RT9018A/B
Maximum 3A, Ultra Low Dropout Regulator
General Description
The RT9018A/B is a high performance positive voltage
regulator designed for use in applications requiring very
low Input voltage and very low dropout voltage at up to
3A(Peak). It operates with a VIN as low as 1.0V and VDD
voltage 3V with output voltage programmable as low as
0.8V. The significant feature includes ultra low dropout,
ideal for applications where VOUT is very close to VIN.
Additionally, there is an enable pin to further reduce power
dissipation while shutdown. The RT9018A/B provides
excellent regulation over variations in line, load and
temperature. and provides a power OK signal to indicate
if the voltage level of Vo reaches 90% of its rating value.
The RT9018A/B is available in the SOP-8 (Exposed Pad)
and WDFN-10L 3x3 packages with 1V, 1.05V, 1.2V,
1.5V,
1.8V and 2.5V internally preset outputs that are also
adjustable using external resistors.
Features
Maximum 3A Low-Dropout Voltage Regulator
High Accuracy Output Voltage
±
1.5%
Typically 220mV Dropout at 3A
Power Good Output
Output Voltage Pull Low Resistance when Disable
Thermal and Over Current Protection
RoHS Compliant and 100% Lead (Pb)-Free
Applications
Front Side Bus VTT (1.2V/3A)
NoteBook PC Applications
Motherboard Applications
Marking Information
For marking information, contact our sales representative
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
Ordering Information
RT9018A/B
Package Type
SP : SOP-8 (Exposed Pad-Option 1)
QW : WDFN-10L 3x3
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
Output Voltage
10 : 1V/Adj
1K : 1.05V/Adj
12 : 1.2V/Adj
15 : 1.5V/Adj
18 : 1.8V/Adj
25 : 2.5V/Adj
Enable Pin Function
A : Internal Pull High
B : Internal Pull Low
Note :
Richtek Pb-free and Green 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.
100% matte tin (Sn) plating.
Pin Configurations
(TOP VIEW)
PGOOD
EN
VIN
VDD
2
3
4
8
7
GND
6
9
5
GND
ADJ
VOUT
NC
SOP-8 (Exposed Pad)
WDFN-10L 3x3
DS9018A/B-04
September 2007
9
VOUT
VOUT
VOUT
ADJ
PGOOD
1
2
3
4
5
GND
11
10
9
8
7
VDD
VIN
VIN
VIN
EN
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1
RT9018A/B
Pin Description
Pin No.
PSOP-8
3
2
4
1
7
6
5
WDFN 3x3
7, 8, 9
6
10
5
4
1, 2, 3
--
VIN
EN
VDD
PGOOD
ADJ
VOUT
NC
Supply Input Voltage.
Chip Enable (Active-High).
Supply Voltage of Control Circuitry.
Power Good Open Drain Output.
Set the output voltage by the internal feedback resistors when
ADJ is grounded. If external feedback resistors is used, V
OUT
=
0.8V x (R1 + R2)/R2.
Output Voltage.
No Internal Connection.
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
Pin Name
Pin Function
8,
Exposed Pad (11) GND
Exposed Pad (9)
Typical Application Circuit
V
OUT
=
0.8
×
R1
+
R2
R2
V
IN
10uF
Chip Enable
V
DD
1uF
V
OUT
VIN
VOUT
10uF
Chip Enable
V
DD
V
OUT
V
IN
10uF
VIN
VOUT
C
Dummy
R1
V
OUT
10uF
RT9018A/B
EN
VDD
GND
ADJ
PGOOD
100k
RT9018A/B
EN
VDD
GND
ADJ
PGOOD
R2
100k
V
OUT
1uF
Figure 1. Fixed Voltage Regulator
Figure 2. Adjustable Voltage Regulator
Function Block Diagram
VIN
OCP
VOUT
Driver
Error
Amplifier
OTP
+
-
EN
VDD
POR
0.8V
-
0.72V
+
Mode
ADJ
PGOOD
GND
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2
DS9018A/B-04
September 2007
RT9018A/B
Absolute Maximum Ratings
(Note 1)
Supply Voltage, V
IN
--------------------------------------------------------------------------------------------------- 1V to 6V
Control Voltage, V
DD
-------------------------------------------------------------------------------------------------- 3V to 6V
Output Voltage, V
OUT
------------------------------------------------------------------------------------------------- 0.8 to 6V
Power Dissipation, P
D
@ T
A
= 25°C
SOP-8 (Exposed Pad) ----------------------------------------------------------------------------------------------- 1.33W
WDFN-10L 3x3 --------------------------------------------------------------------------------------------------------- 1.67W
Package Thermal Resistance (Note 4)
SOP-8 (Exposed Pad),
θ
JA
------------------------------------------------------------------------------------------ 75°C/W
SOP-8 (Exposed Pad),
θ
JC
----------------------------------------------------------------------------------------- 15°C/W
WDFN-10L 3x3,
θ
JA
--------------------------------------------------------------------------------------------------- 60°C/W
