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Analog Devices Inc. LTC1735IGN#PBF
- Part No.:
- LTC1735IGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1735IGN#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:226
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Product details
Overview
LTC1735IGN#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 delivers 0.8V to 6V output at up to 9A, supports 4V–30V input, features ±1% output voltage accuracy, OPTI-LOOP™ compensation, and Burst Mode™ for high efficiency at light loads - used in notebook DC/DC power rails and wireless modem baseband supplies.
For engineers reviewing the LTC1735IGN#PBF datasheet, LTC1735IGN#PBF pinout, LTC1735IGN#PBF application, or LTC1735IGN#PBF equivalent, key selection criteria include programmable foldback current limit (60–85mV), forced continuous mode via FCB pin, 0.8V precision reference, 16-lead narrow SSOP package, and compatibility with external 500kHz synchronization - all critical for low-noise, high-efficiency POL designs.
Technical Context
The LTC1735IGN#PBF implements a constant-frequency, current-mode control architecture with dual N-channel gate drivers (TG/BG), internal 5.2V INTVCC LDO, and an error amplifier whose transconductance (gm = 1.3 mmho) sets loop gain. Its ITH pin directly controls peak inductor current, while VOSENSE monitors feedback voltage against a 0.8V reference with ±0.008V tolerance over temperature.
Burst Mode™ operation disables switching when ITH falls below 0.5V, reducing quiescent current to <25µA in shutdown; forced continuous mode is activated by pulling FCB ≤0.84V, eliminating burst noise but increasing light-load losses. The device includes internal foldback current limiting, output overvoltage crowbar (VOVL = 0.86V), and latched short-circuit shutdown triggered by RUN/SS capacitor discharge.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 30V operating, 36V absolute max - supports wide-input industrial and telecom rails. |
| Output Voltage Range | 0.8V to 6V set by external resistor divider - compatible with sub-1V microprocessor cores and 3.3V/5V logic rails. |
| Output Voltage Accuracy | ±1% over line/load/temperature - ensures stable regulation for sensitive analog and digital loads. |
| Switching Frequency | 265–335kHz (COSC = 43pF), synchronizable up to 500kHz - balances efficiency vs. EMI and component size. |
| Current Sense Threshold | 60–85mV (ΔVSENSE(MAX)) - sets peak inductor current with RSENSE = 0.005Ω for ~9A output. |
| Shutdown Quiescent Current | <25µA (IQ) - enables ultra-low-power standby in battery-backed systems. |
| Duty Cycle Max | 98–99.4% - supports ultra-low dropout operation down to VIN – VOUT ≈ 100mV at full load. |
Pinout & Package
Package: 16-lead narrow plastic SSOP (GN), 5.3mm × 4.4mm body, 0.65mm pitch, exposed pad not present. Thermal resistance θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC | Oscillator timing capacitor node | Connects to ground via external capacitor (e.g., 43pF) to set nominal 300kHz frequency; enables sync input when driven externally. |
| RUN/SS | Soft-start ramp & shutdown control | Capacitor-to-ground sets soft-start time (~1.25s/µF); pulled low (<1.5V) disables all circuitry including INTVCC and triggers latchoff on overcurrent. |
| ITH | Error amplifier output / current limit control | Voltage (0–2.4V) sets peak inductor current; clamped at 0.86V in Burst Mode to limit light-load current. |
| FCB | Forced continuous / sync input | Tied to GND for continuous mode; driven with >1.3V clock for synchronization; disables Burst Mode when <0.8V. |
| SGND | Small-signal reference ground | Single-point tie for feedback divider, COSC, CSS - isolates noise-sensitive analog circuitry from PGND return paths. |
| VOSENSE | Feedback voltage input | Receives divided output voltage; regulated to 0.8V ±0.008V; used by EA to maintain output accuracy. |
| SENSE– / SENSE+ | Current sense differential inputs | Measure voltage across RSENSE; built-in offset sets trip threshold; common-mode range extends to 1.1×INTVCC. |
| TG / BG | Top/bottom N-MOSFET gate drivers | High-current (3A peak) drivers with 50–90ns transition times; TG is floating, referenced to SW node. |
| SW | Switch node | Connects to inductor and bootstrap capacitor; swings from –0.4V (Schottky drop) to VIN - defines high-side drive path. |
| VIN | Main power input | Supplies internal circuits and top driver via BOOST path; requires local 22µF/50V ceramic + bulk decoupling. |
