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Analog Devices Inc. LTC1435AIG#PBF
- Part No.:
- LTC1435AIG#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1435AIG#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,708
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Product details
Overview
LTC1435AIG#PBF 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 ≤300ns minimum on-time and 99% duty cycle for ultra-low dropout, and targets high-efficiency DC/DC conversion in battery-powered portable electronics.
For engineers reviewing the LTC1435AIG#PBF datasheet, LTC1435AIG#PBF pinout, LTC1435AIG#PBF application, or LTC1435AIG#PBF equivalent, key selection criteria include its dual-N-MOSFET synchronous drive capability, programmable soft start via external capacitor, secondary feedback control (SFB) for multi-output regulation, Burst Mode™ operation for sub-100mA load efficiency, and compatibility with logic-level MOSFETs under INTVCC-referenced gate drive.
Technical Context
The LTC1435AIG#PBF implements a constant-frequency current-mode control architecture with an internal 1.19V reference, error amplifier output at ITH, and peak-current sensing via SENSE+ and SENSE−. Its oscillator frequency is set externally by COSC (100pF yields ~125kHz), and it features dedicated pins for secondary winding feedback (SFB) and remote voltage sensing (VOSENSE).
It integrates a 5V internal LDO (INTVCC) with switchover to EXTVCC above 4.7V, dual high-current gate drivers (TG and BG) with ≤150ns transition times, and shutdown logic with <25µA IQ. The device enforces continuous conduction when SFB < 1.19V and inhibits Burst Mode when SFB is pulled low-enabling precise coordination across primary and auxiliary outputs.
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 resistive divider on VOSENSE; 1.19V reference enables accurate low-VOUT regulation. |
| Minimum On-Time | ≤300ns - enables high-frequency, high-input-to-low-output conversion (e.g., 24V→1.2V at 400kHz) without pulse-skipping instability. |
| Duty Cycle Range | 5% to 99% - supports both high-ratio step-down and near-dropout operation (e.g., 3.6V→3.3V at >95% duty). |
| Shutdown Current | <25µA - ensures micropower holdover in battery-backed systems during standby or sleep modes. |
| Oscillator Frequency | 112–138kHz (with 100pF COSC) - user-programmable via capacitor; higher frequencies require trade-offs in gate loss vs. size. |
| Operating Temp Range | –40°C to +85°C - qualified for extended industrial environments; denoted by 'I' grade in part number. |
| Package | 16-Lead SSOP (G package) - surface-mount, thermally enhanced footprint compatible with automated assembly. |
Pinout & Package
Package: 16-lead plastic SSOP (G package), 0.150" body width, exposed pad not present, JEDEC MS-013AC compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC | Oscillator timing capacitor connection | Sets switching frequency; 100pF yields ~125kHz; charge/discharge current defines fOSC. |
| RUN/SS | Soft-start ramp and shutdown enable | Capacitor to ground sets soft-start time (~0.5s/µF); <1.3V forces shutdown with <25µA IQ. |
| ITH | Error amplifier output / current limit threshold control | Voltage controls peak inductor current; 0–2.5V range maps to full current range; used for compensation. |
| SFB | Secondary winding feedback input | Pull low to force 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 avoid noise coupling into VOSENSE and current sense paths. |
| VOSENSE | Main output voltage feedback input | Receives resistive divider voltage; servo-controlled to 1.19V reference for ±0.8% load regulation. |
| SENSE− / SENSE+ | Current sense differential inputs | Measure voltage across RSENSE; built-in offset sets trip point at 150mV typical; common-mode range = SGND to INTVCC. |
| PGND | Power ground for bottom MOSFET source | Return path for high di/dt switch currents; must connect directly to CIN(−) and M2 source. |
| BG | Bottom N-MOSFET gate driver output | Drives M2 gate from 0V to INTVCC (5V); rated for 2A peak for <10µs; requires low-inductance layout. |
| INTVCC | Internal 5V regulator output & driver supply | Supplies all internal circuitry and gate drivers; bypass with ≥2.2µF tantalum; switchover to EXTVCC occurs at 4.7V. |
| VIN | Main input supply | 3.5–36V input; powers internal LDO when EXTVCC is open; must be decoupled locally to SGND/PGND. |
| SW | Switch node connection | Connects to inductor and MOSFET drains; swings from −0.3V (Schottky drop) to VIN; high dv/dt node requiring tight loop area. |
| BOOST | Floating supply for top MOSFET driver | Bootstrap capacitor return; voltage swing = INTVCC superimposed on SW node; enables high-side N-MOSFET drive. |
