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Analog Devices Inc. LTC3869IGN-2
- Part No.:
- LTC3869IGN-2
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3869IGN-2.pdf
- Description:
- IC POWER MANAGEMENT
- Quantity:
- Payment:
- Shipping:
Inventory:3,069
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Product details
Overview
LTC3869IGN-2 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 180° out-of-phase outputs (reducing input capacitance and noise), supports 4V–38V input, delivers 0.6V–12.5V output per channel, and features ±0.75% output voltage accuracy at 0.6V feedback reference. It is used in high-efficiency dual-rail power supplies for telecom base stations.
For engineers reviewing the LTC3869IGN-2 datasheet, LTC3869IGN-2 pinout, LTC3869IGN-2 application, or LTC3869IGN-2 equivalent, key selection criteria include phase-matched current sensing (≤2mV mismatch), programmable current limit via ILIM pin (30–82mV range), OPTI-LOOP® compensation for wide output capacitor/ESR tolerance, and support for Burst Mode®, pulse-skipping, or forced CCM operation.
Technical Context
The LTC3869IGN-2 implements a constant-frequency current-mode control architecture with independent error amplifiers (EA), transconductance gm = 2 mmho, and dual ITH pins for per-channel current threshold control. Its 250kHz–780kHz phase-lockable oscillator enables synchronization to external clocks via MODE/PLLIN.
It integrates dual N-channel gate drivers (TG/BG) with 25ns transition times, 30ns dead-time control, and internal 5V INTVCC LDO (4.8–5.2V, ±2% load regulation). The device uses RSENSE or DCR current sensing, supports coincident tracking via TK/SS pins, and includes foldback current limiting and output overvoltage protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - accommodates 12V/24V industrial rails and multi-cell Li-ion battery inputs without external pre-regulation. |
| Output Voltage Range | 0.6V to 12.5V - supports core logic (0.6–1.8V), I/O (3.3V), and auxiliary rails (5V, 12V) from single controller. |
| Feedback Voltage Accuracy | ±0.75% at 0.6V - ensures tight regulation of low-voltage CPU/GPU cores under load transients. |
| Switching Frequency Range | 250kHz to 780kHz - balances efficiency (lower f) vs. size (higher f); adjustable via FREQ pin's 10µA current sink. |
| Current Sense Threshold Range | 30mV to 82mV (ILIM-selectable) - enables precise MOSFET current limiting across temperature (-40°C to 125°C). |
| Channel Current Mismatch | ≤2mV - guarantees balanced phase current sharing in multiphase configurations, minimizing thermal stress on MOSFETs. |
| INTVCC Regulator | 5V ±2%, 100mA peak - powers internal logic and gate drivers; bypassed by EXTVCC ≥4.7V for higher efficiency. |
Pinout & Package
The LTC3869IGN-2 is housed in a 28-lead narrow plastic SSOP package (GN-2), with exposed pad not present (unlike QFN variants). Thermal resistance θJA = 80°C/W requires careful PCB copper area allocation for thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 (Pins 1,13) | Independent channel enable inputs | Pull below 1.2V to disable individual channel; 1µA internal pull-up enables soft-start sequencing. |
| VFB1, VFB2 (Pins 4,5) | Error amplifier feedback inputs | Compare output voltage divider to 0.6V reference; ±0.75% accuracy ensures stable regulation. |
| ITH1, ITH2 (Pins 3,6) | Current threshold & EA compensation nodes | Set peak inductor current per channel; gm = 2 mmho enables robust loop compensation. |
| TK/SS1, TK/SS2 (Pins 5,9) | Soft-start/tracking control inputs | 1.2µA internal charge current ramps output voltage linearly; supports voltage tracking between rails. |
| MODE/PLLIN (Pin 27) | Operating mode select & sync input | Selects Burst Mode® (float), pulse-skipping (INTVCC), or forced CCM (SGND); accepts external clock for synchronization. |
| FREQ (Pin 28) | Oscillator frequency programming | 10µA current sink sets frequency via external resistor; enables precise matching across multiple controllers. |
| ILIM (Pin 11) | Current sense threshold configuration | Connect to GND/FLOAT/INTVCC to select 30/50/82mV max sense voltage - critical for MOSFET SOA protection. |
