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Analog Devices Inc. LTC3869EUFD#PBF
- Part No.:
- LTC3869EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3869EUFD#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:376
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Product details
Overview
LTC3869EUFD#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 operates with phase-locked constant-frequency current mode control up to 780 kHz, delivers ±0.75% output voltage accuracy at 0.6 V, supports 4 V–38 V input and 0.6 V–12.5 V output ranges, and minimizes input capacitor ESR noise via 180° out-of-phase operation - used in high-efficiency server and telecom power supplies.
For engineers reviewing the LTC3869EUFD#PBF datasheet, LTC3869EUFD#PBF pinout, LTC3869EUFD#PBF application, or LTC3869EUFD#PBF equivalent, key selection considerations include dual-channel current matching tolerance, RSENSE/DCR sensing flexibility, OPTI-LOOP® compensation tuning, MODE/PLLIN programmable operating modes (Burst/Pulse-Skipping/Continuous), and thermal performance of the 4 mm × 5 mm QFN package with exposed SGND pad.
Technical Context
The LTC3869EUFD#PBF implements a dual-channel, constant-frequency current-mode architecture with independent error amplifiers (EA), transconductance gm = 2 mmho, and ITH-based peak-current control per phase. Each channel features dedicated TK/SS pins for independent soft-start ramping or tracking, and a MODE/PLLIN pin enabling synchronization to external clocks or selection among Burst Mode®, pulse-skipping, or forced continuous conduction.
It integrates dual N-channel gate drivers with TG/BG rise/fall times ≤25 ns, minimum on-time of 90 ns, and internal 5 V INTVCC regulator (4.8 V–5.2 V, ±2% load regulation). Input undervoltage lockout (UVLO) triggers at 3.2 V with 0.6 V hysteresis, and output overvoltage protection activates when VFB deviates >±10% from setpoint.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4 V to 38 V - accommodates 12 V/24 V industrial rails and multi-cell Li-ion battery inputs without external pre-regulation. |
| Output Voltage Range | 0.6 V to 12.5 V - supports core logic (0.6 V–1.8 V), I/O (3.3 V), and intermediate bus (5 V, 12 V) generation. |
| Feedback Accuracy | ±0.75% at 0.6 V - ensures tight regulation under load transients and temperature variation across –40°C to 125°C. |
| Switching Frequency | 250 kHz to 780 kHz (phase-lockable) - enables optimization of size vs. efficiency; 180° phasing reduces input ripple current by ~70%. |
| Current Sensing | RSENSE or DCR - flexible sensing supports low-loss inductor-based designs or precision shunt-based current limiting. |
| Thermal Performance | θJA = 34°C/W (UFD package) - requires exposed SGND pad soldering to PCB for rated junction temperature (125°C max). |
| Protection Features | Foldback current limiting, output overvoltage lockout (±10%), and power-good monitoring - enables robust system-level fault handling without external circuitry. |
Pinout & Package
The LTC3869EUFD#PBF is housed in a 28-lead, 4 mm × 5 mm plastic QFN package (UFD) with an exposed SGND pad (Pin 29) that must be soldered to PCB ground for electrical integrity and thermal performance (θJA = 34°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 (Pins 26, 9) | Channel enable control inputs | Independent shutdown: <1.2 V disables respective channel; internal 1 µA pull-up enables restart; logic-compatible interface. |
| VFB1, VFB2 (Pins 3, 4) | Error amplifier feedback inputs | Remote sense points for 0.6 V reference; ±15 nA bias current enables high-impedance resistor dividers. |
| ITH1, ITH2 (Pins 2, 5) | Error amplifier output / current threshold control | Directly sets peak inductor current; gm = 2 mmho enables stable loop compensation across wide COUT/ESR range. |
| TK/SS1, TK/SS2 (Pins 1, 6) | Soft-start and tracking inputs | 1.2 µA internal charge current ramps voltage for controlled VOUT rise; supports master-slave voltage sequencing. |
| MODE/PLLIN (Pin 24) | Operating mode select & sync input | SGND = forced continuous; INTVCC = pulse-skipping; float = Burst Mode®; external clock synchronizes both phases. |
| FREQ (Pin 25) | Oscillator frequency programming | 10 µA sink current - resistor to SGND sets fSW from 250 kHz to 780 kHz; DC voltage override enables dynamic frequency scaling. |
| TG1, TG2 (Pins 22, 14) | Top gate driver outputs | Floating N-channel drivers with 2.6 Ω pull-up / 1.5 Ω pull-down - drive high-side MOSFET gates referenced to SW nodes. |
| BG1, BG2 (Pins 20, 17) | Bottom gate driver outputs | PGND-referenced N-channel drivers with 2.4 Ω pull-up / 1.1 Ω pull-down - optimized for fast turn-on/turn-off of low-side FETs. |
| SENSE1+/–, SENSE2+/– (Pins 27/28, 8/7) | Differential current sense inputs | Supports bidirectional DCR networks or precision shunts; ±2 mV channel mismatch ensures balanced multiphase current sharing. |
