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Analog Devices Inc. LTC3850EGN-1#PBF
- Part No.:
- LTC3850EGN-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 28-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3850EGN-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 28SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,444
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Product details
Overview
LTC3850EGN-1#PBF from Analog Devices is a dual, 2-phase synchronous step-down switching controller driving all-N-channel MOSFET stages. It delivers up to 95% efficiency, supports 4V–24V input, provides ±1% 0.8V reference accuracy, and operates at phase-lockable frequencies from 250kHz to 780kHz - ideal for high-density DC/DC conversion in portable instruments and battery-powered digital devices.
For engineers reviewing the LTC3850EGN-1#PBF datasheet, LTC3850EGN-1#PBF pinout, LTC3850EGN-1#PBF application, or LTC3850EGN-1#PBF equivalent, key selection considerations include dual-phase interleaving for reduced input ripple, EXTVCC-enabled power efficiency optimization, RSENSE/DCR current sensing flexibility, and independent soft-start/tracking via TK/SS pins.
Technical Context
The LTC3850EGN-1#PBF implements constant-frequency current-mode control with two 180° out-of-phase channels, enabling interleaved operation that halves input capacitor RMS current and suppresses supply-induced noise. Its OPTI-LOOP® compensation adapts transient response across wide output capacitance and ESR ranges.
It features independent ITH-based current limit control per channel, selectable operating modes (Burst Mode®, pulse-skipping, or forced CCM) via MODE/PLLIN, and programmable frequency via FREQ/PLLFLTR. The LTC3850-1 variant fixes maximum current sense threshold at 50mV typical and replaces ILIM with EXTVCC on Pin 14.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 24V (28V absolute max); supports common battery chemistries and intermediate bus rails. |
| Output Voltage Accuracy | ±1% at 0.8V feedback reference; ensures tight regulation across load/temperature for precision point-of-load supplies. |
| Switching Frequency Range | 250kHz to 780kHz, phase-lockable; balances efficiency vs. magnetics size - lower f reduces MOSFET switching loss, higher f enables smaller L/C. |
| Efficiency | Up to 95%; achieved via synchronous N-MOSFET drive, low RDS(on) gate drivers (TG RUP = 2.6Ω, BG RDOWN = 1.1Ω), and optimized dead-time control. |
| Current Sense Threshold | Fixed 50mV typical (LTC3850-1); eliminates external resistor selection error and simplifies design of foldback-limited short-circuit protection. |
| Operating Temperature | –40°C to +85°C; qualified for industrial and portable equipment environments without derating. |
| Package | 28-pin narrow plastic SSOP (GN); 4mm × 5.5mm footprint with exposed thermal pad connection to PGND for enhanced thermal performance. |
Pinout & Package
Package: 28-lead narrow plastic SSOP (GN), lead-free, RoHS-compliant. Exposed pad not present - thermal path relies on standard PCB copper pour under package body.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN1, RUN2 (Pins 1, 13) | Independent channel enable inputs | Pull below 1.2V to shut down respective channel; internal 0.5µA pull-up allows logic-level or RC-controlled sequencing. |
| TK/SS1, TK/SS2 (Pins 4, 10) | Soft-start and tracking inputs | Internal 1.3µA current charges external capacitor for linear VOUT ramp; also accepts resistor-divided master rail for coordinated startup. |
| SENSE1+/–, SENSE2+/– (Pins 2,3,11,12) | Differential current sense inputs | Accepts RSENSE or DCR network; common-mode range supports high-side sensing in buck topology with accurate foldback limiting. |
| VFB1, VFB2 (Pins 6, 8) | Feedback voltage inputs | Compare against 0.8V reference; remote sensing capability minimizes regulation error from PCB trace IR drop. |
| EXTVCC (Pin 14) | External bias input (LTC3850-1 only) | When >4.7V, bypasses internal 5V LDO to power INTVCC - improves efficiency by eliminating LDO dropout loss in multi-rail systems. |
| PGOOD (Pin 15) | Open-drain power-good indicator | Asserts low when either VOUT deviates >±7.5% from target after 17µs mask timer; enables system power sequencing and fault reporting. |
