RT9179 Adjustable, 300mA LDO Regulator with Enable General Description Features The RT9179 is a high performance linear voltage regulator with enable high function and adjustable output with a 1.175V reference voltage. It operates from an input of 3V to 5.5V and provides output current up to 300mA with two external resistors to set the output voltage ranges from 1.175V to 4.5V. z 300mV Dropout @ 300mA z 150uA Low Ground Pin Current Excellent Line and Load Regulation <1uA Standby Current in Shutdown Mode Guaranteed 300mA Output Current Stable with 1uF Input and Output Ceramic Capacitor Adjustable Output Voltage Ranges from 1.175V to 4.5V Over-Temperature/Over-Current Protection RoHS Compliant and 100% Lead (Pb)-Free The RT9179 has superior regulation over variations in line and load. Also it provides fast respond to step changes in load. Other features include over-current and overtemperature protection. The device has enable pin to reduce power consumption in shutdown mode. The devices is available in the popular SOT-23-5 package. z z z z z z z Applications z Ordering Information RT9179 z z z Package Type B : SOT-23-5 Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) Note : Battery-Powered Equipment Graphic Card Peripheral Cards PCMCIA Card Marking Information For marking information, contact our sales representative directly or through a Richtek distributor located in your area. Richtek 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. Pin Configurations (TOP VIEW) VOUT ADJ 5 4 2 3 VIN GND EN SOT-23-5 DS9179-11 April 2011 www.richtek.com 1 RT9179 Typical Application Circuit RT9179 VIN VOUT VOUT VIN Chip Enable R1 EN C1 1uF C3 0.1uF GND ADJ R2 VOUT = 1.175 x ( 1 + C2 1uF R1 ) Volts R2 Adjustable Operation Note: The external feedback resistors are in hundreds of OHM to hundreds of kOHM ranges. Functional Pin Description Pin No. Pin Name Pin Function 1 VIN Power Input Voltage 2 GND Ground 3 EN Chip Enable (Active High) Adjust Output Voltage. The output voltage is set by the internal feedback resistors when 4 5 ADJ this pin grounded. If external feedback resistors are applied, the output voltage will be: VOUT Output Voltage VOUT = 1.175 × (1 + R1 ) Volts R2 Function Block Diagram EN Shutdown and Logic Control 1.175V VREF Current-Limit and Thermal Protection VIN Thermal SHDN +_ Error Amplifier MOS Driver VOUT ADJ GND www.richtek.com 2 DS9179-11 April 2011 RT9179 Absolute Maximum Ratings z z z z z z z (Note 1) Supply Input Voltage ------------------------------------------------------------------------------------------------ 6V Power Dissipation, PD @ TA = 25°C SOT-23-5 --------------------------------------------------------------------------------------------------------------- 0.4W Package Thermal Resistance (Note 2) SOT-23-5, θJA --------------------------------------------------------------------------------------------------------- 250°C/W Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260°C Junction Temperature ----------------------------------------------------------------------------------------------- 150°C Storage Temperature Range --------------------------------------------------------------------------------------- −65°C to 150°C ESD Susceptibility (Note 3) HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V Recommended Operating Conditions z z z (Note 4) Supply Input Voltage ------------------------------------------------------------------------------------------------ 3V to 5.5V Enable Input Voltage ------------------------------------------------------------------------------------------------ 0V to 5.5V Junction Temperature Range -------------------------------------------------------------------------------------- −40°Cto 125°C Electrical Characteristics (VIN = VOUT + 0.7V, IOUT = 10uA, CIN = COUT = 1uF (Ceramic), TA = 25° C unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Reference Voltage Tolerance VREF 1.163 1.175 1.187 V Adjust Pin Current IADJ -- -- 10 nA Output Voltage Range VOUT 1.175 -- 4.5 V Quiescent Current IQ Enabled, IOUT = 0mA -- 150 -- μA ISTBY V IN = 5.5V, Shutdown -- -- 1 μA 0.5 -- -- A IOUT = 10mA -- 10 -- IOUT = 300mA -- 300 - V OUT + 0.7V < VIN < 5.5V -- 0.001 -- %/V Standby Current (Note 5) (Note 6) Current Limit Dropout Voltage ILIM (Note 7) VDROP mV Line Regulation ΔVLINE Thermal Shutdown Temperature TSD -- 170 -- °C Thermal Shutdown Hysteresis ΔTSD -- 40 -- °C -- -- 0.4 EN Threshold Logic-Low Voltage VIL V IN = 3.3V, Shutdown Logic-High Voltage VIH V IN = 3.3V, Enable 2.0 -- -- IEN V IN = 5.5V, Enable -- -- 10 EN Current DS9179-11 April 2011 V nA www.richtek.com 3 RT9179 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 T A = 25°C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard. 