| TG | Top N-MOSFET gate driver output | Floating driver output referenced to SW; swing = INTVCC; drives M1 gate with ≤150ns transitions. |
| EXTVCC | External VCC switchover input | Enables INTVCC sourcing from VOUT or auxiliary winding when >4.7V; max rating = 10V; must be |
Key Features
| Feature | Design Value |
|---|---|
| Dual N-channel synchronous drive | Eliminates external Schottky losses; enables >90% efficiency at 3A with proper MOSFET selection and layout. |
| Programmable fixed-frequency operation | External COSC capacitor allows optimization of size, EMI, and efficiency-no internal oscillator drift or variation. |
| Secondary feedback control (SFB) | Guarantees regulation of auxiliary outputs (e.g., isolated secondaries) independent of main load, preventing cross-regulation errors. |
| Burst Mode™ operation | Maintains >75% efficiency down to 100mA loads by disabling gate drives during light-load idle periods, reducing quiescent power. |
| Logic-controlled micropower shutdown | Reduces system standby current to <25µA while preserving state; compatible with processor GPIO wake-up signals. |
| Remote output voltage sense (VOSENSE) | Compensates for PCB trace IR drop, enabling ±0.5% output accuracy at load point even with 100mΩ routing resistance. |
Applications
| Portable Instrument Power Supply | Notebook CPU Core Voltage |
|---|---|
Use Scenario: Precision analog front-end in handheld multimeters or data loggers requiring stable 3.3V/5V rails from single-cell Li-ion or 9V alkaline. IC Role / Device Role / Timing Role: Primary step-down controller regulating main system rail; uses SFB to coordinate isolated ADC reference supply. Use Value: 99% duty cycle extends battery runtime in dropout; low 25µA shutdown current preserves charge during measurement intervals. | Use Scenario: Core voltage regulation for Intel Pentium MMX or AMD K6-era CPUs in sub-notebooks with 12V input and 1.6–2.0V output requirements. IC Role / Device Role / Timing Role: High-current (3A) synchronous buck controller; employs programmable soft start (RUN/SS) for safe power sequencing with chipset reset logic. Use Value: ≤300ns minimum on-time enables direct 12V→1.6V conversion at 125kHz, avoiding intermediate stages and reducing BOM count. |
| Cellular Baseband Power | Industrial DC Distribution Module |
Use Scenario: Dual-rail power for GSM/GPRS baseband ICs requiring tightly regulated 2.8V RF and 1.8V digital supplies from 3.6–4.2V Li-ion battery. IC Role / Device Role / Timing Role: Main converter for 2.8V rail; SFB pin tied to 1.8V rail's feedback divider to enforce simultaneous regulation. Use Value: Secondary feedback eliminates need for separate LDO on 1.8V rail, cutting cost and thermal load while maintaining ±1% cross-regulation. | Use Scenario: DIN-rail mounted 24V-to-5V/3.3V converter in PLC I/O modules where ambient temperature reaches 70°C continuously. IC Role / Device Role / Timing Role: Industrial-grade synchronous buck controller (I-grade temp range); uses EXTVCC connected to VOUT for reduced input current and junction temperature rise. Use Value: INTVCC switchover lowers total power dissipation by ~8% at full load, enabling reliable operation without heatsink in enclosed enclosures. |
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 |
|---|---|---|---|
| LTC3850EGN#PBF | Higher integration: includes 5V bias LDO, precision 0.6V reference, and adjustable current limit; supports up to 40V input but no SFB pin. | Lacks secondary feedback capability; cannot regulate auxiliary outputs independently; better suited for single-output high-precision designs. | Select LTC3850EGN#PBF only when SFB functionality is unnecessary and tighter output tolerance (±0.5%) is required over temperature. |
| LM5116MH/NOPB | Wider input range (6–100V), integrated bootstrap diode, no SFB pin; uses external VREF and requires separate soft-start circuit. | Designed for high-input industrial and telecom applications; lacks native support for multi-output coordination or low-IQ shutdown. | Choose LM5116MH/NOPB for >40V input systems where secondary feedback is not needed and board space permits discrete soft-start components. |
Compared with LTC3850EGN#PBF and LM5116MH/NOPB, the LTC1435AIG#PBF uniquely provides secondary feedback control (SFB) for auxiliary output regulation, maintains <25µA shutdown current, and supports true 3.5V start-up-making it optimal for compact, multi-rail battery-powered systems where cross-regulation and standby power are critical.
Availability
LTC1435AIG#PBF is available at Aetrix Electronics and suitable for portable instrumentation, notebook computing, cellular baseband power, industrial DC distribution, and battery-operated devices requiring stable component supply across extended temperature ranges.
