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Analog Devices Inc. LTC3835IUFD#TRPBF
- Part No.:
- LTC3835IUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LTC3835IUFD#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,996
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Product details
Overview
LTC3835IUFD#TRPBF from Analog Devices (formerly Linear Technology) is a high-performance, constant-frequency current-mode synchronous step-down DC/DC controller driving dual N-channel MOSFETs. It operates from 4V to 36V input, delivers 0.8V–10V output with ±1% accuracy, features 80µA no-load quiescent current, and supports phase-locked synchronization up to 650kHz - ideal for battery-powered telecom and automotive power systems requiring high efficiency and tight regulation.
For engineers reviewing the LTC3835IUFD#TRPBF datasheet, LTC3835IUFD#TRPBF pinout, LTC3835IUFD#TRPBF application, or LTC3835IUFD#TRPBF equivalent, key selection criteria include its OPTI-LOOP® compensation for wide output capacitor/ESR tolerance, 99% duty cycle capability for low-dropout operation, integrated PGOOD monitoring, and selectable light-load modes (Burst Mode®, pulse-skipping, or forced continuous).
Technical Context
The LTC3835IUFD#TRPBF implements a current-mode control architecture with a transconductance error amplifier (gm = 1.55 mmho), precision 0.8V reference (±1% over temperature), and internal 5.25V/7.5V dual-LDO INTVCC supply selectable via EXTVCC. Its ITH pin serves as both error amplifier output and current limit setpoint, directly modulating peak inductor current.
Phase-lockable oscillator frequency ranges from 140kHz to 650kHz (guaranteed lock range), with PLLIN/MODE pin serving dual function: external clock sync input or light-load mode selector (Burst Mode® <0.7V, pulse-skipping 0.9V–INTVCC−0.5V, forced continuous = INTVCC). The device integrates reverse-current prevention, output overvoltage protection, and current foldback limiting during short-circuit conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 36V - supports 12V/24V automotive, 5V–32V telecom, and multi-cell Li-ion battery inputs. |
| Output Voltage Range | 0.8V to 10V - programmable via external resistor divider; 0.8V reference enables low-voltage core rail generation. |
| No-Load Quiescent Current | 80µA - extends battery runtime in always-on systems like IoT sensors or telematics modules. |
| Switching Frequency | 140kHz to 650kHz (phase-lockable) - balances efficiency vs. size; 400kHz typical default for optimal EMI/inductor tradeoff. |
| Feedback Accuracy | ±1% over –40°C to +85°C - ensures stable regulation across industrial temperature range without calibration. |
| Duty Cycle Max | 99% - enables ultra-low dropout operation (e.g., 12V→11.5V conversion) without external bias supply. |
| PGOOD Threshold | ±10% of VFB - provides reliable power-good assertion for system sequencing and fault detection. |
Pinout & Package
Package: 20-pin 4mm × 5mm QFN (UFD), exposed thermal pad (Pin 21 = SGND), rated for –40°C to +85°C operation. Exposed pad must be soldered to PCB for thermal performance (θJA = 37°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ITH (Pin 1) | Error amplifier output / current limit control | Directly sets peak inductor current; voltage range 0.4V–1.2V determines load regulation and transient response. |
| TRACK/SS (Pin 2) | Soft-start and tracking input | Internal 1µA pull-up charges external capacitor for controlled VOUT ramp; also accepts external voltage for supply tracking. |
| VFB (Pin 3) | Feedback input | Compares output voltage (via resistive divider) to 0.8V reference; ±1% accuracy ensures precise regulation. |
| SGND (Pin 4, Pin 21) | Small-signal ground | Must be isolated from PGND; connects to input capacitor negative terminal and forms reference for all analog circuitry. |
| PGND (Pin 5) | Power ground | Return path for bottom MOSFET source, Schottky anode, and input capacitor - critical for noise immunity and current sensing. |
| BG (Pin 6) | Bottom gate driver output | Drives synchronous N-MOSFET gate from 0V to INTVCC; fast rise/fall times (40–90ns) minimize switching losses. |
| INTVCC (Pin 7) | Internal LDO output | Supplies 5.25V (from VIN) or 7.5V (from EXTVCC >4.7V); requires ≥4.7µF low-ESR capacitor for stability. |
| EXTVCC (Pin 8) | External bias input | Enables higher-efficiency INTVCC sourcing from secondary rail (e.g., post-regulated 5V or 8V), reducing VIN dissipation. |
| VIN (Pin 9) | Main input supply | Primary power source; bypassed to SGND with ceramic capacitor to suppress high-frequency noise and supply ripple. |
| SW (Pin 10) | Switch node | Connects to inductor and top MOSFET drain; swings from ~–0.3V (Schottky drop) to VIN - requires careful layout to minimize EMI. |
| TG (Pin 11) | Top gate driver output | Floating driver referenced to SW; swing = INTVCC − 0.5V superimposed on SW - enables high-side N-MOSFET drive. |
| BOOST (Pin 12) | Bootstrap supply | Charged via external diode/capacitor from INTVCC; supplies floating TG driver - critical for top MOSFET turn-on reliability. |
| RUN (Pin 13) | Enable/shutdown control | Logic-level input; <0.7V disables controller, reducing IQ to 10µA - used for system-level power sequencing. |