| PGOOD (Pin 12) | Open-drain power-good indicator | Asserts low after 20 µs mask timer if either VOUT deviates >±10%; enables system power sequencing and fault reporting. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased controllers | Reduces RMS input capacitor current by ~70%, enabling smaller, lower-cost bulk capacitance and lower EMI in high-current supplies. |
| OPTI-LOOP® compensation | Allows single compensation network to stabilize loops across wide output capacitor values (10 µF–1000 µF) and ESR ranges (0.5 mΩ–50 mΩ). |
| RSENSE or DCR current sensing | Eliminates need for separate current-sense resistors in high-efficiency designs; DCR sensing preserves conversion efficiency while supporting accurate current limiting. |
| Accurate multiphase current matching | ≤2 mV inter-channel VSENSE(MAX) mismatch ensures balanced thermal loading and derating margin in parallel-phase configurations. |
| Three selectable light-load modes | Burst Mode® (highest efficiency), pulse-skipping (low ripple/audio noise), or forced continuous (lowest output ripple) - configurable per system requirements. |
| Integrated 5 V INTVCC regulator | Delivers up to 100 mA at 4.8–5.2 V with ±2% load regulation - powers internal logic and gate drivers without external LDO. |
Applications
| Server VR13/VR14 Core Power | Telecom Intermediate Bus Converter |
|---|---|
Use Scenario: Dual-phase 1.8 V/15 A CPU core supply in rack-mounted servers requiring tight transient response and thermal balance. IC Role / Device Role / Timing Role: Dual-channel synchronous buck controller managing two interleaved 180°-phased power stages with independent ITH loop control and OPTI-LOOP® compensation. Use Value: 180° phasing cuts input ripple current amplitude by ~70%, reducing bulk capacitor count and board area; ±0.75% VOUT accuracy maintains CPU stability under dynamic load steps. |
Use Scenario: 48 V-to-12 V/20 A intermediate bus converter in 5G base station power systems with strict efficiency and thermal constraints. IC Role / Device Role / Timing Role: High-voltage dual-phase controller operating at 450 kHz with RSENSE sensing, EXTVCC bypass, and thermal-aware layout using exposed SGND pad. Use Value: 4 V–38 V input range accepts wide-range telecom rectified inputs; 95% peak efficiency at full load reduces heatsink requirements; phase-locking enables synchronized downstream converters. |
| Industrial PLC I/O Power | Medical Imaging System Auxiliary Supply |
Use Scenario: 24 V-to-3.3 V/5 A and 24 V-to-5 V/5 A dual-output supply for programmable logic controller I/O modules requiring precise sequencing and fault reporting. IC Role / Device Role / Timing Role: Dual independent buck controller with TK/SS tracking, PGOOD monitoring, and RUN-pin enable/disable for safe hot-swap and firmware-controlled power-up. Use Value: Independent soft-start via TK/SS pins enables controlled voltage ramping; open-drain PGOOD signals system host before enabling downstream loads; –40°C to 125°C rating supports harsh environments. |
Use Scenario: Low-noise, high-reliability 28 V-to-1.2 V/10 A supply for FPGA-based image processing in portable MRI subsystems. IC Role / Device Role / Timing Role: Dual-phase current-mode controller configured in forced continuous mode to suppress audible noise and minimize output ripple affecting analog signal chains. Use Value: Pulse-skipping or forced CCM eliminates sub-harmonic switching artifacts; ±0.75% output accuracy ensures consistent ADC reference stability; DCR sensing avoids shunt resistor losses in compact 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 |
|---|---|---|---|
| LTC3850EUF#PBF | Pin-compatible predecessor; fixed 500 kHz fSW; no MODE/PLLIN programmability; lacks EXTVCC bypass and ILIM-selectable current limit. | Lower feature set limits flexibility in burst-mode efficiency optimization and external clock synchronization. | Select when legacy design reuse is prioritized and advanced light-load modes are unnecessary. |
| MP2918GL-Z | Monolithic dual-phase controller (integrated MOSFETs); 4.5 V–16 V VIN; 0.6 V–5.5 V VOUT; no DCR sensing; fixed 600 kHz fSW. | Not suitable for high-input-voltage (>16 V) or high-output-current (>20 A) applications due to integrated FET thermal limits. | Select for space-constrained, medium-power (<100 W) designs where board area outweighs efficiency and voltage range flexibility. |
Compared with LTC3850EUF#PBF and MP2918GL-Z, the LTC3869EUFD#PBF provides wider input voltage (4 V–38 V), programmable operating modes, DCR/RSENSE flexibility, and superior thermal management via exposed-pad QFN - making it optimal for high-reliability, high-efficiency, and high-voltage industrial and telecom power systems.
