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Analog Devices Inc. LTC1435IG#TRPBF
- Part No.:
- LTC1435IG#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1435IG#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,261
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Product details
Overview
LTC1435IG#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller driving external N-channel MOSFETs in fixed-frequency current-mode operation. It supports 3.5V–36V input, delivers regulated output from 1.19V to 9V, achieves up to 99% duty cycle for ultra-low dropout, and operates across –40°C to +85°C. It is used in battery-powered portable instruments requiring high efficiency at light loads via Burst Mode™.
For engineers reviewing the LTC1435IG#TRPBF datasheet, LTC1435IG#TRPBF pinout, LTC1435IG#TRPBF application, or LTC1435IG#TRPBF equivalent, key selection criteria include its programmable oscillator frequency (via COSC), secondary feedback control (SFB), remote voltage sensing (VOSENSE), logic-controlled micropower shutdown (<25µA), and dual N-MOSFET synchronous drive capability - all critical for low-noise, high-efficiency DC/DC conversion in space-constrained systems.
Technical Context
The LTC1435IG#TRPBF implements a constant-frequency current-mode architecture with peak-current control, where the ITH pin voltage sets the current comparator threshold and directly modulates duty cycle. Its internal 5V INTVCC regulator powers gate drivers and control circuitry, with automatic switchover to EXTVCC when ≥4.7V is applied - enabling efficiency optimization by sourcing driver power from the output rail.
Burst Mode™ operation disables both TG and BG drives during light load conditions when inductor current reverses and RSENSE voltage remains below ~20mV for one full cycle, reducing quiescent current and RF emissions. Continuous operation is enforced if SFB < 1.19V or SENSE+/- common-mode voltage falls below 1.4V - ensuring regulation integrity in multi-winding or precision-sense configurations.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 36V - supports wide industrial and battery-input systems including 12V/24V rails and Li-ion stacks. |
| Output Voltage Range | 1.19V to 9V - set via external resistive divider on VOSENSE; reference voltage is 1.19V ±1.02% over temperature. |
| Max Duty Cycle | 99% - enables ultra-low dropout operation, extending runtime in battery systems near end-of-discharge. |
| Shutdown Current | <25µA - ensures minimal battery drain during system sleep or standby modes. |
| Oscillator Frequency | 112–138 kHz (with 100pF COSC) - externally programmable for EMI optimization and efficiency trade-off tuning. |
| Operating Temp Range | –40°C to +85°C - qualified for industrial and extended-temperature embedded applications. |
| Current Sense Threshold | 130–180 mV - defines peak inductor current limit; set by RSENSE and determines max output current capability. |
Pinout & Package
Package: 16-lead plastic SSOP (G package), 0.150" wide, RoHS-compliant, moisture-sensitive level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC | Oscillator timing capacitor connection | Sets switching frequency; charge/discharge current defines fOSC - critical for EMI and efficiency tuning. |
| RUN/SS | Soft-start ramp and shutdown enable | Capacitor-to-ground sets startup time (~0.5s/µF); <1.3V forces shutdown with <25µA IQ. |
| ITH | Error amplifier output / current limit control | Voltage controls peak inductor current threshold; clamped during soft-start for controlled ramp-up. |
| SFB | Secondary winding feedback input | Forces continuous mode when pulled low; enables regulation of auxiliary windings independent of main output. |
| SGND | Small-signal ground reference | Must be isolated from PGND and COUT(–) to prevent noise coupling into feedback path. |
| VOSENSE | Main output voltage feedback input | Connects to resistive divider across VOUT; error amplifier compares to 1.19V reference for regulation. |
| SENSE– / SENSE+ | Differential current sense inputs | Measure voltage across RSENSE to detect peak inductor current; built-in offset enables accurate current limiting. |
| PGND | Power ground for bottom MOSFET source | Return path for high-current switch node; must connect directly to CIN(–) and MOSFET source. |
| BG | Bottom N-MOSFET gate driver output | Drives gate from 0V to INTVCC (≈5V); requires low-inductance layout to minimize shoot-through risk. |
| INTVCC | Internal 5V regulator output | Powers control logic and drivers; bypass with ≥2.2µF tantalum; switchover to EXTVCC occurs at 4.7V. |
| VIN | Main input supply | 3.5V–36V input; must be decoupled locally with low-ESR capacitors to handle high di/dt transients. |
