1A Variable Output Termination Regulator for DDR-SDRAMs

BD3539NUX is a termination regulator that complies with JEDEC requirements for DDR1-SDRAM, DDR2-SDRAM, and DDR3-SDRAM. This linear power supply uses a built-in N-channel MOSFET and high-speed OP-AMPS specially designed to provide excellent transient response. It has a sink/source current capability of up to 1A and has a power supply bias requirement of 3.3 V (for DDR2 and DDR3) and 5.0 V (for DDR1, DDR2, and DDR3) for driving the N-channel MOSFET. By employing an independent reference voltage input (VDDQ) and a feedback pin (VTTS), this termination regulator provides excellent output voltage accuracy and load regulation as required by JEDEC standards. Additionally, BD3539 has a reference power supply output (VREF)for DDR-SDRAM or for memory controllers. Unlike the VTT output that goes to "Hi-Z" state, the VREF output is kept unchanged when EN input is changed to "Low", making this IC suitable for DDR-SDRAM under "Self Refresh" state.

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Product Detail

Part Number | BD3539NUX-TR
Status | Recommended
Package | VSON008X2030
Unit Quantity | 4000
Minimum Package Quantity | 4000
Packing Type | Taping
RoHS | Yes










Vout (Typ.) [V]

0.75 to 1.25



Circuit Current[mA]


Thermal Shut-down


Under Voltage Lock Out


Soft Start


Operating Temperature (Min.)[°C]


Operating Temperature (Max.)[°C]


Package Size

2x3 (t=0.6)


· Incorporates a Push-Pull Power Supply for Termination (VTT)
· Incorporates a Reference Voltage Circuit (VREF)
· Incorporates an Enabler
· Incorporates an Under Voltage Lockout (UVLO)
· Incorporates a Thermal Shutdown Protector (TSD)
· Compatible with Dual Channel (DDR1, DDR2, DDR3)
· Usable Ceramic Capacitor at Output

Design Resources


Technical Articles

Schematic Design & Verification

  • Basics of Linear Regulators
  • Linear Regulator Specifications
  • Reverse Voltage Protection
  • Power Source ON/OFF Characteristics for Linear Regulator
  • Simple Test Method for Estimating the Stability of Linear Regulators
  • Connecting LDOs in Parallel
  • Problem Situations: Power Supply Does Not Start
  • Power Supply Sequence Circuit with General Purpose Power Supply IC
  • Suppression Method of Switching Noise Using Linear Regulator and Low Pass Filter
  • Measurement Method for Phase Margin with Frequency Response Analyzer (FRA)
  • BAxxCC0 Series Circuit Using a Ceramic Output Capacitor
  • Importance of Probe Calibration When Measuring Power: Deskew
  • Impedance Characteristics of Bypass Capacitor

Thermal Design

  • What Is Thermal Design
  • Basics of Thermal Resistance and Heat Dissipation
  • Method for Calculating Junction Temperature from Transient Thermal Resistance Data
  • Thermal Calculation for Linear Regulator
  • Thermal Resistance



  • VSON008X2030 Footprint / Symbol

Packaging & Quality

Package Information

  • Package Information
  • Anti-Whisker formation

Manufacturing Data

  • Factory Information

Environmental Data

  • UL94 Flame Classifications of Mold Compound
  • Compliance with the ELV directive
  • REACH SVHC Non-use Declaration
  • RoHS Comission Delegated Directive

Export Information

  • The Export Control Order
  • Export Administration Regulations(EAR)