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Analog Devices Inc. LTC1709EG-85#PBF
- Part No.:
- LTC1709EG-85#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 36-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
LTC1709EG-85#PBF.pdf
- Description:
- IC REG CTRLR BUCK 36SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,439
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Product details
Overview
LTC1709EG-85 from Analog Devices (formerly Linear Technology) is a 2-phase, 5-bit VID-programmable, current-mode synchronous step-down switching regulator controller driving two external N-channel MOSFET stages. It operates at fixed frequencies from 150kHz to 300kHz, delivers ±1% output voltage accuracy across 1.05V–1.825V (VRM 8.5), supports true remote differential sensing, and integrates OPTI-LOOP® compensation for wide ESR capacitor compatibility - deployed in high-current server CPU core power supplies.
For engineers reviewing the LTC1709EG-85 datasheet, LTC1709EG-85 pinout, LTC1709EG-85 application, or LTC1709EG-85 equivalent, key selection criteria include its dual-phase antiphase operation reducing input RMS ripple, programmable forced-PWM/Burst Mode/cycle-skip modes via FCB pin, integrated overvoltage soft-latch, and 36-lead narrow SSOP package with verified thermal performance (θJA = 85°C/W).
Technical Context
The LTC1709EG-85 implements a constant-frequency, current-mode control architecture with two independent 180° out-of-phase channels, each using an ITH-controlled peak-current comparator and separate SENSE+/- inputs. Its internal 5V LDO (INTVCC) powers gate drivers and logic, while EXTVCC support enables efficient self-biasing from the output rail.
Frequency is set via PLLFLTR voltage (120–360kHz range) or synchronized externally via PLLIN; FCB pin selects among three operating modes - forced continuous PWM (FCB < 0.8V), Burst Mode (0.8V < FCB < VINTVCC–2V), or constant-frequency discontinuous mode (FCB = INTVCC). Remote sensing is implemented through a precision differential amplifier (ADA = 0.995–1.005 V/V, CMRR ≥ 46dB) feeding VDIFFOUT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | 1.05V to 1.825V via 5-bit VID (VRM 8.5 compliant); enables dynamic CPU voltage scaling. |
| Switching Frequency | 150kHz to 300kHz programmable; antiphase operation halves effective input ripple frequency. |
| Output Voltage Accuracy | ±1% over temperature; ensures tight regulation for sensitive microprocessor cores. |
| Current Sense Threshold | 62–88mV (typ. 75mV); sets peak inductor current with RSENSE-based foldback during short-circuit. |
| Operating Input Voltage | 4V to 36V VIN; supports wide-range DC distribution systems including 5V, 12V, and 24V rails. |
| Thermal Resistance | θJA = 85°C/W (36-lead SSOP); validated for sustained 40A dual-phase operation with proper PCB copper. |
| Soft-Start Control | RUN/SS pin with adjustable ramp; provides controlled inrush limiting and timed short-circuit shutdown. |
Pinout & Package
Package: 36-lead narrow-body SSOP (G package), JEDEC MS-012AC, 0.209" body width, 0.025" lead pitch. Exposed pad not present; thermal dissipation relies on PCB copper area under package footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TG1, TG2 | Top Gate Drive Outputs | Floating high-side drivers (INTVCC-referenced) for N-MOSFETs; require external bootstrap capacitors on BOOST1/2. |
| BG1, BG2 | Bottom Gate Drive Outputs | GND-referenced low-side drivers for N-MOSFETs; sink/source capability supports synchronous rectification. |
| SENSE1+/−, SENSE2+/− | Differential Current Sense Inputs | Measure voltage drop across RSENSE to regulate peak channel current; common-mode range up to 1.1×INTVCC. |
| EAIN | Error Amplifier Inverting Input | Receives feedback from VDIFFOUT divider; compared to 0.800V internal reference for closed-loop regulation. |
| VDIFFOUT | Differential Amplifier Output | True remote sense output; drives external resistor divider to set VOUT with minimal PCB trace IR loss impact. |
| VID0–VID4 | 5-Bit VRM 8.5 Digital Input | Programmable output voltage code; VID25mV–VID3 accept 0–5.5V logic levels with internal 40kΩ pull-ups. |
| FCB | Forced Continuous/Burst Mode Select | Three-mode control: <0.8V = forced PWM, 0.8–(VINTVCC–2V) = Burst Mode®, =INTVCC = constant-frequency discontinuous. |
