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Analog Devices Inc. LTC3717EGN#PBF
- Part No.:
- LTC3717EGN#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 16-SSOP (0.154", 3.90mm Width)
- Datasheet:
-
LTC3717EGN#PBF.pdf
- Description:
- IC REG CTRLR DDR 1OUT 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,603
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Product details
Overview
LTC3717EGN#PBF from Analog Devices (formerly Linear Technology) is a synchronous step-down switching regulator controller designed specifically for DDR and QDR memory termination, functioning as a supply splitter with VOUT = ½ VIN. It delivers symmetrical ±20A sink/source current limit, ±0.65% output voltage accuracy, operates from 4V to 36V VCC, and achieves up to 97% efficiency without requiring an external sense resistor.
For engineers reviewing the LTC3717EGN#PBF datasheet, LTC3717EGN#PBF pinout, LTC3717EGN#PBF application, or LTC3717EGN#PBF equivalent, key selection considerations include valley current mode control architecture, no-RSENSE operation, programmable 2%–90% duty cycle at 200kHz, tON(MIN) ≤ 100ns, and support for ceramic output capacitors in high-speed memory power systems.
Technical Context
The LTC3717EGN#PBF implements true valley current mode control using the bottom MOSFET's RDS(ON) as the current sensing element-eliminating need for discrete sense resistors. Its one-shot timer sets top MOSFET on-time based on ION pin current, enabling frequency stabilization across input voltage variations.
It integrates dual N-channel gate drivers (TG/BG), internal 5V INTVCC regulator (4.7–5.3V), EXTVCC switchover logic, PGOOD monitoring with ±10% hysteresis, and overvoltage/undervoltage protection. The VRNG pin scales current sense thresholds from 50mV to 200mV nominal, supporting adjustable symmetrical current limiting up to ±20A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4V to 36V - enables direct operation from industrial 5V/12V/24V rails and notebook battery inputs |
| Output Accuracy | ±0.65% - ensures tight DDR/QDR VTT regulation within JEDEC SSTL-2/HSTL compliance windows |
| Max Switching Freq | 1.5MHz - supports compact magnetics and low-profile layouts in space-constrained memory modules |
| tON(MIN) | ≤100ns - allows stable operation down to ~1.25V output at high input voltages (e.g., VIN = 28V → D ≈ 4.5%) |
| Current Limit | Adjustable ±20A symmetrical - matches DDR termination load transients while avoiding false trips during bidirectional current flow |
| Efficiency | Up to 97% - minimizes thermal stress in dense DIMM or server memory subsystems |
| Package | 16-pin narrow SSOP - surface-mount compatible with automated assembly and thermal pad grounding via PGND pin 13 |
Pinout & Package
Package: 16-lead plastic narrow SSOP (GN), 0.15mm max height, exposed thermal pad connected to PGND.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RUN/SS (1) | Run enable & soft-start control | Pull below 0.8V shuts down both MOSFETs; external CSS capacitor sets ramp time (~3s/µF) and latchoff delay |
| PGOOD (2) | Open-drain power-good flag | Pulled low when VFB deviates >±10% from regulation point - used for system sequencing and fault reporting |
| VRNG (3) | Sense voltage range scaling | 0.5V–2V input sets nominal sense voltage (50–200mV); determines ±20A current limit threshold via RDS(ON) |
| ITH (4) | Error amplifier output & current threshold | 0–2.4V control voltage sets valley current comparator threshold - directly programs current limit and loop compensation |
| SGND (5) | Signal ground reference | Star-ground connection point for feedback divider, compensation network, and small-signal components only |
| ION (6) | On-time current setting | Resistor from VIN sets one-shot timer current - determines switching frequency and stabilizes f vs VIN |
| VFB (7) | Feedback input | Internally divides VOUT to 2/3 × VFB; connects to output rail - must not exceed 1.5V to avoid damage |
| VREF (8) | Reference input | Divides external reference to 1/3 × VREF - sets VOUT = ½ × VREF, PGOOD thresholds, and short-circuit timing |
| EXTVCC (9) | External bias supply input | Switches internal LDO off above 4.7V - allows efficient 5V sourcing from secondary rail or dedicated supply |
| VCC (10) | Main bias supply | Primary 4–36V input powering internal circuits; requires RC decoupling (1Ω + 0.1µF) to PGND |
| INTVCC (11) | Internal 5V regulator output | Supplies TG/BG drivers and control logic; requires ≥4.7µF low-ESR capacitor to PGND for transient gate drive current |
