GSI-3000C Series
External Variable Output Voltage Circuit
1. Variable output voltage with a single external resistor
35
30
25
20
15
10
5
V
IN
VO
5
2
3
4
V
IN=VO+1V
SI-3000C
1
I
REX
R
EX
OPEN
47µF
+
+
V04
47µF
GND
GND
The output voltage may be increased by inserting resistor REX between
terminals No.4 (sensing terminal) and No.3 (output terminal). The cur-
rent IREX flowing into terminal No.4 is 1mA (typ.)(SI-3033C:0.43mA (typ.)),
therefore the adjusted output voltage VOUT is:
VO=V04+IREX•REX
*V04: output voltage of SI-3000C series
However, the internal resistor (between terminals No. 4 and No.1) is a
semiconductor resistor, which has approximately thermal characteris-
tics of +0.2%/°C.
It is important to keep the thermal characteristics in mind when adjust-
ing the output voltage.
0
2
4
6
8
10
2. Variable output voltage with two external resistors
External Resistor REX (kΩ)
VIN
VO
5
2
3
4
SI-3000C
1
I
REX1
REX1
OPEN
47µF
35
30
25
20
15
10
5
+
+
V04
47µF
I4IN
R
EX2
V
IN=VO+1V
GND
GND
The output voltage may be increased by inserting resistors REX1 be-
tween terminals No.4 (sensing terminal) and No.3 (output terminal) and
REX2 between terminals No.4 and No.1 (ground terminal).
The current I4IN flowing into terminal No.4 is 1mA (typ.)(SI-3033C:
0.43mA (typ.)) so the thermal characteristics may be improved com-
pared to the method shown in 1 by setting the external current IREX1 at
approximately 5 times the value of I4IN (stability coefficient S=5).
The adjusted output voltage VOUT in this case is:
VO=V04+REX1•IREX1
IREX1=S•I4IN
The value of the external resistors may be obtained as follows:
VO-V04
V04
REX1=
REX2=
S•I4IN
,
(S-1)•I4IN
0
1.0
External Resistor REX1 (kΩ)
2.0
*V04: Output voltage of SI-3000C series
S: Stability coefficient of I4IN (may be set to any value)
Note: In the SI-3000C series, the output voltage increase can be ad-
justed as mentioned above. However, when the rise is set to ap-
proximately 10V compared to output voltage V04, the necessary
output current may not be obtained due to the S.O.A. protection
circuit in the SI-3000C series.
40