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Analog Devices Inc. LTC3869IUFD#PBF
- Part No.:
- LTC3869IUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3869IUFD#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:256
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Product details
Overview
LTC3869IUFD#PBF from Analog Devices (formerly Linear Technology) is a dual, 2-phase synchronous step-down DC/DC controller driving all-N-channel MOSFET stages. It delivers ±0.75% output voltage accuracy at 0.6V, supports 4V–38V input and 0.6V–12.5V output ranges, operates up to 780kHz with phase-lockable frequency, and minimizes input ripple via 180° out-of-phase operation - used in high-power server and telecom power supplies.
For engineers reviewing the LTC3869IUFD#PBF datasheet, LTC3869IUFD#PBF pinout, LTC3869IUFD#PBF application, or LTC3869IUFD#PBF equivalent, key selection considerations include dual-phase current matching accuracy, RSENSE/DCR sensing flexibility, OPTI-LOOP® compensation for wide output capacitor/ESR tolerance, foldback current limiting, and independent soft-start/tracking control per channel.
Technical Context
The LTC3869IUFD#PBF implements constant-frequency current-mode control with two independent 180°-phased channels, each featuring an error amplifier (EA), current comparator (ICMP), slope compensation, and anti-shoot-through logic. Its OPTI-LOOP® architecture dynamically adjusts loop response based on output capacitance and ESR, enabling stable regulation across diverse ceramic/polymer capacitor selections without external compensation redesign.
It integrates dual N-channel gate drivers (TG/BG) with 2.6Ω/1.5Ω pull-up/down RDS(ON), internal 5V INTVCC LDO (4.8–5.2V), and programmable current limit thresholds (25–82mV) selectable via ILIM pin configuration. The MODE/PLLIN pin enables selection among Burst Mode®, pulse-skipping, or forced continuous conduction - critical for optimizing light-load efficiency versus output ripple in multi-rail systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports 12V/24V industrial buses and wide-range battery inputs (e.g., 4S–10S Li-ion). |
| Output Voltage Accuracy | ±0.75% at 0.6V - ensures tight regulation for low-voltage ASIC/FPGA core rails requiring sub-15mV tolerance. |
| Switching Frequency | 250kHz to 780kHz, phase-lockable - enables EMI reduction via synchronization and optimized magnetics sizing. |
| Current Sensing | RSENSE or DCR - eliminates sense resistor losses in high-current designs while maintaining ±2mV channel mismatch. |
| Thermal Performance | θJA = 34°C/W (UFD package) - supports >5A per phase operation with standard 2-layer PCB and exposed pad soldering. |
| Protection Features | Foldback current limiting, output overvoltage lockout (±10%), and undervoltage lockout (3.2V) - prevents MOSFET thermal runaway and system fault propagation. |
| Soft-Start Control | Independent TK/SS1 & TK/SS2 pins with 1.25µA charge current - enables precise ramp rate setting or supply tracking for sequenced power-up. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN (UFD), exposed thermal pad (Pin 29) connected to SGND - requires soldering to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SGND (Pin 29) | Signal Ground Reference | Reference node for all small-signal circuitry (error amps, comparators); must be star-connected to PGND at single point to avoid noise coupling. |
| VIN (Pin 19) | Main Input Supply | Primary power source for INTVCC LDO and driver bias; requires local 0.1–1µF ceramic decoupling to PGND. |
| INTVCC (Pin 18) | Internal 5V Regulator Output | Powers control logic and gate drivers; requires ≥4.7µF low-ESR capacitor to PGND - not intended for external load sourcing. |
| TG1/TG2 (Pins 22,14) | Top Gate Driver Outputs | Floating high-side drivers with 2.6Ω pull-up/1.5Ω pull-down - drive N-MOSFET gates referenced to SW nodes; require bootstrap capacitors. |
| BG1/BG2 (Pins 20,17) | Bottom Gate Driver Outputs | Ground-referenced drivers for synchronous rectifiers; 2.4Ω pull-up/1.1Ω pull-down enables fast turn-on/turn-off of low-RDS(ON) MOSFETs. |
| SENSE1+/SENSE2+ (Pins 27,8) | Current Sense Positive Inputs | Accept DCR network or sense resistor voltage - enable lossless or precision current monitoring with configurable threshold (25–82mV). |
| MODE/PLLIN (Pin 24) | Operating Mode & Sync Input | Selects Burst Mode® (float), pulse-skipping (INTVCC), or forced CCM (SGND); also accepts external clock for phase synchronization. |
