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Analog Devices Inc. LTC1435ACS#TRPBF
- Part No.:
- LTC1435ACS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1435ACS#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,897
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Product details
Overview
LTC1435ACS#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 ≥99% duty cycle for ultra-low dropout, and features programmable fixed-frequency operation via external capacitor (112–138 kHz typical). It is used in notebook computers and battery-powered instrumentation requiring stable, low-noise power delivery.
For engineers reviewing the LTC1435ACS#TRPBF datasheet, LTC1435ACS#TRPBF pinout, LTC1435ACS#TRPBF application, or LTC1435ACS#TRPBF equivalent, key selection criteria include its dual-N-MOSFET synchronous drive capability, secondary feedback control (SFB), programmable soft start, remote output voltage sense, and ≤300 ns minimum on-time for high-frequency, low-duty-cycle designs.
Technical Context
The LTC1435ACS#TRPBF implements a constant-frequency, current-mode control architecture with an internal 1.19V reference and error amplifier output at the ITH pin. Its peak inductor current is regulated by the ITH voltage, while the SFB pin enables forced continuous operation or secondary-winding regulation - critical for multi-output flyback-derived topologies.
It integrates a 5V internal LDO (INTVCC) with switchover to EXTVCC above 4.7V, enabling efficiency-optimized power sourcing from the output rail. Gate drivers TG and BG deliver ≥2A peak current with <150 ns rise/fall times into 3000pF loads, supporting fast-switching logic-level MOSFETs in high-VIN-to-low-VOUT applications.
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 systems and unregulated adapters. |
| Output Voltage Range | 1.19V to 9V - set via external resistive divider on VOSENSE; 1.19V reference enables precise low-voltage regulation (e.g., 1.2V, 1.5V, 1.8V, 3.3V, 5V). |
| Switching Frequency | 112–138 kHz (COSC = 100 pF) - externally programmable; higher frequencies reduce inductor size but increase gate loss. |
| Minimum On-Time | ≤300 ns - enables high-frequency operation at very low duty cycles (e.g., 5V→1.2V at 12V VIN), avoiding pulse-skipping instability. |
| Duty Cycle Range | 5% to 99% - supports both high-ratio step-down and near-dropout operation (e.g., 36V→35V), extending battery runtime. |
| Shutdown Current | <25 µA - ensures micropower shutdown for long-term battery hold-up in portable devices. |
| Current Sense Threshold | 130–180 mV - sets overcurrent limit via RSENSE; enables accurate peak-current-mode control with ±0.5% load regulation. |
Pinout & Package
Package: 16-lead narrow SO (SOIC-16), 1.27 mm pitch, JEDEC MS-012AC, RoHS-compliant, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC | Oscillator timing capacitor connection | Sets switching frequency; 100 pF yields ~125 kHz; charge/discharge current defines fOSC. |
| RUN/SS | Soft-start ramp and shutdown enable | Capacitor to ground sets soft-start time (~0.5 s/µF); <1.3 V forces shutdown with <25 µA IQ. |
| ITH | Error amplifier output / current comparator threshold control | Voltage (0–2.5 V) sets peak inductor current; clamped during soft-start to limit inrush. |
| SFB | Secondary feedback input | Pull to GND for forced continuous mode; connect to secondary winding divider for auxiliary output regulation. |
| SGND | Small-signal ground reference | Must be routed separately from PGND to avoid noise coupling into VOSENSE and SENSE+/- paths. |
| VOSENSE | Main output voltage feedback input | Receives resistive divider voltage; servo-controlled to 1.19 V reference for ±0.8% load regulation. |
| SENSE– / SENSE+ | Current sense differential inputs | Measure voltage across RSENSE; built-in offset enables accurate current limiting without external amplifiers. |
| PGND | Power ground for bottom MOSFET source | Return path for CIN negative terminal and M2 source; must be low-inductance connection to minimize noise. |
| BG | Bottom N-MOSFET gate driver output | Drives M2 gate from GND to INTVCC (≈5 V); supports logic-level MOSFETs with fast turn-on/turn-off. |
| INTVCC | Internal 5 V regulator output | Supplies gate drivers and internal circuitry; requires ≥2.2 µF tantalum bypass to PGND. |
| VIN | Main input supply | 3.5–36 V input; must be decoupled with low-ESR capacitors rated for RMS current up to IOUT/2. |
| SW | Switch node connection | Connects to inductor; swings from ≈−0.4 V (Schottky drop) to VIN; high dv/dt node requiring tight layout. |
