MAX1624 Datasheet, PDF (12/24 Pages) Maxim Integrated Products – High-Speed Step-Down Controllers with Synchronous Rectification for CPU Power

High-Speed Step-Down Controllers with
Synchronous Rectification for CPU Power
Table 2. Component Suppliers
SUPPLIER
AVX
Central
Semiconductor
Coilcraft
Coiltronics
Dale Inductors
International
Rectifier
IRC
Matsuo
Motorola
Murata-Erie
Nichicon
NIEC
Sanyo
Siliconix
Sprague
Sumida
USA PHONE
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]*
[phone]
[phone]
[phone]
[phone]
FACTORY FAX
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[phone]
[81] 3-3494-7414
[81] 7-2070-1174
[phone]
[phone]
[81] 3-3607-5144
*Distributor
Table 3. MAX1624 Output Voltage
Adjustment Settings (Abbreviated^†)
D4 D3 D2 D1 D0
10 0 00
10 0 01
1 — — ——
11 1 10
11 1 11
OUTPUT
VOLTAGE
(V)
3.5
3.4
Decreases
in 100mV
increments
2.1
No CPU (OFF)
COMPATIBILITY
Intel-compatible
codes
00 0 00
1.9
00 0 01
1.8
0 0 — ——
00 1 11
Decreases
in 100mV
increments
1.2
Non-Intel
compatible codes
01 0 00
1.1
0 1 — ——
1.1
01 1 10
1.1
0 1 1 1 1 No CPU (OFF)
†_{See Table 4 for a complete listing.}
_____Standard Application Circuits
The predesigned MAX1624/MAX1625 circuits shown in
Figures 1 and 2 meet a wide range of applications with
output currents up to 12A and higher. Use Table 1 to
select components appropriate for the desired output
current range, and adapt the evaluation kit PC board
layout as necessary. Table 2 lists suggested vendors.
These circuits represent 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.
These MAX1624/MAX1625 circuits were designed for
the specified frequencies. Do not change the switching
frequency without first recalculating component val-
ues—particularly the inductance, output filter capaci-
tance, and RC1 resistance values. Recalculate the
voltage-feedback resistor and compensation-capacitor
values (CC1 and CC2) as necessary to reconfigure
them for different output voltages. Table 3 lists voltage
adjustment DAC codes for the MAX1624.
_______________Detailed Description
The MAX1624/MAX1625 are BiCMOS switch-mode,
power-supply controllers designed for buck-topology
regulators. They are optimized for powering the latest
high-performance CPUs—demanding applications
where output voltage precision, good transient
response, and high efficiency are critical for proper
operation. With appropriate external components, the
MAX1624/MAX1625 deliver over 15A between 1.1V and
3.5V with ±1% accuracy. The MAX1625 offers 1% typi-
cal transient-load regulation from a +5V supply, while the
MAX1624 offers a selectable transient-load regulation of
0.5%, 1%, or 2%. Remote output sensing ensures volt-
age precision by eliminating errors caused by PC board
trace impedance. These controllers achieve 90% effi-
ciency by using synchronous rectification.
A typical application circuit consists of two N-channel
MOSFETs, a rectifier, and an LC output filter (Figure 1).
At each of the internal oscillator’s rising edges, the
high-side MOSFET switch (N1) is turned on and allows
current to ramp up through the inductor to the output
filter capacitor and load, storing energy in a magnetic
field. The current is monitored by reading the voltage
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