| FREQ (Pin 25) | Frequency Setting Input | 10µA current sink - connect resistor to SGND to set switching frequency from 250kHz to 780kHz with ±10% tolerance. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces RMS input capacitor current by ~30% and lowers conducted EMI vs. single-phase designs at same total output current. |
| OPTI-LOOP® compensation | Automatically adapts loop bandwidth and phase margin to match actual output capacitor ESR and capacitance - eliminates trial-and-error compensation. |
| Accurate multiphase current sharing | ≤2mV inter-channel VSENSE(MAX) mismatch ensures balanced thermal loading between phases - critical for long-term reliability in 50A+ supplies. |
| Independent soft-start & tracking | Separate TK/SS1/TK/SS2 pins allow staggered startup or precise voltage ramp alignment with other rails - essential for FPGA/ASIC sequencing. |
| Three-mode light-load optimization | Burst Mode® (highest efficiency), pulse-skipping (low ripple), or forced CCM (lowest noise) - selectable per system requirement without hardware change. |
Applications
| Server VR13 Core Power | Telecom Base Station Bias Rails |
|---|---|
|
Use Scenario: Dual-phase 1.8V/15A core supply for high-end Xeon or AMD EPYC processors with dynamic load steps up to 100A/µs. IC Role / Device Role / Timing Role: Dual-channel synchronous buck controller managing parallel inductor currents, providing fast transient response via OPTI-LOOP® and current-mode stability. Use Value: Achieves >92% efficiency at full load and maintains <±1% regulation during 5A–15A load transients - reducing thermal design burden and enabling compact 2-oz copper layouts. |
Use Scenario: Dual-output 5V/3.3V power for RF front-end modules and baseband processors in 4G/5G macrocells with strict EMI limits. IC Role / Device Role / Timing Role: Phased controller minimizing input ripple and enabling spread-spectrum synchronization via MODE/PLLIN pin to avoid band-specific interference. Use Value: 180° phase shift cuts peak input current by 40%, easing compliance with EN55022 Class B conducted emissions - no additional input filter required. |
| Industrial PLC I/O Power | Medical Imaging Detector Bias |
|
Use Scenario: Isolated 24V-to-5V/3.3V conversion for programmable logic controller digital I/O modules operating in harsh 0°C–70°C ambient. IC Role / Device Role / Timing Role: Dual-controller managing separate 5V logic and 3.3V interface rails with independent RUN/TK-SS control for safe power sequencing. Use Value: Independent shutdown (RUN1/RUN2) and tracking (TK/SS1/TK/SS2) enable fail-safe power-up/down sequences - preventing latch-up in mixed-voltage FPGA interfaces. |
Use Scenario: Low-noise ±12V analog bias supply for CT/PET detector ASICs requiring <10µVpp ripple and zero reverse inductor current. IC Role / Device Role / Timing Role: Controller configured in Burst Mode® with DCR sensing to eliminate sense resistor thermal drift and maintain sub-0.1% line/load regulation. Use Value: Burst Mode® operation reduces light-load power loss to <15mW per channel - extending thermal hold time in air-cooled enclosures during standby. |
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 |
|---|---|---|---|
| LTC3850EUFD#PBF | Pin-compatible predecessor; fixed 500kHz frequency, no ILIM-selectable current limit, no EXTVCC support. | Lacks programmable light-load modes and flexible current sensing - limited to fixed-frequency, medium-efficiency designs. | Select when legacy layout reuse is critical and advanced features like Burst Mode® or DCR sensing are unnecessary. |
| MP8765GL-Z | Single-chip dual-phase controller with integrated MOSFETs; 4.5V–16V input; no ILIM pin; lower max frequency (1MHz). | Eliminates external MOSFETs but restricts input range and lacks independent channel control - unsuitable for 24V+ or asymmetric rail designs. | Select for cost-sensitive, space-constrained 12V-input applications where integration outweighs flexibility needs. |
Compared with LTC3850EUFD#PBF, the LTC3869IUFD#PBF adds phase-lockable frequency, three light-load modes, and ILIM-programmable current limits - enabling higher efficiency and broader input range. Versus MP8765GL-Z, it offers discrete MOSFET control, wider VIN, and independent channel management - essential for high-reliability, high-input-voltage systems.
