500mA CMOS Ultra Low Dropout Linear Regulator

Transcription

1 500mA CMOS Ultra Low Dropout Linear Regulator Description The series are 500mA CMOS ultra low dropout positive voltage regulators which operate from 2.4V to 5.5V input supply. The ultra low dropout linear regulator responds very quickly to step changes in load which makes them suitable for low voltage microprocessor applications. The features very low quiescent current and ultra low dropout characteristics which make it suitable for power-saving systems. The current limit protection and on-chip thermal shutdown features provide protection against any combination of overload or ambient temperature that could exceed junction temperature. Features Low Dropout Voltage: Typical 700mV at 500mA Very Low Quiescent Current about 1.1mA Current Limiting and Thermal Protection Maximum Output Current: 500mA Excellent Line and Load Regulation Fast Transient Response RoHS Compliant SOP-8 and SOT-23-5 Packages Applications Communication Equipments High Current Linear Regulators Microprocessor Supply Pin Assignments SO Package (SOP-8) Ordering Information - TR: Tape/Reel Blank: Tube P: Green G: Green Package Type SO: SOP-8 S5: SOT-23-5 S5 Package (SOT-23-5) Output Voltage 18: 1.8V 25: 2.5V 33: 3.3V SOT-23-5 Marking Part Number Product Code -25S5G b5= Figure 1. Pin Assignment of 1

2 Typical Application Circuit Figure 2. Typical Application Circuit of Functional Pin Description Pin Name VOUT GND EN VIN Pin Function The output supplies power to loads. The output capacitor is required to prevent output voltage unstable. The larger output capacitor will be required for application with large transit load to limit peak voltage transits, besides could reduce output noise and improve stability, PSRR. Common ground pin Enable Pin. Logic input control this device active or shut off. The EN pin can t be left floating and must be tied to the Vin pin if not used. Power is supplied to this device from this pin which is required an input filter capacitor. In general, the input capacitor in the range of 1µF to 10µF is sufficient. Block Diagram Figure 3. Block Diagram of 2

3 Absolute Maximum Ratings Supply Input Voltage (V IN ) V Maximum Junction Temperature (T J ) ºC Storage Temperature Range (T S ) to + 150ºC Lead Temperature (Soldering, 10 sec.) (T LEAD ) ºC Package Thermal Resistance (θ JA ): SOP /W SOT-25 (P D ) /W Power 70ºC (P D ): SOP W SOT-25 (P D ) W Note:Stresses greater than those listed under "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 under Recommended Operating Conditions are not implied. Exposure to "Absolute Maximum Ratings" for extended periods may affect device reliability. Recommended Operating Conditions Input Voltage (V IN ) to + 5.5V Operating Junction Temperature Range (T J ) to + 125ºC Electrical Characteristics (V IN =V OUT + 1V, C IN =1µF, C OUT =1µF, T A =25 ºC, unless otherwise specified) Parameter Symbol Conditions Min Typ Max Unit Output Voltage Accuracy ΔV OUT I O = 1mA % Current Limit I LIMIT R Load =1Ω A Quiescent Current I Q I O = 0mA 1.1 ma Dropout Voltage (Note 1, 2) V DROP I O =0.5A 1.2V V OUT 2.0V mv Line Regulation ΔV LINE I O =1mA, V IN =V OUT +1V to 5V 3 10 mv Load Regulation (Note 1) ΔV LOAD I O =0mA to 0.5A mv Ripple Rejection PSRR V IN =V OUT +1V f RIPPLE = 120Hz, C OUT = 1µF 55 db Temperature Coefficient TC I OUT = 1mA, V IN = 5V 50 ppm/ ºC Thermal Shutdown Temperature TSD 170 ºC Thermal Shutdown Hysteresis ΔTSD 25 ºC Note 1:Load regulation and dropout voltage are measured at a constant junction temperature by using a 20ms low duty cycle current pulse. Note 2:Dropout voltage is specified over the full output current range of the device. Dropout voltage is defined as the minimum input/output differential at which the output voltage drops 2% below its normal value measured at the specified output current. 3

4 Typical Performance Curves Quiescent Current(mA) V IN =V OUT +1V V OUT =1.8V C IN C OUT IQ (ma) Load Current(A) Figure 4. Quiescent Current vs. Load Current Input Voltage (V) Figure 5. Quiescent Current vs. Input Voltage Quiescent Current(uA) V IN =V OUT +1V V OUT C IN =1.8V C OUT Output Voltage(V) V IN =V OUT +1V V OUT =1.8V C IN C OUT Temperature( 0 C) Temperature( 0 C) Figure 6. Quiescent Current vs. Temperature Figure 7. Temperature Stability V IN =3.5V,V OUT =1.8V,I OUT =10mA~0.5A C IN,C OUT Figure 8. Load Transient Response V IN =3.5V,V OUT =1.8V,I OUT =1mA,C IN,C OUT Figure 9. Line Transient Response 4

5 Applications Information Introduction The is a low dropout, high accuracy, linear regulator capable of 500mA output current and dropout voltage is typically 700mV of 1.8V output voltage. As shown in the Block Diagram, the consists of error amplifier, p-channel pass transistor, and internal feedback voltage divider. The incorporates several protection features. Current limit and thermal limit protection protect the device against current overload conditions at the output. Enable Pull EN high to enable the device and low to force shutdown. The EN pin can t be left floating and must be tied to the Vin pin if not used. Dropout Voltage Dropout voltage is defined as the minimum input to output voltage differential at which the output voltage drops 2% below its normal value measured at the specified output current. The minimum dropout voltage of regulator determines the lowest usable supply voltage. Power Supply Ripple Rejection Power Supply Ripple Rejection (PSRR) is the ability of suppressing input ripple at output terminal. PSRR is the ratio of output to input ripple which expressed in db. Increase the values of the input and output capacitors can improve ripple rejection and transient response. Capacitor Selection A 10uF input capacitor with a 10uF output capacitor is recommended for. The tantalum and aluminum electrolytic capacitor can be used. Give more consideration to the use of ceramic capacitors. The equivalent series resistance (ESR) of output capacitor affects stability and output noise. Maximum Power Dissipation The maximum power is limited by the maximum junction temperature and thermal resistance of package. The has internal thermal limit designed to protect the device during overload conditions. For normal operation, do not exceed the maximum junction temperature rating of 125 C. The power dissipated of the device is: P = I OUT (Vin - V OUT ). The maximum allowed power dissipation is: P MAX = (T J-MAX - T A ) / Rθ JA where T J-MAX is the maximum temperature, 125 C. T A is the operated ambient temperature of the regulator. Rθ JA is the thermal resistance of the junction to the ambient. Layout Consideration 1. Connect C IN and C OUT as close to the as possible to minimize the impact of PCB trace inductance. 2. Expand the copper connected to the GND can assist in spreading heat to the PCB. 5

6 Outline Information SOP- 8 Package (Unit: mm) SYMBOLS DIMENSION IN MILLIMETER UNIT MIN MAX A A A B D E e H L Note:Followed From JEDEC MO-012-E SOT-23-5 Package (Unit: mm) SYMBOLS DIMENSION IN MILLIMETER UNIT MIN MAX A A A B D E E e e L Note:Followed From JEDEC MO-178-C. Life Support Policy Fitipower s products are not authorized for use as critical components in life support devices or other medical systems. 6