®
RT8020
Dual High-Efficiency PWM Step-Down DC/DC Converter
General Description
The RT8020 is a dual high-efficiency Pulse-Width-
Modulated (PWM) step-down DC/DC converter. It is
capable of delivering 1A output current over a wide input
voltage range from 2.5V to 5.5V, the RT8020 is ideally
suited for portable electronic devices that are powered
from 1-cell Li-ion battery or from other power sources within
the range such as cellular phones, PDAs and other hand-
held devices.
Two operational modes are available : PWM/Low-Dropout
auto-switch and shutdown modes. 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 RT8020 enters Low-Dropout mode when normal PWM
cannot provide regulated output voltage by continuously
turning on the upper PMOS. The RT8020 enter shutdown
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 operation
frequency of 1.5MHz. This along with small
WDFN-12L 3x3 package provides small PCB area
application. Other features include soft start, lower internal
reference voltage with 2% accuracy, over temperature
protection, and over current protection.
Features
2.5V to 5.5V Input Range
Adjustable Output From 0.6V to V
IN
1.2V, 1.3V, 1.8V, 2.5V and 3.3V Fixed/ Adjustable
Output Voltage
1A Output Current
95% Efficiency
No Schottky Diode Required
50uA Quiescent Current per Channel
1.5MHz Fixed Frequency PWM Operation
Small 12-Lead WDFN Package
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Mobile Phones
Personal Information Appliances
Wireless and DSL Modems
MP3 Players
Portable Instruments
Ordering Information
RT8020
Package Type
QW : WDFN-12L 3x3 (W-Type)
Lead Plating System
P : Pb Free
G : Green (Halogen Free and Pb Free)
Output Voltage : VOUT1/VOUT2
Default : Adjustable
A : 3.3V/1.8V
B : 3.3V/1.3V
C : 3.3V/1.2V
D : 2.5V/1.8V
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.
Pin Configurations
(TOP VIEW)
VIN2
LX2
GND
FB1
NC1
EN1
1
2
3
4
5
6
12
11
10
9
8
7
GND
13
EN2
NC2
FB2
GND
LX1
VIN1
WDFN-12L 3x3
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8020-06 March 2012
www.richtek.com
1
RT8020
Marking Information
RT8020APQW
C2- : Product Code
RT8020CPQW
C4- : Product Code
YMDNN : Date Code
C2-YM
DNN
C4-YM
DNN
YMDNN : Date Code
RT8020AGQW
C2= : Product Code
RT8020CGQW
C4= : Product Code
YMDNN : Date Code
C2=YM
DNN
C4=YM
DNN
YMDNN : Date Code
RT8020BPQW
C3- : Product Code
RT8020DPQW
C5- : Product Code
YMDNN : Date Code
C3-YM
DNN
C5-YM
DNN
YMDNN : Date Code
RT8020BGQW
C3= : Product Code
RT8020DGQW
C5=: Product Code
YMDNN : Date Code
C3=YM
DNN
C5=YM
DNN
YMDNN : Date Code
Typical Application Circuit
L2
2.2µH
V
IN2
1 VIN2
C
IN2
4.7µF
R12
2
3, Exposed Pad (13)
4
LX2
GND
FB1
C
OUT2
4.7µF
V
OUT2
RT8020
EN2 12
NC2 11
FB2 10
GND
LX1
VIN1
L1
2.2µH
C
OUT1
4.7µF
9
8
7
C
IN1
4.7µF
V
IN1
R22
R21
850k
C21
22pF
5 NC1
C11
22pF
V
OUT1
R11
850k
6 EN1
V
OUTx
=
V
REF
×
1
+
Rx1
Rx2
(
)
Figure 1. Adjustable Voltage Regulator
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8020-06 March 2012
RT8020
L2
2.2µH
V
OUT2
V
IN2
1 VIN2
C
IN2
4.7µF
2
LX2
GND
FB1
RT8020
EN2 12
NC2 11
FB2 10
GND
LX1
VIN1
L1
2.2µH
C
OUT1
4.7µF
9
8
7
C
IN1
4.7µF
V
IN1
C
OUT2
4.7µF
3, Exposed Pad (13)
4
5 NC1
6 EN1
V
OUT1
V
OUTx
= 1.2V, 1.3V, 1.8V, 2.5V or 3.3V
Figure 2. Fixed Voltage Regulator
Functional Pin Description
Pin No.
