R1
R2
V+
VO = VCL (1 + R2/R1)
15000 (4.75V)
4.75V
13750Ω
V–
IO
=
VCL
13750Ω + RCL
ILIM
For Example:
RCL
0.01µF
If ILIM = 3A, RCL = 10kΩ
10kΩ • 4.75V
(Optional, for noisy
environments)
VCL
=
= 2V
20
(10kΩ + 13750Ω)
Uses voltage developed at ILIM pin
as a moderately accurate reference
voltage.
Desired VO = 20V,G =
= 10
2
R1 = 1kΩ and R2 = 9kΩ
FIGURE 15. Voltage Source.
1kΩ
9kΩ
9kΩ
G = 1 +
= 10
1kΩ
+5V
+30V
V+
10.5kΩ
2
5
6
VO = 1.2V to 25V(1)
IO = 0 to 5A
OPA548
0.12V to 2.5V
E/S
10kΩ
7
1
Output
Adjust
4
74HCT04
ILIM
R ≥ 250Ω
3
499Ω
V–
+5V
V–
Thermal
Shutdown Status
(LED)
0V to 4.75V
1kΩ
Current
Limit
Adjust
NOTES: (1) For VO ≤ 0V, V– ≤ –1V.
(2) Optional: Improves noise
immunity.
0.01µF(2)
20kΩ
FIGURE 16. Resistor-Controlled Programmable Power Supply.
®
OPA548
14
BB [ BURR-BROWN CORPORATION ]
