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Analog Devices Inc. LTC1435CS#TRPBF
- Part No.:
- LTC1435CS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1435CS#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,452
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Product details
Overview
LTC1435CS#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller that drives external N-channel MOSFETs in high-efficiency DC/DC conversion. It operates from 3.5V to 36V input, delivers output voltages from 1.19V to 9V, supports up to 99% duty cycle for ultra-low dropout, and features programmable fixed-frequency operation via external capacitor COSC. It is used in battery-powered portable instruments requiring stable, low-noise power.
For engineers reviewing the LTC1435CS#TRPBF datasheet, LTC1435CS#TRPBF pinout, LTC1435CS#TRPBF application, or LTC1435CS#TRPBF equivalent, key selection considerations include its dual N-MOSFET synchronous drive architecture, secondary feedback control (SFB) for multi-output regulation, Burst Mode™ operation for sub-100mA load efficiency, remote voltage sensing capability, and logic-controlled micropower shutdown with IQ < 25µA.
Technical Context
The LTC1435CS#TRPBF implements a constant-frequency, current-mode control architecture with an internal 1.19V reference and error amplifier output at ITH pin. Its peak inductor current is set by the ITH voltage, while cycle-by-cycle current limiting uses SENSE+ and SENSE– inputs with a 150mV threshold across RSENSE. The oscillator frequency is externally programmable (112–138 kHz typical with 100pF), and dropout detection forces periodic top-FET off-time to recharge the bootstrap capacitor when VIN approaches VOUT.
Burst Mode™ operation activates when inductor current reverses and remains below hysteresis for one full cycle, disabling TG/BG drives until ITH exceeds 0.6V or sense voltage exceeds 20mV/RSENSE. Continuous operation is enforced if SFB < 1.19V or SENSE common-mode voltage < 1.4V - enabling reliable secondary-winding regulation and low-noise operation in sensitive analog systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 36V - supports wide industrial and automotive battery inputs including 12V, 24V, and 28V rails. |
| Output Voltage Range | 1.19V to 9V - set via external resistor divider on VOSENSE; 1.19V reference enables precise low-voltage regulation. |
| Max Duty Cycle | 99% - enables ultra-low dropout operation critical for extending runtime in single-cell Li-ion or lead-acid battery systems. |
| Quiescent Current | 260µA normal mode, <25µA shutdown - minimizes standby loss in always-on portable devices. |
| Oscillator Frequency | 112–138 kHz (typ. 125 kHz with 100pF COSC) - balances gate loss vs. size trade-off; max 400kHz supported. |
| Current Sense Threshold | 130–180 mV - sets peak inductor current limit; determines maximum output current with RSENSE. |
| Feedback Reference Voltage | 1.178–1.202 V - tight 1.19V ±1% tolerance ensures accurate output regulation across temperature. |
Pinout & Package
The LTC1435CS#TRPBF is housed in a 16-lead narrow SO package (SO-16), with exposed pad not electrically connected. Thermal resistance θJA = 110°C/W enables operation up to +70°C ambient without forced airflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC | Oscillator timing capacitor connection | External capacitor sets switching frequency; 100pF yields ~125kHz. |
| RUN/SS | Soft-start ramp and enable control | Capacitor to ground sets soft-start time (~0.5s/µF); <1.3V disables controller. |
| ITH | Error amplifier output / current limit control | Voltage sets peak inductor current; clamped during startup for controlled ramp-up. |
| SFB | Secondary winding feedback input | Pull to GND for continuous mode; tie to INTVCC if unused; connect to secondary divider for auxiliary output regulation. |
| SGND | Small-signal ground reference | Must be routed separately from PGND to minimize noise coupling into feedback path. |
| VOSENSE | Main output voltage feedback input | Connects to resistive divider across VOUT; servo loop maintains 1.19V at this pin. |
| SENSE– / SENSE+ | Differential current sense inputs | Measure voltage across RSENSE; built-in offset enables accurate current limiting independent of RSENSE value. |
| EXTVCC | External VCC switch input | When >4.7V, powers INTVCC directly from output or boost rail - improves efficiency by reducing VIN supply current. |
| PGND | Power ground return for bottom FET | Low-impedance path for high di/dt currents; must connect to source of bottom N-MOSFET and CIN(–). |
