Datasheet

14/16
Technical Note
Fig.36 Equivalent circuit
Fig.37 T
ypical simple construction of monolithic IC
P layer
E
B
C
(Pin B)
Transistor (NPN)
P
N
N
N
N
GND
Parasitic element
GND
P
+
P
+
(Pin A)
GND
Parasitic element
(PIN B)
GND
B
E
C
Parasitic element
P
+
P layer
(Pin A)
Resistor
P
N
N
N
GND
Parasitic element
P
+
Notes for use
1) Absolute maximum ratings
An excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc.,
can break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit.
If any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices,
such as fuses. Furthermore, don't turn on the IC with a fast rising edge of V
IN. ( rise time << 10V / µsec )
2) GND potential
GND potential should maintain at the minimum ground voltage level. Furthermore, no terminals should be lower than the GND
potential voltage including an electric transients.
3) Thermal design
Use a thermal design that allows for a sufficient margin in light of the power dissipation (Pd) in actual operating conditions.
4) Inter-pin shorts and mounting errors
Use caution when positioning the IC for mounting on printed circuit boards. The IC may be damaged if there is any connection
error or if positive and ground power supply terminals are reversed. The IC may also be damaged if pins are shorted
together or are shorted to other circuits power lines.
5) Operation in strong electromagnetic field
Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction.
6) Inspection with set printed circuit board
When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress.
Always discharge capacitors after each process or step. Always turn the IC's power supply off before connecting it to,
or removing it from a jig or fixture, during the inspection process. Ground the IC during assembly steps as an antistatic
measure. Use similar precaution when transporting and storing the IC.
VIN
EN/SYNC
222
kΩ
221
kΩ
2kΩ
VREGA
139
kΩ
145
kΩ
SW
SW
EN
VIN
10k
Ω
300kΩ
250kΩ
VIN
2kΩ
300kΩ
50k
Ω
RT
VIN
VREF
VIN
EN/SYNC&BD9781HFP'
EN&BD9778F/HFP, BD9001F
'
1kΩ
VIN
FB
VREF
1kΩ
INV
VIN
VREF
FB&BD9778F/HFP, BD9781HFP '
INV
RT
FB&BD9001F
'
1kΩ
VIN
FB
VREF
1kΩ
2010.02 - Rev. B
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BD9778F, BD9778HFP, BD9001F, BD9781HFP