1kΩ
9kΩ
–5V
VREF
OUTPUT ADJUST
+30V
G = 10
+5V
VREF A
+5V
RFB A
V
O = 0.8 to 25V(1)
IO = 0 to 5A
OPA548
10pF
IOUT A
1/2
OPA2336
74HCT04
1/2 DAC7800/1/2(3)
DAC A
R ≥ 250Ω
E/S
V–
AGND A
ILIM
Thermal
(LED)
Shutdown Status
VREF B
RFB B
10pF
IOUT B
1/2
OPA2336
1/2 DAC7800/1/2(3)
DAC B
0.01µF(2)
DGND
AGND B
CURRENT LIMIT ADJUST
NOTES: (1) For VO ≤ 0V, V– ≤ –1V. (2) Optional, improves noise immunity. (3) Chose DAC780X based on
digital interface: DAC7800—12-bit interface, DAC7801—8-bit interface
+ 4 bits, DAC7802—serial
interface.
FIGURE 17. Digitally-Controlled Programmable Power Supply.
R1
R2
VIN1
OPA548
ILIM
AMP1
E/S
RCL1
RCL2
Close for high current
(Could be open drain
output of a logic gate).
VO
R3
R4
VE/S
VIN2
V–
AMP2
E/S
FIGURE 19. Multiple Current Limit Values.
VE/S > (V–) +2.4V: Amp 1 is on, Amp 2 if off
VO = –VIN1 R2
VO
OPA548
(R )
As VO increases,
1
ILIM
I
LIM decreases.
VE/S < (V–) +2.4V: Amp 2 is on, Amp 1 if off
VO = –VIN2 R4
RCL
(R )
3
FIGURE 20. Single Quadrant V • I Limiting.
FIGURE 18. Switched Amplifier.
OPA548
SBOS070B
15
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