MAX1809EEE Datasheet Download

Part No.:
MAX1809EEE
Download:
Download Datasheet
Description:
[3A, 1MHz, DDR Memory Termination Supply]
File Size:
802 K
Page:
17 Pages
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Manufacturer:
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
PCB Prototype
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19-2142; Rev 1; 9/02
3A, 1MHz, DDR Memory Termination Supply
General Description
The MAX1809 is a reversible energy flow, constant-off-
time, pulse-width modulated (PWM), step-down DC-DC
converter. It is ideal for use in notebook and subnote-
book computers that require 1.1V to 5V active
termination power supplies. This device features an
internal PMOS power switch and internal synchronous
rectifier for high efficiency and reduced component
count. The internal 90mΩ PMOS power switch and
70mΩ NMOS synchronous-rectifier switch easily deliver
continuous load currents up to 3A. The MAX1809 accu-
rately tracks an external reference voltage, produces
an adjustable output from 1.1V to V
IN
, and achieves
efficiencies as high as 93%.
The MAX1809 uses a unique current-mode, constant-
off-time, PWM control scheme that allows the output to
source or sink current. This feature allows energy to
return to the input power supply that otherwise would
be wasted. The programmable constant-off-time archi-
tecture sets switching frequencies up to 1MHz, allowing
the user to optimize performance trade-offs between
efficiency, output switching noise, component size, and
cost. The MAX1809 features an adjustable soft-start to
limit surge currents during startup, a 100% duty-cycle
mode for low-dropout operation, and a low-power shut-
down mode that disables the power switches and
reduces supply current below 1µA. The MAX1809 is
available in a 28-pin QFN with an exposed backside
pad, a 28-pin thin QFN, or a 16-pin QSOP.
o
Source/Sink 3A
o
±1% Output Accuracy
o
Up to 1MHz Switching Frequency
o
93% Efficiency
o
Internal PMOS/NMOS Switches
90mΩ/70mΩ On-Resistance at V
IN
= 4.5V
110mΩ/80mΩ On-Resistance at V
IN
= 3V
o
1.1V to V
IN
Adjustable Output Voltage
o
3V to 5.5V Input Voltage Range
o
<1µA Shutdown Supply Current
o
Programmable Constant-Off-Time Operation
o
Thermal Shutdown
o
Adjustable Soft-Start Inrush Current Limiting
o
Output Short-Circuit Protection
Features
MAX1809
Ordering Information
PART
MAX1809EGI*
MAX1809EEE
MAX1809ETI
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 QFN
16 QSOP
28 Thin QFN
Applications
DDR Memory Termination
Active Termination Buses
*Contact
factory for availability.
Pin Configurations
SHDN
N.C.
LX
LX
Typical Operating Circuit
V
IN
IN
MAX1809
V
CC
SHDN
V
SET
EXTREF
TOFF
REF
SS
LX
PGND
V
OUT
TOP VIEW
28
N.C.
27
26
25
24
N.C.
23
N.C.
IN
LX
IN
22
N.C.
1
2
3
4
5
6
7
10
11
12
13
14
8
9
21
20
19
PGND
PGND
LX
LX
PGND
V
CC
GND
GND
N.C.
MAX1809
18
17
16
15
FB
SS
EXTREF
N.C.
N.C.
N.C.
TOFF
THIN QFN
Pin Configurations continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
GND
REF
FB