| TG1/BG1, TG2/BG2 (Pins 25,23,17,20) | Top/bottom gate drivers | Drive N-MOSFET gates with 2.6Ω pull-up / 1.1Ω pull-down; 25ns transition times support high-f switching with minimal shoot-through risk. |
| SW1, SW2 (Pins 26, 16) | Switch node connections | Connect to inductor high-side; swing from ~–0.7V (body diode drop) to VIN; requires low-inductance layout to minimize ringing and EMI. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 180° interleaved controllers | Reduces input capacitor RMS current by ~70%, cuts input ripple amplitude, and lowers EMI compared to single-phase designs. |
| OPTI-LOOP® compensation | Enables stable loop response across diverse output capacitor types (ceramic, polymer, electrolytic) and ESR values without redesign. |
| Three selectable light-load modes | Burst Mode® (highest efficiency), pulse-skipping (low ripple/audio noise), or forced CCM (lowest output ripple) - configured via MODE/PLLIN pin state. |
| Pre-biased output startup support | Allows safe startup into pre-charged output capacitors without reverse current flow - critical for hot-swap and redundant power systems. |
| Independent channel shutdown & tracking | Enables flexible power sequencing (e.g., core before I/O) and rail coordination (e.g., DDR memory VDDQ/VTT tracking) without external circuitry. |
Applications
| Notebook Power Management | Portable Test Instrumentation |
|---|---|
Use Scenario: Dual-rail CPU core (1.8V) and I/O (3.3V) supply in space-constrained ultrabooks. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing independent output voltages with precise sequencing and ripple suppression. Use Value: Interleaved operation halves input capacitor count and volume; EXTVCC option improves overall system efficiency by powering INTVCC from regulated 3.3V rail. | Use Scenario: Battery-powered handheld oscilloscope requiring clean, low-noise analog and digital supplies. IC Role / Device Role / Timing Role: Primary DC/DC controller generating isolated 5V analog and 3.3V digital rails from single Li-ion cell (3.0–4.2V). Use Value: Burst Mode® operation extends battery life during idle; ±1% reference and OPTI-LOOP® ensure stable ADC/DAC reference accuracy across temperature. |
| Industrial Portable Meters | DC Power Distribution Systems |
Use Scenario: Multifunction energy meter with isolated communication interface and precision sensor front-end. IC Role / Device Role / Timing Role: Dual-output controller delivering 2.5V sensor bias and 3.3V microcontroller supply with independent soft-start and fault monitoring. Use Value: PGOOD output enables MCU watchdog reset on undervoltage; TK/SS tracking ensures orderly sensor power-up before data acquisition begins. | Use Scenario: Telecom shelf with distributed 12V intermediate bus feeding multiple point-of-load converters. IC Role / Device Role / Timing Role: High-efficiency dual-phase controller stepping 12V bus to 5V/3.3V for FPGA and peripheral logic. Use Value: 780kHz max frequency allows compact 1.5µH inductors; phase-locking synchronizes switching to system clock, reducing beat-frequency EMI in dense board 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 |
|---|---|---|---|
| LTC3850EGN#PBF | Lacks EXTVCC pin; uses ILIM pin (Pin 14) for current sense threshold selection (GND/FLOAT/INTVCC = 20/40/60mV). | Requires external resistor network for current limit tuning; less efficient in multi-rail systems where one output can power INTVCC. | Select when design needs adjustable current limit or does not require EXTVCC efficiency optimization. |
| MP2918GL-Z | Single-chip dual-phase controller with integrated MOSFET drivers and PMBus interface; fixed 5mV current sense threshold; no EXTVCC option. | Supports digital telemetry and dynamic voltage scaling; lacks analog tracking/soft-start flexibility of LTC3850-1. | Select when digital control, telemetry, or smaller solution size outweighs need for analog sequencing and EXTVCC efficiency gain. |
Compared with LTC3850EGN#PBF, the LTC3850EGN-1#PBF offers fixed 50mV current sensing and EXTVCC for improved efficiency, while MP2918GL-Z trades analog configurability for digital control and integration - making LTC3850EGN-1#PBF optimal for high-precision analog-heavy systems needing sequenced, low-noise dual-rail generation.
