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Analog Devices Inc. LTC3850IGN-1#TRPBF
- Part No.:
- LTC3850IGN-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3850IGN-1#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,304
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Product details
Overview
LTC3850IGN-1#TRPBF from Analog Devices is a dual, 2-phase synchronous step-down switching controller driving all-N-channel MOSFET stages. It delivers ±1% 0.8V output voltage accuracy, phase-lockable 250kHz–780kHz fixed-frequency operation, and supports pre-biased outputs - enabling high-efficiency dual-rail power for notebook CPU core/logic supplies.
For engineers reviewing the LTC3850IGN-1#TRPBF datasheet, LTC3850IGN-1#TRPBF pinout, LTC3850IGN-1#TRPBF application, or LTC3850IGN-1#TRPBF equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, and two confirmed alternative parts with documented functional and application differences.
Technical Context
The LTC3850IGN-1#TRPBF implements constant-frequency current-mode control with independent error amplifiers (EA), slope compensation, and dual 180° out-of-phase PWM generators. Each channel features dedicated ITH pins for current threshold control, VFB inputs for remote sensing, and TK/SS pins supporting both soft-start ramping and voltage tracking.
It integrates OPTI-LOOP® compensation for transient optimization across wide output capacitance/ESR ranges, Burst Mode®/pulse-skipping/continuous conduction mode selection via MODE/PLLIN, and EXTVCC support for bypassing the internal 5V LDO - reducing power loss in high-current, multi-output systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Dual synchronous buck controller - drives two independent N-channel top/bottom MOSFET pairs with 180° phase shift to halve input ripple current and reduce required bulk capacitance. |
| Input Voltage Range | 4V to 24V (30V max for LTC3850I grade) - supports 12V intermediate bus, Li-ion battery packs (3S–6S), and industrial 24V rails without external regulators. |
| Output Accuracy | ±1% at 0.8V reference - ensures tight regulation for modern low-voltage ICs (e.g., 1.8V, 1.2V, 0.9V cores) even under load/line/temperature variation. |
| Switching Frequency | 250kHz to 780kHz, phase-lockable - enables EMI reduction via synchronization and trade-off between efficiency (lower fSW) and size (higher fSW). |
| Current Sensing | RSENSE or DCR sensing with selectable 20/40/60mV max thresholds (ILIM pin-configurable) - allows flexible, low-loss sensing for high-current (>10A) applications. |
| Soft-Start/Tracking | Independent TK/SS1/TK/SS2 pins with 1.3µA internal charge current - enables controlled ramp-up, sequencing, or voltage tracking between dual outputs without external circuitry. |
| Power Good | Open-drain PGOOD with ±7.5% trip window and 17µs mask timer - provides reliable system-level power sequencing and fault indication for downstream logic. |
Pinout & Package
Package: 28-pin narrow plastic SSOP (GN), lead-free, RoHS-compliant, –40°C to +85°C operating range. Exposed pad not present (unlike QFN variants); thermal resistance θJA = 95°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 | Channel enable/disable control | Independent shutdown: <1.2V disables channel; internal 0.5µA pull-up enables restart - supports staggered power-up and dynamic rail control. |
| TK/SS1, TK/SS2 | Soft-start and tracking input | 0–0.8V ramp sets output voltage rise rate; external resistor divider enables precise sequencing with other supplies - eliminates need for discrete timers. |
| SENSE1+/SENSE1−, SENSE2+/SENSE2− | Differential current sense inputs | Accepts Kelvin-connected sense resistors or DCR networks - rejects common-mode noise and enables accurate current limiting during short-circuit events. |
| ITH1, ITH2 | Error amplifier output / current limit threshold | Voltage controls peak inductor current per cycle; direct interface to compensation network - enables fast transient response and foldback current limiting. |
| VFB1, VFB2 | Feedback input for output regulation | Compares remote-sensed output voltage to 0.8V reference; high-impedance (–50nA bias) minimizes divider loading error. |
| MODE/PLLIN | Mode selection & external clock sync | SGND = forced CCM; INTVCC = pulse-skipping; float = Burst Mode® - also accepts external clock up to 780kHz for EMI control. |
| FREQ/PLLFLTR | Oscillator frequency programming | DC voltage (0–INTVCC) sets fSW from 250kHz to 780kHz; also serves as PLL loop filter node when synchronized. |
| PGOOD | Power-good status indicator | Open-drain output pulled low if either VOUT deviates >±7.5% - used for system reset, enable sequencing, or fault logging. |
