# A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

ROHM BD9850FVM Data Sheet Manual

Summary

These advanced DC/DC switching regulator controllers provide robust and efficient power solutions for demanding applications, including consumer electronics, PCs, routers, and display panels. Featuring high-frequency operation up to 3 MHz, these single- or dual-channel regulators offer FET direct drive and integrated protections like UVLO and TSD, ensuring system reliability. The manual provides comprehensive details on operating limits, electrical characteristics, and performance across various supply voltage ranges, making it essential for engineers designing compact, high-performance digital devices.

📄 Preview PAGE OF 17

Page 1 Text Content

TECHNICAL NOTE

Large Current External FET Controller Type Switching Regulators

High temperature ESD operating Resistance

Single-output High-frequency Step-down

Now available Now available

Switching Regulator(Controller type) BD9850FVM Dual-output Step-up, Negative, Step-down Switching Regulator(Controller type) BD9851EFV Description The BD9850FVM is a 1-channel DC/DC step-down switching regulator controller, while the BD9851EFV is a 2-channel DC/DC step-down switching regulator controller. The BD9850FVM is adaptable for a maximum switching frequency of 2 MHz and the BD9851EFV for that of 3 MHz. Both provide space saving in all applications.

Features 1) Adaptable for 2-MHz switching frequency (externally variable) (BD9850FVM) Adaptable for 3-MHz switching frequency (externally variable) (BD9851EFV) 2) FET direct drive 3) High-accuracy reference voltage (Accuracy: ±1%) 4) Built-in Under Voltage Lock Out circuit (UVLO) 5) Built-in Thermal Shutdown circuit (TSD) 6) The BD9851EFV provides two channels: Channel 1 available for selection of step-down/step-up switching Channel 2 available for selection of step-down/inverting switching. 7) Compact MSOP8 package (BD9850FVM) / HTSSOP-B20 package (BD9851EFV)

Applications TFT panel, TA/Router, digital consumer electronics, PC, and portable CD/DVD/DVC

Product lineup

BD9850FVM BD9851EFV Input range 4V to 9V 4V to 18V Oscillation frequency range 100k Hz to 2MHz 10k Hz to 3MHz External synchronization Not provided Not provided Standby function Not provided Provided Operating temperature –40 C̊ to 85 C̊ –40 C̊ to 85 C̊ Package MSOP8 HTSSOP-B20

Sep. 2008

ROHM CO., LTD

Page Summary Contents For ROHM BD9850FVM Data Sheet Manual

Page 1 TECHNICAL NOTE Large Current External FET Controller Type Switching Regulators High temperature ESD operating Resistance Single-output High-frequency Step-down Now available Now available Switching Re...
Page 2 Absolute maximum ratings (Ta=25˚C) BD9850FVM Item Symbol Rating Unit Power supply voltage Vcc Storage temperature Tstg –55 to +150 ºC Operating temperature Topr –40 to +85 ºC Power dissipation Pd m W ...
Page 3 BD9850FVM Electrical characteristics (Unless otherwise specified, Ta=25 C̊, Vcc=7V, fosc=600k Hz) Limits Item Symbol Unit Conditions Typ. max.min. [Oscillator block] Oscillation frequency fosc k Hz RR...
Page 4 BD9851EFV Electrical characteristics (Unless otherwise specified, Ta=25 C̊, Vcc=12V, fosc=300k Hz, STB=3V) Limits Item Symbol Unit Conditions Typ. max.min. [Total device] Standby mode circuit current ...
Page 5 Characteristic data (BD9850FVM) VR EF LT E: VR EF [V SO RC RR EN : I [m ER RO R- P. RE SH LD LT : V IN V( AMBIENT TEMPERATURE : Ta(˚C) FB VOLTAGE : VFB(V) Fig.1 Error Amp threshold voltage vs. Ambient...
Page 6 (BD9851EFV) RE FE RE VO LT : V RE (V SO RC RR EN : I (m ER RO R- P. RE SH LD LT : V EA TH (V 0.99 fosc=1MHz fosc=300k Hz AMBIENT TEMPERATURE : Ta(˚C) DTC VOLTAGE : VDTC (V) Fig.7 Error Amp threshold v...
Page 7 Block diagram / Pin assignment (BD9850FVM) Vcc RTVREF SE L1 U.V.L.O VREF Vc TRI VR EF Vc IN V2 IN V1 Vcc TL /S FB FB TC SC FB PV cc TC Error Amp Clamper OUT EF IN T2 PV cc 1.0V Vo PWM COMP PG T1 CTL/S...
Page 8 Description of operations 1) Reference voltage block The reference voltage block generates a constant voltage with temperature compensated through inputting the power supplied from the Vcc pin. The ou...
Page 9 Timing chart • In startup/normal operation (BD9850FVM) FB pin voltage Soft start set voltage Oscillator output Control threshold OUT pin waveform Vcc waveform Output voltage waveform Fig.15 BD9850FVM ...
Page 10 Description of external components sc ill at in fr eq ue nc [k z] • Setting of output voltage (BD9850FVM) Setting of output voltage for the step-down application can be calculated by the formula below...
Page 11 • Setting of oscillation frequency (BD9851EFV) Connecting a resistor to the RT pin (pin 2) and a capacitor to the CT pin allows for the setting of oscillation frequency. RT (2) sc ill at in Fr eq ue n...
Page 12 Application circuit / Directions for pattern layout (BD9850FVM) Vcc R1 Vcc RT C1 OUTOUT CT/SS GND FB R1 GND Vcc Vcc RT VREF INV OUT CTL/SS C1: In order to reduce ripple noises, set the shortest distan...
Page 13 BD9851EFV 1PIN (SEL1) 2PIN (RT) 7,13PIN (DTC2,DTC1) Vcc Vcc Vcc VREF VREF Vcc Vcc 9PIN (OUT2) 3PIN (CT) 4PIN (NON2) Vcc Vcc PVcc2 VREF Vcc Vcc VREF VCC VREF VREF VREF VREF VREF 11PIN (OUT1 14PIN (SCP)...
Page 14 8) IC pin input This monolithic IC contains P+ isolation and P substrate layers between adjacent elements to keep them isolated. Pin junctions are formed at the intersection of these P layers with the...
Page 15 11) Although ROHM is confident that the example application circuit reflects the best possible recommendations, be sure to verify circuit characteristics for your particular application. Modification ...
Page 16 Catalog No.08T679A '08.9 ROHM ©
Page 17 Appendix Notes 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 wit...

Manual Details

Brand ROHM
Pages 17
File Size 785.99 KB
Published May 31, 2026
55 views

Enter the captcha to get the download link:

captcha

Frequently Asked Questions

Which regulator is suitable for single-channel DC/DC step-down conversion?

The BD9850FVM handles 1-channel DC/DC step-down switching regulation.

What are the maximum switching frequencies supported by each controller?

BD9850FVM is adaptable up to 2 MHz, while BD9851EFV supports up to 3 MHz.

Does the BD9851EFV support different power conversion modes?

Yes, it offers two channels: Channel 1 can be step-down or step-up, and Channel 2 can be used for step-down or inverting switching.

What protection features do these regulators include?

They both feature built-in Under Voltage Lock Out (UVLO) circuit and Thermal Shutdown (TSD) circuit.