BH28FB1WHFV ROHM [Rohm], BH28FB1WHFV Datasheet - Page 7

• Manufacturer Part Number: BH28FB1WHFV
• Description: SILICON MONOLITHIC INTEGRATED CIRCUIT
• Manufacturer: ROHM [Rohm]

Part number selection
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 VOUT.
Regarding input pin of the IC
This monolithic IC contains P + isolation and P substrate layers 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 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.
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.
ROHM
part number
P
(Terminal A)
B H
N
P +
P-board
Output
voltage
Resistor
N
3
P
Parasitic element
GND
0
Fig. 35: V
P +
N
Current capacity
MA3 : 300mA
FB1 : 150mA
LB1 : 150mA
F B 1
OUT
startup time vs. noise-filtering capacitor capacitance characteristics (Example)
0.01
100
0.1
10
1
100P
noise-filtering capacitor capacitance Cn (F)
(Terminal B)
N
Parasitic elements
P +
1000P
Shutdown
switch
W : With switch
O
W
Fig.37
7/8
B
0.01μ
E
N
N
Transistor (NPN)
P
GND
P
0.1μ
H F V
Package
HFV : HVSOF-6
P +
BH30MA3WHFV
~ Condition ~
VIN=4.0V
Cin=1.0μF
Co=1.0μF
ROUT=3.0kΩ
Ta=25°C
G : SSOP-5
N
HVSOF-5
GND
-
Package specification
TR : Embossed taping
Other adjacent elements
(Terminal B)
Fig. 36: Example of bypass
T R
(Terminal A)
V
CTL
CC
diode connection
GND
back current
B
OUT
GND
C
E
GND
Parasitic element
Parasitic elements