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Analog Devices Inc. LTC3853EUJ#PBF
- Part No.:
- LTC3853EUJ#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 40-WFQFN Exposed Pad
- Datasheet:
-
LTC3853EUJ#PBF.pdf
- Description:
- IC REG CTRLR BUCK 40QFN
- Quantity:
- Payment:
- Shipping:
Inventory:453
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Product details
Overview
LTC3853EUJ#PBF from Analog Devices (formerly Linear Technology) is a triple-output, multiphase synchronous step-down controller driving all-N-channel MOSFET stages for high-efficiency power conversion in multi-rail systems. It supports 120° phased operation across three outputs, delivers up to 13.5V on Phase 3, operates from 4.5V–24V input, and achieves ±0.75% output voltage accuracy at 0.8V reference - used in telecom baseband boards requiring tightly regulated 5V/3.3V/1.2V rails.
For engineers reviewing the LTC3853EUJ#PBF datasheet, LTC3853EUJ#PBF pinout, LTC3853EUJ#PBF application, or LTC3853EUJ#PBF equivalent, key selection criteria include phase configuration flexibility (triple 120°, dual 180° + single, or single 3-phase), DCR/RSENSE current sensing, independent soft-start/tracking per channel, and robust overvoltage/foldback protection for mission-critical embedded power subsystems.
Technical Context
The LTC3853EUJ#PBF implements a constant-frequency current-mode control architecture with three independent error amplifiers and current comparators, each tied to its own ITH pin for precise per-channel current limit and loop compensation. Its 120° phase interleaving reduces input ripple current by √3 and cuts required input capacitance versus single-phase designs.
It integrates dedicated gate drivers for six N-channel MOSFETs (TG1/BG1 through TG3/BG3), supports pre-biased startup, and features programmable operating modes (Burst Mode®, pulse-skipping, or forced continuous conduction) via the MODE/PLLIN pin - enabling optimization of light-load efficiency versus output ripple in server VRMs and FPGA power supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 24V (28V absolute max); supports 12V/19V intermediate bus and Li-ion battery inputs. |
| Output Voltage Range (Phases 1&2) | 0.8V to 5.5V; enables core logic and I/O rail generation (e.g., 3.3V, 2.5V, 1.8V). |
| Output Voltage Range (Phase 3) | 0.8V to 13.5V; allows high-voltage auxiliary rails (e.g., 12V analog, 5V USB PD sink). |
| Feedback Accuracy | ±0.75% at 0.8V reference over –40°C to 125°C; ensures stable regulation under thermal stress. |
| Switching Frequency | 250kHz to 750kHz (phase-lockable); balances MOSFET switching loss vs. inductor size in compact layouts. |
| Current Sensing | RSENSE or DCR; eliminates sense resistor losses and enables accurate current limiting without added board area. |
| Thermal Rating | –40°C to 125°C junction; qualified for industrial and telecom equipment with extended ambient requirements. |
Pinout & Package
Package: 40-lead (6mm × 6mm) plastic QFN with exposed PGND pad (Pin 41), θJA = 33°C/W. Exposed pad must be soldered to PCB for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TG1, TG2, TG3 | Top gate driver outputs | Drive gates of high-side N-MOSFETs; floating outputs referenced to SWx nodes. |
| BG1, BG2, BG3 | Bottom gate driver outputs | Drive gates of low-side N-MOSFETs; referenced to PGND for synchronous rectification. |
| SENSE1+/–, SENSE2+/–, SENSE3+/– | Current sense comparator inputs | Differential inputs supporting RSENSE or DCR sensing; SENSE3+/- tolerate up to 13.5V common mode. |
| VFB1, VFB2, VFB3 | Error amplifier feedback inputs | Receive remote-sensed output voltages via resistive dividers; regulate to 0.8V internal reference. |
| ITH1, ITH2, ITH3 | Error amplifier output / current threshold | Set peak inductor current per channel; voltage directly controls current limit and loop compensation. |
| TK/SS1, TK/SS2, TK/SS3 | Soft-start and tracking inputs | Internal 1.3µA current ramps external capacitor for controlled voltage ramp-up or enables ratiometric tracking between rails. |
| MODE/PLLIN | Mode select & PLL sync input | Selects Burst Mode® (float), pulse-skip (INTVCC), or forced continuous (SGND); accepts external clock for synchronization. |
| PGOOD12, PGOOD3 | Open-drain power-good indicators | Assert low when any monitored VFB deviates >±7.5% from target or RUN pin falls below 1.2V; 17µs debounce mask applied. |