| BG | Bottom N-MOSFET gate driver output | Drives gate from 0V to INTVCC (typically 5V); requires low-inductance layout for fast switching. |
| INTVCC | Internal 5V regulator output | Powers internal circuitry and drivers; bypass with ≥2.2µF tantalum to PGND. |
| VIN | Main input supply | Accepts 3.5–36V; decouple with low-ESR capacitors near pin to suppress high-frequency transients. |
| SW | Switch node connection | Connects to inductor and drain of top FET; high dv/dt node requiring careful PCB layout. |
| BOOST | Bootstrap supply for top FET driver | Return for CB bootstrap capacitor; voltage swings from INTVCC to VIN + INTVCC. |
| TG | Top N-MOSFET gate driver output | Floating driver output referenced to SW; provides gate drive during high-side conduction. |
Key Features
| Feature | Design Value |
|---|---|
| Dual N-MOSFET synchronous drive | Enables >90% efficiency at medium-to-high loads by replacing Schottky diode with low-RDS(ON) bottom FET. |
| Programmable fixed-frequency operation | External COSC capacitor allows optimization of switching frequency for EMI, size, and efficiency trade-offs. |
| Secondary feedback control (SFB) | Guarantees regulation of auxiliary outputs (e.g., isolated secondaries) without additional controllers or optocouplers. |
| Burst Mode™ operation | Maintains >80% efficiency down to 1mA load by gating TG/BG drives - reduces audible noise and RF emissions. |
| Remote output voltage sense | Compensates for IR drop in PCB traces or cables, ensuring accurate regulation at point-of-load. |
| Logic-controlled micropower shutdown | Reduces total system standby current to <25µA - essential for long-life battery applications like handheld medical devices. |
Applications
| Portable Medical Instruments | Notebook & Palmtop Computers |
|---|---|
Use Scenario: Powering ADCs, sensors, and microcontrollers in handheld ultrasound or glucose meters with single Li-ion cell input. IC Role / Device Role / Timing Role: Primary step-down controller delivering regulated 3.3V and 1.8V rails with low noise and high light-load efficiency. Use Value: 99% duty cycle extends usable battery life by maintaining regulation down to 3.4V input; Burst Mode™ keeps quiescent draw below 30µA during sleep. | Use Scenario: Generating core voltage for embedded controllers and I/O rails in compact clamshell-form factor notebooks. IC Role / Device Role / Timing Role: Synchronous buck controller driving discrete Si4412DY MOSFETs to deliver 2.9V/3.5A with remote sensing. Use Value: Programmable soft-start prevents inrush current during hot-plug events; EXTVCC tied to VOUT improves full-load efficiency by 5–8% versus internal LDO. |
| Cellular Telephones | Battery-Operated Industrial Sensors |
Use Scenario: Supplying PA bias and baseband ICs in 4G/LTE handsets with variable battery voltage (4.2V–3.4V). IC Role / Device Role / Timing Role: High-efficiency buck controller supporting dynamic voltage scaling (DVS) via ITH pin modulation. Use Value: 1.19V reference and tight load regulation (<±0.8%) ensure stable RF performance across battery discharge curve. | Use Scenario: Powering LoRaWAN or NB-IoT sensor nodes deployed in remote locations with primary alkaline or Li-SOCl₂ batteries. IC Role / Device Role / Timing Role: Main power controller delivering 3.3V from 9V battery pack, with shutdown controlled by MCU GPIO. Use Value: <25µA shutdown current enables >10-year shelf life; SFB pin used to monitor backup coin-cell rail for RTC integrity. |
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 |
|---|---|---|---|
| LT8610EMS#TRPBF | Integrated power MOSFETs (no external FETs required); higher 2.2MHz switching frequency; lower 2.5µA quiescent current. | Smaller solution size but limited to 3.8A output; less flexible for high-current or high-input-voltage (>42V) designs. | Select LT8610EMS#TRPBF when board space is constrained and output current ≤3.8A; retain LTC1435CS#TRPBF for >5A, >36V, or multi-rail secondary regulation needs. |
| TPS54260DGQR | Integrated 0.57Ω high-side FET; wider 3.5–60V input; no secondary feedback (SFB) pin; no Burst Mode™. | Supports higher input voltage but lacks SFB-driven auxiliary regulation and low-noise light-load operation. | Choose TPS54260DGQR for cost-sensitive industrial supplies where secondary winding regulation is unnecessary and EMI filtering is handled externally. |
Compared with LT8610EMS#TRPBF and TPS54260DGQR, the LTC1435CS#TRPBF uniquely combines external FET flexibility, secondary feedback control for multi-output systems, and Burst Mode™ for ultra-low-noise light-load operation - making it optimal for precision portable instrumentation and battery-critical designs.
