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Analog Devices Inc. LTC3634HFE#TRPBF
- Part No.:
- LTC3634HFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Special Purpose Regulators
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC3634HFE#TRPBF.pdf
- Description:
- IC REG CONV DDR 2OUT 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,731
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Product details
Overview
LTC3634HFE#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic synchronous step-down regulator optimized for DDR1/DDR2/DDR3 memory power delivery. It delivers ±3A per channel across 3.6V–15V input, provides VDDQ (1.8V/3A) and VTT (0.9V/±3A) rails, features 180° out-of-phase operation to reduce input ripple, and operates up to 4MHz with programmable frequency via RT resistor.
For engineers reviewing the LTC3634HFE#TRPBF datasheet, LTC3634HFE#TRPBF pinout, LTC3634HFE#TRPBF application, or LTC3634HFE#TRPBF equivalent, this page details its DDR-specific regulation architecture, VTTR reference buffer accuracy (±1.6% at 0.75V), controlled on-time control loop, thermal-rated TSSOP-28 package (–40°C to 150°C), and dual-channel phase-shifted power delivery for high-density memory subsystems.
Technical Context
The LTC3634HFE#TRPBF implements current-mode control with a unique controlled on-time architecture, enabling stable high-frequency operation (500kHz–4MHz) even at low VOUT/VIN ratios typical in DDR applications. Each channel uses valley-current sensing via bottom-FET RDS(ON) and independent ITH compensation pins (ITH1/ITH2) for precise loop tuning.
Channel 1 supports Burst Mode® for light-load efficiency and external synchronization via MODE/SYNC; Channel 2 operates continuously and tracks VTTR = VDDQIN × 0.5 as its feedback reference. PHMODE selects 90° or 180° inter-channel phase shift, reducing input RMS current and easing capacitor sizing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 15V - supports direct 5V/12V PoL and battery-powered DDR systems without pre-regulation. |
| Output Current per Channel | ±3A - delivers full DDR3 VTT termination current (sourcing + sinking) and 3A VDDQ supply simultaneously. |
| VTTR Reference Accuracy | ±1.6% at 0.75V - ensures tight tracking of VDDQ/2 for DDR bus termination compliance. |
| Switching Frequency Range | 500kHz to 4MHz - adjustable via RT resistor; enables optimization between component size (high-freq) and efficiency (low-freq). |
| Junction Temperature Range | –40°C to 150°C - H-grade rating validated for industrial and extended-temperature DDR memory modules. |
| Phase Shift Configuration | 90° or 180° - selectable via PHMODE pin; 180° mode halves input capacitor RMS current versus in-phase operation. |
| Top/Bottom RDS(ON) | 130mΩ / 65mΩ - low conduction loss supports >95% peak efficiency at 12V input, 1.8V/3A output. |
Pinout & Package
The LTC3634HFE#TRPBF is housed in a thermally enhanced 28-lead plastic TSSOP package with exposed PGND pad (Pin 29), rated θJA = 25°C/W. The package supports high-power DDR applications requiring robust thermal performance and board-level reliability under sustained load.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGOOD1 (Pin 1) | Channel 1 Power Good Output | Open-drain signal pulled low if VFB1 deviates >±8% from 0.6V reference; includes 15mV hysteresis and 40µs glitch filter. |
| PHMODE (Pin 2) | Phase Select Input | Logic-low = 90° phase shift; logic-high (INTVCC) = 180° phase shift; critical for interleaved input current reduction. |
| RUN1 (Pin 3) | Channel 1 Enable Input | Active-high enable: >1.22V starts regulation; <1.01V forces shutdown; internal hysteresis prevents chatter. |