Key Features
| Feature | Design Value |
|---|---|
| Triple 120° phased control | Reduces input RMS ripple current by ~58% and cuts required bulk capacitance versus single-phase design. |
| Configurable topology | Supports triple 120°, dual 180° + single, or unified 3-phase output - adapts to varying current demands per rail. |
| Independent per-channel soft-start | Enables sequenced power-up (e.g., core before I/O) or coincident ramping using external RC networks on TK/SS pins. |
| Foldback current limiting | Reduces MOSFET thermal stress during short-circuit events by lowering peak current as output voltage collapses. |
| Pre-biased output support | Allows safe startup into pre-charged output capacitors - critical for hot-swap and redundant power systems. |
| Output overvoltage protection | Shuts down affected channel if VFB exceeds 0.84V (H/MP-grade) or 0.86V (E/I-grade), preventing downstream IC damage. |
Applications
| Telecom Baseband Processing | Industrial PLC CPU Power |
|---|---|
Use Scenario: Powering multi-core DSPs and FPGAs in 4G/5G remote radio units with strict EMI and thermal constraints. IC Role / Device Role / Timing Role: Triple-output controller delivering 5V (I/O), 3.3V (peripheral), and 1.2V (core) simultaneously with 120° phase shift. Use Value: Input ripple reduction lowers EMI filter cost; ±0.75% accuracy maintains FPGA timing margins across temperature. | Use Scenario: Regulating power for ARM Cortex-A series CPUs and real-time Ethernet PHYs in factory automation controllers. IC Role / Device Role / Timing Role: Configured as dual-phase 180° + single-phase to deliver high-current 1.2V core rail plus isolated 3.3V/5V I/O rails. Use Value: Independent RUN pins enable dynamic rail shutdown during sleep modes; pre-bias support allows seamless firmware updates. |
| Medical Imaging Sensor Array | Test & Measurement ADC Front-End |
Use Scenario: Supplying ultra-low-noise analog rails (±12V derived from 13.5V Phase 3 output) and digital logic rails for CT/MRI detector modules. IC Role / Device Role / Timing Role: Phase 3 regulates up to 13.5V to feed external LDOs generating precision analog supplies; Phases 1&2 supply digital cores. Use Value: 13.5V Phase 3 capability eliminates need for separate boost stage; DCR sensing avoids sense resistor noise coupling into analog paths. | Use Scenario: Powering high-speed SAR and sigma-delta ADCs requiring clean, sequenced 3.3V analog and 1.8V digital supplies with tight transient response. IC Role / Device Role / Timing Role: Uses independent TK/SS pins to track 3.3V rail startup before enabling 1.8V rail, ensuring proper ADC power sequencing. Use Value: Coincident or ratiometric tracking prevents latch-up during power-up; ±7.5% PGOOD window provides reliable fault detection without false triggers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-output synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL95812IRZ-T | Single 3-phase controller only; no dual-phase + single configuration; fixed 0.6V reference; no DCR sensing. | Optimized for CPU VRMs with integrated telemetry; lacks independent soft-start per rail. | Choose ISL95812IRZ-T only when 3-phase-only topology suffices and telemetry reporting is required. |
| TPS546D24RTQR | Single-channel, 60A capable; requires external PMBus controller for multi-rail coordination; no native phase interleaving. | Targeted at high-current GPU/AI accelerators; relies on system-level sequencing rather than on-chip TK/SS tracking. | Choose TPS546D24RTQR when >30A per rail is needed and PMBus-based system management is already in place. |
Compared with ISL95812IRZ-T and TPS546D24RTQR, the LTC3853EUJ#PBF uniquely combines triple independent control loops, flexible phase configuration, DCR/RSENSE flexibility, and per-rail soft-start - making it optimal for space-constrained, multi-rail industrial and telecom systems where layout simplicity and rail autonomy are critical.
Availability
LTC3853EUJ#PBF is available at Aetrix Electronics and suitable for telecom infrastructure, industrial PLCs, and medical imaging systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3853EUJ#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 qualification for all Linear power management ICs.
