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Analog Devices Inc. LTC1435CG
- Part No.:
- LTC1435CG
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1435CG.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,148
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Product details
Overview
LTC1435CG from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller driving external 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 99% duty cycle for ultra-low dropout, and achieves >95% efficiency at 1A load with 3.3V output. It is used in battery-powered portable instruments requiring high efficiency and low-noise regulation.
For engineers reviewing the LTC1435CG datasheet, LTC1435CG pinout, LTC1435CG application, or LTC1435CG equivalent, key selection considerations include its 16-lead SSOP package, programmable soft-start via external capacitor, secondary feedback control (SFB) for multi-output regulation, Burst Mode™ operation for <25µA shutdown current, and compatibility with logic-level MOSFETs driven by 5V INTVCC.
Technical Context
The LTC1435CG implements constant-frequency current-mode control with peak inductor current set by ITH voltage and regulated via VOSENSE feedback to a 1.19V reference. Its dual gate drivers (TG and BG) deliver 2A peak current with 50–150ns transition times, powered by an internal 5V LDO (INTVCC) or external EXTVCC ≥4.7V.
Burst Mode™ operation disables both MOSFET drives when inductor current reverses and RSENSE voltage remains below ~20mV for one full cycle, reducing quiescent current to 260µA typical in normal mode and 16–25µA in shutdown. Dropout detection forces periodic top-MOSFET off-time to recharge the bootstrap capacitor CB when VIN approaches VOUT.
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 resistor divider on VOSENSE; 1.19V reference tolerance ±1.02% over temperature. |
| Switching Frequency | 112–138 kHz (COSC = 100pF) - externally programmable; max 400kHz recommended to limit gate-loss efficiency penalty. |
| Max Duty Cycle | 99% - enables ultralow dropout operation critical for extending runtime in battery-powered systems near end-of-discharge. |
| Shutdown Current | 16–25 µA - logic-controlled micropower shutdown via RUN/SS pin <1.3V; preserves battery life in standby. |
| Current Sense Threshold | 130–180 mV - sets peak inductor current limit; determines maximum output current with RSENSE = 100mV/IMAX. |
| Junction Temp Limit | 125°C - thermal design requires θJA = 130°C/W for G-package; TJ = TA + (PD)(130°C/W) must stay ≤125°C. |
Pinout & Package
Package: 16-lead plastic SSOP (G package), 0.150" wide, JEDEC MO-153 compliant. Thermal resistance θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC (1) | Oscillator timing node | Connects to ground via capacitor (e.g., 100pF) to set switching frequency; charge/discharge current defines fOSC. |
| RUN/SS (2) | Soft-start ramp & enable control | Internal 3µA current source charges external CSS; device enables when voltage reaches 1.3V; <1.3V forces shutdown. |
| ITH (3) | Error amplifier output / current limit control | Voltage sets peak inductor current threshold; clamped during soft-start; range 0–2.5V maps to full current scale. |
| SFB (4) | Secondary winding feedback input | Pull to SGND to force continuous operation; tie to INTVCC if no secondary winding; connect to resistive divider for auxiliary output regulation. |
| SGND (5) | Small-signal ground reference | Must be routed separately from power grounds; connects to (–) terminal of COUT to minimize noise coupling into feedback path. |
| VOSENSE (6) | Main output voltage feedback input | Receives divided VOUT; error amplifier compares to 1.19V reference to regulate output; high-impedance (10–50nA bias). |
| SENSE– (7) | Current sense comparator negative input | Connected to low-side of RSENSE; common-mode range extends to SGND; offset with SENSE+ sets trip threshold. |
| SENSE+ (8) | Current sense comparator positive input | Connected to high-side of RSENSE; built-in offset vs SENSE– defines 130–180mV current limit window. |
| EXTVCC (9) | External VCC switch input | When ≥4.7V, internal switch connects to INTVCC; bypasses internal LDO to improve efficiency; must not exceed 10V. |
| PGND (10) | Power ground return | Connects to source of bottom MOSFET and (–) terminal of CIN; carries high di/dt switching currents; separate from SGND. |
| BG (11) | Bottom N-MOSFET gate driver output | Drives gate of synchronous rectifier; swing from PGND to INTVCC (≈5V); 2A peak capability ensures fast turn-on/turn-off. |
| INTVCC (12) | Internal 5V regulator output | Supplies gate drivers and internal circuitry; requires ≥2.2µF tantalum/low-ESR cap to PGND; max 15mA load. |