Junction Temperature ------------------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260°C
Storage Temperature Range ----------------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 2)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV
MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 3)
Supply Voltage, V
IN
--------------------------------------------------------------------------------------------------- 1.4V to 5.5V
Control Voltage, V
DD
-------------------------------------------------------------------------------------------------- 3.6V to 5.5V
Junction Temperature Range ----------------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range ----------------------------------------------------------------------------------------
−
40°C to 85°C
Electrical Characteristics
(V
IN
= V
OUT
+ 500mV, V
EN
= V
DD
= 5V, C
IN
= C
OUT
= 10uF, T
A
= T
J
= 25°C, unless otherwise specified)
Parameter
VDD Operation Voltage Range
POR Threshold
POR Hysteresis
Adjustable Pin Threshold
Fixed Output Voltage Range
Line Regulation (V
IN
)
Load Regulation
(Note 7)
Symbol
V
DD
Test Conditions
V
DD
Input Range
Min
3.6
2.4
0.15
Typ
--
2.7
0.2
0.2
0.8
0
0.2
0.2
150
210
0.6
4.5
1.8
0.6
150
Max
5.5
3
--
0.4
0.812
+1.5
0.6
1
250
350
1.2
--
--
--
Units
V
V
V
V
V
%
%
%
mV
mV
mA
A
A
A
V
TH_ADJ
ΔV
OUT
ΔV
LINE_IN
ΔV
LOAD
V
DROP
I
Q
I
LIM
I
OUT
= 1mA
I
OUT
= 1mA
V
IN
= V
OUT
+ 0.5V to 5V,
I
OUT
= 1mA
V
IN
= V
OUT
+ 1V,
I
OUT
= 1mA to 3A
I
OUT
= 2A
I
OUT
= 3A
V
DD
= 5.5V
--
0.788
−1.5
--
--
--
--
--
3.2
Reference Voltage (ADJ Pin Voltage) V
ADJ
Dropout Voltage (Note 5)
Quiescent Current (Note 6)
Current Limit
Short Circuit Current
In-rush Current
V
OUT
Pull Low Resistance
DS9018A/B-04
September 2007
V
OUT
< 0.2V
C
OUT
= 10uF, Enable Start-up
V
EN
= 0V
0.5
--
--
--
Ω
To be continued
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3
RT9018A/B
Parameter
Chip Enable
EN Input Bias Current
VDD Shutdown RT9018A
Current
EN Threshold
Power Good
PGOOD Rising Threshold
PGOOD Hysteresis
PGOOD Sink Capability
PGOOD Delay
Thermal Protection
Thermal Shutdown Temperature
Thermal Shutdown Hysteresis
Thermal Shutdown Temperature
Fold-back
T
SD
ΔT
SD
V
OUT
< 0.4V
--
--
--
160
30
110
--
--
--
°C
°C
°C
I
PGOOD
= 10mA
--
3
--
0.5
90
10
0.2
1.5
93
--
0.4
5
%
%
V
ms
RT9018B
I
EN
I
SHDN
V
EN
= 0V
V
EN
= 0V
V
DD
= 5V
V
DD
= 5V
--
--
--
--
1.2
12
10
--
--
--
--
20
1
0.2
--
μA
μA
V
Symbol
Test Conditions
Min
Typ
Max
Units
Logic-Low Voltage V
ENL
Logic-High Voltage V
ENH
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.
Devices are ESD sensitive. Handling precaution recommended.
Note 3.
The device is not guaranteed to function outside its operating conditions.
Note 4.
θ
JA
is measured in the natural convection at T
A
= 25°C on a high effective thermal conductivity test board (4 Layers,
2S2P) of JEDEC 51-7 thermal measurement standard. The case point of
θ
JC
is on the expose pad for SOP-8 (Exposed
Pad) package.
Note 5.
The dropout voltage is defined as V
IN
-V
OUT
, which is measured when V
OUT
is V
OUT(NORMAL)
- 100mV.
Note 6.
Quiescent, or ground current, is the difference between input and output currents. It is defined by I
Q
= I
IN
- I
OUT
under no
load condition (I
OUT
= 0mA). The total current drawn from the supply is the sum of the load current plus the ground pin
current.
Note 7.
Regulation is measured at constant junction temperature by using a 2ms current pulse. Devices are tested for load
regulation in the load range from 1mA to 3A.
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4
DS9018A/B-04
September 2007
RT9018A/B
Typical Operating Characteristics
Load Transient Response
V
DD
= 5V, V
IN
= 1.8V, V
OUT
= 1.2V
Load Transient Response
V
DD
= 5V, V
IN
= 1.8V, V
OUT
= 1.2V
V
OUT
(20mV/Div)
V
OUT
(20mV/Div)
I
OUT
(1A/Div)
Time (2.5ms/Div)
I
OUT
(1A/Div)
Time (2.5ms/Div)
V
IN
Line Transient Response
V
DD
= 5V, V
OUT
= 1.2V, I
OUT
= 0A
V
IN
Line Transient Response
V
DD
= 5V, V
OUT
= 1.2V, I
OUT
= 2A
3
3
V
IN
2
V
IN
2
V
OUT
(20mV/Div)
V
OUT
(20mV/Div)
Time (250μs/Div)
Time (250μs/Div)
V
DD
Line Transient Response
V
IN
= 1.8V, V
OUT
= 1.2V, I
OUT
= 0A
V
DD
Line Transient Response
V
IN
= 1.8V, V
OUT
= 1.2V, I
OUT
= 2A
V
DD
5
4
V
DD
5
4
V
OUT
(20mV/Div)
V
OUT
(20mV/Div)
Time (250μs/Div)
Time (250μs/Div)
DS9018A/B-04
September 2007
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