Datasheet

LM723 Typical performance characteristics
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Table 6. Resistor values (kΩ) for standard output voltages
Output
Volt age
Applicable figures
Fixed output ± 5% Output adjustable ± 10%
(1)
R1 R2 R1 P1 R2
+3 16, 18, 20, 21, 24, 26 4.12 3.01 1.8 0.5 1.2
+5 16, 18, 20, 21, 24, 26 2.15 4.99 0.75 0.5 2.2
+6 16, 18, 20, 21, 24, 26 1.15 6.04 0.5 0.5 2.7
+9 17, 18, 20, 21, 24, 26 1.87 7.15 0.75 1 2.7
+12 17, 18, 20, 21, 24, 26 4.87 7.15 2 1 3
+15 17, 18, 20, 21, 24, 26 7.87 7.15 3.3 1 3
+28 17, 18, 20, 21, 24, 26 21 7.15 5.6 1 2
+45 22 3.57 48.7 2.2 10 39
+75 22 3.57 78.7 2.2 10 68
+100 22 3.57 102 2.2 10 91
+250 22 3.57 255 2.2 10 240
-6
(2)
18 3.57 2.43 1.2 0.5 0.75
-9 18 3.48 5.36 1.2 0.5 2
-12 18 3.57 8.45 1.2 0.5 3.3
-15 18 3.65 11.5 1.2 0.5 4.3
-28 18 3.57 24.3 1.2 0.5 10
-45 23 3.57 21.2 2.2 10 33
-100 23 3.57 97.6 2.2 10 91
-250 23 3.57 249 2.2 10 240
1. Replace R1/R2 divider with the circuit of Figure 27.
2. V+ must be connected to a +3 V or greater supply.
Table 7. Formula for intermediate output voltages
Conditions
Outputs from 2 to 7V
Figure 16, 19, 20, 21, 24, 26
V
O
=(V
REF
xR
2
) /(R
1
+R
2
)
Outputs from 4 to 250V
Figure 22
V
O
=(V
REF
/2)x[ (R
2
-R
1
)/R
1
]; R
3
=R
4
Current Limit
I
LIMIT
=V
SENSE
/R
SC
Outputs from 7 to 37V
Figure 17, 19, 20, 21, 24, 26
V
O
=V
REF
x[ (R
1
+R
2
)/R
2
]
Outputs from -6 to -250V
Figure 18, Figure 23
V
O
=(V
REF
/2)x[ (R
1
+R
2
)/R
1
];
R
3
=R
4
Foldback Current Limiting
I
KNEE
=[(V
O
xR
3
)/(R
SC
xR
4
)] x[ V
SENSE
x(R
3
+R
4
)]
/ (R
SC
xR
4
)
I
SHORTCKT
=(V
SENSE
/R
SC
)x[ (R
3
+R
4
)/R
4
]