RT8048
3MHz 1A Step-Down Converter
General Description
The RT8048 is a high-efficiency Pulse-Width-Modulated
(PWM) step-down DC/DC converter. Capable of delivering
1A output current over a wide input voltage range from
2.5V to 5.5V, the RT8048 is ideally suited for portable
electronic devices that are powered from 1-cell Li-ion
battery or from other power sources such as cellular
phones, PDAs and hand-held devices. Two operating
modes are available including : PWM/Low Dropout auto
switch and shut-down mode. The internal synchronous
rectifier with low R
DS(ON)
dramatically reduces conduction
loss at PWM mode. No external Schottky diode is
required in practical application. The RT8048 enters Low-
Dropout mode when normal PWM cannot provide regulated
output voltage by continuously turning on the upper
P-MOSFET. The RT8048 enters shut-down mode and
consumes less than 0.1μA when EN pin is pulled low. The
switching ripple is easily smoothed-out by small package
filtering elements due to a fixed operating frequency of
3MHz.
Features
2.5V to 5.5V Input Range
3MHz Fix-Frequency PWM Operation
1A Output Current
90% Efficiency
No Schottky Diode Required
0.6V Reference Allows Low Output Voltage
Low Dropout Operation : 100% Duty Cycle
RoHS Compliant and Halogen Free
Applications
Portable Instruments
Microprocessors and DSP Core supplies
Cellular Phones
Wireless and DSL Modems
PC Cards
Pin Configurations
(TOP VIEW)
GND
NC
1
2
3
6
5
4
FB/VOUT
GND
LX
Ordering Information
RT8048(
-
)
Package Type
QW : WDFN-6L 2x2 (W-Type)
Lead Plating System
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Output Voltage
Default : Adjustable
10 : 1.0V
12 : 1.2V
15 : 1.5V
18 : 1.8V
25 : 2.5V
33 : 3.3V
Note :
Richtek products are :
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
EN
VIN
7
WDFN-6L 2x2
Marking Information
HB : Product Code
HBW
W : Date Code
DS8048-01 June 2011
www.richtek.com
1
RT8048
Typical Application Circuit
RT8048
V
IN
C
IN
3
VIN
LX
4
L
V
OUT
C1
FB
GND
6
R2
R1
C
OUT
2 EN
5, 7(Exposed Pad)
Figure 1. Adjustable Voltage Regulator
RT8048
V
IN
C
IN
3
VIN
LX
4
L
V
OUT
C
OUT
2 EN
VOUT
GND
6
5, 7(Exposed Pad)
Figure 2. Fixed Voltage Regulator
Table 1. Recommended Component Selection
V
OUT
(V)
1.2
1.8
2.5
3.3
L (μH)
0.47
0.47
1
1
R1 (kΩ)
82
100
91
82
R2 (kΩ)
82
49.9
28.7
18
C
OUT
(μF)
4.7
4.7
4.7
10
Function Pin Description
Pin No.
Adjustable
Output Voltage
1
2
3
4
Fixed Output
Voltage
1
2
3
4
Pin Name
NC
EN
VIN
LX
No Internal Connection.
Chip Enable (Active High).
Power Input.
Switch Node.
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
Feedback.
Output Voltage.
Pin Function
5,
5,
GND
7 (Exposed Pad) 7 (Exposed Pad)
6
--
--
6
FB
VOUT
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2
DS8048-01 June 2011
RT8048
Function Block Diagram
EN
VIN
OSC &
Shutdown
Control
Slope
Compensation
Current
Sense
Error
Amplifier
PWM
Comparator
R
S1
Current
Limit
Detector
FB/VOUT
Control
Logic
Driver
LX
R
C
COMP
R
S2
UVLO &
Power Good
Detector
GND
V
REF
DS8048-01 June 2011
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3
RT8048
Absolute Maximum Ratings
(Note 1)
6.5V
0.833W
120°C/W
260°C
150°C
Supply Input Voltage, V
IN
----------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-6L 2x2 -------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WDFN-6L 2x2,
θ
JA
-------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) -----------------------------------------------------------------------------
Junction Temperature ---------------------------------------------------------------------------------------------------
Storage Temperature Range -------------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM ------------------------------------------------------------------------------------------------------------------------ 2kV
MM -------------------------------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
Supply Input Voltage, V
IN
---------------------------------------------------------------------------------------------- 2.5V to 5.5V
Junction Temperature Range ------------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range ------------------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
(V
IN
= 3.6V, T
A
= 25°C unless otherwise specified)
Parameter
Quiescent Current
Reference Voltage
Under Voltage Lockout Threshold
Shutdown Current
Switching Frequency
EN Input Threshold
Voltage
Symbol
Test Conditions
Min
--
0.588
Typ
81
0.6
2.3
2.1
0.1
3
--
--
140
250
260
1.5
--
--
Max
--
0.612
--
--
1
--
V
IN
0.4
--
--
--
--
1
1
Unit
μA
V
V
μA
MHz
V
°C
mΩ
mΩ
A
%/V
%
I
Q
V
REF
V
UVLO
V
IN
Rising
V
IN
Falling
--
--
--
--
1.5
--
--
I
SHDN
f
OSC
Logic-High V
IH
Logic-Low
V
IL
T
SD
R
PFET
R
NFET
I
LX
= 0.2A
I
LX
= 0.2A
Thermal Shutdown Temperature
Switch On Resistance, High
Switch On Resistance, Low
Peak Current Limit
Output Voltage Line Regulation
Output Voltage Load Regulation
--
--
--
I
LIM
V
IN
= 2.5V to 5.5V
0mA < I
LOAD
< 0.6A
--
--
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4
DS8048-01 June 2011
RT8048
Note 1.
Stresses listed as the above
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are for
stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational
sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may
remain possibility to affect device reliability.
Note 2.
θ
JA
is measured in natural convection at T
A
= 25°C on a high effective thermal conductivity four-layer test board of JEDEC
51-7 thermal measurement standard.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
DS8048-01 June 2011
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