| MODE/SYNC (Pin 4) | Channel 1 Mode Control & Sync Input | Ground = forced continuous mode; float/INTVCC = Burst Mode®; driven clock = external sync (PLL-locked to SW edge). |
| RT (Pin 5) | Oscillator Frequency Program | Resistor to SGND sets fSW from 500kHz–4MHz; 162kΩ yields ~1.4MHz; ties to INTVCC for default 2MHz. |
| RUN2 (Pin 6) | Channel 2 Enable Input | Same threshold as RUN1; enables VTT rail independently; required for DDR termination sequencing. |
| SGND (Pin 7) | Signal Ground Reference | Low-noise analog ground for feedback dividers, RT, and compensation networks; must be isolated from PGND at single point. |
| PGOOD2 (Pin 8) | Channel 2 Power Good Output | Monitors VFB2 against VTTR; pulled low if error exceeds ±8%; remains low if VTTR < 300mV (undervoltage lockout). |
| VFB2 (Pin 9) | Channel 2 Feedback Input | Connects directly to VTT output; error amplifier compares to VTTR (not internal 0.6V), enabling precise VDDQ/2 tracking. |
| VDDQIN (Pin 10) | External Reference Input | Sets VTTR = VDDQIN × 0.5 via internal divider; supports 1.5V–2.6V range; defines VTT regulation point. |
| ITH2 (Pin 11) | Channel 2 Error Amplifier Output | Compensation node for VTT loop; connects to RC network for stability; sets valley current limit threshold. |
| VON2 (Pin 12) | Channel 2 On-Time Voltage Input | Tied to VTT to make on-time proportional to output voltage; enables constant frequency control below 3V. |
| SW2 (Pins 13,14) | Channel 2 Switch Node | Drives external inductor; swings from ~–0.3V to VIN2 + 0.3V; requires low-ESR ceramic bootstrap capacitor to BOOST2. |
| VIN2 (Pins 15,16) | Channel 2 Power Input | Independent 3.6V–15V supply for VTT rail; may differ from VIN1; powers internal MOSFETs and LDO for INTVCC. |
| BOOST2 (Pin 17) | Channel 2 Bootstrap Supply | Floating gate drive supply; connected to (+) of bootstrap cap; swing range ≈ INTVCC – 0.3V to VIN2 + INTVCC. |
| VTTR (Pin 18) | VDDQ/2 Reference Output | Buffered low-noise output sourcing/sinking ±10mA; drives DDR VREF; accuracy ±1.6% at 0.75V; max 0.01µF capacitive load. |
| INTVCC (Pin 19) | Internal 3.3V Regulator Output | Powers gate drivers and control logic; requires ≥1µF ceramic decoupling to PGND; disabled when both RUN pins are low. |
| BOOST1 (Pin 20) | Channel 1 Bootstrap Supply | Identical function to BOOST2; supplies top-FET gate drive for VDDQ channel; referenced to SW1. |
| VIN1 (Pins 21,22) | Channel 1 Power Input | Independent 3.6V–15V supply for VDDQ rail; powers INTVCC LDO; may be same or different source as VIN2. |
| SW1 (Pins 23,24) | Channel 1 Switch Node | Drives VDDQ inductor; identical voltage swing and layout requirements as SW2; critical for EMI control. |
| VON1 (Pin 25) | Channel 1 On-Time Voltage Input | Tied to VDDQ to scale on-time with output; maintains fixed frequency in controlled on-time mode for VOUT < 3V. |
| ITH1 (Pin 26) | Channel 1 Error Amplifier Output | Compensation node for VDDQ loop; separate from ITH2 to allow independent loop tuning for each rail. |
| TRACKSS (Pin 27) | Channel 1 Tracking/Soft-Start Input | Below 0.6V = tracking mode (follows external voltage); above 0.6V = internal reference; 1.4µA pull-up enables RC soft-start. |
| VFB1 (Pin 28) | Channel 1 Feedback Input | Connects to resistor divider from VDDQ; compared to internal 0.6V reference; enables precise VDDQ programming. |
| PGND (Exposed Pad) | Power Ground Return | Mandatory solder connection to PCB ground plane; carries high di/dt currents; primary thermal path for 150°C operation. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent DDR rails | Simultaneous VDDQ (0.6–3V, 3A) and VTT (VDDQ/2, ±3A) generation eliminates need for discrete regulators or LDOs. |
| VTTR buffered reference | On-chip ±10mA buffer delivers VDDQ/2 with ±1.6% accuracy at 0.75V, meeting JEDEC DDR3 VREF tolerance requirements. |
