RT9035
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DS9035-02 March 2011 www.richtek.com
Ordering Information
Pin Configurations
(TOP VIEW)
3A, Ultra Low Dropout Regulator
General Description
The RT9035 is a high performance positive voltage regulator
designed f or use in applications requiring very low In put
voltage a nd extremely low dropout voltage at up to 3A. It
operates with a VIN as low as 1V and V DD voltage 3V with
progra mmable output voltage a s low as 0.8V . The RT9035
features ultra low dropout that is ideal for applications
where VOUT is very close to VIN. Additionally, it has an
enable pin to further reduce power dissipation while
shutdown and provides excellent regulation over variations
in line, load and temperature. The RT9035 provides a power
good signal to indicate if the voltage level of VOUT reaches
90% of its rating value. The RT9035 is available in the
WQF N-20L 4x4 package with 1.05V, 1.2V, 1.5V, 1.8V and
2.5V internally preset outputs that are also adjustable by
using external resistors.
WQFN-20L 4x4
Features
zz
zz
zMaximum 3A Low-Dropout Voltage Regulator
zz
zz
zHigh Accuracy Output Voltage 2%
zz
zz
zDropout Voltage Typical 270mV at 3A
zz
zz
zPower Good Output
zz
zz
zOutput Voltage Pull Low Resistance when Disable
zz
zz
zThermal and Over Current Protection
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zz
zRoHS Compliant and Halogen Free
Applications
zNote Book PC Applications
zMotherboard Applications
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.
NC
GND
NC
NC
NC
EN
VIN
VIN
NC
NC
NC
NC
VOUT
NC
ADJ
VOUT
PGOOD VDD
VIN VOUT
1
2
3
4
6789
15
14
13
12
1720 1819
21
GND
511
10
16
Marking Information
For marking information, conta ct our sales representative
directly or through a Richtek distributor located in your
area.
Package Type
QW : WQFN-20L 4x4 (W-Type)
RT9035-
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Output Voltage
1K : 1.05V/Adj
12 : 1.2V/Adj
15 : 1.5V/Adj
18 : 1.8V/Adj
25 : 2.5V/Adj
RT9035
2DS9035-02 March 2011www.richtek.com
Functional Pin Description
Pin No. Pin Name Pin Function
1, 3, 4, 6, 12, 13,
14, 15, 20 NC No Intern al Co nnect ion.
2,
21 (Exposed Pad) GND Ground. The exposed pad must be soldered to a large P CB and connected to
GND for maximum power dissipation.
5 PGOOD Power Good Open Dr ain Output.
7 EN Chip Enable (Active High). Internal pull low.
8, 9, 10 VIN Supply Input Voltage.
11 VDD Supply Voltage of Control Circuit.
16, 17, 18 V OU T O ut put Voltage.
19 ADJ Set the output voltage by an external feedback resistor divider. If the ADJ pin is
grounded, the output voltage will be set by internal feedback resistor divider .
Function Block Diagram
Figure 1. Fixed Voltage Regulator Figure 2. Adjustable V oltage Regulator
Typical Application Circuit
R2
R2R1
0.8 VOUT +
×=
OCP
Error
Amplifier
POR
EN
GND
ADJ
VIN
PGOOD
VOUT
VDD Mode
+
-
+
-
0.8V
0.72V
OTP
SD
VIN
EN
GND
VOUT
ADJ
PGOOD
RT9035
VOUT
10µF
10µF
Chip Enable
100k
VOUT
VDD
1µF
VDD
VIN VIN
EN
GND
VOUT
ADJ
PGOOD
RT9035
VOUT
10µF
10µF R1
R2
100k
VOUT
VDD
1µF
VDD
VIN CDummy
Chip Enable
RT9035
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DS9035-02 March 2011 www.richtek.com
Electrical Characteristics
(VIN = VOUT + 500mV, VEN = VDD = 5V, CIN = COUT = 10μF, TA = 25°C, unless otherwise specified)
Absolute Maximum Ratings (Note 1)
zSupply Input Voltage, VIN -------------------------------------------------------------------------------------------- 6V
zControl V oltage--------------------------------------------------------------------------------------------------------- 6V
zOutput V oltage --------------------------------------------------------------------------------------------------------- 6V
