®
RT8057
2.25MHz 1A Synchronous Step-Down Converter
General Description
The RT8057 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 2.7V
to 5.5V. The RT8057 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, hand-
held devices, game console and related accessories.
The internal synchronous rectifier with low R
DS(ON)
dramatically reduces conduction loss at PWM mode.
No external Schottky diode is required in practical
applications. The RT8057 enters Low Dropout Mode when
normal Pulse -Width Mode cannot provide regulated output
voltage by continuously turning on the upper P-MOSFET.
The RT8057 enters shut-down mode and consumes less
than 1μA when
the EN pin is pulled low. The switching
ripple is easily smoothed-out
by small package filtering
elements due to a fixed operating frequency of 2.25MHz.
The RT8057 is available in a small WDFN-6SL 2x2 package.
Features
2.7V to 5.5V Wide Input Operation Range
2.25MHz Fixed-Frequency PWM Operation
Up to 1A Output Current
Up to 90% Efficiency
0.6V Reference Allows Low Output Voltage
Internal Soft-Start
No Schottky Diode Required
Internal Compensation to Reduce External
Components
Low Dropout Operation : 100% Duty Cycle
RoHS Compliant and Halogen Free
Applications
Portable Instruments
Game Console and Accessories
Microprocessors and DSP Core Supplies
Cellular Phones
Wireless and DSL Modems
PC Cards
Ordering Information
RT8057
(2)
Taping Type ( Pin1 at Q2)
Package Type
QW : WDFN-6SL 2x2 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
½
Pin Configurations
(TOP VIEW)
GND
LX
NC
FB
1
2
3
6
5
4
GND
VIN
EN
7
WDFN-6SL 2x2
Marking Information
J7 : Product Code
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
J7W
W : Date Code
½
Suitable for use in SnPb or Pb-free soldering processes.
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8057-04 February 2014
www.richtek.com
1
RT8057
Typical Application Circuit
RT8057
V
IN
C
IN
4.7µF
5
VIN
LX
1
L1
2.2µH
R1
680k
R2
240k
V
OUT
2.3V
C1
10pF
FB
GND
3
C
OUT
10µF
4 EN
6, 7 (Exposed Pad)
Function Pin Description
Pin No.
1
2
3
4
5
Pin Name
LX
NC
FB
EN
VIN
Pin Function
Switch Node. Connect to the external inductor.
No Internal Connection. Connect to GND.
Feedback Pin. Connect to the external resistor divider.
Chip Enable (Active High).
Power Input. Connect to the input capacitor.
Power GND. The Exposed Pad must be soldered to a large PCB and connected
to GND for maximum power dissipation.
6,
GND
7 (Exposed Pad)
Function Block Diagram
EN
VIN
OSC &
Shutdown
Control
Slope
Compensation
Current
Sense
Error
Amplifier
PWM
Comparator
R
S1
Current
Limit
Detector
FB
Control
Logic
Driver
LX
R
C
COMP
R
S2
UVLO &
Power Good
Detector
GND
V
REF
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8057-04 February 2014
RT8057
Absolute Maximum Ratings
(Note 1)
6.5V
0.606W
165°C/W
8.2°C/W
260°C
Supply Input Voltage, V
IN
------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-6SL 2x2 ------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WDFN-6SL 2x2,
θ
JA
-------------------------------------------------------------------------------------------------------
WDFN-6SL 2x2,
θ
JC
------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------
Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
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
------------------------------------------------------------------------------------------------ 2.7V 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
Output Current
Quiescent Current
Reference Voltage (0.6V)
Symbol
I
OUT
Test Conditions
V
IN
= 2.7V to 5.5V
I
OUT
= 0mA
Min
--
--
2
2.5
2
--
--
--
Typ
--
81
--
--
2.2
0.2
0.1
2.25
--
--
150
250
200
1.5
--
--
300
Max
1
--
2
2.5
2.4
--
1
--
V
IN
0.4
--
--
--
2
1
1
400
Unit
A
A
%
V
V
A
MHz
V
V
°C
m
m
A
%/V
%
s
I
Q
V
REF
Note 5
V
IN
Rising
Hysteresis
Under Voltage Lockout Threshold V
UVLO
Shutdown Current
Switching Frequency
EN Threshold Logic-High
Voltage
Logic-Low
Thermal Shutdown Temperature
Switch On
Resistance
High Side
Low Side
V
IH
V
IL
T
SD
I
SHDN
1
--
--
--
--
1.1
V
IN
= 2.7V to 5.5V
0mA < I
OUT
< 0.6A
--
--
200
R
DS(ON)_H
I
SW
= 0.2A
R
DS(ON)_L
I
SW
= 0.2A
Peak Current Limit
Output Voltage Line Regulation
Output Voltage Load Regulation
Start-Up Time
I
LIM
t
ss
Guaranteed by Design
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8057-04 February 2014
www.richtek.com
3
RT8057
Note 1.
Stresses beyond those listed
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are stress
ratings only, and 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 may affect device reliability.
Note 2.
θ
JA
is measured in natural convection at T
A
= 25°C on a low-effective thermal conductivity test board of JEDEC 51-3 thermal
measurement standard. The measurement case position of
θ
JC
is on the exposed pad of the package.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Note 5.
The reference voltage accuracy is
±2.5%
at recommended ambient temperature range, guaranteed by design.
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8057-04 February 2014
RT8057
Typical Operating Characteristics
Efficiency vs. Output Current
100
90
80
Output Voltage vs. Input Voltage
2.38
2.36
V
IN
= 5V
Efficiency (%)
70
60
50
40
30
20
10
0
0.0
0.2
0.4
0.6
0.8
1.0
Output Voltage (V)
V
IN
= 3.3V
2.34
2.32
2.30
2.28
2.26
2.24
V
OUT
= 2.3V
2.22
2.5
3.0
3.5
4.0
V
OUT
= 2.3V, I
OUT
= 0A
4.5
5.0
5.5
Output Current (A)
Input Voltage (V)
Frequency vs. Input Voltage
2.40
2.35
2.30
2.25
Frequency vs. Temperature
V
IN
= 3.3V
Frequency (MHz)1
Frequency (MHz)1
2.30
2.25
2.20
2.15
2.10
2.05
2.00
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.20
2.15
2.10
2.05
2.00
1.95
V
IN
= 5V
V
IN
= 5V, V
OUT
= 2.3V,
I
OUT
= 0.2A
V
OUT
= 2.3V, I
OUT
= 0.2A
1.90
-50
-25
0
25
50
75
100
125
Input Voltage (V)
Temperature (°C)
Output Current Limit vs. Input Voltage
1.6
1.5
1.4
1.3
1.2
1.1
1.6
1.5
1.4
1.3
1.2
1.1
Output Current Limit vs. Temperature
V
OUT
= 2.3V
1.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.0
-50
-25
0
25
Output Current Limit (A)
Output Current limit (A)
V
IN
= 5V, V
OUT
= 2.3V
50
75
100
125
Input Voltage (V)
Temperature (°C)
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8057-04 February 2014
www.richtek.com
5
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