Compact, 600 mA, 3 MHz,
Step-Down DC-to-DC Converter
ADP2108
FEATURES
Peak efficiency: 95%
3 MHz fixed frequency operation
Typical quiescent current: 18 μA
Maximum load current: 600 mA
Input voltage: 2.3 V to 5.5 V
Uses tiny multilayer inductors and capacitors
Current mode architecture for fast load and line
transient response
100% duty cycle low dropout mode
Internal synchronous rectifier
Internal compensation
Internal soft start
Current overload protection
Thermal shutdown protection
Shutdown supply current: 0.2 μA
5-ball WLCSP
GENERAL DESCRIPTION
The ADP2108 is a high efficiency, low quiescent current step-
down dc-to-dc converter in an ultrasmall 5-ball WLCSP
package. The total solution requires only three tiny external
components. It uses a proprietary, high speed current mode,
constant frequency PWM control scheme for excellent stability
and transient response. To ensure the longest battery life in
portable applications, the ADP2108 has a power save mode that
reduces the switching frequency under light load conditions.
The ADP2108 runs on input voltages of 2.3 V to 5.5 V, which
allows for single lithium or lithium polymer cell, multiple alkaline
or NiMH cell, PCMCIA, USB, and other standard power sources.
The maximum load current of 600 mA is achievable across the
input voltage range.
The ADP2108 is available in fixed output voltages of 3.3 V, 3.0 V,
2.5 V, 2.3 V, 1.82 V, 1.8 V, 1.5 V, 1.3 V, 1.2 V, 1.1 V, and 1.0 V. All
versions include an internal power switch and synchronous rect-
ifier for minimal external part count and high efficiency. The
ADP2108 has an internal soft start and is internally compensated.
During logic controlled shutdown, the input is disconnected
from the output and the ADP2108 draws less than 1 μA from
the input source.
Other key features include undervoltage lockout to prevent deep
battery discharge and soft start to prevent input current over-
shoot at startup. The ADP2108 is available in a 5-ball WLCSP.
APPLICATIONS
PDAs and palmtop computers
Wireless handsets
Digital audio, portable media players
Digital cameras, GPS navigation units
TYPICAL APPLICATIONS CIRCUIT
ADP2108
2.3V TO 5.5V
VIN
4.7µF
OFF
ON
EN
FB
07375-003
1µH
SW
1.0V TO 3.3V
10µF
GND
Figure 1.
Rev. A
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