zPower Dissipation, PD @ TA = 25°C
WQFN-20L 4x4 -------------------------------------------------------------------------------------------------------- 1.852W
zPa ckage Thermal Resistance (Note 2)
WQFN-20L 4x4, θJA --------------------------------------------------------------------------------------------------- 54°C/W
WQFN-20L 4x4, θJC -------------------------------------------------------------------------------------------------- 7°C/W
zLead Temperature (Soldering, 10 sec.)--------------------------------------------------------------------------- 260°C
zJunction T emperature------------------------------------------------------------------------------------------------- 150°C
zStorage T emperature Range ---------------------------------------------------------------------------------------- −65°C to 150 °C
zESD Susceptibility (Note 3)
HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV
MM (Ma chine Mode) -------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions (Note 4)
zSupply Input Voltage, VIN -------------------------------------------------------------------------------------------- 1.5V to 5V
zControl V oltage, VDD -------------------------------------------------------------------------------------------------- 4.5V to 5.5V
zJunction T emperature Range---------------------------------------------------------------------------------------- −40°C to 125°C
zAmbient T emperature Range---------------------------------------------------------------------------------------- −40°C to 85°C
To be Continued
Parameter Symbol Test Conditions Min Typ Max Unit
VDD
Quiesc ent Current (G ND Current)
(Note 5) IQ V
DD = 5V -- 0.6 1.2 mA
VDD Operation Range VDD V
DD Input Range 4.5 -- 5.5 V
Powe r On Reset
POR Threshold 2.4 2.7 3 V
POR Falling Hysteresis 0.15 0.2 -- V
VOUT
Fixed Output Voltage VDD = 5V −2 0 2 %
VOUT Load Regulation (Note 6) ΔVLOAD VDD = 5V, I OUT = 3 A ,
VIN = VOUT + 1V -- 0.2 1 %
VOUT Line Regulation (VIN) ΔVLINE_IN VDD = 5V, VIN = VOUT + 1V to 5V
IOUT = 1 m A -- 0.2 0.6 %
D ropout V oltage (Note 7) VDROP V
DD = 5V, IOUT = 3A -- 270 400 mV
C urrent Limit ILIM V
DD = 5V, VIN = 3.6V -- 4.5 -- A
Short Ci r cu it C u rr ent VDD = 5V , VOUT < 0.2V -- 2.5 -- A
RT9035
4DS9035-02 March 2011www.richtek.com
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. θJA is measured in the natural convection at TA = 25°C on a high effective thermal conductivity test board (4 Layers,
2S2P) of JEDEC 51-7 thermal measurement standard. The case point of θJC is on the expose pad for WQFN 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. Quiescent, or ground current, is the difference between input and output currents. It is defined by IQ = IIN - I OUT under
no load condition (IOUT = 0mA).
Note 6. 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.
Note 7. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) − 100mV.
Parameter Symbol Test Conditions Min Typ Max Unit
In-rush Current VDD = 5V, COUT = 10μF, Enable
Start-up, ILOAD = 1A -- 0.5 -- A
VOUT Pull Low Resi stance VEN = 0V -- 150 -- Ω
ADJ
Refere nce Voltag e (Adj) VDD = 5V, V OUT = 2.5V 0.788 0.8 0.812 V
ADJ Pin Threshold -- 0.2 -- V
Power Good
Pow er Good Rising Threshold VDD = 5V -- 90 -- %
Pow er Good Hysteresis VDD = 5V -- 10 -- %
Pow er Good Sink Capability VDD = 5V, I OUT = 10m A -- 0.2 0.4 V
Chip Enable
Logic-Low VEN_L VDD = 5 V -- -- 0.6
EN Threshold
V oltage Logic-High VEN_H VDD = 5 V 1.2 -- -- V
EN Pin Bias Current IEN V
EN = 5V -- 12 -- μA
VDD Shutdown Current ISHDN V
DD = 5V, V EN = 0 V -- -- 1 μA
Over T emperature Protection
Thermal Shutdown Temperature TSD -- 160 -- °C