| INTVCC | Internal 5.2V supply rail | Powered from VIN (via LDO) or EXTVCC (if ≥4.7V); powers drivers and control logic; requires 1µF ceramic + 4.7µF tantalum. |
| PGND | Power ground return | Connects to source of bottom MOSFET and cathode of input capacitor - carries high di/dt switching currents. |
| EXTVCC | External VCC input | Optional 4.5–7V supply to bypass INTVCC LDO; improves efficiency and gate drive strength when sourced from converter output. |
| BOOST | Floating top-driver supply | Returned to bootstrap capacitor; voltage = INTVCC + SW swing - enables high-side N-MOSFET drive without P-MOS or charge pump. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ compensation | Minimizes required output capacitance and relaxes ESR constraints - enables stable operation with low-ESR polymer or MLCC outputs. |
| Burst Mode™ operation | Reduces no-load IQ to <25µA while maintaining ±1% regulation - extends battery life in portable systems without sacrificing transient response. |
| Programmable foldback current limit | Threshold adjusts from 60–85mV via RSENSE - provides scalable overcurrent protection matching specific MOSFET SOA and thermal design. |
| Forced continuous mode control | FCB pin disables Burst Mode and enforces fixed-frequency operation - eliminates audible noise and simplifies EMI filtering in noise-sensitive applications. |
| Remote output voltage sensing | VOSENSE accepts Kelvin connection to load - compensates for PCB trace IR drop to maintain ±1% accuracy at point-of-load. |
| Internal overvoltage crowbar | Triggers at VOSENSE > 0.86V (±7.5% of 0.8V) - clamps output by turning on bottom MOSFET to protect downstream ICs during transients. |
Applications
| Mobile Computing Power Rail | Wireless Baseband Supply |
|---|---|
Use Scenario: Regulating 1.6V/9A core voltage for Intel Pentium M-class processors in ultraportable notebooks. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing dynamic load steps up to 9A with <10µs response. Use Value: OPTI-LOOP™ maintains stability with 180µF Panasonic OS-CON output cap; Burst Mode™ extends battery runtime during idle. |
Use Scenario: Generating clean 3.3V/3A supply for LTE modem RF front-end and baseband ASIC in handheld devices. IC Role / Device Role / Timing Role: High-efficiency POL regulator with forced continuous mode to suppress switching noise near sensitive RF sections. Use Value: FCB pin enables fixed 300kHz operation; remote sensing ensures <±10mV regulation at ASIC pins despite 50mΩ PCB resistance. |
| Industrial DC Distribution | Automotive Infotainment Core |
Use Scenario: Converting 24V vehicle or factory bus to 5V/6A for embedded controllers and I/O modules. IC Role / Device Role / Timing Role: Wide-input buck controller supporting 4V–30V range with UVLO (3.9V) and overvoltage crowbar protection. Use Value: 99.4% max duty cycle enables operation down to 5.1V input; latched short-circuit shutdown prevents thermal runaway during field faults. |
Use Scenario: Powering ARM Cortex-A series SoC in automotive head units requiring AEC-Q200-compliant design margins. IC Role / Device Role / Timing Role: Controller for discrete N-MOSFET stage delivering 1.2V/8A with thermal derating per -40°C to 85°C spec. Use Value: ITH-based current limiting adapts to MOSFET RDS(on) drift over temperature; EXTVCC input improves efficiency using 5V auxiliary rail. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2315DJ-LF-Z | Integrated 2A power stage; fixed 500kHz frequency; no FCB sync or Burst Mode; smaller 8-pin SOIC package. | Suitable only for ≤2A loads; lacks programmable current limit and remote sensing - limited to low-power embedded rails. | Select when board space is constrained and output current ≤2A; avoid for >3A or noise-sensitive designs requiring Burst Mode. |
| LTC3850EGN#PBF | Pin-compatible upgrade with 550kHz max frequency, improved current sense accuracy (±0.5%), and enhanced EXTVCC management. | Supports higher VIN (36V), tighter VOUT accuracy (±0.5%), and faster transient response - targets next-gen high-density power systems. | Choose for new designs needing higher performance; LTC1735IGN#PBF remains valid for cost-sensitive legacy replacements with identical footprint. |
Compared with MP2315DJ-LF-Z, LTC1735IGN#PBF offers scalable 9A output and advanced light-load efficiency; versus LTC3850EGN#PBF, it trades minor accuracy and frequency headroom for proven reliability and lower BOM cost in established designs.
