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Analog Devices Inc. LTC1435IS#TRPBF
- Part No.:
- LTC1435IS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1435IS#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,277
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Product details
Overview
LTC1435IS#TRPBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller that drives external dual N-channel MOSFETs in fixed-frequency current-mode architecture. 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 achieves >95% efficiency at 1A load with 3.3V output - ideal for battery-powered portable instrumentation.
For engineers reviewing the LTC1435IS#TRPBF datasheet, LTC1435IS#TRPBF pinout, LTC1435IS#TRPBF application, or LTC1435IS#TRPBF equivalent, key selection criteria include its programmable soft start, secondary feedback control (SFB), Burst Mode™ operation for low-load efficiency, remote voltage sense capability, and compatibility with logic-level MOSFETs requiring 5V gate drive.
Technical Context
The LTC1435IS#TRPBF implements constant-frequency current-mode control with an internal 1.19V reference and error amplifier output (ITH pin) modulating peak inductor current. Its oscillator frequency (112–138 kHz typical) is set by an external capacitor on COSC, and it features a dedicated SFB pin enabling forced continuous conduction via secondary winding feedback - critical for multi-output flyback-derived supplies.
It integrates dual high-current gate drivers (TG and BG) with 50–150 ns transition times, supports EXTVCC switchover between internal 5V LDO and external supply (≥4.7V), and includes foldback current limiting, overvoltage lockout (1.24–1.32V), and shutdown quiescent current <25 µA - all within a –40°C to +85°C industrial temperature grade.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5V to 36V - enables direct operation from 12V/24V industrial rails and wide-range battery inputs (e.g., 4-cell Li-ion). |
| Output Voltage Range | 1.19V to 9V - set via external resistor divider on VOSENSE; 1.19V reference tolerance ±1.02% ensures tight regulation. |
| Switching Frequency | 112–138 kHz (typ. 125 kHz with 100pF COSC) - balances MOSFET switching loss vs. inductor size; max 400 kHz supported. |
| Duty Cycle Limit | Up to 99% - sustains regulation when VIN approaches VOUT, extending runtime in deep-discharge battery systems. |
| Shutdown Current | <25 µA - preserves battery life during system sleep modes without external enable circuitry. |
| Current Sense Threshold | 130–180 mV - sets peak inductor current via RSENSE; enables accurate current limiting and IMAX = 100 mV / RSENSE. |
| Operating Temperature | –40°C to +85°C - qualified for industrial and automotive under-hood auxiliary power applications. |
Pinout & Package
Package: 16-lead narrow SO (SO-16), RoHS-compliant, moisture-sensitive level 3, rated for 110°C/W junction-to-ambient thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC | Oscillator timing capacitor node | Connects to ground via external capacitor (e.g., 100pF) to set switching frequency; charge/discharge current defines fOSC. |
| RUN/SS | Soft-start ramp and shutdown control | Internal 3µA current source charges external CSS; voltage threshold 0.8–2.0V disables operation when pulled low. |
| ITH | Error amplifier output / current limit control | Voltage (0–2.5V) sets peak inductor current threshold; clamped during soft-start to limit inrush. |
| SFB | Secondary feedback input | Pull to SGND to force continuous mode; connect to resistive divider from secondary winding for cross-regulation. |
| VOSENSE | Main output voltage feedback | Receives divided VOUT; internal 1.19V reference enables precise output setting independent of load. |
| SENSE+ / SENSE− | Differential current sense inputs | Measure voltage across RSENSE; built-in offset enables accurate current sensing down to 130mV threshold. |
| TG / BG | Top/bottom N-MOSFET gate drivers | Deliver 2A peak current with 50–150ns transitions; TG is floating, referenced to SW node; BG referenced to PGND. |
| INTVCC / EXTVCC | Internal LDO output / external VCC switch input | INTVCC supplies 5V to drivers; EXTVCC ≥4.7V bypasses internal LDO for higher efficiency (e.g., tie to VOUT). |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Maintains >85% efficiency at 100mA load (vs. <70% in forced PWM), reducing audible noise and EMI in standby. |
| Secondary feedback (SFB) control | Enables regulation of isolated secondary outputs without optocoupler - simplifies multi-rail flyback designs. |
| Programmable soft start | External CSS capacitor sets controlled ramp time (~0.5s/µF); prevents inrush current and output overshoot. |
| Remote output voltage sense | Separate VOSENSE and SGND pins minimize IR drop errors - essential for stable 1% regulation at high currents. |
| Ultralow dropout (99% duty) | Extends usable battery range: e.g., maintains 3.3V output down to VIN = 3.33V, critical for single-cell LiFePO₄ systems. |
Applications
| Portable Medical Instrumentation | Notebook & PDA Power Management |
|---|---|
Use Scenario: Compact handheld blood glucose meters requiring long battery life and stable 3.3V/5V rails from 2-cell alkaline or Li-ion. IC Role / Device Role / Timing Role: Primary step-down controller managing main system voltage with Burst Mode™ for low-power sleep states. Use Value: 99% duty cycle extends operational time by >15% near end-of-battery; <25µA shutdown current minimizes self-discharge. | Use Scenario: Dual-voltage core/I/O power sequencing in ultraportable notebooks with 12V input and 1.8V/3.3V/5V outputs. IC Role / Device Role / Timing Role: High-efficiency buck controller for 3.3V I/O rail, synchronized via external clock to reduce beat-frequency noise. Use Value: Programmable soft start (via RUN/SS) coordinates power-up sequence with CPU VRM; remote sense ensures ±1% accuracy at SoC load points. |
| Industrial DC Power Distribution | Wireless Modem Baseband Supply |
