BU665XNUX Datasheet, PDF (5/18 Pages) Rohm – High-speed Load Response Full CMOS LDP Regulators

BU6650NUX, BU6651NUX, BU6652NUX, BU6653NUX
 Input/Output terminal equivalent circuit schematic
6,7,8pin (VOUT)
5pin (GND)
VIN
2,3,4pin (STBY)
VIN
VOUT
STBY
Technical Note
1pin (VIN)
Fig.3 Input/Output equivalent circuit
About input/output capacitor
It is recommended to place a capacitor as close as possible to the pins
between the input terminal and GND or between the output terminal and
GND.
The capacitor between the input terminal and GND becomes valid when
source impedance increases or when wiring is long. The larger the
capacity of the output capacitor between the output terminal and GND is,
the better the stability and characteristics in output load fluctuation
become. However, please check the status of actual implementation.
Ceramic capacitors generally have variation, temperature characteristics,
and direct current bias characteristics and the capacity value also
decreases with time depending on the usage conditions. It is
recommended to select a ceramic capacitor upon inquiring about
detailed data of the related manufacturer.
Capacity value of ceramic capacitor - DC bias characteristics
(Example)
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0
10-V withstand voltage
F characteristics
10-V withstand voltage
B1characteristics
GRM188B11A105KA61D
10-V withstand voltage
B characteristics
6.3-V withstand voltage
B characteristics
10-V withstand voltage
F characteristics
4-V withstand voltage
X6S characteristics
0.5
1
1.5
2
2.5
3
3.5
4
DC Bias Voltage [V]
Fig.4 Capacity – bias characteristics
 About the equivalent series resistance (ESR) of a ceramic capacitor
Capacitors generally have ESR (equivalent series resistance) and it
operates stably in the ESR-IOUT area shown on the right. Since
ceramic capacitors, tantalum capacitors, electrolytic capacitors, etc.
generally have different ESR, please check the ESR of the capacitor
to be used and use it within the stability area range shown in the
right graph for evaluation of the actual application.
100
Unstable area
10
1
Stability area
0.1
0.01
0
50
100
150
200
IOUT [mA]
Fig.5 Stability area characteristics (Example)
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2009.09 - Rev.B