® RT2515A 2A, Low Input Voltage, Ultra-Low Dropout Linear Regulator with Enable General Description Features The RT2515A is a high performance positive voltage regulator designed for use in applications requiring ultralow input voltage and ultra-low dropout voltage at up to 2 amperes. It operates with an input voltage as low as 1.4V, with output voltage programmable as low as 0.5V. The RT2515A features ultra low dropout, ideal for applications where output voltage is very close to input voltage. Additionally, the RT2515A has an enable pin to further reduce power dissipation while shutdown. The RT2515A provides excellent regulation over variations in line, load and temperature. The RT2515A is available in the SOP-8 (Exposed Pad) package. The output voltage can be set by an external divider or fixed at 1.2V depending on how the FB pin is configured. z z z z z z z z Applications z z z z z Ordering Information RT2515A z z z Package Type SP : SOP-8 (Exposed Pad-Option 2) Lead Plating System G : Green (Halogen Free and Pb Free) Input Voltage as Low as 1.4V Ultra-Low Dropout Voltage 400mV @ 2A Adjustable Output Voltage from 0.5V to 3.8V Over Current Protection Over Temperature Protection 1μ μA Input Current in Shutdown Mode Enable Control RoHS Compliant and Halogen Free Telecom/Networking Cards Motherboards/Peripheral Cards Industrial Applications Wireless Infrastructure Set Top Box Medical Equipment Notebook Computers Battery Powered Systems Pin Configurations (TOP VIEW) Note : NC Richtek products are : EN 2 VIN NC 3 ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` Suitable for use in SnPb or Pb-free soldering processes. 8 GND ADJ 6 VOUT 5 NC 9 4 GND 7 SOP-8 (Exposed Pad) Marking Information RT2515AGSP : Product Number RT2515A GSPYMDNN YMDNN : Date Code Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS2515A-02 November 2012 is a registered trademark of Richtek Technology Corporation. www.richtek.com 1 RT2515A Typical Application Circuit RT2515A RT2515A 3 VIN VIN VOUT 6 Chip Enable VOUT = 0.5(R1+R2) R2 R1 2 VIN VOUT C1 10µF ADJ 7 3 VOUT 6 C1 10µF C2 10µF Chip Enable 2 R2 EN VIN ADJ 7 C2 10µF VOUT 1.2V EN GND 8, 9 (Exposed Pad) GND 8, 9 (Exposed Pad) (V) Figure 1. Adjustable Voltage Regulator Figure 2. Fixed Voltage Regulator Functional Pin Description Pin No. Pin Name 1, 4, 5 NC 2 EN Pin Function No Internal Connection. Chip Enable (Active-High). Pulling this pin below 0.4V turns the regulator off, reducing the quiescent current to a fraction of its operating value. The device will be enabled if this pin is left open. Connect to VIN if not being used. 3 VIN Input voltage. For regulation at full load, the input to this pin must be between (VOUT + 0.5V) and 5.5V. Minimum input voltage is 1.4V. A large bulk capacitance should be placed closely to this pin to ensure that the input supply does not sag below 1.4V. Also a minimum of 10μF ceramic capacitor should be placed directly at this pin. 6 VOUT Output Voltage. A minimum of 10μF capacitor should be placed directly at this pin. 7 ADJ 8, GND 9 (Exposed pad) When this pin is grounded, an internal resistor divider sets the output voltage to 1.2V. If connected to the VOUT pin, the output voltage will be set at 0.5V. If external feedback resistors are used, the output voltage will be determined by the resistor ratio. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Function Block Diagram RSENSE VOUT VIN VPUMP - - + + Mode Select + VIN ADJ - 0.5µA 0.5V EN VIN Thermal Shutdown VOUT + VIN - 0.1V GND Reverse Voltage Shutdown Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 2 Reference Generator is a registered trademark of Richtek Technology Corporation. DS2515A-02 November 2012 RT2515A Absolute Maximum Ratings z z z z z z z z (Note 1) Supply Voltage, VIN -----------------------------------------------------------------------------------------------------Other I/O Pin --------------------------------------------------------------------------------------------------------------Power Dissipation, PD @ TA = 25°C SOP-8 (Exposed Pad) --------------------------------------------------------------------------------------------------Package Thermal Resistance (Note 2) SOP-8 (Exposed Pad), θJA ---------------------------------------------------------------------------------------------SOP-8 (Exposed Pad), θJC --------------------------------------------------------------------------------------------Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------Junction Temperature ----------------------------------------------------------------------------------------------------Storage Temperature Range -------------------------------------------------------------------------------------------ESD Susceptibility (Note 3) HBM (Human Body Model) ---------------------------------------------------------------------------------------------- Recommended Operating Conditions z z z −0.3V to 7V −0.3V to 6V 2.04W 49°C/W 15°C/W 260°C 150°C −65°C to 150°C 2kV (Note 4) Supply Voltage, VIN ------------------------------------------------------------------------------------------------------ 1.4V to 6V Junction Temperature Range -------------------------------------------------------------------------------------------- −40°C to 125°C Ambient Temperature Range -------------------------------------------------------------------------------------------- −40°C to 85°C Electrical Characteristics (VIN = 1.4V to 6V, IOUT = 10μA to 2A, VADJ = VOUT, −40°C ≤ TA ≤ 85°C, unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Quiescent Current IQ VIN = 3.3V, IOUT = 0A -- 0.7 1.5 mA Shutdown Current ISHDN -- 1.5 10 μA Output Voltage (Fixed Output, VADJ = 0V) VOUT VIN = 5.5V, VEN = 0V VIN = VOUT + 0.5V, IOUT = 10mA TA = 25°C VIN = 1.8V, IOUT = 0.8A, TA = 25°C −2 -- 2 1.4V ≤ VIN ≤ 5.5V, IOUT = 10mA −3 -- 3 % Line Regulation ΔVLINE IOUT = 10mA -- 0.2 0.4 %/V Load Regulation ΔVLOAD IOUT = 10mA to 2A -- 0.5 1.5 % IOUT = 1A, VIN ≥ 1.6V -- 120 200 IOUT = 1A, 1.4V < VIN < 1.6V -- -- 400 IOUT = 1.5A, VIN ≥ 1.6V -- 180 300 IOUT = 1.5A, 1.4V < VIN < 1.6V -- -- 500 IOUT = 2A, VIN ≥ 1.6V -- 240 400 IOUT = 2A, 1.4V < VIN < 1.6V -- -- 600 2.3 3 4.4 Dropout Voltage Current Limit VDROP ILIM VIN = 3.3V Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS2515A-02 November 2012 mV A is a registered trademark of Richtek Technology Corporation. www.richtek.com 3 RT2515A Parameter Symbol Test Conditions Min Typ Max Unit VIN = 3.3V, VADJ = VOUT, IOUT = 10mA, TA = 25°C 0.495 -- 0.505 VIN = 3.3V, VADJ = VOUT, IOUT = 10mA 0.49 -- 0.51 -- 20 200 nA 0.05 0.1 0.15 V -- 1 10 μA Feedback ADJ Reference Voltage VADJ V ADJ Pin Current IADJ VADJ = 0.5V ADJ Pin Threshold VTH_ADJ VIN = 3.3V IEN VEN = 0V, VIN = 5.5V Logic-High VIH VIN = 3.3V 1.6 -- -- Logic-Low VIL VIN = 3.3V -- -- 0.4 OTP Trip Level -- 160 -- °C Hysteresis -- 30 -- °C Enable EN Pin Current EN Threshold Voltage V Over Temperature Protection Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and 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 may affect device reliability. Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package. Note 3. Devices are ESD sensitive. Handling precaution is recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 4 is a registered trademark of Richtek Technology Corporation. DS2515A-02 November 2012 RT2515A Typical Operating Characteristics Quiescent Current vs. Temperature Reference Voltage vs. Temperature 1.15 0.520 Quiescent Current (mA) Reference Voltage (V) 0.515 0.510 0.505 VIN = 5V 0.500 VIN = 3.3V 0.495 0.490 0.95 VIN = 5V 0.75 VIN = 3.3V 0.55 0.485 VOUT = 2.52V 0.35 0.480 -50 -25 0 25 50 75 100 -50 125 -25 0 Shutdown Current vs. Temperature 75 100 125 UVLO vs. Temperature 