| VIN (13) | Main input supply | Accepts 3.5–36V; powers internal LDO when EXTVCC is inactive; must be decoupled locally to SGND/PGND. |
| SW (14) | Switch node connection | Connects to inductor; voltage swings from ≈–0.3V (Schottky drop) to VIN; high di/dt node requiring short PCB trace. |
| BOOST (15) | Bootstrap supply for top gate driver | Return node for CB capacitor; voltage swings from INTVCC to VIN + INTVCC; enables floating drive for high-side N-MOSFET. |
| TG (16) | Top N-MOSFET gate driver output | Floating driver output referenced to SW; swing = INTVCC superimposed on SW node; 2A peak, 50–150ns transitions. |
Key Features
| Feature | Design Value |
|---|---|
| Dual N-channel synchronous drive | Enables >95% efficiency by replacing lossy Schottky diode with actively controlled bottom MOSFET; eliminates reverse recovery losses. |
| Programmable fixed-frequency oscillator | Frequency set by single external capacitor (COSC); avoids EMI banding while enabling optimization of size vs efficiency trade-off. |
| 99% maximum duty cycle | Extends operational time in battery systems down to VIN – VOUT = 100mV; critical for Li-ion discharge tail-end performance. |
| Burst Mode™ low-load operation | Reduces quiescent current to 260µA typical and enables micropower shutdown (<25µA); maintains regulation without burst noise in sensitive analog sections. |
| Secondary feedback (SFB) control | Guarantees regulation of auxiliary outputs (e.g., isolated secondaries) by forcing continuous conduction when SFB < 1.19V. |
| Remote output voltage sensing | VOSENSE pin accepts Kelvin connection from output; rejects IR drops in PCB traces and connectors for ±0.8% load regulation accuracy. |
Applications
| Portable Medical Instruments | Notebook & Palmtop Computers |
|---|---|
Use Scenario: Battery-powered handheld ultrasound or glucose meters requiring stable 3.3V/5V rails with minimal heat generation and long runtime. IC Role / Device Role / Timing Role: Primary step-down controller managing main system voltage from single-cell or dual-cell Li-ion packs. Use Value: 99% duty cycle extends usable battery capacity near end-of-discharge; Burst Mode™ cuts idle current to preserve charge between measurements. |
Use Scenario: Core voltage regulation for embedded controllers and peripherals in compact clamshell-form factor devices. IC Role / Device Role / Timing Role: High-efficiency DC-DC controller driving synchronous MOSFETs to generate 1.8V/3.3V from 12V or 19V adapter input. Use Value: Dual N-MOSFET drive achieves >90% efficiency at 2A load; remote sensing compensates for PCB voltage drop across tight layouts. |
| Cellular Baseband Power Supplies | Industrial Portable Test Equipment |
Use Scenario: Power management for LTE/5G modem subsystems where RF noise must be minimized during data transmission bursts. IC Role / Device Role / Timing Role: Main PMIC controller delivering clean, low-noise 1.2V core and 2.8V I/O rails with selectable Burst Mode™ disable via SFB pin. Use Value: SFB pin pulled low disables Burst Mode™ to eliminate low-frequency switching noise that could interfere with RF front-end sensitivity. |
Use Scenario: Field-deployable multimeters or oscilloscope modules operating from rechargeable 18V battery packs. IC Role / Device Role / Timing Role: Input-stage buck controller stepping 18V battery down to 5V/±12V rails for analog front-end and digital logic. Use Value: Wide 3.5–36V input range accommodates full battery discharge curve; programmable soft-start prevents inrush into large downstream capacitors. |
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 |
|---|---|---|---|
| LT8610EMSE#PBF | Integrated power stage (2A internal MOSFETs); 3.4–42V input; 200kHz–3MHz sync frequency; no external RSENSE required. | Lower BOM count and layout complexity; unsuitable for >2A or discrete MOSFET optimization (e.g., SiC/GaN). | Select LT8610EMSE#PBF when board space and design cycle time are prioritized over peak efficiency and thermal flexibility. |
| TPS40210DGQ | Current-mode controller with integrated 1.5A gate drivers; 4.5–52V input; adjustable frequency 50kHz–1MHz; no SFB pin or Burst Mode™. | Lacks secondary feedback and ultralow-IQ modes; requires external compensation; higher minimum operating voltage. | Select TPS40210DGQ when operating above 4.5V input and secondary regulation is unnecessary; verify loop stability with external compensation. |
Compared with LT8610EMSE#PBF and TPS40210DGQ, the LTC1435CG provides unique support for secondary winding regulation (SFB), true 3.5V start-up, and sub-25µA shutdown-making it optimal for multi-rail battery systems where auxiliary output tracking and ultra-low standby power are mandatory.