| BOOST | Bootstrap supply for top MOSFET driver | Connected to bootstrap capacitor; supplies floating driver with swing from INTVCC to VIN + INTVCC. |
| TG | Top N-MOSFET gate driver output | Floating driver output referenced to SW; delivers full INTVCC swing superimposed on SW node voltage. |
| EXTVCC | External VCC input for INTVCC switchover | Enables >4.7 V external supply (e.g., VOUT) to power INTVCC, reducing input current and improving efficiency. |
Key Features
| Feature | Design Value |
|---|---|
| Dual N-channel synchronous MOSFET drive | Eliminates external Schottky diode losses; enables >90% efficiency at 3A with proper MOSFET selection. |
| Secondary feedback (SFB) control | Guarantees regulation of auxiliary outputs in flyback-derived topologies by forcing continuous conduction mode. |
| Programmable soft start via RUN/SS capacitor | Prevents inrush current and output overshoot; ramp time precisely controlled by external CSS value. |
| Burst Mode™ operation | Maintains high light-load efficiency (>80% at 100 mA) by disabling gate drives during low-current intervals. |
| Logic-controlled micropower shutdown | Reduces quiescent current to <25 µA, enabling months of standby in battery-powered PDAs and sensors. |
| Low minimum on-time (≤300 ns) | Supports high-frequency, high-input-to-low-output conversion (e.g., 24V→1.2V) without pulse skipping. |
Applications
| Portable Instrument Power Supply | Notebook CPU Core Voltage Regulator |
|---|---|
|
Use Scenario: A handheld multimeter uses a single Li-ion cell (2.7–4.2 V) to power a 3.3 V microcontroller and analog front-end with strict noise and efficiency requirements. IC Role / Device Role / Timing Role: LTC1435ACS#TRPBF acts as the main synchronous buck controller, driving Si4412DY MOSFETs to generate clean, regulated 3.3 V from variable battery input. Use Value: 99% duty cycle operation extends usable battery range down to 2.8 V; Burst Mode maintains >85% efficiency at 10 mA load. |
Use Scenario: A thin-and-light notebook requires a compact, high-efficiency 1.2 V/3 A core voltage rail from a 12 V intermediate bus. IC Role / Device Role / Timing Role: LTC1435ACS#TRPBF controls external N-MOSFETs in a synchronous buck stage, using remote sensing and programmable soft start for precise sequencing. Use Value: ≤300 ns minimum on-time enables stable 1.2 V output from 12 V input; SFB pin unused but reserved for future multi-rail coordination. |
| Cellular Baseband Power Management | Industrial DC Power Distribution |
|
Use Scenario: A 4G LTE modem module needs low-noise, dynamically adjustable 1.8 V and 2.8 V rails with fast transient response to RF burst activity. IC Role / Device Role / Timing Role: LTC1435ACS#TRPBF provides the 1.8 V rail; its current-mode control and 125 kHz fixed frequency ensure sub-50 µs load-step recovery. Use Value: Programmable RSENSE and ITH loop compensation allow tuning for optimal transient behavior under varying PCB parasitics. |
Use Scenario: A factory automation I/O module derives 5 V/2 A from a 24 V DC field bus, operating continuously in harsh ambient temperatures. IC Role / Device Role / Timing Role: LTC1435ACS#TRPBF serves as the primary DC/DC controller, leveraging EXTVCC connected to VOUT to reduce input current and thermal stress. Use Value: INTVCC switchover cuts driver-related input current by ~40%, lowering junction temperature and improving reliability at 70°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5116PWPR | Wide-input (6–100 V), current-mode controller with integrated high-side driver; no secondary feedback (SFB) pin. | Designed for high-VIN industrial converters; lacks SFB functionality required for multi-output flyback coordination. | Select LM5116PWPR only when input exceeds 36 V or SFB is unnecessary; requires external bootstrap diode unlike LTC1435ACS#TRPBF. |
| TPS40210DGQR | VIN range 4.5–52 V; voltage-mode control; no integrated 5 V LDO - requires external bias supply. | Targeted at cost-sensitive telecom power; lacks Burst Mode and micropower shutdown (<25 µA). | Choose TPS40210DGQR for high-VIN, non-battery apps where low-IQ and SFB are not required; adds external components vs LTC1435ACS#TRPBF's self-contained INTVCC. |
Compared with LM5116PWPR and TPS40210DGQR, the LTC1435ACS#TRPBF uniquely combines SFB-based auxiliary regulation, Burst Mode for battery life extension, and seamless EXTVCC switchover - making it optimal for portable, multi-rail, and thermally constrained designs where those features are essential.