| PGOOD (Pin 15) | Power-good open-drain output | Asserts low when either VOUT deviates >±10% from target - enables system-level power sequencing and fault reporting. |
Key Features
| Feature | Design Value |
|---|---|
| 180° out-of-phase dual control | Reduces RMS input ripple current by ~30%, enabling smaller input capacitors and lower EMI in compact 2-phase designs. |
| OPTI-LOOP® compensation | Allows stable loop response across wide ranges of output capacitance (10µF–1000µF) and ESR (0.5mΩ–50mΩ), simplifying design reuse. |
| Dual N-channel MOSFET drive | Integrated TG/BG drivers with 2.6Ω/1.5Ω (TG) and 2.4Ω/1.1Ω (BG) RDS(ON) minimize gate drive losses and support high-side switching up to 40V VIN. |
| Burst Mode® operation | Enables >85% efficiency at 1mA load (VIN=12V, VOUT=3.3V), extending battery life in standby modes without audible noise. |
| Independent soft-start & tracking | Per-channel TK/SS pins allow staggered startup or precise voltage ramping (e.g., 1.2V core before 3.3V I/O) to prevent latch-up in FPGAs/ASICs. |
Applications
| Telecom Power Supply | Server VRM |
|---|---|
Use Scenario: Dual-output 5V/3.3V converter powering line cards and backplane interfaces in 48V-powered telecom equipment. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent 5V and 3.3V rails with coordinated soft-start and current balancing. Use Value: 180° phase shift cuts input capacitor RMS current by 30%, reducing 48V-to-5V/3.3V stage size and cost while maintaining <±1% cross-regulation. | Use Scenario: High-current 1.2V/1.8V core supply for multi-core CPUs in rack-mounted servers with strict transient response requirements. IC Role / Device Role / Timing Role: Two-phase interleaved controller delivering up to 50A per rail using external N-MOSFETs, with OPTI-LOOP® tuned for low-ESR ceramic output caps. Use Value: ≤2mV inter-channel current sense mismatch ensures equal current sharing, preventing thermal runaway and enabling reliable 100A+ total output capability. |
| Industrial PLC Controller | Medical Imaging Module |
Use Scenario: Isolated 24V input converted to regulated 5V logic and 3.3V sensor rails in harsh industrial environments with wide temperature swings. IC Role / Device Role / Timing Role: Dual-controller managing separate isolated DC/DC stages, leveraging ILIM pin to set different current limits for logic vs. analog sections. Use Value: –40°C to 125°C guaranteed operation and ±0.75% VFB accuracy ensure stable sensor biasing and microcontroller operation across ambient extremes. | Use Scenario: Low-noise, low-ripple power for CCD/CMOS image sensors and ADC front-ends in portable ultrasound devices. IC Role / Device Role / Timing Role: Dual-phase controller operating in forced CCM mode to eliminate subharmonic noise and maintain <10mVpp output ripple at full load. Use Value: Pulse-skipping and forced CCM modes suppress audible switching noise (<20kHz) and RF emissions that would corrupt sensitive analog imaging signals. |
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 |
|---|---|---|---|
| LTC3850 | Pin-compatible with LTC3869 but lacks ILIM pin; fixed 50mV current sense threshold; no EXTVCC input. | Not suitable for designs requiring programmable current limiting or high-efficiency EXTVCC bypass. | Select LTC3850 only if fixed 50mV current limit and absence of EXTVCC support are acceptable trade-offs for cost-sensitive legacy designs. |
| MP8770GL-Z | Single-channel controller; integrated MOSFETs (40V/5A); no phase synchronization or dual-rail tracking capability. | Cannot replace LTC3869IGN-2 in dual-output or interleaved 2-phase topologies without redesign. | Consider MP8770GL-Z only for space-constrained single-rail applications where integration outweighs flexibility and performance. |
Compared with LTC3850 and MP8770GL-Z, the LTC3869IGN-2 uniquely combines dual independent channels, programmable current limiting (ILIM), EXTVCC bypass, and precise voltage tracking - making it irreplaceable for high-reliability, multi-rail telecom and server power systems requiring matched phase currents and thermal management.
