1A Variable Output, High-Accuracy LDO Regulator

The BD3550HFN / BD3551HFN / BD3552HFN ultra low-dropout linear chipset regulator operates from a very low input supply, and offers ideal performance in low input voltage to low output voltage applications. It incorporates a built-in N-MOSFET power transistor to minimize the input-to-output voltage differential to the ON resistance (RON=400mO / 200mO / 100mO) level. By lowering the dropout voltage in this way, the regulator realizes high current output (Iomax=0.5A / 1.0A / 2.0A) with reduced conversion loss, and thereby obviates the switching regulator and its power transistor, choke coil, and rectifier diode. Thus, the BD355XHFN is designed to enable significant package profile downsizing and cost reduction. An external resistor allows the entire range of output voltage configurations between 0.65 and 2.7V, while the NRCS (soft start) function enables a controlled output voltage ramp-up, which can be programmed to whatever power supply sequence is required.

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* This is a standard-grade product.
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Product Detail

Part Number | BD3551HFN-TR
Status | Recommended
Package | HSON8
Unit Quantity | 3000
Minimum Package Quantity | 3000
Packing Type | Taping
RoHS | Yes




Breakdown Voltage(Max.)[V]








Vout (Typ.) [V]

0.65 to 2.7

Vin 2ch[V]

0.95 to Vcc-1

Vout Precision




Circuit Current[mA]


Thermal Shut-down


Over Current Protection


Under Voltage Lock Out


Soft Start


Operating Temperature (Min.)[°C]


Operating Temperature (Max.)[°C]


Package Size

2.9x3 (t=0.6)


・Internal high-precision reference voltage circuit (0.65V±1%)
・Built-in VCC under voltage lockout circuit
・NRCS (soft start) function reduces the magnitude of in-rush current
・Internal Nch MOSFET driver offers low ON resistance (200mΩ (BD3551HFN typ.))
・Built-in current limit circuit
・Built-in thermal shutdown (TSD) circuit
・Variable output (0.65 to 2.7V)
・Small package HSON8 : 2.9x3x0.6 (mm)
・Tracking function

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
  • Table of resistance for output voltage setting on linear regulator Ics
  • Suppression Method of Switching Noise Using Linear Regulator and Low Pass Filter
  • Measurement Method for Phase Margin with Frequency Response Analyzer (FRA)
  • Usage of SPICE Macromodel (for LDO)
  • 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
  • Method for Calculating Junction Temperature from Transient Thermal Resistance Data
  • Thermal Calculation for Linear Regulator
  • Thermal Resistance



  • HSON8 Footprint / Symbol
  • HSON8 3D STEP Data

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)