MAX8650 Datasheet, PDF (1/25 Pages) Maxim Integrated Products – 4.5V to 28V Input Current-Mode Step-Down Controller with Adjustable Frequency

19-3973; Rev 0; 1/06
EVAALVUAAILTAIOBNLEKIT _{4.5V to 28V Input Current-Mode Step-}
Down Controller with Adjustable Frequency
General Description
The MAX8650 synchronous PWM buck controller oper-
ates from a 4.5V to 28V input and generates an
adjustable 0.7V to 5.5V output voltage at loads up to 25A.
The MAX8650 uses a peak current-mode control archi-
tecture with an adjustable (200kHz to 1.2MHz) constant
switching frequency and is externally synchronizable. The
IC’s current limit uses the inductor’s DC resistance to
improve efficiency or an external sense resistor for high
accuracy. The current-limit threshold is adjusted with an
external resistor. Foldback-type current limit can be
implemented to reduce the power dissipation in overload
or short-circuit conditions. Short-circuit protection is
provided based on sensing the current in the low-side
MOSFET. A reference input is provided for use with a
high-accuracy external reference or for double-data-rate
(DDR)-tracking applications.
Monotonic prebiased startup is available for a safe-start
in applications where the output capacitor may have an
initial charge. This feature prevents the output from
pulling low during startup, which is a common charac-
teristic of conventional buck regulators.
A 180° out-of–phase synchronization output is available
for synchronizing with another converter.
Applications
Base Stations
DDR
Network and Telecom Power Modules
Storage
IBA Applications
Servers
Pin Configuration appears at end of data sheet.
Features
♦ Operates from 4.5V to 28V Supply
♦ 1% FB Voltage Accuracy Over Temperature
♦ Adjustable Output Voltage Down to 0.7V or REFIN
♦ Adjustable Switching Frequency or External
Synchronization from 200kHz to 1.2MHz
♦ 180° Phase-Shifted Clock Output
♦ Adjustable Overcurrent Limit
♦ Adjustable Foldback Current Limit
♦ Adjustable Slope Compensation
♦ Selectable Current-Limit Mode: Latch-Off or
Automatic Recovery
♦ Monotonic Output-Voltage Rise at Startup
♦ Output Sources and Sinks Current
♦ Enable Input
♦ Power-OK (POK) Output
♦ Adjustable Soft-Start
♦ Independently Adjustable Overvoltage Protection
Ordering Information
PART
MAX8650EEG+
TEMP RANGE
-40°C to +85°C
PIN-PACKAGE
PKG
CODE
24 QSOP
E24-1
+Denotes lead-free package.
Typical Operating Circuit
R2
R1
SYNC
ON ^EN
OFF
POK
SYNCO
R3
C3
R4
C4
R5
R6
R7
1
FSYNC
11
EN
2
MODE
4
D2
BST
24
5
POK
DH
3
SYNCO
23
SCOMP
MAX8650EEG
6
C2
LX
DL ⁷
Q1
22
ILIM2
21
REFIN
20
SS
16
ILIM1
19
COMP
18
FB
17
OVP
8
Q2
PGND
VL ⁹
C7
10
C8
IN
C10
12
AVL
14
CS+
15 C11
CS-
13
GND
VIN
7V TO 28V
C1
L1
R8
C6
R9
VOUT
0.7V TO 5.5V
C5
C9
________________________________________________________________ Maxim Integrated Products 1
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