ML4854 Datasheet, PDF (1/13 Pages) Fairchild Semiconductor – Adjustable, Low-Current, 2-Cell Boost Regulator with Shutdown and Low Battery Detect

www.fairchildsemi.com
ML4854
Adjustable, Low-Current, 2-Cell Boost Regulator
with Shutdown and Low Battery Detect
Features
• 95% Efficiency at 200mA Load Current
• Integrated Peak Current Limit
• Variable Output Voltage Determined by External Resistors
• Variable On-time Pulse Frequency Modulation (PFM)
• Fully Internal Synchronous Rectifier (no external diodes)
for High Efficiency and Low Peak Currents
• Low-Battery Detection
• Logic Controlled Shutdown with True Load Disconnect
General Description
The ML4854 is a low power boost regulator designed for
low voltage DC to DC conversion in two-cell battery pow-
ered systems such as cell phones and PDAs. The converter
starts up at 1.3V and has an operating input voltage range
from 1.6V to 4.5V. After the start it operates at an input
voltage as low as 0.8V. Output voltage can be adjusted by
external resistors from 3.3V to 5V with a maximum load
current of 0.5A.
Applications
• 2-3 alkaline/NiMH cells or 1 Li-Ion cell Operated Devices
• Cell Phones
• Medical Devices
• PDAs
• Portable Instrumentation
Quiescent current in shut down mode is less than 30µA,
which maximizes the battery live time. The ON time changes
with the input voltage to maintain the ripple current constant
and to provide the highest efficiency over a wide load range,
while maintaining low peak currents in the boost inductor.
The combination of integrated synchronous rectification,
variable frequency operation, and low supply current make
ML4854 ideal for portable applications.
The ML4854 is available in an 8 lead TSSOP package.
Typical Application
Input 1.6V
to 4.5V
On
Off
Low Battery
Detect In
Low Battery
Detect Out
ML4854
1 V_IN
GND 8
2 SHDN
V_L 7
3 LBI
4 LB0
V_OUT ⁶
FB 5
Output 3.3V to 5V
up to 0.5A
REV. 1.0.7 5/6/03