7/8

Technical Note

BH

□□FB1WG series, BH□□FB1WHFV series,

BH

□□LB1WG series, BH□□LB1WHFV series,

BH

□□MA3WHFV series

Noise terminal (BH

MA3WHFV)

The terminal is directly connected to inward normal voltage source. Because this has low current ability, load exceeding

100nA will cause some instability at the output. For such reasons, we urge you to use ceramic capacitors which have less

leak current. When choosing noise the current reduction capacitor, there is a trade-off between boot-up time and stability. A

bigger capacitor value will result in lesser oscillation but longer boot-up time for VOU T.

~ Condition ~

VIN=4.0V

Cin=1.0

μF

Co=1.0

μF

ROUT=3.0k

Ω

Ta=25

°C

BH30MA3WHFV

100

10

1

0.1

0.01

100P

1000P

0.01

μ

0.1

μ

noise-filtering capacitor capacitance Cn (F)

Regarding input pin of the IC

This monolithi c IC contains P+ isolatio n and P substrat e layer s between adjacent

elements in order to keep them isolated. P/N junctions are formed at the intersection of

these P layers with the N layers of other elements to create a variety of parasitic elements.

For example, when a resistor and transistor are connected to pins as shown in Fig.37

The P/N junction functions as a parasitic diode when GND > (Pin A) for the resistor or

GND > (Pin B) for the transistor (NPN).

Similarly, when GND > (Pin B) for the transistor (NPN), the parasitic diode described

above combines with the N layer of other adjacent elements to operate as a parasitic

NPN transistor.

The formation of parasitic elements as a result of the relationships of the potentials of

different pins is an inevitable result of the IC's architecture. The operation of parasitic

elements can cause interference with circuit operation as well as IC malfunction and

damage. For these reasons, it is necessary to use caution so that the IC is not used in a

way that will trigger the operation of parasitic elements, such as by the application of

voltage lower than the GND (P substrate) voltage to input pins.

Fig. 36: Example of bypass

diode connection

CTL

OUT

GND

back current

Fig.37

GND

C

E

B

Parasitic elements

(Terminal B)

Parasitic element

GND

(Terminal A)

GND

GND

E

N

N

N

N

P

P

+

P

+

P

B

O

Parasitic elements

(Terminal B)

Transistor (NPN)

P-board

GND

N

N

N

P

P

P

+

P

+

(Terminal A)

Resistor

Parasitic element

Other adjacent elements

Part number selection

Package

HFV : HVSOF6

HVSOF5

G : SSOP5

BH

3

F B 1

W

H F V

0

-T R

ROHM

part number

Output

voltage

Current capacity

MA3 : 300mA

FB1 : 150mA

LB1 : 150mA

Shutdown

switch

W : With switch

Package specification

TR : Embossed taping

2010.07 -

Rev. C

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