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Analog Devices Inc. LTC3618IFE#PBF
- Part No.:
- LTC3618IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3618IFE#PBF.pdf
- Description:
- IC REG CONV DDR 2OUT 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,470
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Product details
Overview
LTC3618IFE#PBF from Analog Devices (formerly Linear Technology) is a dual synchronous buck converter IC designed for DDR memory power delivery, providing ±3A VDDQ and VTT outputs with 0.5% VDDQ reference accuracy and programmable 4MHz switching. It integrates VTTR buffering, phase-shift control, and power-good monitoring in a thermally enhanced 24-pin TSSOP package for DDR3/DDR2/DDR systems.
For engineers reviewing the LTC3618IFE#PBF datasheet, LTC3618IFE#PBF pinout, LTC3618IFE#PBF application, or LTC3618IFE#PBF equivalent, key selection criteria include ±3A dual-channel current capability, 2.25V–5.5V input range, 0°/90°/180° channel phase shift, ±1% VDDQ output accuracy, and support for forced continuous or pulse-skipping mode on VDDQ while VTT remains forced-continuous.
Technical Context
The LTC3618IFE#PBF implements a current-mode, constant-frequency architecture with independent control loops for VDDQ and VTT. VDDQ uses an internal 0.6V reference with external resistor feedback, while VTT regulates to VTTR = VDDQIN × 0.5, sourced from a buffered op-amp capable of ±10mA.
It supports three phase configurations (0°, 90°, 180°) via the PHASE pin, external frequency programming up to 4MHz via RT resistor or SYNC clock, and dual soft-start options-internal for both channels, plus external tracking/soft-start for VDDQ via TRACK/SS1. VTT always operates in forced continuous mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.25V to 5.5V - supports wide DDR supply rails including 3.3V, 2.5V, and low-voltage SVIN operation |
| VDDQ Output Accuracy | ±1% - ensures tight regulation for DDR3/DDR2 VDDQ compliance under line/load/temperature variation |
| VTT Output Current | ±3A - delivers bidirectional termination current required for DDR memory bus signaling integrity |
| Switching Frequency | Up to 4MHz - enables use of sub-1µH inductors and compact ceramic output capacitors |
| Phase Shift Options | 0°, 90°, or 180° - reduces input ripple and EMI by staggering SW1/SW2 switching edges |
| Shutdown Current | ≤1µA - minimizes system standby power in DDR memory subsystems during deep sleep |
| VTTR Output | VDDQIN × 0.5, ±10mA - provides accurate, low-noise reference for VTT regulation without external divider |
Pinout & Package
The LTC3618IFE#PBF is housed in a lead-free, thermally enhanced 24-pin plastic TSSOP (FE package) with exposed PGND pad (Pin 25) requiring PCB soldering for thermal and electrical performance. θJA = 33°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PHASE (Pin 1) | Phase configuration selector | Ground = 0°, SVIN = 180°, mid-rail = 90° between SW1 and SW2 |
| VFB1 (Pin 22) | VDDQ feedback input | Connects to resistive divider; regulates VDDQ to 0.6V reference with ±1% accuracy |
| ITH1 (Pin 23) | VDDQ error amplifier compensation | External RC network sets loop stability; tie to SVIN for internal compensation |
| RUN1 (Pin 11) | VDDQ enable control | High >1V enables VDDQ; low disables both channels and reduces IQ to ≤1µA |
| PGOOD1 (Pin 15) | VDDQ power-good indicator | Open-drain output asserts low if VFB1 deviates >±8% from target or RUN1 is inactive |
| VTTR (Pin 14) | Buffered VDDQIN/2 reference | Drives VTT regulation and external loads up to ±10mA; max 0.1µF capacitance allowed |
| PGND (Pin 25) | Power ground return | Exposed pad; must be soldered to PCB plane for thermal dissipation and low-impedance return path |
Key Features
| Feature | Design Value |
|---|---|
| Dual ±3A synchronous buck topology | Monolithic integration eliminates external MOSFETs and gate drivers for VDDQ/VTT, reducing BOM count and layout complexity |
| VTT regulation referenced to VTTR | Eliminates need for precision external resistor divider; VTTR tracks VDDQIN × 0.5 with <0.5% error over temperature |
| Selectable operating mode for VDDQ | Pulse-skipping (MODE = SVIN) improves light-load efficiency; forced continuous (MODE = GND) enables bidirectional current sinking |
| Programmable 0°/90°/180° phase shift | Reduces peak input current and RMS input ripple by up to 30% compared to in-phase operation |
| Internal or external soft-start for VDDQ | TRACK/SS1 pin supports fixed-timing internal start-up, capacitor-based external ramp, or voltage-tracking of another rail |
Applications
| DDR Memory Power Supply | DDR Termination Reference |
|---|---|
Use Scenario: Providing regulated VDDQ (1.5V/1.35V/1.2V) and VTT (½×VDDQ) for DDR3 SODIMM modules in embedded computing platforms. IC Role / Device Role / Timing Role: Dual-channel DC/DC controller generating tightly tracked, high-current power rails synchronized to DDR timing requirements. Use Value: ±1% VDDQ accuracy and ±3A VTT sourcing/sinking ensure JEDEC-compliant signal integrity and stable memory operation at 1600MT/s. | Use Scenario: Generating VTTR and VTT for DDR2 server DIMMs where reference stability directly impacts write-leveling margin. IC Role / Device Role / Timing Role: Precision voltage buffer and regulator delivering VDDQIN/2 reference with <10µV/mA load regulation for VTT feedback path. Use Value: Integrated VTTR buffer eliminates external op-amp and divider errors, improving VTT accuracy to ±0.5% over temperature and load. |
| High-Density Memory Subsystem | Low-Power DDR Interface |