Supply support for LTC1435AIG#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, Inc. (ADI) acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LTC portfolio.
The LTC1435AIG#PBF belongs to Linear's legacy high-efficiency DC/DC controller family, designed specifically for synchronous step-down conversion in space-constrained, battery-sensitive applications demanding low dropout, programmable frequency, and multi-output coordination.
FAQ
What is the minimum input voltage required for the LTC1435AIG#PBF to start switching?
The LTC1435AIG#PBF requires a minimum input voltage of 3.5V to initiate normal switching operation. Below this threshold, internal circuitry-including the INTVCC regulator and gate drivers-cannot sustain bias conditions. Startup is guaranteed at 3.6V across the full –40°C to +85°C temperature range, as verified in the Absolute Maximum Ratings and Electrical Characteristics tables. The LTC1435AIG#PBF will remain latched in shutdown below 3.5V until VIN rises sufficiently to re-enable the RUN/SS comparator and internal LDO.
Can the LTC1435AIG#PBF operate without an external bootstrap capacitor?
No-the LTC1435AIG#PBF requires an external bootstrap capacitor (CB) connected between BOOST and SW pins to enable high-side N-MOSFET gate drive. The internal floating driver relies on CB to generate the voltage boost needed to fully enhance the top MOSFET when SW is near ground. Omitting CB prevents TG from reaching sufficient gate voltage, causing failure to turn on M1 and resulting in no output regulation. Typical CB value is 0.1µF ceramic with X7R dielectric, placed adjacent to BOOST and SW pins per Layout Guidelines in the datasheet.
How does the SFB pin affect Burst Mode™ operation in the LTC1435AIG#PBF?
The SFB pin directly disables Burst Mode™ operation in the LTC1435AIG#PBF when pulled below 1.19V. This forces continuous conduction mode regardless of load current, ensuring stable regulation for auxiliary outputs tied to secondary windings. In contrast, when SFB is left open or tied to INTVCC, Burst Mode™ activates automatically below ~100mA load to minimize quiescent current. The LTC1435AIG#PBF datasheet confirms this behavior in the "Low Current Operation" section and Figure 1435A G17 waveform showing suppressed burst cycles when SFB is grounded.
What is the maximum recommended switching frequency for the LTC1435AIG#PBF?
The maximum recommended switching frequency for the LTC1435AIG#PBF is 400kHz, as stated in the Applications Information section. While the oscillator can be configured beyond this (e.g., using COSC < 50pF), higher frequencies increase MOSFET gate charge losses and reduce overall efficiency-particularly with logic-level MOSFETs driven from 5V INTVCC. At 400kHz, the minimum on-time constraint (≤300ns) remains satisfied for most practical VIN/VOUT ratios, and core losses in standard ferrite inductors remain manageable. The LTC1435AIG#PBF electrical characteristics are specified up to 138kHz; operation at 400kHz requires validation of thermal performance and ripple under actual load conditions.
Does the LTC1435AIG#PBF support remote sensing for output voltage regulation?
Yes-the LTC1435AIG#PBF supports true 4-wire remote sensing via the VOSENSE pin, which accepts feedback from a resistive divider placed directly at the load terminals. This compensates for voltage drop across PCB traces and connectors, improving load regulation accuracy to ±0.5% over full current range. The VOSENSE pin is internally buffered and servo-controlled to the 1.19V reference; its input bias current is only 10–50nA, minimizing error from divider resistor self-heating or leakage. Remote sensing is enabled by routing VOSENSE and SGND separately from power ground, as detailed in the Pin Functions and Layout sections of the LTC1435AIG#PBF datasheet.
LTC1435AIG#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- 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
LTC1435AIG#PBF FAQ
1.How can I place an order for LTC1435AIG#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1435AIG#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 LTC1435AIG#PBF reliable?
The price and inventory of LTC1435AIG#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1435AIG#PBF is usually 5 days.
3.What payment methods are accepted for LTC1435AIG#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1435AIG#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1435AIG#PBF?
LTC1435AIG#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1435AIG#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 LTC1435AIG#PBF?
For technical support, including LTC1435AIG#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1435AIG#PBF requirements.
6.How does Aetrix verify that LTC1435AIG#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1435AIG#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 LTC1435AIG#PBF meets industry standards.
7.What is the process for return or replacement of LTC1435AIG#PBF?
All LTC1435AIG#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1435AIG#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 LTC1435AIG#PBF part is unused and in its original packaging.
Return procedure for LTC1435AIG#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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