rails (e.g., 12V CPU core); not suitable for asymmetric dual-rail generation | Choose LTC3855IUHF#PBF when designing high-current monorail systems requiring >20A output; avoid for dual-rail, low-IQ, or independent sequencing use cases. |
Compared with MP2918GL-Z and LTC3855IUHF#PBF, the LTC3868IUH#TRPBF uniquely delivers true dual independent outputs with programmable fSW, phase control, and sub-200µA sleep IQ - making it the only viable choice for portable instrumentation requiring asymmetric, fault-isolated, low-noise dual-rail power.
Availability
LTC3868IUH#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation, notebook computing, and battery-operated digital devices requiring stable component supply, extended temperature operation (–40°C to +85°C), and long-term industrial lifecycle support.
Supply support for LTC3868IUH#TRPBF 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 with rigorous automotive- and industrial-grade qualification.
The LTC3868IUH#TRPBF belongs to Linear's high-efficiency synchronous controller family, designed specifically for dual-rail, low-IQ, and noise-sensitive applications in portable and distributed power systems.
FAQ
What is the operating temperature range for the LTC3868IUH#TRPBF?
The LTC3868IUH#TRPBF is specified and guaranteed over the industrial temperature range of –40°C to +85°C. This rating is confirmed in the Absolute Maximum Ratings table and Electrical Characteristics notes, where all "l"-denoted specs apply across this full range. The device uses internal thermal protection and is packaged in a thermally enhanced 5mm × 5mm QFN with exposed SGND pad for reliable operation in demanding environments.
Does the LTC3868IUH#TRPBF support both RSENSE and DCR current sensing?
Yes, the LTC3868IUH#TRPBF supports both RSENSE and DCR current sensing methods. Its SENSE+ and SENSE− pins accept differential inputs from either discrete sense resistors or copper trace/inductor DCR networks. The maximum sense voltage threshold is configurable (22–86mV) via the ILIM pin, and the internal current comparators are optimized for low-offset, high-accuracy measurement in both configurations - enabling flexible, efficient current monitoring without added components.
How does the short-circuit latchoff function work on the LTC3868IUH#TRPBF?
The LTC3868IUH#TRPBF implements per-channel short-circuit latchoff using the SS1 and SS2 pins. Once the SS voltage exceeds 2V (arming threshold), a 9µA discharge current pulls SS down if VFB falls below 70% of regulation. If SS drops below 1.5V (latchoff threshold), the channel shuts down permanently until VIN or RUN is cycled. This behavior is documented in the Applications Information section and verified in Figure 1 and associated equations - providing fail-safe protection without external circuitry.
Can the LTC3868IUH#TRPBF synchronize to an external clock?
Yes, the LTC3868IUH#TRPBF supports external synchronization via the PLLIN/MODE pin. When an external clock signal (75kHz–850kHz) is applied, the internal phase-locked loop aligns the rising edge of TG1 with the rising edge of that clock. This capability is explicitly stated in the Features list, Electrical Characteristics (fSYNC parameter), and PIN FUNCTIONS description - enabling precise timing alignment across multiple power stages in complex systems.
What is the purpose of the EXTVCC pin on the LTC3868IUH#TRPBF?
The EXTVCC pin on the LTC3868IUH#TRPBF allows the internal 5.1V INTVCC regulator to be powered from an external source (≥4.7V) instead of VIN. When active, it disables the VIN-based LDO and engages a separate EXTVCC LDO - improving overall system efficiency by avoiding double-conversion losses. This feature is detailed in the "INTVCC/EXTVCC Power" section and Electrical Characteristics (VEXTVCC switchover = 4.5–4.9V), and is commonly used to power INTVCC from a clean, efficient secondary rail like the 5V output.
LTC3868IUH#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PolyPhase®
- Package/Case:
- 32-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC3868IUH#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3868IUH#TRPBF 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#TRPBF reliable?
The price and inventory of LTC3868IUH#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3868IUH#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3868IUH#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3868IUH#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3868IUH#TRPBF?
LTC3868IUH#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3868IUH#TRPBF 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#TRPBF?
For technical support, including LTC3868IUH#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3868IUH#TRPBF requirements.
6.How does Aetrix verify that LTC3868IUH#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3868IUH#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3868IUH#TRPBF?
All LTC3868IUH#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3868IUH#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LTC3868IUH#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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