MAX1556_10 Datasheet, PDF (1/12 Pages) Maxim Integrated Products – 16μA IQ, 1.2A PWM Step-Down DC-DC Converters

19-3336; Rev 2; 6/10
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16µA I_Q, 1.2A PWM
Step-Down DC-DC Converters
General Description
The MAX1556/MAX1556A/MAX1557 are low-operating-
current (16µA), fixed-frequency step-down regulators.
High efficiency, low-quiescent operating current, low
dropout, and minimal (27µA) quiescent current in
dropout make these converters ideal for powering
portable devices from 1-cell Li-ion or 3-cell alkaline/NiMH
batteries. The MAX1556 delivers up to 1.2A; has pin-
selectable 1.8V, 2.5V, and 3.3V outputs; and is also
adjustable. The MAX1557 delivers up to 600mA; has pin-
selectable 1V, 1.3V, and 1.5V outputs; and is also
adjustable.
The MAX1556/MAX1556A/MAX1557 contain a low-on-
resistance internal MOSFET switch and synchronous
rectifier to maximize efficiency and dropout perfor-
mance while minimizing external component count. A
proprietary topology offers the benefits of a high fixed-
frequency operation while still providing excellent effi-
ciency at both light and full loads. A 1MHz PWM
switching frequency keeps components small. Both
devices also feature an adjustable soft-start to minimize
battery transient loading.
The MAX1556/MAX1556A/MAX1557 are available in a
tiny 10-pin TDFN (3mm x 3mm) package.
Applications
PDAs and Palmtop Computers
Cell Phones and Smart Phones
Digital Cameras and Camcorders
Portable MP3 and DVD Players
Hand-Held Instruments
Features
o Up to 97% Efficiency
o 95% Efficiency at 1mA Load Current
o Low 16µA Quiescent Current
o 1MHz PWM Switching
o Tiny 3.3µH Inductor
o Selectable 3.3V, 2.5V, 1.8V, 1.5V, 1.3V, 1.2V, 1.0V,
and Adjustable Output
o 1.2A Guaranteed Output Current
(MAX1556/MAX1556A)
o Voltage Positioning Optimizes Load-Transient
Response
o Low 27µA Quiescent Current in Dropout
o Low 0.1µA Shutdown Current
o No External Schottky Diode Required
o Analog Soft-Start with Zero Overshoot Current
o Small, 10-Pin, 3mm x 3mm TDFN Package
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1556ETB+ -40°C to +85°C 10 TDFN-EP*
MAX1556AETB+ -40°C to +85°C 10 TDFN-EP*
MAX1557ETB+ -40°C to +85°C 10 TDFN-EP*
*EP = Exposed paddle.
+Denotes a lead(Pb)-free/RoHS-compliant package.
TOP
MARK
ACQ
AUJ
ACR
Typical Operating Circuit
Pin Configuration
INPUT
2.6V TO 5.5V
VOLTAGE
SELECT
ON
OFF
INP
LX
MAX1556
MAX1556A
MAX1557
IN
PGND
D1
D2
OUT
SS
SHDN
GND
OUTPUT
0.75V TO V_IN
TOP VIEW
IN 1
GND 2
SS 3
OUT 4
SHDN 5
MAX1556
MAX1556A
MAX1557
10 D1
9 INP
8 LX
7 PGND
6 D2
TDFN
________________________________________________________________ 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.