Availability
LTC1435CG is available at Aetrix Electronics and suitable for portable medical instruments, notebook computers, cellular baseband supplies, and industrial test equipment requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LTC1435CG 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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC1435CG belongs to Linear's legacy high-efficiency DC-DC controller product line, designed specifically for synchronous buck topologies in portable and battery-critical applications demanding wide input range, low IQ, and robust multi-output regulation.
FAQ
What is the operating temperature range for the LTC1435CG?
The LTC1435CG is specified for an ambient operating temperature range of 0°C to 70°C. Its maximum junction temperature is 125°C, and thermal design must satisfy TJ = TA + (PD)(130°C/W) using the SSOP (G) package's θJA value. Derating is required above 70°C ambient to maintain safe junction temperature under load.
How does the SFB pin affect LTC1435CG operation?
The SFB pin on the LTC1435CG enables secondary winding regulation: pulling SFB below 1.19V forces continuous conduction mode, overriding Burst Mode™ to ensure regulation of auxiliary outputs. When tied to INTVCC, it disables secondary control; when grounded, it guarantees continuous operation regardless of load on the main output.
Can the LTC1435CG drive standard-threshold MOSFETs?
The LTC1435CG can drive standard-threshold MOSFETs only if EXTVCC is supplied from an external 5–10V source - because its internal INTVCC regulator delivers only ~5V, which is insufficient for reliable turn-on of VGS(TH) > 2.5V devices. With EXTVCC open, logic-level MOSFETs (VGS(TH) < 1.5V) are required for robust gate drive.
What is the purpose of the EXTVCC pin on the LTC1435CG?
The EXTVCC pin on the LTC1435CG controls power source selection for the INTVCC rail: when EXTVCC ≥ 4.7V, an internal switch connects it to INTVCC, bypassing the internal LDO and improving efficiency by up to 10%. This allows powering gate drivers directly from the regulated output (e.g., 5V rail), reducing input supply current proportionally to duty cycle.
How is soft-start configured on the LTC1435CG?
Soft-start on the LTC1435CG is configured by connecting a capacitor (CSS) from the RUN/SS pin to ground. The internal 3µA current source charges CSS; startup time is approximately 0.5 seconds per microfarad. When CSS reaches 1.3V, the controller enables with ITH clamped at ~30% of full scale, then gradually releases ITH to allow controlled output voltage ramp.
LTC1435CG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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-SSOP
LTC1435CG FAQ
1.How can I place an order for LTC1435CG through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1435CG 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 LTC1435CG reliable?
The price and inventory of LTC1435CG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1435CG is usually 5 days.
3.What payment methods are accepted for LTC1435CG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1435CG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1435CG?
LTC1435CG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1435CG 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 LTC1435CG?
For technical support, including LTC1435CG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1435CG requirements.
6.How does Aetrix verify that LTC1435CG is sourced from the original manufacturer or authorized distributors?
All LTC1435CG 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 LTC1435CG meets industry standards.
7.What is the process for return or replacement of LTC1435CG?
All LTC1435CG units undergo pre-shipment inspection (PSI). If there is an issue with LTC1435CG, 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 LTC1435CG part is unused and in its original packaging.
Return procedure for LTC1435CG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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