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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 Commercial 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 requirements 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 GND 6 9 5 7 GND ADJ VOUT NC
SOP-8 (Exposed Pad)
WDFN-10L 3x3
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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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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, VOUT = 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
VOUT = 0.8 x R1 + R2 R2
VIN 10uF Chip Enable VDD 1uF VOUT VIN VOUT 10uF
Chip Enable VDD
VOUT
VIN 10uF
VIN
VOUT CDummy R1
VOUT 10uF
RT9018A/B EN VDD GND ADJ PGOOD 100k
RT9018A/B EN VDD GND ADJ PGOOD
R2 100k VOUT
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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Absolute Maximum Ratings
(Note 1) Supply Voltage, VIN --------------------------------------------------------------------------------------------------- 1V to 6V Control Voltage, VDD -------------------------------------------------------------------------------------------------- 3V to 6V Output Voltage, VOUT ------------------------------------------------------------------------------------------------- 0.8 to 6V Power Dissipation, PD @ TA = 25C SOP-8 (Exposed Pad) ----------------------------------------------------------------------------------------------- 1.33W WDFN-10L 3x3 --------------------------------------------------------------------------------------------------------- 1.67W Package Thermal Resistance (Note 4) SOP-8 (Exposed Pad), JA ------------------------------------------------------------------------------------------ 75C/W SOP-8 (Exposed Pad), JC ----------------------------------------------------------------------------------------- 15C/W WDFN-10L 3x3, JA --------------------------------------------------------------------------------------------------- 60C/W Junction Temperature ------------------------------------------------------------------------------------------------- 150C Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260C Storage Temperature Range ---------------------------------------------------------------------------------------- -65C to 150C ESD Susceptibility (Note 2) HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V
Recommended Operating Conditions
(Note 3)
Supply Voltage, VIN --------------------------------------------------------------------------------------------------- 1.4V to 5.5V Control Voltage, VDD -------------------------------------------------------------------------------------------------- 3.6V to 5.5V Junction Temperature Range ---------------------------------------------------------------------------------------- -40C to 125C Ambient Temperature Range ---------------------------------------------------------------------------------------- -40C to 85C
Electrical Characteristics
(VIN = VOUT + 500mV, VEN = VDD = 5V, CIN = COUT = 10uF, TA = TJ = 25C, unless otherwise specified)
Parameter VDD Operation Voltage Range POR Threshold POR Hysteresis Adjustable Pin Threshold Fixed Output Voltage Range Line Regulation (VIN) Load Regulation (Note 7)
Symbol VDD
Test Conditions VDD 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
VTH_ADJ VOUT VLINE_IN VLOAD VDROP IQ ILIM
IOUT = 1mA IOUT = 1mA VIN = VOUT + 0.5V to 5V, IOUT = 1mA VIN = VOUT + 1V, IOUT = 1mA to 3A IOUT = 2A IOUT = 3A VDD = 5.5V
-0.788 -1.5 -----3.2
Reference Voltage (ADJ Pin Voltage) VADJ
Dropout Voltage (Note 5) Quiescent Current (Note 6) Current Limit Short Circuit Current In-rush Current VOUT Pull Low Resistance
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VOUT < 0.2V COUT = 10uF, Enable Start-up VEN = 0V
0.5 ---
- To be continued
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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 TSD TSD VOUT < 0.4V ---160 30 110 ---C C C IPGOOD = 10mA -3 -0.5 90 10 0.2 1.5 93 -0.4 5 % % V ms RT9018B IEN ISHDN VEN = 0V VEN = 0V VDD = 5V VDD = 5V ----1.2 12 10 ----20 1 0.2 -A A V Symbol Test Conditions Min Typ Max Units
Logic-Low Voltage VENL Logic-High Voltage VENH
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. JA is measured in the natural convection at TA = 25C on a high effective thermal conductivity test board (4 Layers, 2S2P) of JEDEC 51-7 thermal measurement standard. The case point of JC is on the expose pad for SOP-8 (Exposed Pad) package. Note 5. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) - 100mV. Note 6. Quiescent, or ground current, is the difference between input and output currents. It is defined by IQ = IIN - IOUT under no load condition (IOUT = 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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Typical Operating Characteristics
