Datasheet

MAX1533A/MAX1537A
High-Efficiency, 5x Output, Main Power-Supply
Controllers for Notebook Computers
30 ______________________________________________________________________________________
9a. This configuration constantly monitors the inductor
current, allowing accurate current-limit protection.
Alternatively, high-power applications that do not
require highly accurate current-limit protection may
reduce the overall power dissipation by connecting a
series RC circuit across the inductor (Figure 9b) with an
equivalent time constant:
where R
L
is the inductor’s series DC resistance. In this
configuration, the current-sense resistance equals the
inductor’s DC resistance (R
SENSE
= R
L
). Use the worst-
case inductance and R
L
values provided by the induc-
tor manufacturer, adding some margin for the
inductance drop over temperature and load.
Output Capacitor Selection
The output filter capacitor must have low enough equiv-
alent series resistance (ESR) to meet output ripple and
load-transient requirements, yet have high enough ESR
to satisfy stability requirements. The output capaci-
tance must be high enough to absorb the inductor
L
R
CR
L
EQ EQ
=×
Figure 9. Current-Sense Configurations
MAX1533A
MAX1537A
C
OUT
INPUT (V
IN
)
INDUCTOR
C
IN
b) LOSSLESS INDUCTOR SENSING
CSL_
CSH_
GND
DL_
DH_
LX_
C
EQ
R
EQ
MAX1533A
MAX1537A
C
OUT
INPUT (V
IN
)
N
H
N
L
N
H
N
L
L
C
IN
D
L
D
L
a) OUTPUT SERIES RESISTOR SENSING
GND
DL_
DH_
LX_
CSL_
CSH_
R
SENSE