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Analog Devices Inc. LTC1735CGN-1#PBF
- Part No.:
- LTC1735CGN-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC1735CGN-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,240
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Product details
Overview
LTC1735CGN-1 from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller optimized for CPU core power delivery in mobile computing systems. It delivers 0.8V–7V output at up to 12A, supports 3.5V–30V input, features ±1% output voltage accuracy, OPTI-LOOP™ compensation, and 99% duty cycle for low-dropout operation.
For engineers reviewing the LTC1735CGN-1 datasheet, LTC1735CGN-1 pinout, LTC1735CGN-1 application, or LTC1735CGN-1 equivalent, this controller enables dynamic voltage scaling for SpeedStep-enabled Pentium III processors, provides programmable current limit via external sense resistor, supports external clock synchronization up to 500kHz, and integrates dual N-channel MOSFET gate drivers with BOOST/TG/BG outputs.
Technical Context
The LTC1735CGN-1 implements a constant-frequency, current-mode control architecture with an internal transconductance error amplifier (gm = 1.3 mmho) and dual current comparators for peak-current limiting and foldback protection. Its OPTI-LOOP™ compensation allows stable loop response across wide output capacitance and ESR variations without external compensation redesign.
It integrates a 5.2V internal LDO (INTVCC) powered either from VIN or externally via EXTVCC ≥4.7V, supports forced continuous mode via PGOOD pin grounding, and uses a voltage-controlled oscillator set by COSC (47pF typical) with nominal 300kHz frequency. Burst Mode™ operation enables high efficiency below 10mA load while maintaining regulated output.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 0.8V to 7V - Programmable via external resistive divider on VOSENSE pin; supports dynamic VSEL-based CPU voltage scaling. |
| Input Voltage Range | 3.5V to 30V (max 36V) - Enables direct operation from 5V, 12V, or 24V rails without pre-regulation. |
| Output Voltage Accuracy | ±1% over temperature - Ensures tight regulation for sensitive CPU core supply requirements per Intel Mobile CPU specs. |
| Power Good Threshold | ±7.5% window around setpoint - Open-drain PGOOD asserts low when VOSENSE deviates beyond tolerance, enabling system sequencing. |
| Max Duty Cycle | 99.4% - Enables ultra-low dropout operation (e.g., 1.6V out from 1.8V in), critical for battery-backed or low-VIN scenarios. |
| Shutdown Quiescent Current | <25µA - Achieved via logic-controlled RUN/SS pin; preserves battery life in portable systems during sleep states. |
| Oscillator Frequency | 265–335kHz (typ. 300kHz with 47pF COSC) - Adjustable via external capacitor; synchronizable to external clock up to 500kHz. |
Pinout & Package
Package: 16-lead narrow SSOP (GN), RoHS-compliant, 5.0mm × 6.2mm body, 0.635mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COSC (1) | Oscillator timing input | Connects to external capacitor (e.g., 47pF) to set switching frequency; determines both free-run and sync-lock range. |
| RUN/SS (2) | Soft-start and enable control | Capacitor-to-ground sets soft-start ramp time (~1.25s/µF); <1.5V forces shutdown; >4.1V triggers latchoff during fault. |
| ITH (3) | Error amplifier output / current limit control | Voltage (0–2.4V) sets peak inductor current threshold; directly controls load transient response and foldback behavior. |
| PGOOD (4) | Open-drain status & sync input | Pulled low when VOSENSE outside ±7.5%; tied to INTVCC enables Burst Mode™; driven with >1.3V clock enables sync. |
| SENSE– (5), SENSE+ (6) | Differential current sense inputs | Monitor voltage across external RSENSE (e.g., 4mΩ); built-in offset enables accurate DC current sensing without amplification. |
| VOSENSE (7) | Feedback voltage input | Receives divided output voltage; referenced to 0.8V internal bandgap; enables precise regulation and PGOOD monitoring. |
| SGND (8) | Small-signal ground reference | Star-ground point for feedback divider, COSC, CSS, and compensation network; must be single-point connected to PGND. |
| EXTVCC (9) | External VCC supply input | When ≥4.7V, disables internal LDO and powers INTVCC directly-improves efficiency and gate drive strength. |
| PGND (10) | Power ground return | Return path for bottom MOSFET source, CIN negative, and Schottky diode anode; separates high-current paths from SGND. |
| BG (11) | Bottom N-MOSFET gate driver | Drives bottom FET gate from 0V to INTVCC; capable of 3A peak current for fast turn-on/turn-off with low Qg devices. |