Thermal Shutdown Returned
Temperature -- 110 -- °C
RT9035
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DS9035-02 March 2011 www.richtek.com
Typical Operating Characteristics
Load Transient Response
Time (250μs/Div)
IOUT
(1A/Div)
VOUT
(20mV/Div)
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
Load Transient Response
Time (250μs/Div)
IOUT
(1A/Div)
VOUT
(20mV/Div)
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
VDD Line Transient Response
Time (250μs/Div)
VOUT
(10mV/Div)
VDD
VIN = 1.8V, VOUT = 1.2V, IOUT = 2A
5
4
VDD Line Transient Response
Time (250μs/Div)
VOUT
(10mV/Div)
VDD
VIN = 1.8V, VOUT = 1.2V, IOUT = 10mA
5
4
VIN Line Transient Response
Time (250μs/Div)
VOUT
(10mV/Div)
VIN
VDD = 5V, VOUT = 1.2V, IOUT = 10mA
3
2
VIN Line Transient Response
Time (250μs/Div)
VOUT
(10mV/Div)
VIN
VDD = 5V, VOUT = 1.2V, IOUT = 2A
3
2
RT9035
6DS9035-02 March 2011www.richtek.com
Dropout Voltage vs . Load Current
0
50
100
150
200
250
300
350
400
0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3
Load Curren t ( A)
Dropout Voltage (mV)
125°C
25°C
-40°C
Start Up from VDD
Time (500μs/Div)
PGOOD
(1V/Div)
VDD
(5V/Div)
IOUT = 3A
VOUT
(1V/Div)
IIN
(2A/Div)
Start Up from VIN
Time (1ms/Div)
PGOOD
(1V/Div)
VIN
(1V/Div)
IOUT = 3A
VOUT
(1V/Div)
IIN
(2A/Div)
Start Up from Enable
Time (500μs/Div)
PGOOD
(1V/Div)
EN
(1V/Div)
IOUT = 3A
VOUT
(1V/Div)
IIN
(2A/Div)
Short Circuit Protection
Time (1ms/Div)
IOUT
(1A/Div) VDD = 5V, VIN = 1.8V, VOUT = 1.2V
Short Current vs. Te m pe rature
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
2.6
2.8
3.0
-40-200 20406080100
Tempera ture (°C)
Current Limit (A)
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
RT9035
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DS9035-02 March 2011 www.richtek.com
ADJ Threshold Voltage v s. Temperature
0.10
0.12
0.14
0.16
0.18
0.20
0.22
0.24
0.26
0.28
0.30
-40 -25 -10 5 20 35 50 65 80 95 110 125
Tempera ture (°C)
ADJ Threshold V oltage R ange (V)
Reference Voltage vs. Temperature
0.76
0.77
0.78
0.79
0.80
0.81
0.82
0.83
0.84
-40 -25 -10 5 20 35 50 65 80 95 110 125
Tempera ture (°C)
Reference Voltage (V)
VDD POR Threshold Volta ge vs. Temperature
2.40
2.45
2.50
2.55
2.60
2.65
2.70
2.75
2.80
2.85
2.90
2.95
3.00
-40 -25 -10 5 20 35 50 65 80 95 110 125
Tempera tu re (°C)
POR Volt age (V)
Rising
Falling
Output Voltage vs. Te m pe rature
1.15
1.16
1.17
1.18
1.19
1.20
1.21
1.22
1.23
1.24
1.25
-40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature (°C)
Output Voltage (V)
VIN = 1.8V, VADJ = 0V, IOUT = 0A
Quiescent Current v s . Temperature
0
100
200
300
400
500
600
700
800
900
1000
-40 -25 -10 5 20 35 50 65 80 95 110 125
Tempera ture (°C)
Quiescent Curr ent Iq (uA)
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
Current Limit vs. Temp erature
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
-40-20020406080100
Temperature (°C)
Current Li m it (A)
VDD = 5V, VIN = 2.5V, VOUT = 1.2V
RT9035
8DS9035-02 March 2011www.richtek.com
Application Information
Adjustable Mode Operation
The output voltage of RT9035 is adjustable from 0.8V to
VIN by external voltage divider resisters a s shown in Typical
Application Circuit (Figure 2). The value of resisters R1
and R2 should be more than 10kΩ to reduce the power
loss.
Enable
The RT9035 goes into shutdown mode when the EN pin
is in the logic low condition. During this condition, the
pass transistor, error amplifier, and band gap are turned
off. The RT9035 goes into operation mode when the EN
pin is in the logic high condition. The RT9035 has an internal
pull low resistor at EN pin so that the regulator will be turn
off when EN pin is floating.
