ACT6390/ACT6391
Rev0, 13-May-08
f
Z
(
ESR
)
=
1
=
9.64kHz
2
π
×
33µF
×
0.5
Ω
(31)
f
Z(ESR)
< f
C
R
ESR
×
C
OUT
0.5
Ω
×
33µF
=
=
70.8 pF
R
COMP
233k
Ω
Choose C
COMP2
= 82pF
C
COMP2
=
(32)
Rectifier Selection
For optimal performance, the rectifier should be a
Schottky rectifier that is rated to handle both the
output voltage as well as the peak switch current.
Over Voltage Protection
The ACT6390 and ACT6391 both feature internal
automatic over-voltage protection (OVP). Once the
outputs achieve regulation, if the voltage at FB falls
below 0.125V the controller will automatically dis-
able and latch off, preventing the controller from
running open-loop and potentially damaging the IC
and load.
To re-enable the converters, simply cycle the EN
pin or remove and reapply power to the input.
Shutdown
Drive EN low to disable the IC and reduce the sup-
ply current to just 0.1µA. As with all non-
synchronous step-up DC/DC converters, the exter-
nal Schottky diode provides a DC path from the in-
put to the output in shutdown. As a result, the out-
put drops to one diode voltage drop below the input
in shutdown.
Thermal Shutdown
The ACT6390 and ACT6391 both feature integrated
thermal overload protection. Both devices are auto-
matically disabled when their junction temperatures
exceed 160°C, and automatically re-enable when
the die temperature decreases by 20°C.
Innovative Power
TM
-8-
www.active-semi.com
Copyright © 2008 Active-Semi, Inc.
ACTIVE-SEMI [ ACTIVE-SEMI, INC ]