| INTVCC (12) | Internal 5.2V LDO output | Supplies gate drivers and control circuitry; requires local 1µF ceramic + ≥4.7µF tantalum decoupling at pin. |
| VIN (13) | Main input supply | Accepts 3.5–30V; must be decoupled with low-ESR capacitors near PGND to minimize switching noise injection. |
| SW (14) | Switch node | Connects to inductor and bootstrap capacitor; swings from ~–0.4V (Schottky drop) to VIN; high dV/dt node requiring tight layout. |
| BOOST (15) | Bootstrap supply for top driver | Return node for external bootstrap capacitor; voltage swings from INTVCC–0.4V to VIN+INTVCC; enables floating top-gate drive. |
| TG (16) | Top N-MOSFET gate driver | Floating driver output referenced to SW; delivers full INTVCC swing superimposed on SW node for efficient high-side conduction. |
Key Features
| Feature | Design Value |
|---|---|
| OPTI-LOOP™ Compensation | Minimizes required output capacitance and eliminates need for re-tuning compensation when changing COUT or ESR - reduces BOM cost and design iteration. |
| Dual N-Channel MOSFET Drive | Integrated TG/BG drivers eliminate external level-shifters and gate drivers - simplifies layout, reduces component count, and improves timing alignment. |
| Programmable Current Limit | Set via external RSENSE (e.g., 0.004Ω → 12A max) with ±15% threshold tolerance - enables precise overcurrent protection matched to MOSFET SOA. |
| Remote Output Voltage Sense | VOSENSE pin accepts Kelvin connection to load - rejects PCB trace IR drop and ensures accurate regulation at point-of-load under high-current conditions. |
| Logic-Controlled Micropower Shutdown | IQ < 25µA in shutdown with RUN/SS pulled low - extends battery runtime in notebook sleep modes without auxiliary enable circuitry. |
Applications
| Mobile CPU Core Power | SpeedStep-Enabled Processor Supply |
|---|---|
Use Scenario: Powering Intel Pentium III processors with dynamic voltage scaling in notebook computers. IC Role / Device Role / Timing Role: Primary synchronous buck controller managing real-time Vcore transitions between 1.35V and 1.60V based on workload. Use Value: Meets Intel Mobile CPU Specification for ±7.5% PGOOD window and supports seamless voltage slewing without system reset. |
Use Scenario: Providing regulated core voltage to SpeedStep-capable CPUs during active/idle state transitions. IC Role / Device Role / Timing Role: Voltage regulator controller coordinating with processor VSEL signals to adjust output in <100µs. Use Value: Enables >30% reduction in CPU dynamic power consumption during light-load operation via adaptive voltage scaling. |
| Portable Computing Power Rail | Low-Dropout System Supply |
Use Scenario: Generating stable 1.6V/12A rail from 4.5–24V battery or adapter input in ultraportable notebooks. IC Role / Device Role / Timing Role: High-efficiency step-down controller operating in Burst Mode™ below 10mA and continuous mode above. Use Value: Delivers >85% efficiency at 10mA (Burst Mode™) and >92% at 5A - extends battery life across full load range. |
Use Scenario: Regulating 1.8V output from 2.0V input in battery-backed subsystems where dropout margin is minimal. IC Role / Device Role / Timing Role: Synchronous buck controller leveraging 99.4% max duty cycle to maintain regulation with only 200mV headroom. Use Value: Eliminates need for linear post-regulator or higher-input-voltage sources - reduces thermal stress and board area. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS51220ARGER | Integrated MOSFETs (30V, 25A), fixed 1.0MHz frequency, no external RSENSE current sense, requires external BOOT capacitor. | Targeted at DDR memory termination and GPU rails; lacks programmable VOUT range and OPTI-LOOP™ adaptability. | Choose for space-constrained designs needing integrated power stage; avoid when remote sensing or wide VOUT adjustment is required. |
| ISL6264CRZ | Supports 3-phase interleaving, 0.5–5.5V VOUT, 500kHz max frequency, proprietary ACOT control (not current-mode), no Burst Mode™. | Designed for multi-phase CPU VRMs with tighter transient response; not suitable for single-phase low-noise or micropower standby use. | Prefer for high-performance laptop CPU VRMs demanding sub-10µs load-step response; not drop-in for LTC1735CGN-1's discrete-FET topology. |
Compared with TPS51220ARGER and ISL6264CRZ, the LTC1735CGN-1 uniquely combines external MOSFET flexibility, OPTI-LOOP™ stability across capacitor aging, and Burst Mode™ efficiency below 10mA - making it optimal for discrete, battery-sensitive CPU core supplies where layout control and quiescent power are critical.