| PGOOD | Open-Drain Power-Good Indicator | Asserts low when VOUT deviates >±7.5% from nominal; enables system sequencing and fault reporting. |
Key Features
| Feature | Design Value |
|---|---|
| 2-Phase Antiphase Operation | Reduces input capacitor RMS current by ~70%, enabling smaller CIN and lower EMI in high-power servers. |
| OPTI-LOOP® Compensation | Allows stable loop response with wide range of output capacitor ESR (including polymer and MLCC), simplifying layout. |
| True Remote Differential Sensing | VOS+/VOS− inputs feed precision op-amp (CMRR ≥46dB) to reject PCB trace resistance errors in >20A applications. |
| Three-Mode Efficiency Optimization | FCB-selectable PWM/Burst/cycle-skip adapts control strategy to load: Burst Mode achieves >90% efficiency at light loads. |
| Integrated Overvoltage Soft-Latch | OV comparator disables top MOSFET and activates bottom MOSFET on >±7.5% excursion, preventing nuisance trips during transients. |
| Programmable Fixed-Frequency Range | 150–300kHz via PLLFLTR voltage or external sync (PLLIN); avoids noise-sensitive bands and enables multi-rail synchronization. |
Applications
| Server CPU Core Power | High-Density Memory Arrays |
|---|---|
Use Scenario: Delivering tightly regulated 1.05–1.825V at up to 40A to modern x86 or ARM processors in rack-mounted servers. IC Role / Device Role / Timing Role: Dual-phase synchronous buck controller managing two parallel power stages with antiphase clocking and VID voltage programming. Use Value: ±1% output accuracy and active voltage positioning maintain CPU stability under rapid load transients; reduced input ripple eases front-end filter design. |
Use Scenario: Powering DDR4/DDR5 memory modules requiring low-noise, fast-response 1.2V or 1.1V supplies in enterprise storage arrays. IC Role / Device Role / Timing Role: High-efficiency, multi-phase regulator with Burst Mode operation minimizing idle power in standby states. Use Value: Programmable 150–300kHz switching enables EMI filtering optimization; OPTI-LOOP® ensures stability with low-ESR ceramic output caps. |
| DC Power Distribution Systems | Industrial Embedded Computing |
Use Scenario: Intermediate bus conversion in 48V-to-12V/5V/3.3V distributed power architectures for telecom and datacom equipment. IC Role / Device Role / Timing Role: Primary controller for high-current intermediate bus converters supporting dual-input supply capability for redundancy. Use Value: Wide 4–36V VIN range accommodates varying upstream sources; dual-input capability allows load sharing between independent rails. |
Use Scenario: Core power for ruggedized embedded controllers in factory automation, where thermal reliability and long-term supply continuity are critical. IC Role / Device Role / Timing Role: Robust, thermally characterized controller (0°C to 70°C guaranteed, –40°C to 85°C assured) with latch-off short-circuit protection. Use Value: RUN/SS-based timed shutdown prevents damage during sustained overloads; EXTVCC support enables efficient self-biasing for compact designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-phase synchronous buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ISL6522CRZ-T | Single 5-bit VID controller; no integrated PLL sync; max fSW = 1MHz; requires external bootstrap diodes. | Lacks antiphase input ripple reduction; higher max frequency suits smaller inductors but increases gate loss. | Prefer for cost-sensitive, space-constrained designs where 1MHz operation justifies trade-offs in thermal management and layout complexity. |
| TPS546B24RVFT | Single-chip 60A digital multiphase controller (PMBus); integrates MOSFET drivers; supports AVS and telemetry. | Replaces discrete controller + external FETs with integrated solution; adds digital configurability but requires firmware integration. | Choose when digital control, real-time telemetry, and AVS compliance outweigh analog simplicity and analog BOM cost. |
Compared with ISL6522CRZ-T and TPS546B24RVFT, the LTC1709EG-85 offers proven analog antiphase architecture with minimal external components, guaranteed thermal performance in SSOP, and VRM 8.5 compliance without digital overhead - ideal for high-reliability analog power stages where predictability and long-term component availability are prioritized.
