Datasheet

µA723
PRECISION VOLTAGE REGULATORS
SLVS057D – AUGUST 1972 – REVISED JULY 1999
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
APPLICATION INFORMATION
Table 2. Formulas for Intermediate Output Voltages
OUTPUTS FROM 2 V TO 7 V
SEE FIGURES 1, 5, 6, 9, 11, 12 (4)
AND NOTE 5
OUTPUTS FROM 4 V TO 250 V
SEE FIGURE 7 AND NOTE 5
CURRENT LIMITING
V
O
V
(
ref
)
R2
R1 R2
V
O
V
(
ref
)
2
R2–R1
R1
R3 R4
I
(limit)
0.65 V
R
SC
OUTPUTS FROM 7 V TO 37 V
SEE FIGURES 2, 4, (5, 6, 9, 11, 12)
AND NOTE 5
OUTPUTS FROM –6 V TO –250 V
SEE FIGURES 3, 8, 10
AND NOTES 5 AND 7
FOLDBACK CURRENT LIMITING
SEE FIGURE 6
V
O
V
(
ref
)
R1 R2
R2
V
O
–
V
(
ref
)
2
R1 R2
R1
R3 R4
I
(knee)
V
O
R3 (R3 R4) 0.65 V
R
SC
R4
I
OS
0.65 V
R
SC
R3 R4
R4
NOTES: 5. The R1/R2 divider can be across either V
O
or V
(ref)
. If the divider is across V
(ref)
, use figure numbers without parentheses. If the
divider is across V
O
, use the figure numbers in parentheses.
7. For Figures 3, 8, and 10, the device requires a minimum of 9 V between V
CC+
and V
CC–
when V
O
is equal to or more positive than
–9 V.
REF
V
I
V
CC+
V
C
OUTPUT
V
Z
CURR LIM
CURR SENS
IN+
V
CC–
FREQ COMP
IN–
R
SC
R1
C
(ref)
R2
100 pF
Regulated
Output, V
O
R3 (see Notes A and B)
µA723
NOTES: A.
B. R3 can be eliminated for minimum component count. Use direct connection (i.e., R
3
= 0).
R3
R1 R2
R1 R2
for a minimum
V
O
Figure 1. Basic Low-Voltage Regulator (V
O
= 2 V to 7 V)