| SW | Switch node connection | Connects to inductor and top MOSFET drain; swings from –0.3V (Schottky drop) to VIN - high dv/dt node. |
| BOOST | Bootstrap supply for top MOSFET driver | Supplies floating gate driver; CB capacitor returned here enables high-side N-MOSFET operation. |
| TG | Top N-MOSFET gate driver output | Floating output referenced to SW; swing = INTVCC superimposed on SW voltage - requires bootstrap design. |
| EXTVCC | External VCC input for INTVCC switchover | Enables efficiency gain by powering INTVCC from VOUT (≥4.7V); must not exceed 10V or VIN. |
Key Features
| Feature | Design Value |
|---|---|
| Dual N-MOSFET synchronous drive | Eliminates external Schottky loss; enables >90% efficiency at full load and Burst Mode™ at light loads. |
| Programmable fixed-frequency oscillator | Frequency set by single external capacitor (COSC); avoids EMI peaks and allows optimization for size vs. efficiency. |
| Secondary feedback control (SFB) | Guarantees regulation of auxiliary outputs (e.g., bias rails) even under main output overload or short-circuit. |
| Remote output voltage sensing (VOSENSE) | Compensates for PCB trace IR drop - maintains ±0.8% load regulation at up to 3.5A output. |
| Logic-controlled micropower shutdown | IQ < 25µA in shutdown - preserves battery life in portable devices during idle or sleep states. |
| 99% maximum duty cycle | Supports VIN–VOUT dropout as low as 100mV - extends usable battery range in 3.3V/5V systems powered from single-cell Li-ion. |
Applications
| Portable Medical Instruments | Notebook & Palmtop Computers |
|---|---|
Use Scenario: Powering FPGA I/O banks and ADC front-ends in handheld ultrasound or glucose monitors with strict EMI limits and battery runtime requirements. IC Role / Device Role / Timing Role: Primary step-down controller regulating 1.8V/3.3V rails from 7.4V Li-ion battery; manages dynamic load steps via current-mode control. Use Value: Burst Mode™ reduces no-load IQ to <25µA, extending battery life beyond 12 hours; 99% duty cycle sustains operation down to 3.4V battery voltage. | Use Scenario: Generating core voltage (1.1V–1.5V) and memory rails (1.8V/3.3V) in compact notebook motherboards with thermal constraints. IC Role / Device Role / Timing Role: Synchronous buck controller driving discrete Si4412DY MOSFETs; uses EXTVCC tied to 5V rail for >92% full-load efficiency. Use Value: Programmable COSC allows 250kHz operation to balance inductor size and switching loss; remote sensing maintains ±0.5% output accuracy under 3A load transients. |
| Cellular Baseband Modems | Industrial DC Power Distribution |
Use Scenario: Supplying 2.85V RF transceiver and 1.2V baseband processor in LTE/Wi-Fi modules operating from 5V USB or 12V PoE-derived input. IC Role / Device Role / Timing Role: High-efficiency buck controller with SFB pin connected to secondary winding on coupled inductor for isolated bias rail regulation. Use Value: SFB-enforced continuous mode prevents output droop during RF burst transmission; 3.5V–36V input accommodates wide-range PoE+ or adapter inputs. | Use Scenario: Distributed 5V/3.3V point-of-load regulation in factory automation controllers with 24V DC bus and strict EMC Class B compliance. IC Role / Device Role / Timing Role: Fixed-frequency current-mode controller implementing low-noise Burst Mode™ to meet CISPR-22 conducted emission limits. Use Value: COSC-tuned 125kHz operation minimizes high-frequency harmonics; dual MOSFET drive eliminates diode reverse recovery noise. |
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 |
|---|---|---|---|
| LTC3891EMSE#PBF | Wider VIN range (4V–60V), integrated gate drivers, supports forced continuous mode only - no Burst Mode™. | Preferred for high-input industrial systems (>36V) where low-light-load efficiency is secondary to robustness. | Select LTC3891EMSE#PBF when input exceeds 36V or integrated drivers simplify layout; avoid if Burst Mode™ EMI reduction is required. |
| MP2491DJ-LF-Z | Monolithic 3A buck converter (integrated MOSFETs), fixed 500kHz fSW, no SFB or secondary feedback support. | Suitable for cost-sensitive, space-constrained designs where external FETs are unnecessary and auxiliary rail regulation is not needed. | Select MP2491DJ-LF-Z for simplified BOM and layout in ≤3A applications without multi-rail or low-noise requirements. |
Compared with LTC1435IG#TRPBF, LTC3891EMSE#PBF offers higher input voltage tolerance but sacrifices Burst Mode™ efficiency at light loads, while MP2491DJ-LF-Z integrates power stages at the cost of flexibility, fixed frequency, and missing SFB functionality - making LTC1435IG#TRPBF optimal for battery-powered, multi-output, low-EMI designs requiring programmable frequency and ultra-low dropout.