Availability
LTC3869IGN-2 is available at Aetrix Electronics and suitable for telecom infrastructure, server VRMs, and industrial PLCs requiring stable component supply with long-term lifecycle assurance.
Supply support for LTC3869IGN-2 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 qualification standards.
The LTC3869IGN-2 belongs to Linear's high-efficiency dual-phase controller product line, designed specifically for demanding multi-rail, high-current DC/DC conversion in telecom, computing, and medical equipment where thermal balance and precise voltage sequencing are critical.
FAQ
What is the maximum input voltage rating for the LTC3869IGN-2?
The LTC3869IGN-2 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. Exceeding 40V risks permanent damage per Absolute Maximum Ratings - always include input transient suppression if operating near this limit. The LTC3869IGN-2 datasheet confirms this in Section "Absolute Maximum Ratings".
How does the ILIM pin affect current limiting on the LTC3869IGN-2?
The ILIM pin on the LTC3869IGN-2 selects one of three maximum current sense thresholds: 30mV (ILIM = GND), 50mV (ILIM = FLOAT), or 82mV (ILIM = INTVCC). This directly sets the peak inductor current trip point for both channels. For example, with a 5mΩ sense resistor, ILIM = INTVCC yields a 16.4A current limit. The LTC3869IGN-2 Electrical Characteristics table (Page 3) specifies these values across temperature.
Can the LTC3869IGN-2 synchronize to an external clock, and how is it configured?
Yes, the LTC3869IGN-2 synchronizes to an external clock via the MODE/PLLIN pin (Pin 27). Applying a clean square wave (250kHz–780kHz) to this pin forces continuous conduction mode and locks the internal oscillator phase. No external PLL components are needed - the loop compensation is fully integrated. The LTC3869IGN-2 Functional Block Diagram (Page 11) shows the dedicated PLL-SYNC path feeding the oscillator.
What package type and thermal characteristics define the LTC3869IGN-2?
The LTC3869IGN-2 uses a 28-lead narrow plastic SSOP package (GN-2) with θJA = 80°C/W. Unlike QFN variants, it lacks an exposed thermal pad, so PCB layout must rely on standard copper pours and vias under the body. The datasheet specifies TJMAX = 125°C and notes that ambient temperature limits depend on power dissipation and board thermal design - critical for high-current 2-phase operation.
Does the LTC3869IGN-2 support output voltage tracking, and how is it implemented?
Yes, the LTC3869IGN-2 supports precise output voltage tracking using the TK/SS1 and TK/SS2 pins. To track VOUT1 to VOUT2, connect a resistor divider from VOUT1 to TK/SS2, while TK/SS1 is used for master soft-start. Internal 1.2µA current charges external capacitors for linear ramping. The LTC3869IGN-2 Applications section (Page 12) details tracking circuitry and confirms <1% tracking error across temperature.
LTC3869IGN-2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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 FAQ
1.How can I place an order for LTC3869IGN-2 through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3869IGN-2 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 reliable?
The price and inventory of LTC3869IGN-2 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 is usually 5 days.
3.What payment methods are accepted for LTC3869IGN-2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3869IGN-2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3869IGN-2?
LTC3869IGN-2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3869IGN-2 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?
For technical support, including LTC3869IGN-2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3869IGN-2 requirements.
6.How does Aetrix verify that LTC3869IGN-2 is sourced from the original manufacturer or authorized distributors?
All LTC3869IGN-2 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 meets industry standards.
7.What is the process for return or replacement of LTC3869IGN-2?
All LTC3869IGN-2 units undergo pre-shipment inspection (PSI). If there is an issue with LTC3869IGN-2, 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 part is unused and in its original packaging.
Return procedure for LTC3869IGN-2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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