Output Ca pa citor
The RT9035 is specifically designed to employ ceramic
output ca pacitors a s low as 10μF . The ceramic capacitors
offer signif icant cost and space savings, along with high
frequency noise filtering.
Input Capacitor
Good bypa ssing is recommended from input to ground to
help improve AC performance. A 10μF input capa citor or
greater located as close as possible to the IC is
recommended.
Current Limit
The RT9035 contains an independent current limit and
the short circuit current protection to prevent unexpected
applications. The current limit monitors and controls the
pa ss transistor’s gate voltage, limiting the output current
to higher than 4.5A typical. When the output voltage is
less than 0.2V, the short circuit current protection starts
the current fold back function and maintains the loading
current 2.5A. The output can be shorted to ground
indefinitely without da maging the part.
Power Good
The power good function is an open-drain output. Connects
100kΩ pull up resistor to VOUT to obtain an output voltage.
The PGOOD pin will output high immediately after the
output voltage arrives 90% of normal output voltage. The
PGOOD pin will output high with typical 1.5ms delay time.
Thermal-Shutdown Protection
Thermal protection limits power dissipation to prevent IC
over temperature in RT9035. When the operation junction
temperature exceeds 160°C, the over-temperature
protection circuit starts the thermal shutdown function
a nd turns the pass tra nsistor of f. The pass tra nsistor turn
on again after the junction temperature cools by 30°C.
RT9035 lowers its OTP trip level from 160°C to 110°C
when output short circuit occurs (VOUT < 0.2V). It limits
IC ca se temperature under 100°C and provides maximum
safety to customer while output short circuit occurring.
Power Dissipation
For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The
power dissipation definition in device is:
PD = (VIN − VOUT) x IOUT + VIN x IQ
The maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junctions to a mbient. The maximum power dissipation can
be calculated by following formula:
PD(MAX) = ( TJ(MAX) − TA ) / θJA
Where TJ(MAX) is the maximum operation junction
temperature 125°C, TA is the a mbient temperature and the
θJA is the junction to ambient thermal resista nce.
For recommended operating conditions specification of
RT9035, where TJ (MAX) is the maximum junction
temperature of the die (125°C) and TA is the maximum
ambient temperature. The junction to ambient thermal
resista nce for WQ F N-20L 4x4 pa ckage is 54°C/W on the
standard JEDEC 51-7 (4 layers, 2S2P) thermal test board.
The copper thickness is 2oz. The maximum power
dissipation at TA = 25°C can be calculated by following
formula:
PD (MAX) = (125°C − 25°C) / (54°C/W) = 1.852W
RT9035
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DS9035-02 March 2011 www.richtek.com
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal
resistance θJA . For RT9035 packages, the Figure 3 of de-
rating curves allows the designer to see the effect of rising
a mbient temperature on the maximum power allowed.
Figure 3. De-rating Curve
0
0.4
0.8
1.2
1.6
2
2.4
0 20 40 60 80 100 120 140
Ambien t Tempera tu re ( °C)
Power Dissipation ( W )
4-Layers PCB
RT9035
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Richtek Technology Corporation
Headquarter
5F, No. 20, Taiyuen Street, Chupei City
Hsinchu, Taiwan, R.O.C.
Tel: (8863)5526789 Fax: (8863)5526611
Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit
design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be
guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek.
Richtek Technology Corporation
Taipei Office (Marketing)
5F, No. 95, Minchiuan Road, Hsintien City
Taipei County, Taiwan, R.O.C.
Tel: (8862)86672399 Fax: (8862)86672377
Email: marketing@richtek.com
Outline Dimension
Symbol Dimensions In Millimeters Dimens ions In I nches
Min Max Min Max
A 0.700 0.800 0.028 0.031
A1 0.000 0.050 0.000 0.002
A3 0.175 0.250 0.007 0.010
b 0.150 0.300 0.006 0.012
D 3.950 4.050 0.156 0.159
D2 2.650 2.750 0.104 0.108
E 3.950 4.050 0.156 0.159
E2 2.650 2.750 0.104 0.108
e 0.500 0.020
L 0.350 0.450
0.014 0.018
W-Type 20L QFN 4x4 Package
Note : The configuration of the Pin #1 identifier is optional,
but must be located within the zone indicated.
DETAIL A
Pin #1 ID a nd T ie Bar Mark Option s
1
1
22
