High-Speed Step-Down Controller
for Notebook Computers
Standard Application Circuit
The standard application circuit (Figure 1) generates a
low-voltage rail for general-purpose use in a notebook
computer (I/O supply, fixed CPU core supply, DRAM
supply). This DC-DC converter steps down a battery or
AC adapter voltage to voltages from 1.0V to 5.5V with
high efficiency and accuracy.
See Table 1 for a list of component selections for com-
mon applications. Table 2 lists component manufacturers.
Detailed Description
The MAX1714 buck controller is targeted for low-voltage
power supplies for notebook computers. Maxim‘s propri-
etary Quick-PWM pulse-width modulator in the MAX1714
is specifically designed for handling fast load steps
while maintaining a relatively constant operating fre-
quency and inductor operating point over a wide range
of input voltages. The Quick-PWM architecture circum-
vents the poor load-transient timing problems of fixed-
frequency current-mode PWMs while also avoiding the
problems caused by widely varying switching frequen-
cies in conventional constant-on-time and constant-off-
time PWM schemes.
MAX1714
V
IN
4.5V TO 28V
+5V
BIAS SUPPLY
C5
4.7µF
R1
20Ω
C6
3.3µF
C1
V
CC
V+
ON/OFF
CONTROL
LOW-NOISE
CONTROL
SHDN
SKIP
MAX1714
V
DD
BST
DH
D2
CMPSH-3
Q1
C7
0.1µF
L1
V
OUT
C2
LX
DL
Q2
D1
PGND
(GND)
TON
REF
C4
0.22µF
AGND
(GND)
+5V
R2
100k
PGOOD
POWER-GOOD
INDICATOR
FB
OUT
ILIM
+5V
( ) = ARE FOR THE MAX1714B ONLY.
NOTE: IN THE MAX 1714B, AGND AND PGND ARE INTERNALLY CONNECTED TO THE GND PIN.
Figure 1. Standard Application Circuit
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