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ROHM BD8312HFN Data Manual

Summary

ROHM BD8312HFN single-chip step-down switching regulator datasheet (No.11027EDT04) documenting this 1.5MHz high-efficiency DC-DC converter with built-in synchronous rectification power MOSFETs in HSON8 (2.9mmx3mm) package. Produces fixed outputs of 1.2V/1.8V/3.3V/5V from 3.5V to 14V input, supporting 4-cell dry batteries, 2-cell/3-cell Li-ion, or fixed 5V/12V rails. Delivers 1.2A at 7.4V-to-3.3V conversion. Features built-in Pch/Nch FETs rated 15V/1.0A, on-chip phase compensation between error a

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Single-chip Type with Built-in FET Switching Regulators

Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET

BD8312HFN No.11027EDT04

●Description BD8312HFN produces step-down output including 1.2, 1.8, 3.3, or 5 V from 4 batteries, batteries such as Li2cell or Li3cell, etc. or a 5V/12V fixed power supply line. This IC allows easy production of small power supply by a wide range of external constants, and is equipped with an external coil/capacitor downsized by high frequency operation of 1.5 MHz, built-in synchronous rectification SW capable of withstanding 15 V, and flexible phase compensation system on board.

●Features 1) Incorporates Pch/Nch synchronous rectification SW capable of withstanding 1.0 A/15V. 2) Incorporates phase compensation device between input and output of Error AMP. 3) Small coils and capacitors to be used by high frequency operation of 1.5MHz 4) Input voltage 3.5 V – 14 V Output current 1.2A(7.4V input, 3.3V output) 0.8A(4.5V input, 3.3V output) 5) Incorporates soft-start function. 6) Incorporates timer latch system short protecting function. 7) As small as 2.9mm×3 mm, SON 8-pin package HSON8

●Application For portable equipment like DSC/DVC powered by 4 dry batteries or Li2cell and Li3cell, or general consumer-equipment with 5 V/12 V lines

●Operating Conditions (Ta = 25℃)

Parameter Symbol Voltage circuit Unit

Power supply voltage VCC 3.5 to 14 V Output voltage VOUT 1.2 to 12 V

●Absolute Maximum Ratings

Parameter Symbol Rating Unit

Maximum applied power voltage VCC, PVCC 15 V Maximum input current Iinmax 1.0 A Power dissipation Pd 630 m W Operating temperature range Topr -25 to +85 ℃ Storage temperature range Tstg -55 to +150 ℃ Junction temperature Tjmax +150 ℃ *1 When used at Ta = 25℃ or more installed on a 70×70×1.6tmm board, the rating is reduced by 5.04m W/℃. * These specifications are subject to change without advance notice for modifications and other reasons.

www.rohm.com 2011.04 - Rev.D

© 2011 ROHM Co., Ltd. All rights reserved.

Page Summary Contents For ROHM BD8312HFN Data Manual

Page 1 Single-chip Type with Built-in FET Switching Regulators Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET BD8312HFN No.11027EDT04 ●Description BD8312HFN prod...
Page 2 BD8312HFN Technical Note ●Electrical Characteristics (Unless otherwise specified, Ta = 25 ℃, VCC = 7.4 V) Target Value Parameter Symbol Unit Conditions Min Typ Max [Low voltage input malfunction preve...
Page 3 BD8312HFN Technical Note ●Description of Pins Pin No. Pin Name Function 1 GND Ground terminal GND INV 2 VCC Control part power input terminal VCC STB 5 V output terminal of regulator for 3 VREG intern...
Page 4 BD8312HFN Technical Note ●Description of Blocks 1. Reference This block produces ERROR AMP standard voltage. The standard voltage is 1.0 V. 2. 5 V Reg 5 V low saturation regulator for internal analog ...
Page 5 BD8312HFN Technical Note ys te re si ol ta ge hy s[ [V ●Reference data (Unless otherwise specified, Ta = 25℃, VCC = 7.4 V) TEMPERATURE [℃] VCC [V] TEMPERATURE [℃] Fig.3. INV Fig.4. INV Fig.5. VREG out...
Page 6 BD8312HFN Technical Note lt ag [V si st an [Ω si st an ID=500m A ID=500m A Ta=85℃ 2.5 Ta=25℃ Ta=-25℃ TEMPARATURE [℃] VCC [V] Io [A] si st an Fig.14.Pch FET ON resistance si st an [Ω Fig.12. Pch FET ON...
Page 7 BD8312HFN Technical Note ●Example of Application Input: 4.5 to 10 V, output: 3.3 V / 500m A IC IE VBAT=4.5~10V 1μF GRM188B11A105KA61 (Murata) GND INV VCC STB ON/OFF PGND Lx GRM188B11A105KA61 4.7μH (Mu...
Page 8 BD8312HFN Technical Note ai [d ai [d in ●Reference application data 2 (Input 4.5 V, 6.0 V, 8.4 V, 10 V, output 3.3 V ) Phase Phase Phase ha se [d g] se -60 -180 ai [d in ai [d Frequency [Hz] Frequency...
Page 9 BD8312HFN Technical Note ●Reference board pattern ・The radiation plate on the rear should be a GND flat surface of low impedance in common with the PGND flat surface. ・It is recommended to install a G...
Page 10 BD8312HFN Technical Note (3) Output voltage setting The internal standard voltage of the ERROR AMP is 1.0 V. Output voltage is acquired by Equation (4). ERROR AMPR1 INV (R1+R2) Vo= ×1.0 [V] ・・・ (4) R2...
Page 11 BD8312HFN Technical Note [2] Cs and Rs setting For DC/DC converter, the 2nd dimension pole point is caused by the coil and capacitor as expressed by the following equation. f LC= 2π√(LC) This secondar...
Page 12 BD8312HFN Technical Note ●I/O Equivalence Circuit STB INV VCC VREGVCC STB INV Lx, PGND, PVCC VREG VCC VCC www.rohm.com 2011.04 - Rev.D © 2011 ROHM Co., Ltd. All rights reserved.
Page 13 BD8312HFN Technical Note ●Notes for use 1) Absolute Maximum Rating We dedicate much attention to the quality control of these products, however the possibility of deterioration or destruction exists i...
Page 14 BD8312HFN Technical Note ●Ordering part number Part No. Part No. Package Packaging and forming specification HFN:HSON8 TR: Embossed tape and reel HSON8 <Tape and Reel information> 2.9±0.1 (2.2) ...
Page 15 Notice No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM Co.,Ltd. The content specified herein is subject to change for improvement without not...

Manual Details

Brand ROHM
Pages 15
File Size 430.16 KB
Published June 21, 2026
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Frequently Asked Questions

What are the input voltage limits for this regulator?

The power supply voltage (VCC) ranges from 3.5 V to 14 V.

How does the BD8312HFN protect against system failures?

It includes a timer latch system for short protecting, and operates with soft-start and Unique Voltage Low (UVLO) detection thresholds.

What kind of external batteries can power this IC?

It supports various batteries such as Li2cell or Li3cell, in addition to 5V/12V fixed power lines.