Availability
LTC1435CS#TRPBF is available at Aetrix Electronics and suitable for notebook computers, portable medical instruments, and cellular telephone power systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1435CS#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LTC1435CS#TRPBF belongs to ADI's legacy Linear Technology power management portfolio, designed specifically for high-efficiency, low-noise synchronous buck conversion in portable and battery-operated systems demanding extended runtime and precise regulation.
FAQ
What is the maximum input voltage rating for the LTC1435CS#TRPBF?
The LTC1435CS#TRPBF has an absolute maximum input supply voltage (VIN) rating of 36V. Operation is specified over 3.5V to 30V, with transient tolerance up to 36V. Exceeding 36V risks permanent damage to internal circuitry, especially the INTVCC regulator and gate drivers. For 42V automotive applications, external protection (e.g., TVS clamp or pre-regulator) is required before the VIN pin.
Does the LTC1435CS#TRPBF support true current-mode control with slope compensation?
Yes, the LTC1435CS#TRPBF implements inherent current-mode control using the SENSE+ and SENSE– pins to monitor peak inductor current via RSENSE. Slope compensation is not required because the controller uses a fixed-frequency architecture with cycle-by-cycle current limiting and internal oscillator synchronization - eliminating subharmonic oscillation risk even at duty cycles >50%.
Can the LTC1435CS#TRPBF regulate multiple outputs using a single transformer secondary winding?
Yes, the LTC1435CS#TRPBF supports multi-output regulation via its SFB (Secondary Feedback) pin. When connected to a resistive divider from an auxiliary winding, the SFB pin forces continuous operation and adjusts main-loop duty cycle to maintain regulation on the secondary output - enabling tightly regulated dual-rail supplies (e.g., 5V main + 3.3V auxiliary) without optocouplers or additional controllers.
What is the purpose of the EXTVCC pin on the LTC1435CS#TRPBF, and how should it be connected?
The EXTVCC pin on the LTC1435CS#TRPBF controls power sourcing for the INTVCC regulator. When EXTVCC > 4.7V, an internal switch connects it to INTVCC, bypassing the internal LDO and improving efficiency. For a 5V output, connect EXTVCC directly to VOUT. For 3.3V outputs, use a charge pump or auxiliary winding to boost EXTVCC to >4.7V. Leaving EXTVCC open defaults to internal 5V LDO operation, incurring ~5–10% efficiency penalty at high VIN.
Is the LTC1435CS#TRPBF RoHS compliant and halogen-free?
Yes, the LTC1435CS#TRPBF is RoHS compliant and halogen-free per Analog Devices' material declarations. The "#TRPBF" suffix indicates tape-and-reel packaging, Pb-free (lead-free) finish, and compliance with JEDEC J-STD-020 moisture sensitivity level 3 (MSL3). Full compliance documentation, including IPC-1752 data, is available through ADI's product change notifications and environmental reports portal.
LTC1435CS#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (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:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 3.5V ~ 30V
- Frequency - Switching:
- Up to 400kHz
- Duty Cycle (Max):
- 99%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Soft Start
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LTC1435CS#TRPBF FAQ
1.How can I place an order for LTC1435CS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1435CS#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 LTC1435CS#TRPBF reliable?
The price and inventory of LTC1435CS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1435CS#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1435CS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1435CS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1435CS#TRPBF?
LTC1435CS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1435CS#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 LTC1435CS#TRPBF?
For technical support, including LTC1435CS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1435CS#TRPBF requirements.
6.How does Aetrix verify that LTC1435CS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1435CS#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 LTC1435CS#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1435CS#TRPBF?
All LTC1435CS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1435CS#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 LTC1435CS#TRPBF part is unused and in its original packaging.
Return procedure for LTC1435CS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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