6.6 UVP BLOCK
3.3V
13
5V
14
12V
15
R1
R3
Vref=5V
R5
A
B
SET of
R2
R/S Latch
C
UVP COMP
R2
R6
1.25V
The KA3511 has UVP functions for +3.3V, +5V, +12V Outputs. The block is made up of three input
comparators. Each UVP level is determined by resistor ratio and the typical values are 2.3V/4V/
10V.
UVP Detecting voltage for +3.3V
+
+
R1 R2
R1 R2
(
) = -------------------- ×
= -------------------- ×
=
=
=
VUVP 1 +3.3V
VA
VA
VA
Vref
Vref
Vref
2.3V
4V
R2
R2
UVP Detecting voltage for +5V
) =
+
+
R1 R2
R1 R2
--------------------
--------------------
(
×
=
×
VUVP 2 +5V
R2
R2
UVP Detecting voltage for +12V
+
+
R1 R2
R1 R2
= -------------------- ×
R2
(
) = -------------------- ×
VUVP 3 +12V
10V
R2
Rev C, November 1999
13
FAIRCHILD [ FAIRCHILD SEMICONDUCTOR ]
