19-3257; Rev 2; 8/09
4A Ultra-Low-Input-Voltage
LDO Regulators
6/MAX857
General Description
Features
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-
o 1.425V to 3.6V Input Voltage Range
o Guaranteed 4A Output Current
o
1% Output Accuracy Over Load/Line/
Temperature
o 100mV Dropout at 4A Load (typ)
o Built-In Soft-Start
put voltage is adjustable from 0.5V to V - 0.2V.
IN
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 10ꢀ
of its nominal output voltage. The MAX8557 offers a
power-on reset output that transitions high 140ms after the
output has achieved 90ꢀ of its nominal output voltage.
o 800µA (typ) Operating Supply Current
o 150µA (max) Shutdown Supply Current
o Short-Circuit Current Foldback Protection
o Thermal-Overload Protection
o
10% Power-OK (MAX8556)
o 140ms Power-On Reset Output (MAX8557)
o Fast Transient Response
o 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.
Ordering Information
TEMP
RANGE
PIN-
PACKAGE
Applications
PART
FEATURE
Servers and Storage Devices
MAX8556ETE+
-40°C to +85°C 16 Thin QFN-EP*
POK
POK
POR
Networking
MAX8556ETE/V+ -40°C to +85°C 16 Thin QFN-EP*
MAX8557ETE+ -40°C to +85°C 16 Thin QFN-EP*
Base Stations
Optical Modules
Point-of-Load Supplies
ATE
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V Denotes an automotive qualified part.
*EP = Exposed pad.
Typical Operating Circuit
Pin Configuration
TOP VIEW
V
V
IN
OUT
0.5V TO V - 0.2V
1.425V TO 3.6V
IN
12 11 10
9
IN
OUT
FB 13
8
7
6
OUT
OUT
IN
MAX8556
GND 14
N.C. 15
EN 16
(MAX8557)
MAX8556
(MAX8557)
EN
FB
5
IN
EP
4
+
POK
(POR)
1
2
3
GND
N.C.
THIN QFN
5mm x 5mm
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.