19-3257; Rev 0; 4/04
4 A Ult ra -Lo w -In p u t -Vo lt a g e
LDO Re g u la t o rs
Ge n e ra l De s c rip t io n
Fe a t u re s
The MAX8556/MAX8557 low-dropout linear regulators
operate from input voltages as low as 1.425V and are
able to deliver up to 4A of continuous output current
with a typical dropout voltage of only 100mV. The out-
♦ 1.425V to 3.6V Input Voltage Range
♦ Guaranteed 4A Output Current
♦ ±1% Output Accuracy Over Load/Line/
Temperature
put voltage is adjustable from 0.5V to V - 0.2V.
IN
♦ 100mV Dropout at 4A Load (typ)
♦ Built-In Soft-Start
Designed with an internal p-channel MOSFET pass tran-
sistor, the MAX8556/MAX8557 maintain a low 800µA typi-
cal supply current, independent of the load current and
dropout voltage. Using a p-channel MOSFET eliminates
the need for an additional external supply or a noisy inter-
nal charge pump. Other features include a logic-con-
trolled shutdown mode, built-in soft-start, short-circuit
protection with foldback current limit, and thermal-over-
load protection. The MAX8556 features a POK output that
transitions high when the regulator output is within ±10%
of its nominal output voltage. The MAX8557 offers a
power-on reset output that transitions high 140ms after the
output has achieved 90% of its nominal output voltage.
♦ 800µA (typ) Operating Supply Current
♦ 150µA (max) Shutdown Supply Current
♦ Short-Circuit Current Foldback Protection
♦ Thermal-Overload Protection
♦ ±10% Power-OK (MAX8556)
♦ 140ms Power-On Reset Output (MAX8557)
♦ Fast Transient Response
♦ 16-Pin Thin QFN 5mm x 5mm Package
The MAX8556/MAX8557 are available in a 16-pin thin
QFN 5mm x 5mm package with exposed paddle.
Ord e rin g In fo rm a t io n
Ap p lic a t io n s
Servers and Storage Devices
PIN-
PART
TEMP RANGE
FEATURE
POK
Networking
PACKAGE
16 Thin QFN
5mm X 5mm
16 Thin QFN
5mm X 5mm
Base Stations
Optical Modules
Point-of-Load Supplies
ATE
MAX8556ETE -40°C to +85°C
MAX8557ETE -40°C to +85°C
POR
Typ ic a l Op e ra t in g Circ u it
P in Co n fig u ra t io n
TOP VIEW
V
V
OUT
IN
16 15 14 13
0.5V TO V - 0.2V
1.425V TO 3.6V
IN
IN
OUT
IN
IN
IN
IN
1
2
3
4
12 POK (POR)
11 OUT
MAX8556
(MAX8557)
MAX8556
(MAX8557)
10 OUT
EN
FB
9
OUT
5
6
7
8
POK
(POR)
GND
N.C.
THIN QFN
5mm x 5mm
________________________________________________________________ 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.