1.20 1.50 1.05 1.40 Logic-High 1.30 VIN = 5V UVLO (V) Shutdown Current (µA)1 50 Temperature (°C) Temperature (°C) 0.90 25 0.75 VIN = 3.3V 1.20 1.10 Logic-Low 0.60 1.00 0.45 0.90 0.30 0.80 VEN = 5V -50 -25 0 25 50 75 100 125 -50 -25 0 Temperature (°C) Dropout Voltage vs. Load Current 50 75 100 125 EN Threshold Voltage vs. Temperature 1.3 350 EN Threshold Voltage (V) 300 Dropout Voltage (mV) 25 Temperature (°C) 125°C 250 25°C 200 150 −40°C 100 50 Logic-High 1.2 1.1 1.0 Logic-Low 0.9 0.8 VOUT = 2.5V VIN = 5V 0.7 0 0 0.5 1 1.5 Load Current (A) Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS2515A-02 November 2012 2 -50 -25 0 25 50 75 100 125 Temperature (°C) is a registered trademark of Richtek Technology Corporation. www.richtek.com 5 RT2515A Load Transient Response Line Transient Response VOUT (20mV/Div) VIN (1V/Div) VOUT (10mV/Div) IOUT (1A/Div) VIN = 3.3V, VOUT = 2.5V, IOUT = 1A to 2A VIN = 3.3V to 4.3V, VOUT = 2.5V, IOUT = 2A Time (50μs/Div) Time (500μs/Div) Power On from EN Power Off from EN VEN (5V/Div) VEN (5V/Div) VOUT (2V/Div) VOUT (2V/Div) I IN (2A/Div) I IN (2A/Div) VIN = 3.3V, VOUT = 2.5V, IOUT = 2A Time (250μs/Div) VIN = 3.3V, VOUT = 2.5V, IOUT = 2A Time (250μs/Div) PSRR 0 IOUT = 1mA IOUT = 100mA IOUT = 300mA -10 PSRR (dB) -20 -30 -40 -50 -60 -70 VIN = 3.25V to 3.35V, VOUT = 2.5V -80 100 1000 10000 100000 1000000 Frequency (Hz) Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 6 is a registered trademark of Richtek Technology Corporation. DS2515A-02 November 2012 RT2515A Application Information The RT2515A is a low voltage, low dropout linear regulator with an external bias supply input capable of supporting an input voltage range from 1.4V to 6V with a fixed output voltage from 1V to 2V in 0.1V increments. Output Voltage Setting The RT2515A output voltage is adjustable from 1.4V to 6V via the external resistive voltage divider. The voltage divider resistors can have values of up to 800kΩ because of the very high impedance and low bias current of the sense comparator. The output voltage is set according to the following equation : VOUT = VADJ × ⎛⎜ 1+ R1 ⎞⎟ ⎝ R2 ⎠ The RT2515A is designed specifically to work with low ESR ceramic output capacitor for space saving and performance consideration. Using a ceramic capacitor with capacitance of at least 10μF and ESR larger than 1mΩ on the RT2515A output ensures stability. Nevertheless, the RT2515A can still work well with other types of output capacitors due to its wide range of stable ESR. Figure 3 shows the allowable ESR range as a function of load current for various output capacitance. Output capacitors with larger capacitance can reduce noise and improve load transient response, stability, and PSRR. The output capacitor should be located at a distance of not more than 0.5 inch from the output pin of the RT2515A. Region of Stable COUT ESR vs. Load Current 100 where VADJ is the reference voltage with a typical value of 0.5V. Unstable Range The RT2515A goes into sleep mode when the EN pin is in a logic low condition. In this condition, the pass transistor, error amplifier, and band gap are all turned off, reducing the supply current to only 10μA (max.). The EN pin can be directly tied to VIN to keep the part on. Current Limit The RT2515A contains an independent current limit circuitry, which monitors and controls the pass transistor's gate voltage, limiting the output current to 3A (typ.). COUT ESR (Ω) 10 Chip Enable Operation 1 Stable Range 0.1 0.01 VIN = 3.3V, VOUT = 2.5V, COUT = 10μF / X7R 0.001 0.0 0.3 0.5 0.8 1.0 Load Current (A) Figure 3 CIN and COUT Selection Thermal Considerations Like any low dropout regulator, the external capacitors of the RT2515A must be carefully selected for regulator stability and performance. Using a capacitor of at least 10μF is suitable. The input capacitor must be located