Availability
LTC1735IGN#PBF is available at Aetrix Electronics and suitable for notebook computing power rails, wireless baseband supplies, and industrial DC distribution systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric compliance.
Supply support for LTC1735IGN#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and computing markets.
The LTC1735IGN#PBF belongs to Linear's high-efficiency synchronous buck controller product line, designed specifically for demanding point-of-load applications where precision regulation, low-noise operation, and wide input range are critical.
FAQ
What is the maximum supported input voltage for the LTC1735IGN#PBF?
The LTC1735IGN#PBF has an absolute maximum input voltage rating of 36V, with recommended operating range from 4V to 30V. Exceeding 36V risks permanent damage to the VIN, SW, and BOOST pins. For reliable 24V system designs, the device operates safely with margin, and its undervoltage lockout activates at 3.9V to prevent erratic startup.
Does the LTC1735IGN#PBF integrate power MOSFETs or require external ones?
The LTC1735IGN#PBF is a controller-only IC and requires two external N-channel MOSFETs - one for the high-side (driven by TG) and one for the low-side (driven by BG). This architecture allows optimization of RDS(on), Qg, and thermal performance for specific current and efficiency targets, unlike integrated buck regulators.
How does Burst Mode™ operation improve light-load efficiency in the LTC1735IGN#PBF?
Burst Mode™ in the LTC1735IGN#PBF disables both gate drivers when the ITH voltage drops below 0.5V, allowing the output capacitor to supply load current until regulation error triggers resumption. This reduces average input current to <25µA, achieving >85% efficiency at 10mA load - critical for battery-powered systems.
Can the LTC1735IGN#PBF be synchronized to an external clock, and what are the limits?
Yes, the LTC1735IGN#PBF can be synchronized via the FCB pin to an external clock signal between 0.9×fO and 1.3×fO (e.g., 270–390kHz for nominal 300kHz). The clock must exceed 1.3V for ≥0.3µs high time and fall below 0.3V for ≥0.3µs low time; exceeding 1.3×fO risks slope compensation loss and instability.
What is the purpose of the EXTVCC pin on the LTC1735IGN#PBF?
The EXTVCC pin on the LTC1735IGN#PBF accepts an external 4.5–7V supply to power the INTVCC rail, bypassing the internal 5.2V LDO. This improves conversion efficiency and gate drive strength - especially useful when powering INTVCC from a secondary winding or regulated 5V rail in multi-output designs.
LTC1735IGN#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SSOP (0.154", 3.90mm 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):
- 4V ~ 30V
- Frequency - Switching:
- 300kHz
- Duty Cycle (Max):
- 99.4%
- Synchronous Rectifier:
- Yes
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Enable, Power Good, Soft Start
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC1735IGN#PBF FAQ
1.How can I place an order for LTC1735IGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735IGN#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 LTC1735IGN#PBF reliable?
The price and inventory of LTC1735IGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735IGN#PBF is usually 5 days.
3.What payment methods are accepted for LTC1735IGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1735IGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1735IGN#PBF?
LTC1735IGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1735IGN#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 LTC1735IGN#PBF?
For technical support, including LTC1735IGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735IGN#PBF requirements.
6.How does Aetrix verify that LTC1735IGN#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1735IGN#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 LTC1735IGN#PBF meets industry standards.
7.What is the process for return or replacement of LTC1735IGN#PBF?
All LTC1735IGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735IGN#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 LTC1735IGN#PBF part is unused and in its original packaging.
Return procedure for LTC1735IGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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