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 - 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 6. Standby current is the input current drawn by a regulator when the output voltage is disabled by a shutdown signal (VEN ≤ 0.4V). It is measured with VIN = 5.5V. Note 7. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) − 100mV. www.richtek.com 4 DS9179-11 April 2011 RT9179 Typical Operating Characteristics ADJ Pin Voltage vs. Temperature Output Voltage vs. Temperature 3.29 VIN = 5V R1 = 1.8KΩ R2 = 1kΩ VIN = 5V 1.19 ADJ Pin Voltage (V) 3.28 Output Voltage (V) 1.2 3.27 3.26 3.25 1.18 1.17 1.16 1.15 1.14 3.24 -50 -25 0 25 50 75 100 125 -50 -25 0 Temperature (° C) 25 50 75 100 125 Temperature (° C) Quiescent Current vs. Input Voltage Quiescent Current vs. Temperature 150 160 Quiescent Current (uA)1 Quiescent Current (uA) VIN = 5V 150 140 130 140 130 120 120 -50 -25 0 25 50 75 100 3 125 3.5 4 Temperature (° C) -40 300 Dropout Voltage (mV) PSRR (dB) 350 -50 -60 -70 VIN = 4V IL = 10mA -90 5.5 400 -30 -80 5 Dropout Voltage vs. Io PSRR -20 4.5 Input Voltage (V) COUT = 1uF (X7R) -100 VOUT = 3.3V TJ = 125°C TJ = 25°C 250 200 TJ = -40°C 150 100 50 0 10 100 1K 1000 10K 10000 Frequency (Hz) DS9179-11 April 2011 100K 100000 0 50 100 150 200 250 300 Io (mA) www.richtek.com 5 RT9179 Current Limit vs. Temperature 1 4 VIN = 5V 2 Source Current (A) 0.95 Current Limit (A) Output Short-Circuit Protection 0.9 0.85 0.8 0.75 1 0.8 0.6 0.4 VIN = 5V R1 = 1.8kΩ R2 = 1kΩ CIN = 1uF CO = 1uF 0.2 0 0.7 -50 -25 0 25 50 75 100 125 Time (1ms/Div) Temperature (° C) Load Transient Regulation 6 60 R1=1.8KΩ, R2=1KΩ CIN=1uF(Electrolytic) CO=1uF(Electrolytic) VIN = 4V to 5V ILOAD : 150mA Output Voltage Deviation(mV) Input Voltage Deviation(V) Line Transient Regulation 7 5 4 Load Current(A) Output Voltage Deviation(mV) 20 10 0 -10 - 20 40 0 -20 0.2 0.1 0 -0.1 Enable Threshold Voltage vs. Temperature Enable Voltage(V) 0.9 6 4 2 0 VOUT TURN ON Output Voltage Deviation(V) Enable Threshold Voltage (V)1 Time (100us/Div) Enable Response 1 0.7 CIN = 1uF(Ceramic) CO = 2.2uF(Ceramic) 20 Time (100us/Div) 0.8 VIN = 5V, R1 = 1.8KΩ R2 = 1KΩ VOUT TURN OFF 0.6 VIN =5V R1 =1.8kΩ R2 =1kΩ CIN =1uF CO =1uF 3 2 1 0 ILOAD : 150mA 0.5 -50 -25 0 25 50 75 Temperature (° C) www.richtek.com 6 100 125 Time (100us/Div) DS9179-11 April 2011 RT9179 Application Information Input Capacitor An input capacitance of ≅1μF is required between the device input pin and ground directly (the amount of the capacitance may be increased without limit). The input capacitor MUST be located less than 1 cm from the device to assure input stability (see PCB Layout Section). A lower ESR capacitor allows the use of less capacitance, while higher ESR type (like aluminum electrolytic) require more capacitance. Capacitor types (aluminum, ceramic and tantalum) can be mixed in parallel, but the total equivalent input capacitance/ ESR must be defined as above to stable operation. There are no requirements for the ESR on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will be ≅1μF over the entire operating temperature range. Output Capacitor The RT9179 is designed specifically to work with very small ceramic output capacitors. The recommended minimum capacitance (temperature characteristics X7R or X5R) is 1μF to 4.7μF range with 10mΩ to 50mΩ range ceramic capacitor between LDO output and GND for transient stability, but it may be increased without limit. Higher capacitance values help to improve transient. The output capacitor's ESR is critical because it forms a zero to provide phase lead which is required for loop stability. (When using the Y5V dielectric, the minimum value of the input/output capacitance that can be used for stable over full operating temperature range is 3.3μF.) DS9179-11 April 2011 Region of Stable COUT ESR vs. Load Current Region of Stable CC OUT OUT ESR (Ω) Like any low-dropout regulator, the RT9179 requires input and output decoupling capacitors. These capacitors must be correctly selected for good performance (see Capacitor Characteristics Section). Please note that linear regulators with a low dropout voltage have high internal loop gains which require care in guarding against oscillation caused by insufficient decoupling capacitance. 