Availability
LTC1435ACS#TRPBF is available at Aetrix Electronics and suitable for notebook computers, portable instrumentation, and cellular baseband power supplies requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for LTC1435ACS#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision, industrial, automotive, and communications markets.
The LTC1435ACS#TRPBF belongs to Linear's legacy high-efficiency DC/DC controller family, designed specifically for synchronous step-down regulation in space-constrained, battery-sensitive applications demanding low noise, wide input range, and robust transient response.
FAQ
What is the maximum input voltage rating for the LTC1435ACS#TRPBF?
The LTC1435ACS#TRPBF has an absolute maximum input supply voltage (VIN) rating of 36 V. Operation beyond this voltage risks permanent damage. The device is specified for continuous operation from 3.5 V to 30 V, with 36 V representing the absolute upper limit under transient conditions. Always observe derating guidelines and ensure input transient suppression in 24 V industrial systems.
Does the LTC1435ACS#TRPBF integrate MOSFETs or require external ones?
The LTC1435ACS#TRPBF is a controller-only IC and requires two external N-channel MOSFETs - one for the high-side (top) switch and one for the low-side (bottom) synchronous rectifier. It does not integrate any power switches. This architecture allows designers to optimize efficiency, thermal performance, and cost by selecting MOSFETs matched to specific voltage, current, and RDS(ON) requirements.
How does the SFB pin function in the LTC1435ACS#TRPBF?
The SFB (Secondary Feedback) pin on the LTC1435ACS#TRPBF enables regulation of auxiliary outputs in multi-winding transformer topologies. When pulled low (to GND), it forces continuous conduction mode regardless of load. When tied to a resistive divider from a secondary winding, it guarantees regulation of that winding's output - a feature absent in most standard buck controllers and critical for isolated flyback-derived supplies.
Can the LTC1435ACS#TRPBF operate in dropout mode, and what is its minimum dropout voltage?
Yes, the LTC1435ACS#TRPBF supports ultra-low dropout operation up to 99% duty cycle. Its minimum dropout voltage is determined by the RDS(ON) of the selected bottom MOSFET and PCB trace resistance - not by the IC itself. With a 5 mΩ RDS(ON) MOSFET and 3 A load, dropout can be as low as ~15 mV, enabling operation down to VIN ≈ VOUT + 0.015 V under full load.
What package type and lead count does the LTC1435ACS#TRPBF use?
The LTC1435ACS#TRPBF uses a 16-lead narrow SO (SOIC-16) package with 1.27 mm lead pitch, per JEDEC MS-012AC. It is distinct from the SSOP variant (LTC1435AGS) and carries the "S" suffix in its orderable part number to denote this SOIC packaging. The package is RoHS-compliant and rated for 0°C to 70°C ambient operation.
LTC1435ACS#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
LTC1435ACS#TRPBF FAQ
1.How can I place an order for LTC1435ACS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1435ACS#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 LTC1435ACS#TRPBF reliable?
The price and inventory of LTC1435ACS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1435ACS#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1435ACS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1435ACS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1435ACS#TRPBF?
LTC1435ACS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1435ACS#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 LTC1435ACS#TRPBF?
For technical support, including LTC1435ACS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1435ACS#TRPBF requirements.
6.How does Aetrix verify that LTC1435ACS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1435ACS#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 LTC1435ACS#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1435ACS#TRPBF?
All LTC1435ACS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1435ACS#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 LTC1435ACS#TRPBF part is unused and in its original packaging.
Return procedure for LTC1435ACS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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