RT4805B
2.5MHz, Synchronous Boost Regulator with Bypass Mode
General Description
The RT4805B allows systems to take advantage of
new battery chemistries that can supply significant
energy when the battery voltage is lower than the
required voltage for system power ICs. By combining
built-in power transistors, synchronous rectification,
and low supply current; this IC provides a compact
solution for systems using advanced Li-Ion battery
chemistries.
The RT4805B is a boost regulator designed to provide
a minimum output voltage from a single-cell Li-Ion
battery, even when the battery voltage is below system
minimum. In boost mode, output voltage regulation is
guaranteed to a maximum load current of 2A.
Quiescent current in Shutdown Mode is less than 1A,
which maximizes battery life. The regulator transitions
smoothly between Bypass and normal Boost Mode.
The device can be forced into Bypass Mode to reduce
quiescent current.
The RT4805B is available in the WL-CSP-16B
1.67x1.67 (BSC) package.
Features
4 Few External Components : 0.47H Inductor
and 0603 Case Size Input and Output Capacitors
Input Voltage Range : 1.8V to 5V
Output Range from 2.85V to 4.4V
VSEL = L 3.15V
VSEL = H 3.6V
Maximum Continuous Load Current : 2A at V
IN
>
2.65V Boosting V
OUT
to 3.35V
Up to 96% Efficient
True Bypass Operation when V
IN
> Target V
OUT
Internal Synchronous Rectifier
True Load Disconnect when Shut Down
Forced Bypass Mode
V
SEL
Control to Optimize Target V
OUT
Short-Circuit Protection
I
2
C Controlled Interface
Ultra Low Operating Quiescent Current
Small WL-CSP 16B Package
Applications
Single-Cell Li-Ion, LiFePO4 Smart-Phones or Tablet
2.5G/3G/4G Mini-Module Data Cards
Simplified Application Circuit
RT4805B
VIN
VOUT
C
OUT
C
IN
L1
LX
VSEL
EN
nBYP
SDA
SCL
PGOOD
To pull high voltage
+
-
AGND PGND
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS4805B-01
April 2017
www.richtek.com
1
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