Use Scenario: DIN-rail mounted 24V-to-5V conversion for PLC I/O modules operating in harsh ambient (-40°C to +70°C). IC Role / Device Role / Timing Role: Robust primary regulator with wide VIN range and industrial temp grade, driving Si4412DY MOSFETs. Use Value: –40°C to +85°C rating ensures reliability; EXTVCC tied to VOUT improves full-load efficiency by ~8% vs. internal LDO. | Use Scenario: 3.6V-to-2.8V point-of-load conversion for LTE modem RF transceivers with strict ripple and transient response requirements. IC Role / Device Role / Timing Role: Low-noise synchronous buck controller delivering clean 2.8V with fast load-step response (<50µs settling). Use Value: Current-mode control provides <10µs line/load transient recovery; 130–180mV current sense threshold enables precise 3A current limiting. |
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 |
|---|---|---|---|
| LTC3855EFE#PBF | Higher integration: includes 5V bias LDO, MOSFET drivers, and PMBus interface; supports up to 40V input and 2-phase operation. | Targeted at high-current server/telecom POLs requiring digital monitoring; not pin-compatible. | Select LTC3855EFE#PBF only when digital control, higher current (>10A), or multi-phase sync is required. |
| LM5116MH/NOPB | Wider VIN (6–100V), no integrated gate drivers (requires external drivers), no SFB pin, lower quiescent current (13µA). | Designed for high-input industrial/automotive systems (e.g., 48V bus); lacks secondary feedback for isolated outputs. | Choose LM5116MH/NOPB for >40V input or where SFB functionality is unnecessary; verify external driver compatibility. |
Compared with LTC1435IS#TRPBF, LTC3855EFE#PBF adds digital control but increases BOM cost and complexity, while LM5116MH/NOPB extends input range but removes SFB-based cross-regulation - making LTC1435IS#TRPBF optimal for cost-sensitive, multi-output isolated supplies below 36V.
Availability
LTC1435IS#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation, notebook power management, industrial DC distribution, and wireless modem baseband supply requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC1435IS#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 legacy Linear parts including the LTC series.
The LTC1435IS#TRPBF belongs to Linear's high-efficiency DC/DC controller family, designed specifically for synchronous buck topologies in battery-powered and industrial systems demanding low quiescent current, wide input range, and robust secondary-side regulation.
FAQ
What is the maximum recommended switching frequency for LTC1435IS#TRPBF?
The maximum recommended switching frequency for LTC1435IS#TRPBF is 400 kHz. While the oscillator can be configured beyond this (e.g., using smaller COSC), gate charge losses increase significantly above 400 kHz, reducing overall efficiency and raising thermal stress on external MOSFETs and the IC itself. The typical 125 kHz operation with 100 pF COSC balances size, efficiency, and EMI performance.
How does the SFB pin function in LTC1435IS#TRPBF, and what happens when it is grounded?
When the SFB pin of LTC1435IS#TRPBF is grounded, the device is forced into continuous conduction mode regardless of load current - disabling Burst Mode™ operation. This ensures stable regulation for secondary outputs in flyback-derived topologies and eliminates low-frequency output ripple associated with burst cycling, at the cost of slightly reduced light-load efficiency.
Can LTC1435IS#TRPBF drive standard-threshold MOSFETs, or are logic-level devices required?
LTC1435IS#TRPBF requires logic-level N-channel MOSFETs in most configurations because its INTVCC-regulated gate drive is typically 5V. Standard-threshold MOSFETs (VGS(th) > 3V) may not fully enhance unless EXTVCC is supplied externally at ≥8V - a condition explicitly noted in the datasheet as the only exception. For reliable 3.5–36V operation, Si4412DY or similar logic-level devices are recommended.
What is the purpose of the EXTVCC pin on LTC1435IS#TRPBF, and how should it be connected for best efficiency?
The EXTVCC pin on LTC1435IS#TRPBF controls power source selection for the internal gate drivers: when ≥4.7V, it disables the internal 5V LDO and connects directly to INTVCC. For best efficiency, connect EXTVCC to VOUT (e.g., 5V rail) - this reduces input supply current by the duty-cycle ratio, improving full-load efficiency by up to 8% compared to internal LDO operation.
Does LTC1435IS#TRPBF include overvoltage protection, and what is its trip threshold?
Yes, LTC1435IS#TRPBF includes output overvoltage lockout (OVL) triggered when VOSENSE exceeds 1.24–1.32V. This corresponds to a 5–7.5% overvoltage condition relative to the nominal 1.19V reference, protecting downstream loads from damage during feedback loop faults or resistor divider failure. The OVL circuit immediately disables the top MOSFET (TG) until the fault clears.
LTC1435IS#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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LTC1435IS#TRPBF FAQ
1.How can I place an order for LTC1435IS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1435IS#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 LTC1435IS#TRPBF reliable?
The price and inventory of LTC1435IS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1435IS#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1435IS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1435IS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1435IS#TRPBF?
LTC1435IS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1435IS#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 LTC1435IS#TRPBF?
For technical support, including LTC1435IS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1435IS#TRPBF requirements.
6.How does Aetrix verify that LTC1435IS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1435IS#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 LTC1435IS#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1435IS#TRPBF?
All LTC1435IS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1435IS#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 LTC1435IS#TRPBF part is unused and in its original packaging.
Return procedure for LTC1435IS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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