at a distance of not more than 0.5 inch from the input pin of the IC. Any good quality ceramic capacitor can be used. However, a capacitor with larger value and lower ESR (Equivalent Series Resistance) is recommended since it will provide better PSRR and line transient response. Thermal protection limits power dissipation in RT2515A. When the operation junction temperature exceeds 160°C, the OTP circuit starts the thermal shutdown function and turns the pass element off. The pass element turns on again after the junction temperature cools by 30°C. Copyright © 2012 Richtek Technology Corporation. All rights reserved. DS2515A-02 November 2012 RT2515A output voltage will be closed to zero when output short circuit occurs as shown in Figure 4. It can reduce the IC temperature and provides maximum safety to end users when output short circuit occurs. is a registered trademark of Richtek Technology Corporation. www.richtek.com 7 RT2515A VOUT Short to GND ILIM ILIM＇ IOUT IC Temperature Maximum Power Dissipation (W) VOUT 3.2 Four-Layer PCB 2.8 2.4 2.0 1.6 1.2 0.8 0.4 0.0 Figure 4. Short Circuit Protection when Output Short Circuit Occurs 0 25 50 75 100 125 Ambient Temperature (°C) Figure 5. Derating Curve of Maximum Power Dissipation For continuous operation, do not exceed absolute maximum junction temperature. The maximum power dissipation depends on the thermal resistance of the IC package, PCB layout, rate of surrounding airflow, and difference between junction and ambient temperature. The maximum power dissipation can be calculated by the following formula : PD(MAX) = (TJ(MAX) − TA) / θJA where TJ(MAX) is the maximum junction temperature, TA is the ambient temperature, and θJA is the junction to ambient thermal resistance. For recommended operating condition specifications, the maximum junction temperature is 125°C. The junction to ambient thermal resistance, θJA, is layout dependent. For SOP-8 (Exposed Pad) package, the thermal resistance, θJA, is 49°C/W on a standard JEDEC 51-7 four-layer thermal test board. The maximum power dissipation at TA = 25°C can be calculated by the following formula : PD(MAX) = (125°C − 25°C) / 49°C/W) = 2.04W for SOP-8 (Exposed Pad) package The maximum power dissipation depends on the operating ambient temperature for fixed T J(MAX) and thermal resistance, θJA. The derating curve in Figure 5 allows the designer to see the effect of rising ambient temperature on the maximum power dissipation. Copyright © 2012 Richtek Technology Corporation. All rights reserved. www.richtek.com 8 is a registered trademark of Richtek Technology Corporation. DS2515A-02 November 2012 RT2515A Outline Dimension H A M EXPOSED THERMAL PAD (Bottom of Package) Y J X B F C I D Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 4.000 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.510 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.000 0.152 0.000 0.006 J 5.791 6.200 0.228 0.244 M 0.406 1.270 0.016 0.050 X 2.000 2.300 0.079 0.091 Y 2.000 2.300 0.079 0.091 X 2.100 2.500 0.083 0.098 Y 3.000 3.500 0.118 0.138 Option 1 Option 2 8-Lead SOP (Exposed Pad) Plastic Package Richtek Technology Corporation 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Richtek products are sold by description only. Richtek reserves the right to change the circuitry and/or specifications without notice at any time. Customers should obtain the latest relevant information and data sheets before placing orders and should verify that such information is current and complete. Richtek cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Richtek product. Information furnished by Richtek is believed to be accurate and reliable. However, no responsibility is assumed by Richtek or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Richtek or its subsidiaries. DS2515A-02 November 2012 www.richtek.com 9