LTC3634
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LTC3634

15V Dual 3A Monolithic Step-Down Regulator for DDR Power

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Part Models 16
1ku List Price Starting From $5.07
Features
  • 3.6V to 15V Input Voltage Range
  • ±3A Output Current per Channel
  • Up to 95% Efficiency
  • Selectable 90°/180° Phase Shift Between Channels
  • Adjustable Switching Frequency: 500kHz to 4MHz
  • VTTR = VDDQ/2 = VTT Reference
  • ±1.6% Accurate VTTR at 0.75V
  • Optimal VOUT Range: 0.6V to 3V
  • ±10mA Buffered Output Supplies VREF Reference Voltage
  • Current Mode Operation for Excellent Line and Load Transient Response
  • External Clock Synchronization
  • Short-Circuit Protected
  • Input Overvoltage and Overtemperature Protection
  • Power Good Status Outputs
  • Available in (4mm × 5mm) QFN-28 and Thermally Enhanced 28-Lead TSSOP Packages
Additional Details
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The LTC3634 is a high efficiency, dual-channel monolithic synchronous step-down regulator which provides power supply and bus termination rails for DDR1, DDR2, and DDR3 SDRAM controllers. The operating input voltage range is 3.6V to 15V, making it suitable for point-of-load power supply applications from a 5V or 12V input, as well as various battery powered systems.

The VTT regulated output voltage is equal to VDDQIN • 0.5. An on-chip buffer capable of driving a 10mA load provides a low noise reference output (VTTR) also equal to VDDQIN • 0.5.

The operating frequency is programmable and synchronizable from 500kHz to 4MHz with an external resistor. The two channels can operate 180° out-of-phase, which relaxes the requirements for input and output capacitance. The unique controlled on-time architecture is ideal for powering DDR applications from a 12V supply at high switching frequencies, allowing the use of smaller external components.

The LTC3634 is offered in both 28-pin 4mm × 5mm QFN and 28-pin exposed pad TSSOP packages.

Applications

  • DDR Memory Power Supplies
Part Models 16
1ku List Price Starting From $5.07

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Documentation

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Part Model Pin/Package Drawing Documentation CAD Symbols, Footprints, and 3D Models
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Apr 6, 2022

- 22_0068

Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL

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Laser Top Mark for ETSSOP and TSSOP Packages Assembled in ADPG [PNG] and UTL

LTC3634EFE#PBF

PRODUCTION

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Software & Part Ecosystem

Evaluation Kits 2

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DC1839A

LTC3634EFE Demo Board (TSSOP) | VIN = 3.6V to 15V, VOUT1 = 1.5V/1.8V/2.5V @ ±3A, VOUT2 = 0.5VIN (VTT) @ ±3A, VOUT3 = 0.5VIN (VTTR) @ ±10mA

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DC1839A

LTC3634EFE Demo Board (TSSOP) | VIN = 3.6V to 15V, VOUT1 = 1.5V/1.8V/2.5V @ ±3A, VOUT2 = 0.5VIN (VTT) @ ±3A, VOUT3 = 0.5VIN (VTTR) @ ±10mA

LTC3634EFE Demo Board (TSSOP) | VIN = 3.6V to 15V, VOUT1 = 1.5V/1.8V/2.5V @ ±3A, VOUT2 = 0.5VIN (VTT) @ ±3A, VOUT3 = 0.5VIN (VTTR) @ ±10mA

Product Detail

Demonstration circuit 1839A is a dual output regulator focused specifically for DDR memory power applications. It is built based on the LTC3634EFE (TSSOP-28E package), a high voltage dual channel, controlled on-time monolithic synchronous buck regulator. The DC1839A has an input voltage range of 3.6V to 15V. demo board's output voltage of the first channel, VDDQ, has three fixed voltage settings; 1.5V, 1.8V, and 2.5V, and is capable of delivering up to ±3A of output current. The second channel, VTT, is set to regulate to half the voltage on the VDDQIN pin, which can be either the channel 1 output or an external reference voltage. It can also source or sink a maximum of 3A. The LTC3634 also provides a ±10mA buffered output, VTTR, which is half of VDDQIN and is used to provide the reference voltage needed for DDR applications.

