Datasheet

TC648
DS21448D-page 8  2001-2012 Microchip Technology Inc.
FIGURE 4-1: TC648 Behavioral Algorithm Flowcharts.
V
OUT
= 0
V
IN
> V
OTF
?
Auto-
Shutdown
V
OUT
= 0
No
Yes
Normal
Operation
V
IN
< V
AS
?
No
Yes
V
OUT
Duty
Cycle Prop.
to V
IN
OTF = 0
OTF = 1
No
YES
Fire Start-up
Timer
Normal
Operation
V
AS
≈ 0V
V
IN
< V
AS
?
Auto-
Shutdown
V
OUT
= 0
Yes
No
Yes
Power-Up
Minimum
Speed Mode
Power-on
Reset
OTF = 1
V
IN
>
(V
AS
+ V
HAS
)
No
Power-Up
V
IN
≈ 0V ?
V
IN
> 1.25V ?
V
IN
> 1.25V
No
No
Yes
Yes
No
Yes
Yes
Minimum
Speed Mode
No
V
OUT
= 0
OTF = 0
V
IN
> V
OTF
?
V
OUT
Duty Cycle Proportional to V
IN
OTF = 1