RX5RE40A Datasheet, PDF (20/20 Pages) RICOH electronics devices division – VOLTAGE REGULATOR FOR MIDDLE OUTPUT CURRENT

R×5RE
• CURRENT BOOST CIRCUIT
Tr.1
VIN
+
C1
GND
VIN
R×5RE ^VOUT
SERIES
VOUT
GND
+
C2
GND
Output current of 120mA or more can be obtained
by the current boost circuit constructed as shown in
this circuit diagram.
• CURRENT BOOST CIRCUIT WITH OVERCURRENT LIMIT CIRCUIT
A circuit for protecting Tr.1 from the destruction
caused by output short-circuit or overcurrent is shown in
R2 Tr.1
this circuit diagram.
Vbe2
Tr.2
VIN
R1
+
When the voltage reduction caused by the current ( aa
IOUT
VIN
R×5RE ^VOUT
IOUT) which flows through R2 reaches Vbe2 of Tr.2 by
SERIES
GND
additionally providing the current boost circuit with Tr.2
+ ^VOUT
C2
and R2, Tr.2 is turned ON and the base current of Tr.1 is
GND
increased, so that the output current is limited.
GND
Current limit of Overcurrent Limit Circuit is obtained
as follows :
IOUT Vbe2/R2
• CURRENT SOURCE
VIN
VIN
+
C1
R×5RE ^VOUT
SERIES
R
GND
ISS
IOUT
A current source with the structure as shown in
this circuit diagram can be used. Output Current
IOUT is obtained as follows :
IOUT=Vreg*¹/R + ISS
Take care that Output Current IOUT does not exceed
its allowable current.
*^{1) Vreg : Set Output Voltage of R×5RE Series.}
19