RT8026
1.5MHz, 1A, High Efficiency PWM Step-Down DC/DC
Converter
General Description
The RT8026 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 RT8026 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 autoswitch and shut-down modes. 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 RT8026 enters Low-Dropout mode when normal PWM
cannot provide regulated output voltage by continuously
turning on the upper P-MOSFET. The RT8026 enter shut-
down mode and consumes less than 0.1μA 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 1.5MHz. This along with small MSOP-10
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
Input Voltage Range : 2.7V to 5.5V
Adjustable Output Voltage : 1V to V
IN
Output Current : 1A
High Efficiency : up to 95%
No Schottky Diode Required
1.5MHz Fixed Frequency PWM Operation
Current Limiting Protection
Thermal Shutdown Protection
Small MSOP-10 Package
RoHS Compliant and Halogen Free
Applications
Mobile Phones
Personal Information Appliances
Wireless and DSL Modems
MP3 Players
Portable Instruments
Pin Configurations
(TOP VIEW)
VIN
NC
GND
NC
FB
10
2
3
4
5
9
8
7
6
PGND
LX
EN
NC
NC
MSOP-10
Ordering Information
RT8026
Package Type
F : MSOP-10
Lead Plating System
G : Green (Halogen Free and Pb Free)
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.
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area.
DS8026-02 March 2011
www.richtek.com
1
RT8026
Typical Application Circuit
V
IN
2.7V to 5.5V
1
C
IN
4.7µF
8
VIN
LX
9
L
2.2µH
C1
R1
5
I
R2
R2
C
OUT
10µF
V
OUT
RT8026
EN
PGND
10
FB
GND
3
V
OUT
=
V
REF
x
⎛
1
+
R1
⎞
⎜
⎟
⎝
R2
⎠
with R2 = 300kΩ to 60kΩ so the I
R2
= 2μA to 10μA,
and (R1 x C1) should be in the range between 3x10
-6
and 6x10
-6
for component selection.
Figure 1. Typical Application Circuit for RT8026
Functional Pin Description
Pin No.
1
2, 4, 6, 7
3
5
Pin Name
VIN
NC
GND
FB
Power Input.
No Internal Connection.
Ground Pin.
Feedback Input Pin. Receives the feedback voltage from a resistive divider
connected across the output.
8
9
10
EN
LX
PGND
Chip Enable (Active High). It is recommended to add a 100kΩ resistor between EN
and GND pin.
Pin for Switching. Connect this pin to the inductor.
Power Ground Pin.
Pin Function
Function Block Diagram
EN
VIN
OSC &
Shutdown
Control
Slope
Compensation
Current
Sense
RS1
Current
Limit
Detector
FB
Error
Amplifier
RC
COMP
PWM
Comparator
Control
Logic
Driver
LX
Current
Detector
UVLO &
Power Good
Detector
RS2
V
REF
PGND
GND
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2
DS8026-02 March 2011
RT8026
Absolute Maximum Ratings
(Note 1)
6.5V
−0.3V
to V
IN
833mW
120°C/W
260°C
Supply Input Voltage ------------------------------------------------------------------------------------------------------
EN, FB Pin Voltage -------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
MSOP-10 --------------------------------------------------------------------------------------------------------------------
Package Thermal Resistance (Note 2)
MSOP-10,
θ
JA
--------------------------------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------------
Storage Temperature Range --------------------------------------------------------------------------------------------
−65°C
to 150°C
Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------------ 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, V
OUT
= 2.5V, V
REF
= 0.6V, L = 2.2μH, C
IN
= 4.7μF, C
OUT
= 10μF, T
A
= 25°C unless otherwise specified)
Parameter
Quiescent Current
Shutdown Current
Reference Voltage
Adjustable Output Range
Output Voltage Accuracy
FB Input Current
PMOSFET R
ON
NMOSFET R
ON
P-Channel Current Limit
EN High-Level Input Voltage
EN Low-Level Input Voltage
UVLO Hysteresis
Oscillator Frequency
Thermal Shutdown Temperature
Max. Duty Cycle
Symbol
I
Q
I
SHDN
V
REF
V
OUT
ΔV
OUT
I
FB
Test Conditions
I
OUT
= 0mA, V
FB
= V
REF
+ 5%
EN = GND
For Adjustable Output Voltage
(Note 6)
V
IN
= V
OUT
+
ΔV
to 5.5V
0A < I
OUT
< 1A (Note 5)
V
FB
= V
IN
Min
--
--
0.588
1
Typ
50
0.1
0.6
--
--
--
0.28
0.25
1.5
--
--
1.8
0.1
1.5
160
--
Max
70
1
0.612
V
IN
−
0.2V
+3
50
--
--
--
--
0.4
--
--
1.8
--
--
Unit
μA
μA
V
V
%
nA
Ω
Ω
A
V
V
V
V
MHz
°C
%
−
3
−50
--
--
1.2
1.5
--
--
--
R
DS(ON)_P
I
OUT
= 200mA, V
IN
= 3.6V
R
DS(ON)_N
I
OUT
= 200mA, V
IN
= 3.6V
I
LIM_P
V
EN_H
V
EN_L
V
IN
= 2.7V to 5.5 V
V
IN
= 2.7V to 5.5V
V
IN
= 2.7V to 5.5V
Under Voltage Lock Out threshold UVLO
f
OSC
TSD
V
IN
= 3.6V, I
OUT
= 100mA
1.2
--
100
DS8026-02 March 2011
www.richtek.com
3
RT8026
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 the natural convection at T
A
= 25°C on a high effective four layers thermal conductivity 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.
Note 5.
ΔV
= I
OUT
x P
RDS(ON)
Note 6.
Guarantee by design.
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4
DS8026-02 March 2011
RT8026
Typical Operating Characteristics
Efficiency vs. Output Current
100
90
80
Output Voltage vs. Temperature
3.60
3.58
V
IN
= 5V
V
IN
= 5.5V
Efficiency (%)
70
60
50
40
30
20
10
0
0.001
0.01
Output Voltage (V)
3.55
3.53
3.50
3.48
3.45
3.43
V
OUT
= 3.5V
0.1
1
3.40
-50
-25
0
25
50
V
IN
= 5V, I
OUT
= 0mA
75
100
125
Output Current (A)
Temperature (°C)
Frequency vs. Input Voltage
1.50
1.48
Frequency vs. Temperature
1.60
1.55
Frequency (MHz)
1.43
1.40
1.38
1.35
1.33
1.30
4
4.25
4.5
Frequency (MHz)
V
OUT
= 3.5V, I
OUT
= 300mA
4.75
5
5.25
5.5
1.45
1.50
1.45
1.40
1.35
1.30
1.25
1.20
-50
-25
0
V
IN
= 5V, V
OUT
= 3.5V, I
OUT
= 300mA
25
50
75
100
125
Input Voltage (V)
Temperature (°C)
Current Limit vs. Input Voltage
1.70
1.65
Current Limit vs. Temperature
1.8
1.6
1.4
Current Limit (A)
Current Limit (A)
1.60
1.55
1.50
1.45
1.40
4
4.25
4.5
4.75
5
1.2
1.0
0.8
0.6
0.4
V
OUT
= 3.5V
5.25
5.5
0.2
0.0
-50
-25
0
25
V
IN
= 5V, V
OUT
= 3.5V
50
75
100
125
Input Voltage (V)
Temperature (°C)
DS8026-02 March 2011
www.richtek.com
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