PQ7RV4 Datasheet, PDF (4/5 Pages) Sharp Electrionic Components – Variable Output (1.5 to 7V), 4.6A Output Low Power-loss Voltage Regulator

Low Power-Loss Voltage Regulators
s Standard Connection
D1
VIN
1q
2q
VO
+
R2
CIN
3q
4q
Cref
+
R1
390Ω
to5kΩ
CO
PQ7RV4
D1 : This device is necessary to protect the element from damage when reverse voltage may be applied to the regulator in case of
input short-circuiting.
Cref : This device is necessary when it is required to enhance the ripple rejection or to delay the output start-up time. Otherwise, it
is not necessary.
(Care must be taken since Cref may raise the gain,facilitating oscillation.)
* The output start-up time si proportional to Cref X R2.
CIN,CO : Be sure to mount the devices CIN and CO as close to the device terminal as possible so as to prevent oscillation.
The standard specification of CIN and CO is 0.33µF and 47µF, respectively. However, adjust them as necessary after
checking.
R1,R2 : These devices are necessary to set the output voltage. The output voltage VO is given by the following formula:
VO=Vref X (1+R2/R1)
(Vref is 1.25V TYP)
The standard value of R1 is 2kΩ. But value up to 390Ω to 5kΩ does not cause any trouble.
s Asjustment of Output Voltage
Output voltage is able to set (1.5V to 7V) when resistors R1,R2 are attached to ™, £, ¢ terminals. As for the external
resistors to set output voltage, refer to the following figure.
2
-
4
+
3
Vref
VO
R2
VO=Vref X (1+R2/R1)
R1
=1.25 X (1+R2/2000)
(R1=2kΩ,Vref =1.25V)
s ON/OFF Operation
D1
VIN
1q
2q
VO
R2
D2
CIN
4q
3q
VADJ ^R1
R3
+
CO
RL
High : Output OFF
VC
Low : Output ON
VADJ
D2
R2
R1
RL
RD
VO’
Equivalent Circuit
in OFF-state