Use Scenario: Powering quad-channel DDR3L memory in space-constrained industrial controllers with strict thermal limits. IC Role / Device Role / Timing Role: Dual buck converter with 180° phase shift minimizing input capacitor RMS current and enabling smaller 1206-size ceramics. Use Value: 4MHz max switching frequency allows 0.47µH inductors, reducing solution footprint by 35% vs 1MHz designs while maintaining >90% efficiency at 2A. | Use Scenario: Supporting LPDDR2 mobile applications requiring fast VDDQ ramp-up and low quiescent current during self-refresh mode. IC Role / Device Role / Timing Role: Dual-output regulator with internal soft-start (1.1ms typical) and ≤1µA shutdown current for battery-sensitive memory interfaces. Use Value: TRACK/SS1-configurable soft-start prevents inrush current during wake-from-sleep, while shutdown IQ extends system standby time. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output DDR termination regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS51220RGER | Single-channel VDDQ + integrated VTT LDO; no VTTR buffer; max VTT = ±2A; 3mm × 3mm QFN | Lacks true dual synchronous buck architecture; unsuitable for high-current DDR3 VTT sinking | Choose only for cost-sensitive DDR2 designs with <±2A VTT and no VTTR buffering requirement |
| ISL95831IRZ | Dual buck with 0.5% VDDQ accuracy; supports DDR4; includes telemetry interface; 4mm × 4mm QFN | Higher pin count (32-pin), requires I²C configuration; no native 90° phase option | Prefer for DDR4 systems needing digital control and telemetry, but avoid when pin count or 90° phase is critical |
Compared with TPS51220RGER and ISL95831IRZ, the LTC3618IFE#PBF uniquely combines ±3A bidirectional VTT, integrated VTTR buffering, and selectable 0°/90°/180° phase in a 24-pin TSSOP-making it optimal for space-constrained DDR3/DDR2 designs requiring analog simplicity and robust termination current.
Availability
LTC3618IFE#PBF is available at Aetrix Electronics and suitable for DDR3 memory subsystems, industrial embedded controllers, and telecom baseband boards requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LTC3618IFE#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 and maintains its high-performance analog and power management portfolio with rigorous automotive and industrial qualification standards.
The LTC3618IFE#PBF belongs to Linear's DDR-specific power management product line, engineered to replace discrete solutions with monolithic, high-accuracy dual-buck regulators meeting JEDEC DDR2/DDR3 voltage and timing specifications.
FAQ
What is the maximum supported switching frequency for the LTC3618IFE#PBF?
The LTC3618IFE#PBF supports an externally programmable switching frequency up to 4MHz using either an RT resistor or an external clock applied to the MODE/SYNC pin. At 4MHz, minimum on-time (80ns) limits achievable duty cycle, so input-to-output voltage ratio must remain ≥1.2× to maintain regulation. The default internal oscillator runs at 2.25MHz when RT is tied to SVIN.
Does the LTC3618IFE#PBF support bidirectional current on both outputs?
The LTC3618IFE#PBF supports ±3A bidirectional current only on the VTT output (SW2). VDDQ (SW1) delivers +3A sourcing but does not sink current unless configured in forced continuous mode-however, even then, sinking capability is limited and not specified for VDDQ. VTT is explicitly designed for ±3A termination current per JEDEC DDR standards.
How is VTTR generated and what is its load capability in the LTC3618IFE#PBF?
In the LTC3618IFE#PBF, VTTR is generated by an internal precision op-amp buffer that outputs exactly VDDQIN × 0.5. It is rated for ±10mA continuous output current and remains stable with up to 0.1µF capacitance. VTTR serves as both the VTT feedback reference and an external reference source-exceeding 0.1µF risks instability, and short-circuit current is internally limited to ~20mA.
Can the LTC3618IFE#PBF operate with input voltages below 2.5V?
Yes, the LTC3618IFE#PBF operates down to 2.25V input (SVIN), supporting low-voltage DDR3L and LPDDR2 systems. However, RDS(ON) of internal P- and N-MOSFETs increases ~50% at 2.25V vs 5V, raising conduction losses. Designers must verify thermal performance at 100% duty cycle, especially under high load, using θJA = 33°C/W and TJmax = 125°C.
What are the power-good window tolerances for VDDQ and VTT in the LTC3618IFE#PBF?
The LTC3618IFE#PBF specifies a ±8% power-good window for VDDQ (PGOOD1) and ±5% for VTT (PGOOD2) relative to their respective setpoints. For VDDQ, the window dynamically tracks the TRACK/SS1 voltage during startup. Both open-drain outputs pull low if the feedback voltage falls outside the window, RUNx is deasserted, or SVIN undervoltage is detected.
LTC3618IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Applications:
- Converter, DDR
- Voltage - Input:
- 2.25V ~ 5.5V
- Number of Outputs:
- 2
- Voltage - Output:
- Adj to 0.6V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-TSSOP
LTC3618IFE#PBF FAQ
1.How can I place an order for LTC3618IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3618IFE#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 LTC3618IFE#PBF reliable?
The price and inventory of LTC3618IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3618IFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3618IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3618IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3618IFE#PBF?
LTC3618IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3618IFE#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 LTC3618IFE#PBF?
For technical support, including LTC3618IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3618IFE#PBF requirements.
6.How does Aetrix verify that LTC3618IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3618IFE#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 LTC3618IFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3618IFE#PBF?
All LTC3618IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3618IFE#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 LTC3618IFE#PBF part is unused and in its original packaging.
Return procedure for LTC3618IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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