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DC1708A

LTC3634EUFD Demo Board (QFN) | VIN= 3.6V to 15V, VOUT1 =1.5V/1.8V/2.5V@±3A, VOUT2 = 0.5VIN (VTT)@±3A, VOUT3 = 0.5VIN (VTTR)@±10mA

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DC1708A

LTC3634EUFD Demo Board (QFN) | VIN= 3.6V to 15V, VOUT1 =1.5V/1.8V/2.5V@±3A, VOUT2 = 0.5VIN (VTT)@±3A, VOUT3 = 0.5VIN (VTTR)@±10mA

LTC3634EUFD Demo Board (QFN) | VIN= 3.6V to 15V, VOUT1 =1.5V/1.8V/2.5V@±3A, VOUT2 = 0.5VIN (VTT)@±3A, VOUT3 = 0.5VIN (VTTR)@±10mA

Product Detail

Demonstration circuit DC1708A is a dual-output regulator focused specifically for DDR memory power applications. It is built based on the LTC3634, a high voltage dualchannel, controlled on-time monolithic synchronous buck regulator. The DC1708A has an input voltage range of 3.6V to 15V. The output voltage of the first channel, VDDQ, of the DC1708A has three fixed voltage settings: 1.5V, 1.8V and 2.5V, and is capable of delivering up to 3A of output current. The second channel, VTT, is set to regulate to half the voltage on the VDDQIN pin, which can be either the channel 1 output or an external reference voltage. It can source or sink a maximum of 3A of output current. The LTC3634 also provides a 10mA buffered output of half VDDQIN – VTTR, which is used to provide the reference voltage needed for DDR applications. With the use of a timing resistor, the DC1708A can have its operating frequency programmed from 500kHz to 4MHz. Additionally the DC1708A can be easily synchronized to an external clock, due to an internal phase-locked loop, within this same frequency range. The DC1708A VDDQ output can operate in either Burst Mode® operation or forced continuous mode. In Burst Mode operation, which is the preferred mode of low load current operation, the DC supply current is typically only 1.3mA (both channels) at no load (sleep mode), and less than 15µA in shutdown. In Burst Mode operation or continuous mode operation, the DC1708A is a very efficient circuit at high load currents: over 80% for either channel. The LTC3634 is also capable of 90° or 180° out-of-phase operation, and can allow its output to track an external voltage, either coincidentally or ratiometrically. The LTC3634 comes in a 28-pin QFN package, featuring an exposed pad on the bottom-side of the IC for better thermal performance. All of these features make the DC1708A an ideal circuit for powering DDR memory applications.

Tools & Simulations 2

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.

Reference Designs 5

Versal AI Core Board

Edge Core FPGA Power Delivery Reference Design

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Versal AI Core XCVC1902

Edge Core FPGA Power Delivery Reference Design

Versal AI Core XCVC1902

Circuits from the lab

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Edge Core FPGA Power Delivery Reference Design

Features and Benefits

The ADI Versal AI Core Power Reference Design Board has been tested and proven to power the key rails for the Xilinx Versal AI Core ACAP series. Using a PMBUs Multi Phase DC/DC controller coupled with ADI SilentMOS (ADI version of DrMOS) to deliver up to 240A of output current.

The ADI LTC3888-1 is an 8 Phase PMBUs DC/DC controller that is coupled with the LTC7051 ADI SilentMOS to provide a flexible and scalable design that can be tailored as needed for both higher and lower power applications by adding or subtracting the LTC7051 ADI SilentMOS.

Request schematic for ADI power used on the board.

Contact ADI if you have questions about the ADI power management solutions used on this board.

View Detailed Reference Design external link

AI XCXM1802 for Optimized Efficiency

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Versal PRIME

AI XCXM1802 for Optimized Efficiency

Versal PRIME

Circuits from the lab

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AI XCXM1802 for Optimized Efficiency

Features and Benefits

ADI Key Power Management Features for Versal ACAP XCXM1802 for Optimized Efficiency

