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Analog Devices Inc. LTC3869EUF#PBF
- Part No.:
- LTC3869EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3869EUF#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,534
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Product details
Overview
LTC3869EUF#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 capacitor stress via 180° out-of-phase operation - used in high-efficiency server and telecom power supplies.
For engineers reviewing the LTC3869EUF#PBF datasheet, LTC3869EUF#PBF pinout, LTC3869EUF#PBF application, or LTC3869EUF#PBF equivalent, key selection criteria include dual-phase current matching tolerance, RSENSE/DCR sensing flexibility, OPTI-LOOP® compensation adaptability across output capacitance/ESR, and precise 1.2µA TK/SS soft-start ramp current for controlled voltage tracking.
Technical Context
The LTC3869EUF#PBF implements constant-frequency current-mode control with independent error amplifiers (EA), ITH-based peak-current regulation, and integrated slope compensation. Each channel features dedicated RUN, TK/SS, VFB, ITH, and SENSE+/- pins enabling independent startup sequencing, output voltage tracking, and current-sense threshold programming via ILIM pin states (GND/FLOAT/INTVCC).
Its dual-phase architecture uses 180° phase shift to halve input ripple current, reducing required input capacitance and supply-induced noise. The MODE/PLLIN pin selects among Burst Mode®, pulse-skipping, or forced continuous conduction - with internal PLL synchronization capability supporting external clock alignment up to 780kHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 38V - supports wide battery chemistries and industrial bus rails without external pre-regulation. |
| Output Voltage Accuracy | ±0.75% at 0.6V - ensures tight regulation for low-voltage ASIC/FPGA core supplies. |
| Switching Frequency Range | 250kHz to 780kHz - adjustable via FREQ pin current; enables optimization of size vs. efficiency trade-offs. |
| Current Sense Threshold | 25mV to 82mV (configurable via ILIM pin) - allows precise overcurrent protection scaling for RSENSE or DCR sensing. |
| Soft-Start Current | 1.25µA typical - charges external TK/SS capacitor for linear, predictable output voltage ramp during startup. |
| Thermal Performance | θJA = 37°C/W (4mm × 4mm QFN) - requires exposed pad soldering to SGND for rated junction temperature handling up to 125°C. |
| Feedback Reference Voltage | 0.600V ±0.0045V (0°C to 85°C) - stable reference enabling accurate closed-loop regulation across load/temperature. |
Pinout & Package
Package: 28-lead (4mm × 4mm) plastic QFN with exposed thermal pad (Pin 29 = SGND). Must be soldered to PCB ground for electrical integrity and thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 (Pins 26, 9) | Independent channel enable inputs | Pull below 1.2V to disable respective channel; internal 1µA pull-up enables logic-controlled sequencing. |
| VFB1, VFB2 (Pins 3, 4) | Error amplifier feedback inputs | Connect to resistor dividers for remote sensing; regulate output to 0.6V reference with ±0.75% accuracy. |
| ITH1, ITH2 (Pins 2, 5) | Error amplifier outputs / current threshold controls | Set peak inductor current per channel; voltage determines PWM on-time in current-mode control loop. |
| TK/SS1, TK/SS2 (Pins 1, 6) | Soft-start and tracking inputs | Internal 1.2µA current ramps external capacitor; enables controlled voltage ramp or master-slave tracking. |
| MODE/PLLIN (Pin 24) | Operating mode selector & sync input | Selects Burst Mode® (float), pulse-skipping (INTVCC), or forced CCM (SGND); accepts external clock for phase lock. |
| FREQ (Pin 25) | Frequency setting input | 10µA precision current source - connect resistor to ground to set 250–780kHz oscillator frequency. |
| SENSE1+/–, SENSE2+/– (Pins 27/28, 8/7) | Differential current sense inputs | Interface with RSENSE or DCR networks; support programmable current limit thresholds (25–82mV). |
| TG1, TG2 (Pins 22, 14) | Top gate drivers | Drive N-channel high-side MOSFET gates with floating bootstrap supply (BOOST1/2); 25ns transition times. |
| BG1, BG2 (Pins 20, 17) | Bottom gate drivers | Drive N-channel low-side MOSFET gates referenced to PGND; 25ns transition times; anti-shoot-through logic included. |
| SW1, SW2 (Pins 23, 13) | Switch node connections | Connect to inductor high-side terminals; swing from ~0V to VIN; require Schottky catch diodes if no synchronous rectification. |
| PGOOD (Pin 12) | Power-good open-drain output | Asserts low when either output deviates >±10% from target after 20µs debounce - used for system power sequencing. |