Availability
LTC3869IUFD#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom power shelves, industrial PLCs, and medical imaging systems requiring stable component supply, long lifecycle support, and guaranteed parametric performance across –40°C to 125°C junction temperature.
Supply support for LTC3869IUFD#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, emphasizing precision, efficiency, and robustness for mission-critical applications.
The LTC3869IUFD#PBF belongs to Linear's PolyPhase® controller family, designed specifically for high-current, multi-phase DC/DC conversion in datacenter, communications, and industrial infrastructure where thermal density and transient response are paramount.
FAQ
What is the maximum supported switching frequency for LTC3869IUFD#PBF?
The LTC3869IUFD#PBF supports a phase-lockable switching frequency range of 250kHz to 780kHz. This is set via the FREQ pin using an external resistor to SGND, with typical nominal frequency at 500kHz when FREQ is biased at 1.2V. Operation above 780kHz is not guaranteed and may compromise stability or gate drive strength.
Does LTC3869IUFD#PBF support both RSENSE and DCR current sensing?
Yes, the LTC3869IUFD#PBF supports both RSENSE (shunt resistor) and DCR (inductor winding resistance) current sensing methods. The SENSE1+/SENSE1− and SENSE2+/SENSE2− pins accept either topology, and the ILIM pin configures the current limit threshold (25mV/50mV/75mV) independently for each channel - enabling optimal trade-offs between accuracy and conduction loss.
How does the OPTI-LOOP® compensation in LTC3869IUFD#PBF improve design flexibility?
OPTI-LOOP® compensation in the LTC3869IUFD#PBF automatically adjusts loop dynamics to match the actual output capacitor's ESR and capacitance value - eliminating manual compensation network tuning. This allows seamless migration between ceramic, polymer, and hybrid output capacitors without redesigning feedback components, accelerating qualification for varying load profiles.
Can LTC3869IUFD#PBF operate with only one channel enabled?
Yes, the LTC3869IUFD#PBF supports independent channel control via RUN1 and RUN2 pins. Pulling RUN1 low disables Channel 1 while leaving Channel 2 fully operational - useful for asymmetric rail generation or redundancy schemes. Both channels share internal references and clocks but maintain separate ITH, VFB, and TK/SS paths.
What thermal performance can be expected from the UFD package of LTC3869IUFD#PBF?
The LTC3869IUFD#PBF in its 4mm × 5mm QFN package has θJA = 34°C/W when the exposed pad (Pin 29) is properly soldered to a minimum 1-in² copper area on the PCB. At 2W dissipation, this yields ~68°C rise above ambient - enabling reliable 5A-per-phase operation in industrial environments without forced airflow.
LTC3869IUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-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 ~ 38V
- Frequency - Switching:
- 250kHz ~ 780kHz
- Duty Cycle (Max):
- 95%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3869IUFD#PBF FAQ
1.How can I place an order for LTC3869IUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3869IUFD#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 LTC3869IUFD#PBF reliable?
The price and inventory of LTC3869IUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3869IUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3869IUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3869IUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3869IUFD#PBF?
LTC3869IUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3869IUFD#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 LTC3869IUFD#PBF?
For technical support, including LTC3869IUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3869IUFD#PBF requirements.
6.How does Aetrix verify that LTC3869IUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3869IUFD#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 LTC3869IUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3869IUFD#PBF?
All LTC3869IUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3869IUFD#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 LTC3869IUFD#PBF part is unused and in its original packaging.
Return procedure for LTC3869IUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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