Availability
LTC1709EG-85 is available at Aetrix Electronics and suitable for server/desktop computers, internet servers, large memory arrays, and DC power distribution systems requiring stable component supply, long lifecycle support, and guaranteed parametric performance over temperature.
Supply support for LTC1709EG-85 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; Linear pioneered high-performance analog ICs for power management, signal conditioning, and precision timing.
The LTC1709EG-85 belongs to Linear's PolyPhase® controller family, designed specifically for high-current, low-voltage CPU and ASIC core power delivery with emphasis on efficiency, transient response, and thermal robustness in dense computing environments.
FAQ
What is the guaranteed operating temperature range for the LTC1709EG-85?
The LTC1709EG-85 is guaranteed to meet all specifications from 0°C to 70°C. Performance over the extended –40°C to 85°C range is assured by design, characterization, and statistical process controls - confirmed in the official datasheet revision 170985f. This makes LTC1709EG-85 suitable for commercial and industrial server applications where ambient temperatures remain within these bounds.
How does the FCB pin affect LTC1709EG-85 operation in Burst Mode versus forced continuous mode?
When the FCB pin voltage is between 0.8V and (VINTVCC – 2V), the LTC1709EG-85 enters Burst Mode® operation - disabling switching cycles during light load to maximize efficiency. Pulling FCB below 0.8V forces continuous PWM mode for lowest output ripple, while tying FCB to INTVCC enables constant-frequency discontinuous mode. These three distinct behaviors are explicitly defined in the LTC1709EG-85 datasheet Section "Low Current Operation".
Can the LTC1709EG-85 support remote voltage sensing, and how is it implemented?
Yes, the LTC1709EG-85 supports true remote differential sensing via dedicated VOS+ and VOS– pins feeding an internal precision op-amp. Its output (VDIFFOUT) drives an external resistive divider to set VOUT, rejecting voltage drops across PCB traces and connectors. The differential amplifier has 0.995–1.005 V/V gain and ≥46dB CMRR - critical for maintaining ±1% accuracy in high-current (>20A) applications where trace resistance would otherwise degrade regulation.
What is the purpose of the RUN/SS pin on the LTC1709EG-85, and how does it enable short-circuit protection?
The RUN/SS pin on the LTC1709EG-85 serves dual functions: soft-start control (via external capacitor ramp) and timed short-circuit shutdown. If VOUT falls below 70% of nominal during operation, the RUN/SS capacitor discharges; if discharge exceeds the timeout threshold, the LTC1709EG-85 latches off. This behavior - including foldback current limiting activation - is fully documented in the "Short-Circuit Detection" section of the LTC1709EG-85 datasheet.
Does the LTC1709EG-85 support external frequency synchronization, and what pins are involved?
Yes, the LTC1709EG-85 supports external synchronization via the PLLIN pin, which connects to an internal phase detector. The PLL aligns the rising edge of TG1 with the rising edge of the external clock applied to PLLIN. The PLLFLTR pin provides DC voltage control of oscillator frequency (120–360kHz) and also outputs the phase detector current. Both functions are verified in the "Frequency Synchronization" section of the LTC1709EG-85 datasheet.
LTC1709EG-85#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-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:
- 2
- Output Phases:
- 2
- Voltage - Supply (Vcc/Vdd):
- 4V ~ 36V
- Frequency - Switching:
- 140kHz ~ 310kHz
- Duty Cycle (Max):
- 99.5%
- 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:
- 36-SSOP
LTC1709EG-85#PBF FAQ
1.How can I place an order for LTC1709EG-85#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1709EG-85#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 LTC1709EG-85#PBF reliable?
The price and inventory of LTC1709EG-85#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1709EG-85#PBF is usually 5 days.
3.What payment methods are accepted for LTC1709EG-85#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1709EG-85#PBF transactions.
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4.How is shipping managed for LTC1709EG-85#PBF?
LTC1709EG-85#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1709EG-85#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 LTC1709EG-85#PBF?
For technical support, including LTC1709EG-85#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1709EG-85#PBF requirements.
6.How does Aetrix verify that LTC1709EG-85#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1709EG-85#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 LTC1709EG-85#PBF meets industry standards.
7.What is the process for return or replacement of LTC1709EG-85#PBF?
All LTC1709EG-85#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1709EG-85#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 LTC1709EG-85#PBF part is unused and in its original packaging.
Return procedure for LTC1709EG-85#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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