| SENSE– (Pin 14) | Current sense negative input | Low-impedance return for RSENSE; total input bias current ≤ –660nA minimizes offset error in precision sensing. |
| SENSE+ (Pin 15) | Current sense positive input | Connects to high-side of RSENSE; differential pair with SENSE– enables accurate peak current detection. |
| PGOOD (Pin 16) | Power-good open-drain output | Pulled low when VFB deviates >±10% from 0.8V; drives external pull-up for system reset or enable signaling. |
| PLLIN/MODE (Pin 17) | PLL sync input / light-load mode select | Accepts external clock (140–650kHz) or DC voltage to configure Burst Mode®, pulse-skipping, or forced continuous operation. |
| PHASMD (Pin 18) | Phase select input | Configures CLKOUT phase relationship (0° or 180°) for PolyPhase® multi-phase converter stacking. |
| CLKOUT (Pin 19) | Open-drain clock output | Provides synchronized clock signal to daisy-chain additional controllers - enables scalable multi-phase designs. |
| PLLLPF (Pin 20) | PLL loop filter connection | Connects external RC network when synchronizing to external clock; sets PLL bandwidth and lock stability. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP® Compensation | Allows stable loop compensation across wide range of output capacitor values (150µF typical) and ESR - eliminates need for custom compensation per design. |
| Low-IQ Light-Load Operation | 80µA quiescent current in Burst Mode® extends battery life in standby without sacrificing startup speed or regulation accuracy. |
| Integrated PGOOD Monitoring | Dedicated open-drain output asserts within 10ms of VOUT deviation >±10%, enabling robust system power sequencing and fault isolation. |
| Flexible Frequency Control | Three fixed frequencies (250/400/530kHz) via PLLLPF pin tie-off, plus guaranteed 140–650kHz PLL sync range - simplifies EMI filtering and multi-rail coordination. |
| Robust Short-Circuit Protection | Current foldback limits MOSFET power dissipation during overload while maintaining regulation - prevents thermal runaway without latch-off. |
Applications
| Automotive Infotainment Power | Telecom Base Station Bias |
|---|---|
Use Scenario: Generating 3.3V/5A for DSP, FPGA, and RF front-end ICs in vehicle head units under cold-crank (4.5V) and load-dump (36V) conditions. IC Role / Device Role / Timing Role: Primary synchronous buck controller regulating main logic rail; handles wide VIN transients and maintains ±1% VOUT accuracy across temperature. Use Value: 80µA IQ extends backup battery life; 99% duty cycle sustains output during engine cranking; PGOOD enables safe processor reset. | Use Scenario: Providing 5V/10A intermediate bus for distributed point-of-load converters in 48V telecom rectifier systems. IC Role / Device Role / Timing Role: High-efficiency intermediate converter with phase-locked operation to synchronize switching with upstream/downstream rails and reduce beat-frequency EMI. Use Value: CLKOUT and PHASMD pins enable seamless PolyPhase® stacking; EXTVCC allows efficient biasing from 5V auxiliary rail, cutting VIN losses by >30%. |
| Industrial IoT Sensor Hub | Medical Portable Diagnostic Device |
Use Scenario: Powering ARM Cortex-M7 MCU, BLE radio, and analog front-end from single Li-ion cell (3.0–4.2V) boosted to 12V, then stepped down to 1.2V/3.3V rails. IC Role / Device Role / Timing Role: Secondary buck controller accepting 12V input; uses TRACK/SS for coordinated soft-start with primary boost stage. Use Value: Tracking capability ensures orderly power-up sequence; Burst Mode® achieves >85% efficiency at 1mA load, extending field-deployed battery life to >1 year. | Use Scenario: Regulating 1.8V/2A for high-speed ADC and 3.3V/1A for microcontroller in handheld ultrasound probe operating from 7.4V Li-Poly battery. IC Role / Device Role / Timing Role: Low-noise synchronous controller with pulse-skipping mode to suppress audible switching noise near sensitive analog circuits. Use Value: Pulse-skipping reduces acoustic noise vs. Burst Mode® while maintaining >82% efficiency at 50mA; ±1% VOUT accuracy ensures ADC reference stability. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3833EUFD#TRPBF | Single N-channel driver (no bottom gate drive); 500kHz max frequency; no PGOOD or CLKOUT. | Lacks synchronous rectification support and multi-phase capability - suitable only for low-cost, non-critical applications. | Select only if cost sensitivity outweighs efficiency, thermal, and feature requirements; not drop-in compatible. |
| MP2918GL-Z | Fixed 500kHz frequency; no PLL sync; 100µA IQ; no EXTVCC or TRACK/SS pins. | Missing soft-start/tracking and external bias flexibility - limited to simple fixed-output designs with stable input. | Choose for basic industrial supplies where advanced sequencing and efficiency optimization are unnecessary. |
Compared with LTC3833EUFD#TRPBF and MP2918GL-Z, the LTC3835IUFD#TRPBF delivers superior light-load efficiency (80µA vs. ≥100µA), full dual-N synchronous drive, phase-lockable frequency, and comprehensive system integration (PGOOD, CLKOUT, TRACK/SS, EXTVCC) - making it the preferred choice for demanding automotive, telecom, and portable medical applications.