Availability
LTC1735CGN-1 is available at Aetrix Electronics and suitable for notebook computers, mobile Pentium III systems, and cellular baseband power supplies requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for LTC1735CGN-1 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 ICs, serving precision instrumentation, automotive, industrial, and communications markets.
The LTC1735CGN-1 belongs to Linear's legacy CPU power controller family, specifically engineered for Intel Mobile CPU compliance, dynamic voltage scaling, and high-efficiency discrete-FET buck conversion in portable computing platforms.
FAQ
What is the maximum supported input voltage for the LTC1735CGN-1?
The LTC1735CGN-1 has an absolute maximum input voltage rating of 36V on the VIN pin. Continuous operation is specified from 3.5V to 30V. Exceeding 30V risks violating the recommended operating conditions and may impact reliability or trigger undervoltage lockout recovery instability. Always observe the 36V absolute max limit across all temperature ranges.
How does the PGOOD pin function in synchronization mode for the LTC1735CGN-1?
In synchronization mode, an external clock signal (≥1.3V high, ≤0.3V low, 0.3µs min pulse width) applied to the PGOOD pin via a series resistor locks the LTC1735CGN-1's internal oscillator to frequencies between 90% and 130% of its nominal COSC-set rate. During sync, Burst Mode™ is disabled, but cycle-skipping remains active at light loads - ensuring constant-frequency operation while preserving regulation integrity.
Can the LTC1735CGN-1 operate with only the INTVCC supply, without EXTVCC?
Yes, the LTC1735CGN-1 operates fully with only INTVCC supplied internally from VIN via its 5.2V LDO. EXTVCC is optional: when left open or below 4.5V, the internal LDO powers INTVCC. When EXTVCC ≥4.7V, the internal switch connects EXTVCC to INTVCC - improving efficiency and gate drive capability. Do not exceed 7V on EXTVCC.
What is the purpose of the RUN/SS pin's latchoff behavior in the LTC1735CGN-1?
The RUN/SS pin implements a fault timeout: if the output voltage falls below 70% of its nominal value, the internal circuit begins discharging the external CSS capacitor. If CSS discharges fully (e.g., due to sustained short-circuit), the LTC1735CGN-1 latches off until RUN/SS is recycled. This prevents thermal runaway and enables safe automatic recovery after fault removal.
Does the LTC1735CGN-1 support remote voltage sensing, and how is it implemented?
Yes, the LTC1735CGN-1 supports true remote sensing via the VOSENSE pin. Connect the feedback divider's top node directly to the load's Vcore point and its bottom node to local SGND - routing both traces away from high-current PGND paths. This compensates for IR drop across PCB traces, ensuring ±1% regulation accuracy at the actual CPU pad, not just at the converter output.
LTC1735CGN-1#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):
- 3.5V ~ 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:
- 0°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC1735CGN-1#PBF FAQ
1.How can I place an order for LTC1735CGN-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1735CGN-1#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 LTC1735CGN-1#PBF reliable?
The price and inventory of LTC1735CGN-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1735CGN-1#PBF is usually 5 days.
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Once your LTC1735CGN-1#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 LTC1735CGN-1#PBF?
For technical support, including LTC1735CGN-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1735CGN-1#PBF requirements.
6.How does Aetrix verify that LTC1735CGN-1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1735CGN-1#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 LTC1735CGN-1#PBF meets industry standards.
7.What is the process for return or replacement of LTC1735CGN-1#PBF?
All LTC1735CGN-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1735CGN-1#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 LTC1735CGN-1#PBF part is unused and in its original packaging.
Return procedure for LTC1735CGN-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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