The LTC3853EUJ#PBF belongs to Linear's high-performance multiphase DC/DC controller family, designed specifically for complex, multi-rail power systems in telecom, industrial, and medical equipment where efficiency, accuracy, and configurability are non-negotiable.
FAQ
What is the maximum output voltage supported by LTC3853EUJ#PBF on Phase 3?
The LTC3853EUJ#PBF supports an output voltage range of 0.8V to 13.5V on Phase 3, as confirmed in the Electrical Characteristics table (Channel 3 Output Voltage Range). This enables direct regulation of higher-voltage rails such as 12V analog supplies or 5V USB-PD sinks without requiring external boost circuitry. The SENSE3+ and SENSE3– pins are rated for up to 13.5V common-mode voltage, ensuring safe operation at this maximum output.
Does LTC3853EUJ#PBF support DCR current sensing on all three phases?
Yes, the LTC3853EUJ#PBF supports DCR current sensing on all three phases. The SENSE1+/–, SENSE2+/–, and SENSE3+/– pins are explicitly designed for differential sensing across either discrete current-sense resistors or copper traces/inductor DCR networks. The datasheet confirms DCR compatibility in both the Features list and Applications Information section, and SENSE3+/- tolerates up to 13.5V common-mode voltage - essential for accurate DCR sensing at high output voltages.
How does the LTC3853EUJ#PBF implement power sequencing between its three outputs?
The LTC3853EUJ#PBF implements power sequencing via independent TK/SS1, TK/SS2, and TK/SS3 pins. Each pin accepts an external RC network to set individual soft-start ramp rates, or a resistor divider to track another rail's voltage. When configured as master-slave, the master's VFB is reproduced at slave TK/SS pins, enabling precise ratiometric or delayed startup. This per-channel control - documented in the Pin Functions and Operation sections - eliminates need for external sequencers in applications like FPGA or ASIC power delivery.
What protection features are integrated into the LTC3853EUJ#PBF?
The LTC3853EUJ#PBF integrates output overvoltage protection (OVP), foldback current limiting, undervoltage lockout (UVLO) on INTVCC, and open-drain PGOOD monitoring with ±7.5% regulation window. OVP triggers shutdown if VFB exceeds 0.84–0.89V depending on grade; foldback reduces peak current during shorts to limit MOSFET heating; UVLO disables operation below 3.35V INTVCC; and PGOOD12/PGOOD3 assert low on regulation faults or RUN pin deactivation - all verified in Absolute Maximum Ratings and Electrical Characteristics tables.
Can LTC3853EUJ#PBF operate with pre-biased outputs during startup?
Yes, the LTC3853EUJ#PBF supports pre-biased output startup, as explicitly stated in the Features list and detailed in the Operation section. When enabled, the controller safely ramps the top MOSFET gate drive while the output capacitor is already charged, preventing reverse current flow through the low-side MOSFET. This capability is critical in hot-swap, redundant power, and system-level firmware update scenarios - and is validated across all temperature grades in the datasheet's Applications Information.
LTC3853EUJ#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 40-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 3
- Output Phases:
- 3
- Voltage - Supply (Vcc/Vdd):
- 4.5V ~ 24V
- Frequency - Switching:
- 250kHz ~ 750kHz
- Duty Cycle (Max):
- 98%
- 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:
- 40-QFN (6x6)
LTC3853EUJ#PBF FAQ
1.How can I place an order for LTC3853EUJ#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3853EUJ#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 LTC3853EUJ#PBF reliable?
The price and inventory of LTC3853EUJ#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3853EUJ#PBF is usually 5 days.
3.What payment methods are accepted for LTC3853EUJ#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3853EUJ#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3853EUJ#PBF?
LTC3853EUJ#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3853EUJ#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 LTC3853EUJ#PBF?
For technical support, including LTC3853EUJ#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3853EUJ#PBF requirements.
6.How does Aetrix verify that LTC3853EUJ#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3853EUJ#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 LTC3853EUJ#PBF meets industry standards.
7.What is the process for return or replacement of LTC3853EUJ#PBF?
All LTC3853EUJ#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3853EUJ#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 LTC3853EUJ#PBF part is unused and in its original packaging.
Return procedure for LTC3853EUJ#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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