| PGND (Pin 16) | Power ground return | Low-impedance return path for bottom MOSFET sources, input/output capacitors, and driver circuits. |
| SGND (Pin 29) | Signal ground reference | Reference for all small-signal circuitry (error amps, comparators); must tie to PGND at single point near IC. |
| VIN (Pin 19) | Main input supply | Primary power source for INTVCC regulator and internal logic; decouple with 0.1–1µF ceramic to PGND. |
| INTVCC (Pin 18) | Internal 5V LDO output | Supplies gate drivers and control circuitry; requires ≥4.7µF low-ESR capacitor to PGND; not for external loads. |
| EXTVCC (Pin 11) | External bias input | When >4.7V, bypasses internal LDO to improve efficiency; internal switchover hysteresis prevents oscillation. |
| BOOST1, BOOST2 (Pins 21, 15) | Bootstrap supply connections | Connect to boost capacitors for high-side gate drive; swing from ~INTVCC–0.7V to VIN+INTVCC. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® compensation | Adapts loop response dynamically across wide output capacitance (10µF–1000µF) and ESR (0.5mΩ–100mΩ) ranges without manual tuning. |
| 180° dual-phase interleaving | Reduces RMS input ripple current by ~70%, cutting required input capacitance and lowering EMI emissions. |
| Accurate multiphase current matching | Channel-to-channel current sense mismatch ≤2mV - ensures balanced thermal loading and extended MOSFET lifetime. |
| RSENSE or DCR current sensing | Configurable ILIM pin (GND/FLOAT/INTVCC) selects 25/50/75mV max sense threshold - supports lossless DCR or precision RSENSE schemes. |
| Three light-load operating modes | Burst Mode® (highest efficiency), pulse-skipping (low ripple), or forced CCM (lowest noise) - selected via MODE/PLLIN pin state. |
| Output overvoltage protection | VOVL lockout triggers at VFB ≥0.66V - disables top MOSFETs and asserts PGOOD low to prevent downstream damage. |
Applications
| Server VRMs | Telecom Power Systems |
|---|---|
Use Scenario: Dual-output 1.8V/1.2V core and I/O supplies for multi-core processors and memory interfaces in 1U rack servers. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent 5A channels with coincident tracking and current balancing. Use Value: Achieves >95% full-load efficiency and <1% cross-regulation drift between outputs under dynamic load steps. | Use Scenario: Intermediate bus converter generating 5V/3.3V from –48V telecom rectified input in distributed power architectures. IC Role / Device Role / Timing Role: High-input-voltage dual controller operating in forced CCM mode to meet strict ripple and transient response specs. Use Value: 4V–38V input range accommodates wide line variations; phase interleaving reduces bulk capacitor count by 40%. |
| Industrial PLC Power | Medical Imaging Power Modules |
Use Scenario: Isolated auxiliary supplies powering FPGA, ADCs, and isolated communication interfaces in programmable logic controllers. IC Role / Device Role / Timing Role: Dual-channel controller with independent RUN and TK/SS pins enabling sequenced startup and fault isolation. Use Value: ±0.75% output accuracy and 125°C junction rating ensure reliable operation in uncooled enclosures. | Use Scenario: High-reliability dual-rail supply for CT/MRI detector front-ends requiring ultra-low noise and precise voltage tracking. IC Role / Device Role / Timing Role: Controller operating in pulse-skipping mode to minimize conducted EMI while maintaining <10mVpp output ripple. Use Value: OPTI-LOOP® compensation maintains stability with low-ESR polymer capacitors; PGOOD enables system-level safety interlocks. |
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 but fixed 600kHz frequency; lacks ILIM pin for current threshold scaling and MODE/PLLIN sync capability. | Suitable only for fixed-frequency designs without need for external clock synchronization or programmable OCP. | Select LTC3850 when cost sensitivity outweighs flexibility needs and 600kHz meets design constraints. |
| MP8765GL-Z | Single-channel controller; requires two units for dual-phase; no OPTI-LOOP®; lower max input (28V) and switching frequency (1MHz). | Used where board space permits discrete dual implementation and tighter input voltage limits apply. | Choose MP8765 for cost-driven, non-critical applications where dual-phase timing coordination is less critical. |
Compared with LTC3850IGN#PBF and MP8765GL-Z, the LTC3869EUF#PBF provides superior design flexibility through programmable frequency (250–780kHz), three selectable light-load modes, and configurable current-limit thresholds - making it optimal for high-density, thermally constrained, or dynamically loaded systems.