| EXTVCC | External bias supply input (LTC3850-1 only) | When >4.7V, bypasses internal 5V LDO to power INTVCC - improves efficiency in multi-rail designs where one output powers the controller. |
| TG1/TG2, BG1/BG2 | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6Ω/1.5Ω (TG) and 2.4Ω/1.1Ω (BG) on-resistance - supports high-side bootstrapping and fast switching with minimal dead-time risk. |
| SW1/SW2 | Switch node connections | Connects to inductor and MOSFET source/drain nodes; rated for 30V swing - requires careful layout to minimize ringing and EMI. |
| VIN, PGND, SGND | Main input, power ground, signal ground | Separate PGND (high-current return) and SGND (low-noise reference) - mandatory star-point connection prevents ground bounce in sensitive feedback paths. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° phased control | Reduces RMS input capacitor current by ~30% vs. single-phase, lowering heat and enabling smaller ceramic input caps in space-constrained notebooks. |
| OPTI-LOOP® compensation | Allows stable loop response across 10µF–1000µF output capacitance and 1mΩ–100mΩ ESR - eliminates re-tuning when changing capacitor types (e.g., polymer → MLCC). |
| Pre-biased output start-up | Enables safe powering of already-charged rails (e.g., hot-swap, backup supplies) without reverse current flow or output overshoot. |
| Independent current foldback | Each channel limits MOSFET conduction during short-circuit by scaling ITH threshold - protects FETs without disabling healthy channel. |
| AEC-Q100 qualified variant available | LTC3850IGN-1 meets automotive reliability standards (Grade I, –40°C to +85°C), enabling use in infotainment and ADAS power modules. |
Applications
| Notebook Dual-Rail Power | Portable Instrument Core Supply |
|---|---|
Use Scenario: Generating tightly regulated 3.3V and 2.5V rails for CPU I/O and memory interfaces in ultraportable laptops. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent voltage domains with precise sequencing and fast transient response. Use Value: Achieves >95% peak efficiency at 5A per rail while minimizing input ripple and thermal footprint - extending battery life and enabling fanless operation. |
Use Scenario: Powering precision ADCs, DACs, and microcontrollers in handheld test equipment requiring low-noise, stable analog supplies. IC Role / Device Role / Timing Role: Dual-channel controller delivering clean, sequenced 1.8V and 3.3V outputs with Burst Mode® for ultra-low quiescent current during standby. Use Value: Maintains ±1% output accuracy over temperature and load, while reducing no-load IQ to 30µA - maximizing runtime between charges. |
| Battery-Operated Digital Systems | DC Power Distribution |
Use Scenario: Supplying FPGA core (1.2V) and I/O (2.5V) rails from a 3S Li-ion battery (9–12.6V) in portable edge AI devices. IC Role / Device Role / Timing Role: High-input-voltage dual controller supporting wide VIN range and pre-biased start-up during battery hot-swap events. Use Value: Enables seamless transition between battery and external adapter without brownout or reset - critical for always-on connectivity. |
Use Scenario: Centralized 12V-to-5V/3.3V conversion in industrial IoT gateways with multiple sensor and communication modules. IC Role / Device Role / Timing Role: Dual-phase controller providing scalable, parallelable power with phase synchronization to suppress conducted EMI on shared bus lines. Use Value: Reduces total input capacitance by 40% and simplifies EMI filtering - lowering BOM cost and PCB area in dense multi-module designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3850EGN-1#TRPBF | Same architecture and pinout, but commercial-grade (0°C to 85°C) instead of industrial-grade (–40°C to 85°C). | Suitable for consumer electronics with benign thermal environments; not qualified for extended temperature industrial or automotive use. | Select when ambient operating temperature stays above 0°C and AEC-Q100 or extended temp compliance is unnecessary. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers and PMBus interface; lacks EXTVCC and independent TK/SS pins. | Supports digital monitoring and telemetry but offers less analog flexibility for custom sequencing or external bias sourcing. | Choose when telemetry, programmability, and compactness outweigh need for analog soft-start control or EXTVCC efficiency optimization. |
Compared with LTC3850EGN-1#TRPBF, the LTC3850IGN-1#TRPBF adds guaranteed operation down to –40°C and automotive qualification readiness; compared with MP2918GL-Z, it provides superior analog control granularity and higher efficiency in EXTVCC-enabled configurations, at the cost of digital configurability.