Availability
LTC3869EUFD#PBF is available at Aetrix Electronics and suitable for server systems, telecom infrastructure, and industrial PLC power supplies requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC3869EUFD#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- and industrial-grade qualification.
The LTC3869EUFD#PBF belongs to Linear's high-efficiency multiphase controller product line, designed specifically for high-current, low-voltage DC/DC conversion in datacenter, telecom, and industrial applications demanding precision regulation and thermal resilience.
FAQ
What is the maximum switching frequency supported by the LTC3869EUFD#PBF?
The LTC3869EUFD#PBF supports a phase-lockable switching frequency up to 780 kHz, set via the FREQ pin using a resistor to SGND (10 µA sink current) or overridden by a DC voltage. This upper limit enables compact magnetics and reduced output ripple while maintaining stable current-mode control across the full 250 kHz–780 kHz range.
How does the LTC3869EUFD#PBF achieve accurate current sharing between its two phases?
The LTC3869EUFD#PBF achieves accurate current sharing through matched current-sense comparator thresholds (≤2 mV inter-channel VSENSE(MAX) mismatch) and independent ITH control loops. When configured in multiphase mode with tied ITH, VFB, and TK/SS pins, it maintains balanced channel currents under dynamic load conditions - critical for thermal derating in high-power applications.
Can the LTC3869EUFD#PBF operate with only one phase active?
Yes, the LTC3869EUFD#PBF supports independent channel control: pulling RUN1 low disables Channel 1 while Channel 2 remains operational, and vice versa. This allows flexible power staging, redundancy, or partial-load operation - useful in systems requiring graceful degradation or dynamic power scaling.
What is the role of the EXTVCC pin on the LTC3869EUFD#PBF?
The EXTVCC pin on the LTC3869EUFD#PBF enables efficient bypass of the internal 5 V INTVCC linear regulator. When driven above 4.7 V (with 200 mV hysteresis), it closes an internal switch to power INTVCC directly - reducing heat dissipation and improving overall system efficiency, especially when powered from a clean, regulated auxiliary rail.
Does the LTC3869EUFD#PBF support DCR current sensing, and how is it implemented?
Yes, the LTC3869EUFD#PBF supports DCR current sensing via differential SENSE1+/– and SENSE2+/– inputs. A small RC network across the inductor's DCR provides a voltage proportional to inductor current; this is fed into the current comparators, eliminating shunt resistor losses and enabling high-efficiency, thermally optimized designs.
LTC3869EUFD#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)
LTC3869EUFD#PBF FAQ
1.How can I place an order for LTC3869EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3869EUFD#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 LTC3869EUFD#PBF reliable?
The price and inventory of LTC3869EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3869EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3869EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3869EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3869EUFD#PBF?
LTC3869EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3869EUFD#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 LTC3869EUFD#PBF?
For technical support, including LTC3869EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3869EUFD#PBF requirements.
6.How does Aetrix verify that LTC3869EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3869EUFD#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 LTC3869EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3869EUFD#PBF?
All LTC3869EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3869EUFD#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 LTC3869EUFD#PBF part is unused and in its original packaging.
Return procedure for LTC3869EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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