RN5RG RICOH electronics devices division, RN5RG Datasheet - Page 6

• Manufacturer Part Number: RN5RG
• Description: VOLTAGE REGULATOR WITH EXTERNAL POWER TRANSISTOR
• Manufacturer: RICOH electronics devices division

OPERATION
SELECTION GUIDE FOR EXTERNAL COMPONENTS
2.Base Resistor R2
However, since this current limit circuit is provided for the purpose of protecting the IC, use a resistor R2 for the
protection of the External Transistor, although this IC can be operated without such a resistor. It is required that
the resistance of the Resistor R2 be determined with the input voltage, output voltage,output current, tempera-
ture, and the h
mination, check the characteristics by calculating the respective values by using the following formula :
3.Phase Compensation
For this purpose, be sure to use a capacitor C
R1 with a resistance of about 10kΩ between the base and the emitter.There may be the case the loop oscillation
takes place when a tantalum capacitor C
quency characteristics.
V
IN
In these ICs, phase compensation is made for securing stable operation even when the load current is varied.
EXT Pin of these ICs is protected by a current limit circuit from the destruction caused by excess current.
IN
V
DD
External PNP Transistor
V
2
IN
R1
[MIN.] –1.2(V)
Vref
R2
FE
Error
Amplifier
External PNP Transistor
R2
4
value taken into consideration and the dispersion of these values. Before making such a deter-
EXT
+
–
CE
5
4
3
–
EXT
V
OUT
0.7(V)
RB
RA
OUT
R1
V
3
1
GND
OUT
C
>
L
I
GND
L
OUT
OUT
with a large ESR is used, so select the C
h
L
[MAX.]
FE
(tantalum type) with a capacitance of 10µF or more and a resistor
Feed-back Registers RA, RB, and the detected Output
Voltage is compared with a reference voltage by Error
Amplifier, so that the base current of External PNP
Transistor is adjusted and Output Voltage V
lated.
1.External PNP Transistor
points of output current, input voltage and power dis-
sipation.
and high h
Select External PNP Transistor from the view-
Generally External PNP Transistor with low V
In these ICs, Output Voltage V
FE
is suitable.
L
carefully including the fre-
OUT
is detected by
OUT
RN5RG
is regu-
CE
(
SAT
)
5