The ISL91110 is a high-current buck-boost switching regulator
for systems using new battery chemistries. It uses Intersil’s
proprietary buck-boost algorithm to maintain voltage regulation
while providing excellent efficiency and very low output voltage
ripple when the input voltage is close to the output voltage.
The ISL91110 is capable of delivering at least 2A continuous
output current (VOUT = 3.3V) over a battery voltage range of 2.5V
to 4.35V. This maximizes the energy utilization of advanced
single-cell Li-ion battery chemistries that have significant
capacity left at voltages below the system voltage. Its fully
synchronous low ON-resistance 4-switch architecture and a low
quiescent current of only 35µA optimize efficiency under all load
conditions.
The ISL91110 supports standalone applications with a fixed 3.3V
or 3.5V output voltage or adjustable output voltage with an
external resistor divider. Output voltages as low as 1.0V or as
high as 5.2V are supported.
The ISL91110 is available in a 25-bump, 0.4mm pitch WLCSP
(2.33mmx2.07mm) and a 2.5MHz switching frequency, which
further reduces the size of external components.

Features
• Accepts input voltages above or below regulated output
voltage
• Automatic and seamless transitions between buck and boost
modes
• Input voltage range: 1.8V to 5.5V
• Output current: up to 2A (PVIN = 2.5V, VOUT = 3.3V)
• Burst current: up to 3A (PVIN = 3V, VOUT = 3.3V, tON < 600µs,
t = 4.6ms)
• High efficiency: up to 96%
• 35µA quiescent current maximizes light-load efficiency
• 2.5MHz switching frequency minimizes external component
size
• Fully protected for short-circuit, over-temperature, and
undervoltage
• Small 2.33mmx2.07mm WLCSP

Applications
• Brownout free system voltage for smartphones and tablet PCs
• Wireless communication devices
• 2G/3G/4G RF power amplifiers