| 180° interleaved switching | Reduces input capacitor RMS current by ~30% versus in-phase operation, allowing smaller, lower-cost bulk capacitance. |
| Controlled on-time architecture | Maintains constant frequency and fast transient response at low duty cycles (e.g., 1.8V/12V = 15%), critical for DDR stability. |
| H-grade temperature rating | Guaranteed operation from –40°C to 150°C junction temperature, qualified for industrial DDR memory modules and base stations. |
| Comprehensive protection | Includes input overvoltage lockout (17.5V), overtemperature shutdown, short-circuit current limiting, and PGOOD status with filtering. |
Applications
| DDR3 Memory Modules | Server Memory Subsystems |
|---|---|
|
Use Scenario: Powering DDR3 SDRAM on enterprise DIMMs requiring strict VDDQ (1.5V) and VTT (0.75V) rails with tight tracking and fast load transients. IC Role / Device Role / Timing Role: Dual-channel synchronous buck regulator generating both supply and termination voltages with VTTR = VDDQ/2 reference buffering. Use Value: Eliminates discrete VTT LDO and external VREF buffer; achieves ±1.6% VTTR accuracy and <200ns VDDQ load-step recovery per JEDEC spec. |
Use Scenario: High-density RDIMM/LRDIMM designs where thermal management and board space constrain power solution size and efficiency. IC Role / Device Role / Timing Role: Primary DDR power IC delivering 3A VDDQ and ±3A VTT with 180° phase shift to minimize input ripple and heat buildup. Use Value: Reduces input capacitor count by 40% vs. in-phase dual bucks; supports 150°C operation for uncooled server memory slots. |
| Industrial Embedded DDR Systems | Telecom Baseband Units |
|
Use Scenario: Ruggedized industrial controllers using DDR2/DDR3 memory in wide-temperature environments (–40°C to 85°C ambient). IC Role / Device Role / Timing Role: H-grade dual buck providing VDDQ and VTT with guaranteed –40°C to 150°C operation and integrated protection. Use Value: No derating required up to 150°C TJ; built-in UVLO, OVLO, and thermal shutdown ensure reliable memory power under harsh conditions. |
Use Scenario: 4G/5G baseband units with DDR3 memory interfaces requiring low-noise, tightly regulated VREF and termination. IC Role / Device Role / Timing Role: DDR power manager supplying VDDQ, VTT, and clean VTTR reference to memory PHY and controller. Use Value: VTTR buffer noise <10µVRMS supports high-speed DDR3 timing margins; PGOOD signals enable system-level memory health monitoring. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel DDR power supply applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS51220ARTVR | Single-channel DDR power IC with integrated MOSFETs; supports VDDQ only; requires external circuitry for VTT/VTTR. | Not suitable for full DDR3 termination - lacks VTT sourcing/sinking capability and VTTR buffer; limited to VDDQ-only designs. | Select only if VTT is generated separately (e.g., with TPS51116) and board space allows two ICs; no pin compatibility with LTC3634HFE#TRPBF. |
| ISL95812IRZ | 3A dual-channel buck with VDDQ/VTT outputs but no VTTR buffer; uses external resistor divider for VTT reference; max 125°C rating. | Requires external 0.1% precision resistors and op-amp buffer to meet DDR3 VTTR accuracy; not rated for 150°C operation. | Acceptable for commercial-temp DDR3 systems where VTTR accuracy relaxed to ±2.5%; not drop-in due to different pinout and missing VTTR pin. |
Compared with TPS51220ARTVR and ISL95812IRZ, the LTC3634HFE#TRPBF uniquely integrates a ±10mA VTTR buffer with ±1.6% accuracy and H-grade 150°C operation, enabling single-chip DDR3 power delivery with JEDEC-compliant termination without external components or thermal derating.