Load Transient Response
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
Load Transient Response
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
VOUT (20mV/Div)
VOUT (20mV/Div)
IOUT (1A/Div) Time (2.5ms/Div)
IOUT (1A/Div) Time (2.5ms/Div)
VIN Line Transient Response
VDD = 5V, VOUT = 1.2V, IOUT = 0A
VIN Line Transient Response
VDD = 5V, VOUT = 1.2V, IOUT = 2A
3
3
VIN
2
VIN
2
VOUT (20mV/Div)
VOUT (20mV/Div)
Time (250s/Div)
Time (250s/Div)
VDD Line Transient Response
VIN = 1.8V, VOUT = 1.2V, IOUT = 0A
VDD Line Transient Response
VIN = 1.8V, VOUT = 1.2V, IOUT = 2A
VDD
5 4
VDD
5 4
VOUT (20mV/Div)
VOUT (20mV/Div)
Time (250s/Div)
Time (250s/Div)
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RT9018A/B
Dropout Voltage vs. Load Current
400
Start Up from Enable
IOUT = 3A
350
125C
Dropout Voltage (mV)
300 250 200 150 100 50 0 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3
25C
EN (1V/Div) VOUT (1V/Div)
-40C
PGOOD (1V/Div) I IN (2A/Div) Time (500s/Div)
Load Current (A)
Start Up from VIN
IOUT = 3A IOUT = 3A
Start Up from VDD
VIN (1V/Div) VOUT (1V/Div) PGOOD (1V/Div) I IN (2A/Div) Time (1ms/Div)
VDD (5V/Div) VOUT (1V/Div) PGOOD (1V/Div) I IN (2A/Div) Time (500s/Div)
Short Circuit Protection
2.6
Short Circuit Current vs. Temperature
Short Circuit Current Ishort (A)
2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0
VDD = 5V, VIN = 1.8V, VOUT = 1.2V
IOUT (1A/Div) Time (100s/Div)
-40
-20
0
20
40
60
80
100
Temperature (C)
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VDD Standby Current vs. Temperature
32
Quiescent Current vs. Temperature
1200 1.2 1100 1.1 1000 1.0 900 0.9 800 0.8 700 0.7 600 0.6 500 0.5 400 0.4 300 0.3 200 0.2 100 0.1 0 0 -40 -25 -10
VIN = 3.3V, VEN = 0V, VDD = 5V
VIN = 1.8V, VOUT = 1.2V, IOUT = 0A
VDD Standby Current (uA)1
28 24 20 16 12 8 4 0 -4 -50 -25 0 25 50 75 100 125
RT9018A
RT9018B
Quiescent Current (mA) Quiescent Current (uA)
5
20
35
50
65
80
95 110 125
Temperature (C)
Temperature (C)
Reference Voltage vs. Temperature
0.84 0.83
Output Voltage vs. Temperature
1.25
VIN = 1.8V, VADJ = 0V, IOUT = 0A
1.24 1.23
Reference Voltage (V)
Output Voltage (V)
-40 -25 -10 5 20 35 50 65 80 95 110 125
0.82 0.81 0.80 0.79 0.78 0.77 0.76
1.22 1.21 1.20 1.19 1.18 1.17 1.16 1.15 -40 -25 -10 5 20 35 50 65 80 95 110 125
Temperature (C)
Temperature (C)
VDD POR Threshold Voltage vs. Temperature
3.00 2.95 2.90 2.85
ADJ Threshold Voltage vs. Temperature
0.30
ADJ Threshold Voltage Range (V)
50 65 80 95 110 125
0.28 0.26 0.24 0.22 0.20 0.18 0.16 0.14 0.12 0.10 -40 -25 -10 5 20 35 50 65 80 95 110 125
POR Voltage (V)
2.80 2.75 2.70 2.65 2.60 2.55 2.50 2.45 2.40 -40 -25 -10 5
Rising
Falling
20
35
Temperature (C)
Temperature (C)
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RT9018A/B
Over Current Protection Fold Back
3
VIN = VEN = 3.3V, VDD = 5V
Output Voltage VOUT (V)
2.5 2 1.5 1 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4
Loading Current I OUT (A)
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Application Information
Adjustable Mode Operation The output voltage of RT9018A/B is adjustable from 0.8V to VIN by external voltage divider resisters as shown in Typical Application Circuit (Figure 2). The value of resisters R1 and R2 should be more than 10k to reduce the power loss. Enable The RT9018A/B 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, reducing the supply current to 10uA typical. The RT9018A/B goes into operation mode when the EN pin is in the logic high condition. If the EN pin is floating, NOTE that the RT9018A/B internal initial logic level. For RT9018A, the EN pin function pulls high level internally. So the regulator will be turn on when EN pin is floating. For RT9018B, the EN pin function pulls low level internally. So the regulator will be turn off when EN pin is floating. Output Capacitor The RT9018A/B is specifically designed to employ ceramic output capacitors as low as 10uF. The ceramic capacitors offer significant cost and space savings, along with high frequency noise filtering. Input Capacitor Good bypassing is recommended from input to ground to help improve AC performance. A 10uF input capacitor or greater located as close as possible to the IC is recommended. Current Limit The RT9018A/B contains an independent current limit and the short circuit current protection to prevent unexpected applications. The current limit monitors and controls the pass transistor' s gate voltage, limiting the output current to higher than 4.5A typical. When the output voltage is less than 0.4V, the short circuit current protection starts the current fold back function and