1
2
3, 9,
Exposed Pad (13)
4
5, 11
6
7
8
10
12
Pin Name
VIN2
LX2
GND
FB1
NC1, NC2
EN1
VIN1
LX1
FB2
EN2
Power Input of Channel 2.
Pin for Switching of Channel 2.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
Feedback of Channel 1.
No Connection or Connect to V
IN
.
Chip Enable of Channel 1 (Active High). V
EN1
≦
V
IN1.
Power Input of Channel 1.
Pin for Switching of Channel 1.
Feedback of Channel 2.
Chip Enable of Channel 2 (Active High). V
EN2
≦
V
IN2.
Pin Function
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8020-06 March 2012
www.richtek.com
3
RT8020
Function Block Diagram
ENx
VINx
RS1
OSC and
Shutdown
Control
Slope
Compensation
Current
Sense
PWM
Comparator
Current Limit
Detector
Control
Logic
Driver
LXx
FBx
Error
Amplifier
UVLO and
Power Good
Detector
V
REF
RC
COMP
RS2
GND
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8020-06 March 2012
RT8020
Absolute Maximum Ratings
(Note 1)
−0.3V
to 6.5V
−0.3V
to (V
IN
+ 0.3V)
1.667W
60°C/W
8.2°C/W
Supply Input Voltage, V
IN1
, V
IN2
----------------------------------------------------------------------------------
EN1, FB1, LX1, EN2, FB2 and LX2 Pin Voltage --------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-12L 3x3 --------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
WDFN-12L 3x3,
θ
JA
--------------------------------------------------------------------------------------------------
WDFN-12L 3x3,
θ
JC
--------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------- 260°C
Junction Temperature ------------------------------------------------------------------------------------------------ 150°C
Storage Temperature Range ---------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 4)
Supply Input Voltage ------------------------------------------------------------------------------------------------- 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, V
OUT
= 2.5V, V
REF
= 0.6V, L = 2.2uH, C
IN
= 4.7μF, C
OUT
= 10μF, T
A
= 25°C, I
MAX
= 1A unless otherwise specified)
Parameter
Channel 1 and Channel 2
Input Voltage Range
Under Voltage Lock Out
threshold
Hysteresis
Quiescent Current
Shutdown Current
Reference Voltage
Adjustable Output Voltage
Range
Symbol
Test Conditions
Min
2.5
--
--
Typ
--
1.8
0.1
50
0.1
0.6
--
--
--
--
--
--
Max
5.5
--
--
70
1
0.612
V
IN
−ΔV
3
3
3
3
3
Unit
V
V
V
μA
μA
V
V
%
%
%
%
%
V
IN
UVLO
I
Q
I
SHDN
V
REF
V
OUT
ΔV
OUT
ΔV
OUT
I
OUT
= 0mA, V
FB
= V
REF
+ 5%
EN = GND
For Adjustable Output Voltage
(Note 6)
V
IN
= 2.5V to 5.5V, V
OUT
= 1.2V
0A < I
OUT
< 1A
V
IN
= 2.5V to 5.5V, V
OUT
= 1.3V
0A < I
OUT
< 1A
V
IN
= 2.5 to 5.5V, V
OUT
= 1.8V
0A < I
OUT
< 1A
(Note 5)
V
IN
= V
OUT
+
ΔV
to 5.5V
V
OUT
= 2.5V, 0A < I
OUT
< 1A
(Note 5)
V
IN
= V
OUT
+
ΔV
to 5.5V
V
OUT
= 3.3V, 0A < I
OUT
< 1A
--
--
0.588
V
REF
−3
−3
−3
−3
−3
Output Voltage
Fix
Accuracy
ΔV
OUT
ΔV
OUT
ΔV
OUT
Copyright
©
2012 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8020-06 March 2012
www.richtek.com
5
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