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Analog Devices Inc. LTC3869IGN-2#PBF
- Part No.:
- LTC3869IGN-2#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3869IGN-2#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:611
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Product details
Overview
LTC3869IGN-2#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 from 4V to 38V input, delivers 0.6V–12.5V outputs with ±0.75% feedback accuracy, and supports phase-locked frequencies up to 780kHz. Used in high-efficiency server and telecom power supplies where input capacitance reduction and noise suppression are critical.
For engineers reviewing the LTC3869IGN-2#PBF datasheet, LTC3869IGN-2#PBF pinout, LTC3869IGN-2#PBF application, or LTC3869IGN-2#PBF equivalent, key selection factors include its SSOP-28 package, independent soft-start/tracking (TK/SS1/2), RSENSE/DCR current sensing, foldback current limiting, and MODE/PLLIN-selectable operating modes (Burst, pulse-skipping, or continuous conduction).
Technical Context
The LTC3869IGN-2#PBF implements constant-frequency current-mode control with two 180° out-of-phase channels, minimizing input ripple and EMI. Each channel features independent error amplifiers (ITH1/2, VFB1/2), programmable current limit via ILIM pin (GND/FLOAT/INTVCC), and OPTI-LOOP® compensation for transient optimization across wide output capacitance and ESR ranges.
It integrates dual N-channel gate drivers (TG1/TG2, BG1/BG2) with 25ns transition times, 5V INTVCC LDO, EXTVCC switchover at 4.7V, and PGOOD monitoring with ±10% output voltage window. The MODE/PLLIN pin enables external clock synchronization or mode selection without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports 12V/24V industrial buses and multi-cell Li-ion battery inputs without pre-regulation. |
| Output Voltage Range | 0.6V to 12.5V - covers core logic (0.6–1.8V), I/O (3.3V), and intermediate rails (5V, 12V) in single-controller dual-output designs. |
| Feedback Accuracy | ±0.75% at 0.6V - ensures tight regulation for low-voltage ASIC/FPGA cores under load transients. |
| Switching Frequency | 250kHz to 780kHz (phase-lockable) - enables compact magnetics while supporting synchronization to system clocks to avoid beat frequencies. |
| Current Sense Threshold | 45mV typical (ILIM = FLOAT) - sets precise overcurrent protection with minimal power loss in sense resistors or DCR networks. |
| Thermal Performance | θJA = 80°C/W (SSOP-28) - requires moderate PCB copper area for 125°C junction operation at full load in industrial ambient. |
| Shutdown Current | 30µA max - enables low-power standby in battery-backed systems without external enable sequencing. |
Pinout & Package
Package: 28-Lead Narrow Plastic SSOP (GN-2), 5.3mm × 10.2mm body, 0.635mm pitch, exposed pad not present - suitable for automated assembly and thermal management via PCB trace conduction.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| RUN1 / RUN2 | Independent channel enable inputs | Pull below 1.2V to disable respective channel; internal 1µA pull-up allows simple RC soft-start sequencing. |
| VFB1 / VFB2 | Feedback inputs for output voltage regulation | Connect to resistor dividers; ±0.75% accuracy referenced to 0.6V internal bandgap enables precision rail generation. |
| TK/SS1 / TK/SS2 | Soft-start and tracking inputs | Internal 1.2µA current charges external capacitor for linear voltage ramp; also accepts master supply voltage for coordinated startup. |
| MODE/PLLIN | Operating mode selector & PLL sync input | Ground = forced CCM; INTVCC = pulse-skipping; float = Burst Mode; external clock = synchronization source. |
| FREQ | Frequency setting terminal | 10µA sink current - connect resistor to SGND to set frequency (e.g., 100kΩ → ~500kHz); voltage control also supported. |
| ILIM | Current limit threshold select | Three levels (GND/FLOAT/INTVCC) set VSENSE(MAX) to 45mV/50mV/55mV - adjusts OCP sensitivity without changing sense resistor. |
| TG1 / TG2 | Top gate driver outputs | Drive high-side N-MOSFET gates with floating bootstrap supply; 2.6Ω pull-up / 1.5Ω pull-down ensures fast turn-on/turn-off. |
| BG1 / BG2 | Bottom gate driver outputs | Drive low-side N-MOSFET gates referenced to PGND; 2.4Ω pull-up / 1.1Ω pull-down minimizes conduction losses. |
| SENSE1+/– / SENSE2+/– | Differential current sense inputs | Accept RSENSE or DCR-based sensing; ±2µA bias current enables accurate high-side or low-side placement. |
| PGOOD | Open-drain power-good indicator | Asserts low when either output deviates >±10% from target after 20µs debounce - used for system power sequencing. |
Key Features
| Feature | Design Value |
|---|---|
| 180° out-of-phase dual control | Reduces RMS input capacitor current by ~30% and suppresses fundamental input ripple, lowering required bulk capacitance. |
| OPTI-LOOP® compensation | Enables stable loop response across 10× variation in output capacitance and ESR - eliminates re-tuning when changing ceramic/tantalum mix. |
| Accurate multiphase current matching | Channel-to-channel VSENSE mismatch ≤2mV ensures balanced load sharing and equal thermal stress between phases. |
| Programmable current foldback | Reduces MOSFET conduction loss during short-circuit by lowering peak current limit - improves reliability under fault conditions. |
| Independent soft-start and tracking | Enables staggered or synchronized startup of dual outputs - prevents inrush current stacking and meets FPGA/ASIC power sequencing requirements. |
Applications
| Server VRM | Telecom Intermediate Bus |
|---|---|
Use Scenario: Dual-output 1.8V/1.2V power for CPU core and I/O domains in 1U rack servers. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent voltage rails with coordinated soft-start and current balancing. Use Value: Achieves >92% efficiency at 5A per rail while reducing input capacitor count by 40% versus single-phase solutions. |
Use Scenario: 5V/3.3V dual-rail conversion from 48V intermediate bus in optical line cards. IC Role / Device Role / Timing Role: High-input-voltage dual controller enabling efficient point-of-load regulation with minimal board space. Use Value: Wide 4V–38V input range accommodates 48V bus derating; phase interleaving cuts EMI filter size by 35%. |