Availability
LTC3869EUF#PBF is available at Aetrix Electronics and suitable for server VRMs, telecom power systems, and industrial PLC power supplies requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 125°C.
Supply support for LTC3869EUF#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 continues its legacy of high-performance analog and power management ICs for demanding industrial, automotive, and communications applications.
The LTC3869EUF#PBF belongs to Linear's high-efficiency polyphase controller product line, designed specifically for high-current, low-voltage DC/DC conversion in space-constrained, thermally aggressive environments.
FAQ
What is the maximum supported switching frequency for the LTC3869EUF#PBF?
The LTC3869EUF#PBF supports a phase-lockable switching frequency up to 780kHz, set via the FREQ pin's 10µA current source and external resistor. At VFREQ ≥ 2.4V, the nominal frequency reaches 780kHz (typical), with guaranteed operation from 250kHz to 780kHz across temperature and supply conditions. This enables compact magnetics and optimized efficiency in high-density power designs.
How does the LTC3869EUF#PBF achieve accurate current matching between its two phases?
The LTC3869EUF#PBF achieves channel-to-channel current sense mismatch ≤2mV through matched internal comparator offsets and precision current mirrors. Combined with identical ITH-to-PWM gain paths and 180° interleaved timing, this ensures balanced current sharing within ±3% across load and temperature - critical for thermal derating and reliability in dual-phase applications.
Can the LTC3869EUF#PBF operate with only one phase enabled?
Yes, the LTC3869EUF#PBF supports independent channel control: pulling RUN1 low disables Channel 1 while Channel 2 remains fully operational, and vice versa. Both channels retain full functionality - including soft-start (TK/SS), current limiting (ILIM), and mode selection (MODE/PLLIN) - allowing flexible single-phase operation without hardware modification.
What is the purpose of the ILIM pin on the LTC3869EUF#PBF?
The ILIM pin on the LTC3869EUF#PBF configures the maximum current sense threshold for both channels: grounding sets 25mV, floating sets 50mV, and tying to INTVCC sets 75mV (typical). This enables scalable overcurrent protection for different RSENSE values or DCR-based sensing networks - ensuring robust short-circuit response without redesigning the sense network.
Does the LTC3869EUF#PBF require external compensation components?
Yes, the LTC3869EUF#PBF requires external compensation components connected to the ITH pins - typically an RC network (resistor + capacitor) from ITHx to SGND - to stabilize the current-mode control loop. OPTI-LOOP® simplifies design by adapting loop dynamics to output capacitor ESR and capacitance, but physical compensation elements remain necessary for stability across operating conditions.
LTC3869EUF#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 (4x4)
LTC3869EUF#PBF FAQ
1.How can I place an order for LTC3869EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3869EUF#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 LTC3869EUF#PBF reliable?
The price and inventory of LTC3869EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3869EUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3869EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3869EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3869EUF#PBF?
LTC3869EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3869EUF#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 LTC3869EUF#PBF?
For technical support, including LTC3869EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3869EUF#PBF requirements.
6.How does Aetrix verify that LTC3869EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3869EUF#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 LTC3869EUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3869EUF#PBF?
All LTC3869EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3869EUF#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 LTC3869EUF#PBF part is unused and in its original packaging.
Return procedure for LTC3869EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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