maintains the loading current 1.8A. The output can be shorted to ground indefinitely without damaging the part. Power Good The power good function is an open-drain output. Connects 100k 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 RT9018A/B. When the operation junction temperature exceeds 160C, the over-temperature protection circuit starts the thermal shutdown function and turns the pass transistor off. The pass transistor turn on again after the junction temperature cools by 30C. RT9018A/B lowers its OTP trip level from 160C to 110C when output short circuit occurs (VOUT < 0.4V). It limits IC case temperature under 100C and provides maximum safety to customer while output short circuit occurring. Power Dissipation For continuous operation, do not exceed absolute maximum operation junction temperature 125C. 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 ambient. The maximum power dissipation can be calculated by following formula: PD(MAX) = ( TJ(MAX) - TA ) / JA Where T J(MAX) is the maximum operation junction temperature 125C, TA is the ambient temperature and the JA is the junction to ambient thermal resistance. For recommended operating conditions specification of RT9018A/B, where TJ (MAX) is the maximum junction temperature of the die (125C) and TA is the maximum ambient temperature. The junction to ambient thermal resistance for SOP-8 (Exposed Pad) package is 75C/W on the standard JEDEC 51-7 (4 layers, 2S2P) thermal test board. The copper thickness is 2oz. The maximum power dissipation at TA = 25C can be calculated by following formula:
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PD (MAX) = (125C - 25C) / (75C/W) = 1.33W (SOP-8 Exposed Pad on the minimum layout) Layout Considerations The thermal resistance JA of SOP-8 (Exposed Pad) is determined by the package design and the PCB design. However, the package design had been designed. If possible, it' s useful to increase thermal performance by the PCB design. The thermal resistance JA can be decreased by adding a copper under the exposed pad of SOP-8 (Exposed Pad) package. As shown in Figure 3, the amount of copper area to which the SOP-8 (Exposed Pad) is mounted affects thermal performance. When mounted to the standard SOP-8 (Exposed Pad) pad (Figure 3.a), JA is 75C/W. Adding copper area of pad under the SOP-8 (Exposed Pad) Figure 3.b) reduces the JA to 64C/W. Even further, increasing the copper area of pad to 70mm2 (Figure 3.e) reduces the JA to 49C/W.
Figure 3 (d). Copper Area = 50mm2, JA = 51C/W
Figure 3 (e). Copper Area = 70mm2, JA = 49C/W Figure 3. Thermal Resistance vs. Different Cooper Area Layout Design The maximum power dissipation depends on operating ambient temperature for fixed T J(MAX) and thermal resistance JA . For RT9018A/B packages, the Figure 4 of de-rating curves allows the designer to see the effect of rising ambient temperature on the maximum power allowed.
Figure 3 (a). Minimum Footprint, JA = 75C/W
2.2 2
Copper Area 70mm2 50mm2 30mm2 10mm2 Minimum Layout
Power Dissipation (W)
1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0
Figure 3 (b). Copper Area = 10mm2, JA = 64C/W
JEDEC 4-Layers PCB
0 20 40 60 80 100 120 140
Ambient Temperature (C)
Figure 4. De-rating Curves
Figure 3 (c). Copper Area = 30mm2, JA = 54C/W
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RT9018A/B
Outline Dimension
A
H M
EXPOSED THERMAL PAD (Bottom of Package)
Y J X B
F
C I D
Dimensions In Millimeters Symbol A B C D F H I J M Option 1 X Y X Option 2 Y Min 4.801 3.810 1.346 0.330 1.194 0.170 0.000 5.791 0.406 2.000 2.000 2.100 3.000 Max 5.004 4.000 1.753 0.510 1.346 0.254 0.152 6.200 1.270 2.300 2.300 2.500 3.500
Dimensions In Inches Min 0.189 0.150 0.053 0.013 0.047 0.007 0.000 0.228 0.016 0.079 0.079 0.083 0.118 Max 0.197 0.157 0.069 0.020 0.053 0.010 0.006 0.244 0.050 0.091 0.091 0.098 0.138
8-Lead SOP (Exposed Pad) Plastic Package
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RT9018A/B
D
D2
L
E
E2 SEE DETAIL A
1
e A A1 A3
b
2
1
2
1
DETAIL A Pin #1 ID and Tie Bar Mark Options Note : The configuration of the Pin #1 identifier is optional, but must be located within the zone indicated.
Symbol A A1 A3 b D D2 E E2 e L
Dimensions In Millimeters Min 0.700 0.000 0.175 0.180 2.950 2.300 2.950 1.500 0.500 0.350 0.450 Max 0.800 0.050 0.250 0.300 3.050 2.650 3.050 1.750
Dimensions In Inches Min 0.028 0.000 0.007 0.007 0.116 0.091 0.116 0.059 0.020 0.014 0.018 Max 0.031 0.002 0.010 0.012 0.120 0.104 0.120 0.069
W-Type 10L DFN 3x3 Package
Richtek Technology Corporation
Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611
Richtek Technology Corporation
Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com
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