Availability
LTC1435IG#TRPBF is available at Aetrix Electronics and suitable for portable medical instruments, notebook computers, cellular modems, and industrial DC power distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant manufacturing.
Supply support for LTC1435IG#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 semiconductor leader specializing in high-performance analog, mixed-signal, and power management ICs for precision, power, and signal chain applications.
The LTC1435IG#TRPBF belongs to ADI's legacy Linear Technology power controller family, designed specifically for high-efficiency, low-noise synchronous buck conversion in battery-powered and industrial systems demanding wide input range and programmable operation.
FAQ
What is the recommended minimum value for the soft-start capacitor on the RUN/SS pin of the LTC1435IG#TRPBF?
The LTC1435IG#TRPBF features an internal 3µA current source charging the RUN/SS capacitor. A 1µF capacitor yields ~0.5s soft-start time (0.5s/µF), which is typical for controlled inrush limiting. For faster startup, use 0.1µF (50ms); for slower sequencing, use 10µF (5s). Always ensure capacitor voltage rating exceeds VRUN/SS threshold (2V max) and use X7R ceramic for stability. The LTC1435IG#TRPBF datasheet confirms this linear relationship across temperature.
Can the LTC1435IG#TRPBF operate with a 3.3V output using EXTVCC connected directly to VOUT?
No - connecting EXTVCC directly to a 3.3V output will not activate the internal switchover switch, as the LTC1435IG#TRPBF requires ≥4.7V on EXTVCC to disable its internal 5V LDO and route power from EXTVCC to INTVCC. For 3.3V outputs, use a capacitive charge pump (e.g., BAT85 diodes + 0.22µF) or auxiliary winding to boost EXTVCC to ≥4.8V. This is explicitly documented in the LTC1435IG#TRPBF Applications Information section.
What is the maximum allowable voltage on the SW pin of the LTC1435IG#TRPBF?
The SW pin of the LTC1435IG#TRPBF has an absolute maximum rating of VIN + 5V. Since VIN is rated up to 36V, SW may swing as high as 41V during transient conditions. This rating accounts for ringing and overshoot from parasitic inductance in the switch-node layout. Layout best practices - short traces, minimized loop area, and proper snubbing - are essential to keep SW within safe operating limits per the LTC1435IG#TRPBF datasheet.
Does the LTC1435IG#TRPBF support foldback current limiting, and how is it enabled?
Yes, the LTC1435IG#TRPBF supports optional foldback current limiting, implemented by connecting a resistor between the SFB pin and INTVCC. When SFB voltage drops below 1.19V, the controller reduces peak current limit proportionally to protect against sustained overloads. This feature is detailed in the Functional Diagram footnote and Applications Information section of the LTC1435IG#TRPBF datasheet, and requires external component selection per load fault profile.
How does the SFB pin affect Burst Mode™ operation in the LTC1435IG#TRPBF?
The SFB pin directly inhibits Burst Mode™ operation in the LTC1435IG#TRPBF: when SFB is pulled below 1.19V, the controller forces continuous conduction mode regardless of load current. This ensures stable regulation of auxiliary windings or bias rails during light-load conditions where Burst Mode™ could cause output ripple or instability. The LTC1435IG#TRPBF Electrical Characteristics table specifies VSFB threshold as 1.16–1.22V, confirming precise control over this behavior.
LTC1435IG#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.209", 5.30mm 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC1435IG#TRPBF FAQ
1.How can I place an order for LTC1435IG#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1435IG#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 LTC1435IG#TRPBF reliable?
The price and inventory of LTC1435IG#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1435IG#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1435IG#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1435IG#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1435IG#TRPBF?
LTC1435IG#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1435IG#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 LTC1435IG#TRPBF?
For technical support, including LTC1435IG#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1435IG#TRPBF requirements.
6.How does Aetrix verify that LTC1435IG#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1435IG#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 LTC1435IG#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1435IG#TRPBF?
All LTC1435IG#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1435IG#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 LTC1435IG#TRPBF part is unused and in its original packaging.
Return procedure for LTC1435IG#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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