Availability
LTC3850IGN-1#TRPBF is available at Aetrix Electronics and suitable for notebook computing, portable instrumentation, and industrial DC power distribution systems requiring stable component supply, long-term lifecycle support, and industrial-grade reliability.
Supply support for LTC3850IGN-1#TRPBF 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 (now part of Analog Devices, Inc., following merger with Maxim Integrated) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3850 product line delivers high-efficiency, dual-phase synchronous buck controllers targeting space- and thermally-constrained applications in computing, portable, and industrial power systems - emphasizing precision regulation, robust protection, and flexible sequencing.
FAQ
What is the key difference between LTC3850IGN-1#TRPBF and LTC3850IGN#TRPBF?
The LTC3850IGN-1#TRPBF includes the EXTVCC pin for external biasing of the INTVCC regulator, whereas the LTC3850IGN#TRPBF uses the same pin as ILIM for current-sense threshold selection. This makes the -1 version more efficient in multi-output systems where one regulated rail can power the controller, reducing heat and improving overall system efficiency. Both share identical industrial temperature rating (–40°C to +85°C) and SSOP package.
Does LTC3850IGN-1#TRPBF support pre-biased output start-up?
Yes, LTC3850IGN-1#TRPBF supports pre-biased output start-up. When enabled, the controller prevents reverse current flow into a pre-charged output by disabling bottom-FET turn-on until the top-FET duty cycle brings the output voltage above the pre-bias level. This avoids output voltage droop or overshoot and protects downstream circuitry during hot-swap or backup-power transitions - a verified feature confirmed in the datasheet's Operation section.
What is the maximum supported switching frequency for LTC3850IGN-1#TRPBF?
The LTC3850IGN-1#TRPBF supports a maximum switching frequency of 780kHz when the FREQ/PLLFLTR pin voltage exceeds 2.4V. This is confirmed in the Electrical Characteristics table (fHIGH = 700–860kHz, typical 780kHz). At this frequency, minimum on-time is 90ns, enabling use with small inductors in compact designs - though efficiency trade-offs versus lower frequencies (e.g., 500kHz) must be evaluated per application.
Can LTC3850IGN-1#TRPBF synchronize to an external clock?
Yes, LTC3850IGN-1#TRPBF can synchronize to an external clock via the MODE/PLLIN pin. When an external clock signal (250kHz–780kHz) is applied to this pin, the internal oscillator locks to it using the integrated phase-locked loop (PLL), eliminating beat frequencies and reducing EMI in noise-sensitive systems. The FREQ/PLLFLTR pin simultaneously serves as the PLL loop filter node - a dual-function capability explicitly documented in the datasheet.
What thermal considerations apply to LTC3850IGN-1#TRPBF in SSOP package?
LTC3850IGN-1#TRPBF in the 28-pin narrow SSOP (GN) package has a junction-to-ambient thermal resistance (θJA) of 95°C/W. To maintain safe operation below the 125°C maximum junction temperature, PCB layout must include adequate copper pour on the component side and inner layers tied to PGND, plus thermal vias under the IC body. Derating is required above +70°C ambient - for example, at 85°C ambient, maximum continuous power dissipation drops to ~420mW assuming no airflow.
LTC3850IGN-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-SSOP (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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 ~ 30V
- Frequency - Switching:
- 250kHz ~ 780kHz
- Duty Cycle (Max):
- 97.2%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Current Limit, Enable, Frequency Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-SSOP
LTC3850IGN-1#TRPBF FAQ
1.How can I place an order for LTC3850IGN-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3850IGN-1#TRPBF 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 LTC3850IGN-1#TRPBF reliable?
The price and inventory of LTC3850IGN-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3850IGN-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3850IGN-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3850IGN-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3850IGN-1#TRPBF?
LTC3850IGN-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3850IGN-1#TRPBF 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 LTC3850IGN-1#TRPBF?
For technical support, including LTC3850IGN-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3850IGN-1#TRPBF requirements.
6.How does Aetrix verify that LTC3850IGN-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3850IGN-1#TRPBF 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 LTC3850IGN-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3850IGN-1#TRPBF?
All LTC3850IGN-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3850IGN-1#TRPBF, 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 LTC3850IGN-1#TRPBF part is unused and in its original packaging.
Return procedure for LTC3850IGN-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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