| BG (12) | Bottom gate driver | Drives source-follower N-MOSFET gate between PGND and INTVCC - handles continuous conduction during low-side active period |
| PGND (13) | Power ground return | High-current return path for CIN, CVCC, bottom MOSFET source, and bootstrap diode cathode - must be low-inductance star point |
| SW (14) | Switch node | Connects to MOSFET bridge midpoint; swings from ~–0.4V to VIN+0.4V - critical for bootstrap capacitor charging and layout EMI control |
| TG (15) | Top gate driver | Drives high-side N-MOSFET gate with swing equal to INTVCC superimposed on SW - requires floating bootstrap supply (CB/DB) |
| BOOST (16) | Bootstrap capacitor positive terminal | Charged from INTVCC via DB when SW is low; floats to VIN+INTVCC when SW is high - supplies TG driver voltage |
Key Features
| Feature | Design Value |
|---|---|
| No RSENSE operation | Uses bottom MOSFET RDS(ON) for current sensing - eliminates 2–3W sense resistor losses and PCB area in high-current DDR termination |
| Valley current mode control | Enables stable sub-5% duty cycles required for VTT = ½ VIN in DDR3/DDR4 systems without slope compensation |
| Symmetrical ±20A current limit | Programmable via VRNG and ITH - matches bidirectional termination current demands of DDR/QDR I/O buffers during read/write transitions |
| True 1.5MHz max switching | Supported by tON(MIN) ≤ 100ns and fast gate drivers - enables <1µH inductors and reduces output capacitance requirements |
| Ceramic-capacitor stable | Compensated for zero-ESR output caps - avoids need for bulk electrolytic or polymer capacitors in thin-profile memory modules |
Applications
| DDR Memory Termination | QDR RAM Power Supply |
|---|---|
Use Scenario: Termination of DDR2/DDR3 memory data/strobe lines on server DIMMs and workstation motherboards. IC Role / Device Role / Timing Role: Supplies precise VTT = ½ VDDQ termination voltage with bidirectional ±15A current handling during fast signal transitions. Use Value: Maintains ±0.65% VTT accuracy under dynamic load steps, ensuring signal integrity margins meet JEDEC SSTL-18 specifications. | Use Scenario: Powering QDR SRAM termination in high-bandwidth networking ASIC interfaces (e.g., packet buffer controllers). IC Role / Device Role / Timing Role: Acts as tracking supply splitting VDDQ into matched VTT and VREF rails with synchronized transient response. Use Value: Delivers ultrafast transient recovery (<2µs) and 97% peak efficiency - critical for maintaining timing closure in 200+ MHz QDR bus designs. |
| Notebook DDR Power | Tracking Supply for Memory Subsystems |
Use Scenario: Compact DDR termination in ultrabook and 2-in-1 platform memory subsystems with constrained board area. IC Role / Device Role / Timing Role: Synchronous buck controller operating from 5V or 12V battery-derived rail to generate 0.625V/0.75V/0.9V VTT. Use Value: 16-pin SSOP package and ceramic-capacitor compatibility reduce solution footprint by >40% vs resistor-sense alternatives. | Use Scenario: Generating matched VTT and VREF rails from single input in FPGA-based memory controllers with strict tracking requirements. IC Role / Device Role / Timing Role: Uses shared VREF pin to force VOUT = ½ VREF - inherently tracks VREF variations due to temperature or line regulation. Use Value: Eliminates need for separate error amplifiers or precision dividers - simplifies BOM and improves long-term tracking drift <±0.1%/°C. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar DDR/QDR memory termination controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3716EGN#PBF | Same pinout and core architecture but lacks VRNG pin - fixed 140mV sense threshold limits current limit adjustability | Supports only unidirectional current limiting; unsuitable for QDR or DDR4 where sink/source symmetry is mandatory | Select LTC3717EGN#PBF when bidirectional ±20A current limiting and VRNG-based threshold scaling are required |
| TPS51220ARUKT | Integrated MOSFET drivers only - requires external high-side/high-current N-MOSFETs; no valley current mode | Designed for DDR3 Laptops with integrated 5V LDO; lacks EXTVCC switchover and ceramic-capacitor stability guarantees | Choose LTC3717EGN#PBF for industrial/server DDR termination demanding >95% efficiency, wide 4–36V input, and no-RSENSE operation |
Compared with LTC3716EGN#PBF and TPS51220ARUKT, the LTC3717EGN#PBF uniquely combines programmable symmetrical current limiting, valley current mode for ultra-low duty cycles, and full 4–36V operation - making it the only option qualified for QDR memory and high-input-voltage DDR termination in servers and telecom infrastructure.