Availability
LTC3835IUFD#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, telecom base station bias, and portable medical device power systems requiring stable component supply, long-term lifecycle support, and guaranteed industrial-grade temperature performance.
Supply support for LTC3835IUFD#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LTC portfolio.
The LTC3835IUFD#TRPBF belongs to Linear's high-performance power controller family, designed specifically for efficient, flexible, and robust DC/DC conversion in automotive, industrial, and communications infrastructure applications.
FAQ
What is the absolute maximum input voltage rating for the LTC3835IUFD#TRPBF?
The LTC3835IUFD#TRPBF has an absolute maximum input voltage (VIN) rating of 36V. Exceeding this voltage, even momentarily, may cause permanent damage. The device operates reliably across its specified 4V to 36V input range, making it suitable for 24V automotive and 48V telecom intermediate bus applications with appropriate transient protection.
How does the EXTVCC pin improve efficiency in the LTC3835IUFD#TRPBF?
The EXTVCC pin on the LTC3835IUFD#TRPBF allows the internal INTVCC LDO to be powered from an external 4.7V–10V supply instead of VIN. When enabled, this bypasses the higher-loss VIN-to-INTVCC regulation, reducing power dissipation in the controller and improving overall system efficiency - especially beneficial when VIN is significantly higher than the required INTVCC voltage.
Can the LTC3835IUFD#TRPBF operate in forced continuous conduction mode (CCM)?
Yes, the LTC3835IUFD#TRPBF can operate in forced continuous conduction mode by tying the PLLIN/MODE pin to INTVCC. In this mode, inductor current is allowed to reverse at light loads, providing lower output voltage ripple and reduced audible noise compared to Burst Mode®, though at the expense of higher light-load quiescent current (≥125µA vs. 80µA).
What is the purpose of the TRACK/SS pin on the LTC3835IUFD#TRPBF?
The TRACK/SS pin on the LTC3835IUFD#TRPBF serves dual functions: soft-start control and supply voltage tracking. An internal 1µA current source charges an external capacitor to generate a linear VOUT ramp at startup; alternatively, connecting a resistor divider from another supply enables the LTC3835IUFD#TRPBF output to track that supply's rise time, ensuring safe power sequencing.
Does the LTC3835IUFD#TRPBF support phase synchronization with other controllers?
Yes, the LTC3835IUFD#TRPBF supports phase synchronization via its PLLIN/MODE and PLLLPF pins. It guarantees lock to external clocks between 140kHz and 650kHz, and its CLKOUT pin provides a synchronized clock signal for daisy-chaining additional controllers - enabling clean multi-phase operation and EMI reduction in high-current applications.
LTC3835IUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 36V
- Frequency - Switching:
- 250kHz ~ 530kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Phase Control, Power Good, Soft Start, Tracking
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x5)
LTC3835IUFD#TRPBF FAQ
1.How can I place an order for LTC3835IUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3835IUFD#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 LTC3835IUFD#TRPBF reliable?
The price and inventory of LTC3835IUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3835IUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3835IUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3835IUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3835IUFD#TRPBF?
LTC3835IUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3835IUFD#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 LTC3835IUFD#TRPBF?
For technical support, including LTC3835IUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3835IUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3835IUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3835IUFD#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 LTC3835IUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3835IUFD#TRPBF?
All LTC3835IUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3835IUFD#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 LTC3835IUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3835IUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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