Availability
LTC3850EGN-1#PBF is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, battery-operated digital devices, industrial meters, and DC power distribution systems requiring stable component supply and long-term industrial-grade availability.
Supply support for LTC3850EGN-1#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3850 product line delivers high-efficiency, dual-phase synchronous buck controllers for demanding point-of-load applications where precision regulation, low noise, and flexible power sequencing are critical - especially in portable and battery-powered systems.
FAQ
What is the key functional difference between LTC3850EGN-1#PBF and LTC3850EGN#PBF?
The LTC3850EGN-1#PBF replaces the ILIM pin (used for selecting current sense thresholds of 20/40/60mV) with an EXTVCC pin that enables bypassing the internal 5V LDO when an external ≥4.7V supply is available. Its current sense threshold is fixed at 50mV typical, simplifying design and improving efficiency in multi-rail systems. The LTC3850EGN#PBF retains ILIM and offers adjustable current limiting but lacks EXTVCC.
Does LTC3850EGN-1#PBF support pre-biased output startup?
Yes, LTC3850EGN-1#PBF supports pre-biased output startup. Its current-mode architecture and controlled gate drive sequencing prevent reverse current flow during startup into a pre-charged output capacitor. This behavior is confirmed in the Applications Information section and typical performance curves (e.g., Figure G09 "Prebiased Output at 2V") of the official datasheet Rev. D.
What package type and thermal characteristics apply to LTC3850EGN-1#PBF?
LTC3850EGN-1#PBF uses the 28-lead narrow plastic SSOP (GN) package, measuring 4mm × 5.5mm with standard gull-wing leads. It has θJA = 95°C/W and a maximum junction temperature of 125°C. Unlike QFN variants, it lacks an exposed thermal pad - thermal performance relies on PCB copper area connected to PGND and VIN traces per AN136 guidelines.
How is frequency set and synchronized on LTC3850EGN-1#PBF?
Frequency on LTC3850EGN-1#PBF is set via the FREQ/PLLFLTR pin: applying a DC voltage from 0V to INTVCC selects 250kHz to 780kHz. For synchronization, an external clock applied to the MODE/PLLIN pin forces continuous conduction mode and locks the internal oscillator phase. The PLL achieves lock within 10 cycles and tolerates ±10% frequency deviation per datasheet Section "Frequency Selection and Phase-Locked Loop".
Can LTC3850EGN-1#PBF operate with only one channel active?
Yes, LTC3850EGN-1#PBF supports single-channel operation. Pulling RUN2 low disables Channel 2 while Channel 1 remains fully functional with independent control of soft-start (TK/SS1), feedback (VFB1), and current sense (SENSE1+/–). The datasheet confirms this in the "Shutdown and Start-Up" section and Figure 14 (single-channel test circuit), with no performance degradation or stability impact on the active channel.
LTC3850EGN-1#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 ~ 24V
- 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
LTC3850EGN-1#PBF FAQ
1.How can I place an order for LTC3850EGN-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3850EGN-1#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 LTC3850EGN-1#PBF reliable?
The price and inventory of LTC3850EGN-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3850EGN-1#PBF is usually 5 days.
3.What payment methods are accepted for LTC3850EGN-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3850EGN-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3850EGN-1#PBF?
LTC3850EGN-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3850EGN-1#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 LTC3850EGN-1#PBF?
For technical support, including LTC3850EGN-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3850EGN-1#PBF requirements.
6.How does Aetrix verify that LTC3850EGN-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3850EGN-1#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 LTC3850EGN-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC3850EGN-1#PBF?
All LTC3850EGN-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3850EGN-1#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 LTC3850EGN-1#PBF part is unused and in its original packaging.
Return procedure for LTC3850EGN-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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