Availability
LTC3717EGN#PBF is available at Aetrix Electronics and suitable for DDR memory termination, QDR RAM power supplies, and tracking supply designs requiring stable component supply, long-lifecycle availability, and guaranteed parametric performance over –40°C to 85°C.
Supply support for LTC3717EGN#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3717EGN#PBF belongs to ADI's Power by Linear™ high-efficiency DC/DC controller product line, engineered specifically for demanding memory interface power applications including DDR, QDR, LPDDR, and HBM termination where precision, speed, and reliability are critical.
FAQ
What is the primary function of the LTC3717EGN#PBF in DDR memory systems?
The LTC3717EGN#PBF serves as a synchronous step-down controller that generates the precise VTT termination voltage equal to half the VDDQ supply (VOUT = ½ VIN). It provides symmetrical ±20A sink/source current capability to handle rapid bidirectional current transients on DDR data lines while maintaining ±0.65% output accuracy - essential for meeting JEDEC SSTL-2 and HSTL interface specifications. Its valley current mode architecture enables stable operation at very low duty cycles without external sense resistors.
How does the LTC3717EGN#PBF achieve no-RSENSE operation?
The LTC3717EGN#PBF eliminates the need for an external current-sense resistor by using the on-resistance (RDS(ON)) of the external bottom N-channel MOSFET as the current-sensing element. The voltage between PGND and SW pins is monitored to determine inductor valley current. The VRNG pin scales this sense voltage range (50–200mV nominal), and the ITH pin sets the comparator threshold - allowing accurate, lossless current limiting up to ±20A without added power dissipation or board space.
What is the role of the VRNG pin on the LTC3717EGN#PBF?
The VRNG pin on the LTC3717EGN#PBF sets the nominal current sense voltage threshold used for symmetrical current limiting. Applying 0.5V–2V to VRNG establishes a nominal sense voltage of 50–200mV (≈0.1×VRNG), which directly determines the ±20A current limit range. When tied to SGND or INTVCC, it defaults to 70mV or 140mV respectively. This programmability allows designers to optimize MOSFET selection and thermal performance across varying load and temperature conditions while maintaining precise DDR/QDR termination compliance.
Can the LTC3717EGN#PBF operate with ceramic output capacitors?
Yes, the LTC3717EGN#PBF is explicitly designed to be stable with ceramic output capacitors - a critical feature for DDR/QDR applications where low-ESR, compact, and high-reliability capacitance is required. Its control loop compensation and valley current mode architecture eliminate the need for minimum ESR requirements, enabling use of X5R/X7R MLCCs without external damping networks. This reduces solution size, improves transient response, and avoids aging-related capacitance drift seen in electrolytic solutions.
What protection features does the LTC3717EGN#PBF include?
The LTC3717EGN#PBF integrates multiple hardware-based protections: output overvoltage protection (OVP) triggers immediate M1 shutdown and M2 latching; undervoltage lockout (UVLO) disables operation if VCC drops below 3.4V; PGOOD monitors VFB with ±10% window and hysteresis; RUN/SS pin enables latch-off shutdown; and optional short-circuit shutdown timer prevents thermal runaway during sustained faults. All protections operate independently of external microcontrollers, ensuring robust DDR system reliability.
LTC3717EGN#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
- Applications:
- Controller, DDR, QDR
- Voltage - Input:
- 4V ~ 36V
- Number of Outputs:
- 1
- Voltage - Output:
- 2V ~ 18V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
LTC3717EGN#PBF FAQ
1.How can I place an order for LTC3717EGN#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3717EGN#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 LTC3717EGN#PBF reliable?
The price and inventory of LTC3717EGN#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3717EGN#PBF is usually 5 days.
3.What payment methods are accepted for LTC3717EGN#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3717EGN#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3717EGN#PBF?
LTC3717EGN#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3717EGN#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 LTC3717EGN#PBF?
For technical support, including LTC3717EGN#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3717EGN#PBF requirements.
6.How does Aetrix verify that LTC3717EGN#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3717EGN#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 LTC3717EGN#PBF meets industry standards.
7.What is the process for return or replacement of LTC3717EGN#PBF?
All LTC3717EGN#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3717EGN#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 LTC3717EGN#PBF part is unused and in its original packaging.
Return procedure for LTC3717EGN#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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