| Industrial PLC Power | Battery-Powered Medical Instrument |
Use Scenario: Dual 5V/3.3V supplies powering microcontroller, analog front-end, and isolated communication interfaces. IC Role / Device Role / Timing Role: Robust dual controller with UVLO (3.2V), OVP, and PGOOD monitoring for safety-critical industrial power sequencing. Use Value: ±0.75% output accuracy maintains ADC reference stability; EXTVCC support enables self-powered operation from first-stage output. |
Use Scenario: Dual 3.3V/1.8V rails for portable ultrasound processor and sensor interface powered by 2S Li-ion battery (6–8.4V). IC Role / Device Role / Timing Role: Low-quiescent-current dual controller with Burst Mode operation extending battery runtime at light loads. Use Value: 30µA shutdown current and selectable light-load modes deliver >85% efficiency at 10mA load - doubling standby time. |
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 |
|---|---|---|---|
| LTC3850IGN#PBF | Pin-compatible with LTC3869 but lacks ILIM pin and programmable current foldback; fixed 50mV current limit. | Less flexible OCP tuning in high-reliability systems requiring adjustable short-circuit response. | Choose LTC3850 only if simplified current limit and lower cost outweigh need for foldback protection. |
| MP2918GL-Z | Monolithic dual-phase controller (integrated MOSFETs); 4.5V–18V input; no EXTVCC or TK/SS tracking capability. | Not suitable for >18V input or applications requiring external MOSFET selection, high efficiency at light load, or rail tracking. | Select MP2918 only for space-constrained 12V-input designs where integration outweighs flexibility and voltage range. |
Compared with LTC3850IGN#PBF and MP2918GL-Z, the LTC3869IGN-2#PBF uniquely combines wide 4V–38V input, independent rail tracking, programmable current foldback, and phase synchronization - making it optimal for high-reliability, multi-rail industrial and telecom power systems.
Availability
LTC3869IGN-2#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom intermediate bus converters, and industrial PLC power supplies requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature.
Supply support for LTC3869IGN-2#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 full product support, documentation, and manufacturing continuity for all Linear ICs including the LTC3869 family.
The LTC3869 series was designed for high-efficiency, dual-output, multiphase DC/DC conversion in space-constrained, thermally demanding environments such as data center and communications infrastructure.
FAQ
What is the maximum input voltage rating for the LTC3869IGN-2#PBF?
The LTC3869IGN-2#PBF has an absolute maximum input voltage rating of 40V on the VIN pin. Its operational input range is specified from 4V to 38V, making it suitable for 24V industrial systems and 36V battery inputs with margin. Exceeding 40V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3869IGN-2#PBF support external clock synchronization?
Yes, the LTC3869IGN-2#PBF supports external clock synchronization via the MODE/PLLIN pin. When driven with a clean square wave within 210kHz–850kHz, the internal oscillator locks to the external clock, eliminating switching frequency beat notes in multi-converter systems. No external PLL components are required.
How does the ILIM pin affect current limiting on the LTC3869IGN-2#PBF?
The ILIM pin on the LTC3869IGN-2#PBF selects one of three maximum current sense thresholds: 45mV (FLOAT), 50mV (INTVCC), or 55mV (GND). This directly scales the overcurrent protection point without changing the sense resistor, enabling design flexibility for different MOSFET RDS(on) or inductor DCR values while maintaining accuracy.
Can the LTC3869IGN-2#PBF operate with only one channel enabled?
Yes, the LTC3869IGN-2#PBF supports independent channel control. Pulling RUN1 low disables Channel 1 while Channel 2 remains fully functional, and vice versa. Both channels share internal resources like INTVCC and oscillators, but regulation, current sensing, and soft-start remain fully isolated per channel.
What is the purpose of the TK/SS pins on the LTC3869IGN-2#PBF?
The TK/SS1 and TK/SS2 pins on the LTC3869IGN-2#PBF provide dual functionality: soft-start ramp generation (via internal 1.2µA current charging an external capacitor) and output voltage tracking (by applying a master rail's scaled voltage). This enables precise power sequencing for FPGAs and processors without external supervisors.
LTC3869IGN-2#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- 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:
- Yes
- 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-SSOP
LTC3869IGN-2#PBF FAQ
1.How can I place an order for LTC3869IGN-2#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3869IGN-2#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 LTC3869IGN-2#PBF reliable?
The price and inventory of LTC3869IGN-2#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3869IGN-2#PBF is usually 5 days.
3.What payment methods are accepted for LTC3869IGN-2#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3869IGN-2#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3869IGN-2#PBF?
LTC3869IGN-2#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3869IGN-2#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 LTC3869IGN-2#PBF?
For technical support, including LTC3869IGN-2#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3869IGN-2#PBF requirements.
6.How does Aetrix verify that LTC3869IGN-2#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3869IGN-2#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 LTC3869IGN-2#PBF meets industry standards.
7.What is the process for return or replacement of LTC3869IGN-2#PBF?
All LTC3869IGN-2#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3869IGN-2#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 LTC3869IGN-2#PBF part is unused and in its original packaging.
Return procedure for LTC3869IGN-2#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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