MAX1639 Maxim, MAX1639 Datasheet - Page 6

• Manufacturer Part Number: MAX1639
• Description: High-Speed Step-Down Controller with Synchronous Rectification for CPU Power
• Manufacturer: Maxim

High-Speed Step-Down Controller with
Synchronous Rectification for CPU Power
6
Figure 1. Standard Application Circuit
The predesigned MAX1639 circuit shown in Figure 1
meets a wide range of applications with output currents
up to 35A. Use Table 1 to select components appropri-
ate for the desired output current range, and adapt the
evaluation kit PC board layout as necessary. This cir-
cuit represents a good set of trade-offs between cost,
size, and efficiency while staying within the worst-case
specification limits for stress-related parameters, such
as capacitor ripple current.
The MAX1639 circuit was designed for the specified fre-
quencies. Do not change the switching frequency with-
_______Standard Application Circuits
_______________________________________________________________________________________
AGND
0.1 F
TO
C5
100k
R6
C4, 1.0 F
CERAMIC
RC1
1k
TO V
10 F
C6
0.056 F
1000pF
DD
CC2
CC1
PWROK
FREQ
REF
CC2
CC1
V
CC
MAX1639
10
R5
V
PGND
AGND
DD
CSH
CSL
BST
DH
DL
LX
FB
0.1 F
(OPTIONAL)
(OPTIONAL)
C7
R3
R4
out first recalculating component values—particularly
the inductance, output filter capacitance, and RC1
resistance values.
The MAX1639 is a BiCMOS power-supply controller
designed for use in switch-mode, step-down (buck)
topology DC-DC converters. Synchronous rectification
provides high efficiency. It is intended to provide the
high precision, low noise, excellent transient response,
and high efficiency required in today’s most demand-
ing applications.
___________________Detailed Description
N1
N2
D2
CMPSH-3
D1
(OPTIONAL)
C3
0.1 F
L1
R8
C1
R1
R7
C8
C2
V
V
OUT
IN
TO 5.5V
TO 4.5V
= 4.5V
= 1.1V