  • Proposed Solution implements new LTC3887-1/LTC7051 combo
  • LTC3887-1 is a PMBus 2-phase, 2 loop, current mode controller. PMBus commands allow Vin, Vout, current, temperature, and fault status read back.
  • LTC7051 is new Silent Switcher 2 ADI MOS capable of delivering increased DC load while switching at higher frequencies. Increased DC load allows for decreased phase count and higher current density. Increased Fsw allows for increase bandwidth and excellent transient response.
  • LTC3636 is dual 6A, controlled on-time current mode monolithic (integrated FETs). Provides high performance compact solution for auxiliary rails.
  • LTC3634 is a single chip solution for DDR rails providing VDD, VTT, and Vref in a monolithic solution.
  • LTC3634 is a single chip solution for DDR rails providing VDD, VTT, and Vref in a monolithic solution.
View Detailed Reference Design external link

AI XCXM1902 Minimum Rails and PL Performance

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Versal PRIME

AI XCXM1902 Minimum Rails and PL Performance

Versal PRIME

Circuits from the lab

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AI XCXM1902 Minimum Rails and PL Performance

Features and Benefits

ADI Key Power Management Features for Versal PRIME XCXM1802 for Minimum Rails / PL Performance

  • Proposed Solution implements new LTC3887-1/LTC7051 combo
  • LTC3887-1 is a PMBus 2-phase, 2 loop, current mode controller. PMBus commands allow Vin, Vout, current, temperature, and fault status read back.
  • LTC7051 is new Silent Switcher 2 ADI MOS capable of delivering increased DC load while switching at higher frequencies. Increased DC load allows for decreased phase count and higher current density. Increased Fsw allows for increase bandwidth and excellent transient response.
  • LTC3636 is dual 6A, controlled on-time current mode monolithic (integrated FETs). Provides high performance compact solution for auxiliary rails.
  • LT8607 is a compact, high efficiency, high speed 750mA synchronous monolithic.
  • LTC3634 is a single chip solution for DDR rails providing VDD, VTT, and Vref in a monolithic solution.
View Detailed Reference Design external link

AI XCXM1802 for Full Management Mid to High Voltage

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Versal PRIME

AI XCXM1802 for Full Management Mid to High Voltage

Versal PRIME

Circuits from the lab

tooltip Info:Circuits from the lab
AI XCXM1802 for Full Management Mid to High Voltage

Features and Benefits

ADI Key Power Management Features for Versal ACAP XCXM1802 for Mid to High Voltage

  • Proposed Solution implements new LTC3887-1/LTC7051 combo
  • LTC3887-1 is a PMBus 2-phase, 2 loop, current mode controller. PMBus commands allow Vin, Vout, current, temperature, and fault status read back.
  • LTC7051 is new Silent Switcher 2 ADI MOS capable of delivering increased DC load while switching at higher frequencies. Increased DC load allows for decreased phase count and higher current density. Increased Fsw allows for increase bandwidth and excellent transient response.
  • LTC3636 is dual 6A, controlled on-time current mode monolithic (integrated FETs). Provides high performance compact solution for auxiliary rails.
  • LTC3644 is a quad 1.25A output, high efficiency synchronous monolithic capable of switching up to 2.25MHz.
  • LTC3634 is a single chip solution for DDR rails providing VDD, VTT, and Vref in a monolithic solution.
View Detailed Reference Design external link
XCXM1802 Low Voltage

AI XCXM1802 for Low Voltage

zoomopens a dialog

Versal PRIME

AI XCXM1802 for Low Voltage

Versal PRIME

Circuits from the lab

tooltip Info:Circuits from the lab
AI XCXM1802 for Low Voltage

Features and Benefits

ADI Key Power Management Features for Versal PRIME XCXM1802 for Low Voltage

  • Proposed Solution implements new LTC3887-1/LTC7051 combo
  • LTC3887-1 is a PMBus 2-phase, 2 loop, current mode controller. PMBus commands allow Vin, Vout, current, temperature, and fault status read back.
  • LTC7051 is new Silent Switcher 2 ADI MOS capable of delivering increased DC load while switching at higher frequencies. Increased DC load allows for decreased phase count and higher current density. Increased Fsw allows for increase bandwidth and excellent transient response.
  • LTC3636 is dual 6A, controlled on-time current mode monolithic (integrated FETs). Provides high performance compact solution for auxiliary rails.
  • LTC3644 is a quad 1.25A output, high efficiency synchronous monolithic capable of switching up to 2.25MHz.
  • LTC3634 is a single chip solution for DDR rails providing VDD, VTT, and Vref in a monolithic solution.
View Detailed Reference Design external link

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