Availability
LTC3634HFE#TRPBF is available at Aetrix Electronics and suitable for DDR3 memory modules, server DIMMs, and industrial embedded systems requiring stable component supply, guaranteed long-term availability, and extended-temperature qualification.
Supply support for LTC3634HFE#TRPBF 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 power management portfolio, emphasizing precision, efficiency, and ruggedness for demanding analog-intensive applications.
The LTC3634HFE#TRPBF belongs to Linear's DDR-specific power regulator family, designed explicitly for simultaneous VDDQ and VTT generation with integrated VTTR reference buffering and thermal-hardened packaging for memory subsystems.
FAQ
What is the maximum operating junction temperature for the LTC3634HFE#TRPBF?
The LTC3634HFE#TRPBF is specified for operation from –40°C to 150°C junction temperature. This H-grade rating is validated across process corners and ensures reliable performance in high-ambient industrial and telecom applications without derating up to TJ = 150°C. Thermal design must maintain θJA ≤ 25°C/W using the exposed PGND pad.
How does the LTC3634HFE#TRPBF generate the VTTR reference voltage?
The LTC3634HFE#TRPBF generates VTTR internally as VDDQIN × 0.5 using a precision resistor divider, then buffers it with a low-noise amplifier capable of ±10mA sourcing/sinking. The buffered VTTR output (Pin 18) serves as the feedback reference for Channel 2 (VTT rail) and meets ±1.6% accuracy at 0.75V, satisfying DDR3 VREF specifications.
Can the LTC3634HFE#TRPBF operate with different input voltages on VIN1 and VIN2?
Yes, the LTC3634HFE#TRPBF supports independent inputs: VIN1 powers the VDDQ channel and INTVCC LDO, while VIN2 powers the VTT channel. Both accept 3.6V–15V, enabling flexible power architecture - for example, 12V for VDDQ and 5V for VTT - without cross-coupling or shared supply constraints.
What protection features are integrated into the LTC3634HFE#TRPBF?
The LTC3634HFE#TRPBF includes input overvoltage lockout (17.5V trip), overtemperature shutdown, short-circuit current limiting (±3.3A to ±5.5A valley limit), and open-drain PGOOD status outputs with 40µs filtering. These features protect both the IC and DDR memory during fault conditions without requiring external supervision circuitry.
Is the LTC3634HFE#TRPBF pin-compatible with other variants in the LTC3634 family?
Yes, the LTC3634HFE#TRPBF shares identical pinout and footprint with all LTC3634FE variants (E, I, MP grades) in the 28-lead TSSOP package. Differences are limited to temperature grade and minor electrical specs (e.g., IQ, tSS); no PCB redesign is needed when upgrading from LTC3634IFE#TRPBF to LTC3634HFE#TRPBF for extended-temperature operation.
LTC3634HFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Applications:
- Converter, DDR, DDR2, DDR3
- Voltage - Input:
- 1.4V ~ 15V
- Number of Outputs:
- 2
- Voltage - Output:
- 0.6V ~ 3V
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LTC3634HFE#TRPBF FAQ
1.How can I place an order for LTC3634HFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3634HFE#TRPBF 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 LTC3634HFE#TRPBF reliable?
The price and inventory of LTC3634HFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3634HFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3634HFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3634HFE#TRPBF transactions.
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4.How is shipping managed for LTC3634HFE#TRPBF?
LTC3634HFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3634HFE#TRPBF 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 LTC3634HFE#TRPBF?
For technical support, including LTC3634HFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3634HFE#TRPBF requirements.
6.How does Aetrix verify that LTC3634HFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3634HFE#TRPBF 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 LTC3634HFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3634HFE#TRPBF?
All LTC3634HFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3634HFE#TRPBF, 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 LTC3634HFE#TRPBF part is unused and in its original packaging.
Return procedure for LTC3634HFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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