How it Works
Richtek
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RT8020CGQW
Schematic [ru]
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Richtek RT8020AGQW, RT8020APQW, RT8020BGQW, RT8020BPQW, RT8020CGQW, RT8020CPQW, RT8020DPQW, RT8020GQW, RT8020PQW Schematic [ru]

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RT8020
®
DS8020-06 March 2012 www.richtek.com
1
©
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Applications
Mobile Phones
Wireless and DSL Modems
MP3 Players
Portable Instruments
Ordering Information
Pin Configurations
(TOP VIEW)
WDFN-12L 3x3
Dual High-Efficiency PWM Step-Down DC/DC Converter
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
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.
VIN2
LX2
NC1
FB1
EN2
NC2
FB2
LX1
GND
GND
EN1
VIN1
11
10
9
1
2
3
4
5
12
67
8
GND
13
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.
RT8020
2
DS8020-06 March 2012www.richtek.com
©
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Typical Application Circuit
Figure 1. Adjustable Voltage Regulator
(
)
Rx2
Rx1
1 VV
REFOUTx
+×=
EN2
NC2
FB2
VIN2
LX2
FB1
RT8020
1
2
4
9
10
11
GND
LX1
GND
8
5
NC1
3, Exposed Pad (13)
12
V
OUT2
L2
2.2µH
850k
4.7µF
C
IN2
22pF
VIN1
7
6
EN1
V
IN1
4.7µF
L1
2.2µH
R22
4.7µF
V
OUT1
850k
22pF
4.7µF
R12
V
IN2
C11
C
OUT1
C
IN1
C
OUT2
C21
R11
R21
Marking Information
RT8020APQW
C2-YM
DNN
RT8020AGQW
C2- : Product Code
YMDNN : Date Code
RT8020BPQW
C3= : Product Code
YMDNN : Date Code
C3=YM
DNN
RT8020BGQW
C3-YM
DNN
C3- : Product Code
YMDNN : Date Code
C4=YM
DNN
C4-YM
DNN
C5=YM
DNN
C5-YM
DNN
RT8020CPQW
C2=YM
DNN
C2= : Product Code
YMDNN : Date Code
C4- : Product Code
YMDNN : Date Code
RT8020CGQW
C4= : Product Code
YMDNN : Date Code
RT8020DPQW
C5- : Product Code
YMDNN : Date Code
RT8020DGQW
C5=: Product Code
YMDNN : Date Code
RT8020
3
DS8020-06 March 2012 www.richtek.com
©
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Figure 2. Fixed Voltage Regulator
V
OUTx
= 1.2V, 1.3V, 1.8V, 2.5V or 3.3V
Functional Pin Description
Pin No. Pin Name Pin Function
1 VIN2 Power Input of Channel 2.
2 LX2 Pin for Switching of Channel 2.
3, 9,
Exposed Pad (13)
GND
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum power dissipation.
4 FB1 Feedback of Channel 1.
5, 11 NC1, NC2 No Connection or Connect to V
IN
.
6 EN1 Chip Enable of Channel 1 (Active High). V
EN1
≦ V
IN1.
7 VIN1 Power Input of Channel 1.
8 LX1 Pin for Switching of Channel 1.
10 FB2 Feedback of Channel 2.
12 EN2 Chip Enable of Channel 2 (Active High). V
EN2
≦ V
IN2.
EN2
NC2
FB2
VIN2
LX2
FB1
RT8020
1
2
4
9
10
11
GND
LX1
GND
8
5
NC1
12
V
OUT2
L2
2.2µH
C
IN2
4.7µF
VIN1
7
6
EN1
V
IN1
4.7µF
L1
2.2µH
4.7µF
V
OUT1
4.7µF
V
IN2
C
OUT1
C
IN1
C
OUT2
3, Exposed Pad (13)
RT8020
4
DS8020-06 March 2012www.richtek.com
©
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Function Block Diagram
Driver
Control
Logic
Current Limit
Detector
OSC and
Shutdown
Control
Current
Sense
V
REF
FBx
GND
LXx
PWM
Comparator
Slope
Compensation
Error
Amplifier
UVLO and
Power Good
Detector
RC
COMP
ENx VINx
RS1
RS2
RT8020
5
DS8020-06 March 2012 www.richtek.com
©
Copyright 2012 Richtek Technology Corporation. All rights reserved. is a registered trademark of Richtek Technology Corporation.
Absolute Maximum Ratings (Note 1)
Supply Input Voltage, V
IN1
, V
IN2
---------------------------------------------------------------------------------- −0.3V to 6.5V
EN1, FB1, LX1, EN2, FB2 and LX2 Pin Voltage -------------------------------------------------------------- −0.3V to (V
IN
+ 0.3V)
Power Dissipation, P
D
@ T
A
= 25°C
WDFN-12L 3x3 -------------------------------------------------------------------------------------------------------- 1.667W
Package Thermal Resistance (Note 2)
WDFN-12L 3x3, θ
JA
-------------------------------------------------------------------------------------------------- 60°C/W
WDFN-12L 3x3, θ
JC
-------------------------------------------------------------------------------------------------- 8.2°C/W
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
Electrical Characteristics
Parameter Symbol Test Conditions Min Typ Max Unit
Channel 1 and Channel 2
Input Voltage Range
V
IN
2.5 -- 5.5 V
Under Voltage Lock Out
threshold
UVLO -- 1.8 -- V
Hysteresis -- 0.1 -- V
Quiescent Current
I
Q
I
OU T
= 0mA, V
FB
= V
REF
+ 5%
-- 50 70 μA
Shutdown Current
I
SHDN
EN = GND -- 0.1 1
μA
Reference Voltage
V
REF
For Adjustable Output Voltage 0.588 0.6 0.612 V
Adjustable Output Voltage
Range
V
OUT
(Note 6)
V
REF
--
V
IN
−ΔV
V
ΔV
OUT
V
IN
= 2.5V to 5.5V, V
OUT
= 1.2V
0A < I
OUT
< 1A
−3
-- 3 %
ΔV
OUT
V
IN
= 2.5V to 5.5V, V
OUT
= 1.3V
0A < I
OUT
< 1A
−3 -- 3 %
ΔV
OUT
V
IN
= 2.5 to 5.5V, V
OUT
= 1.8V
0A < I
OUT
< 1A
−3 -- 3 %
ΔV
OUT
V
IN
= V
OUT
+ ΔV to 5.5V (Note 5)
V
OUT
= 2.5V, 0A < I
OU T
< 1A
−3
-- 3 %
Output Voltage
Accuracy
Fix
ΔV
OUT
V
IN
= V
OUT
+ ΔV to 5.5V (Note 5)
V
OUT
= 3.3V, 0A < I
OU T
< 1A
−3
-- 3 %
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
(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)
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