100 10 Region of Instable 1 Region of Stable 0.1 0.01 Region of Instable 0.001 0 50 100 150 200 250 300 Load Current (mA) No Load Stability The device will remain stable and in regulation with no external load. This is specially important in CMOS RAM keep-alive applications Input-Output (Dropout) Volatge A regulator's minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the device uses a PMOS, its dropout voltage is a function of drain-to-source on-resistance, RDS(ON), multiplied by the load current : VDROPOUT = VIN - VOUT = RDS(ON) × IOUT Current Limit The RT9179 monitors and controls the PMOS’ gate voltage, minimum limiting the output current to 0.5A. The output can be shorted to ground for an indefinite period of time without damaging the part. Short-Circuit Protection The device is short circuit protected and in the event of a peak over-current condition, the short-circuit control loop will rapidly drive the output PMOS pass element off. Once the power pass element shuts down, the control loop will rapidly cycle the output on and off until the average power dissipation causes the thermal shutdown circuit to respond to servo the on/off cycling to a lower frequency. Please refer to the section on thermal information for power dissipation calculations. www.richtek.com 7 RT9179 Capacitor Characteristics Tantalum : It is important to note that capacitance tolerance and variation with temperature must be taken into consideration when selecting a capacitor so that the minimum required amount of capacitance is provided over the full operating temperature range. In general, a good tantalum capacitor will show very little capacitance variation with temperature, but a ceramic may not be as good (depending on dielectric type). Solid tantalum capacitors are recommended for use on the output because their typical ESR is very close to the ideal value required for loop compensation. They also work well as input capacitors if selected to meet the ESR requirements previously listed. Aluminum electrolytics also typically have large temperature variation of capacitance value. Equally important to consider is a capacitor's ESR change with temperature: this is not an issue with ceramics, as their ESR is extremely low. However, it is very important in Tantalum and aluminum electrolytic capacitors. Both show increasing ESR at colder temperatures, but the increase in aluminum electrolytic capacitors is so severe they may not be feasible for some applications. Ceramic : For values of capacitance in the 10μF to 100μF range, ceramics are usually larger and more costly than tantalums but give superior AC performance for by-passing high frequency noise because of very low ESR (typically less than 10mΩ). However, some dielectric types do not have good capacitance characteristics as a function of voltage and temperature. Z5U and Y5V dielectric ceramics have capacitance that drops severely with applied voltage. A typical Z5U or Y5V capacitor can lose 60% of its rated capacitance with half of the rated voltage applied to it. The Z5U and Y5V also exhibit a severe temperature effect, losing more than 50% of nominal capacitance at high and low limits of the temperature range. X7R and X5R dielectric ceramic capacitors are strongly recommended if ceramics are used, as they typically maintain a capacitance range within ± 20% of nominal over full operating ratings of temperature and voltage. Of course, they are typically larger and more costly than Z5U/Y5U types for a given voltage and capacitance. www.richtek.com 8 Tantalums also have good temperature stability: a good quality tantalum will typically show a capacitance value that varies less than 10 to 15% across the full temperature range of 125° C to -40° C. ESR will vary only about 2X going from the high to low temperature limits. The increasing ESR at lower temperatures can cause oscillations when marginal quality capacitors are used (if the ESR of the capacitor is near the upper limit of the stability range at room temperature). Aluminum : This capacitor type offers the most capacitance for the money. The disadvantages are that they are larger in physical size, not widely available in surface mount, and have poor AC performance (especially at higher frequencies) due to higher ESR and ESL. Compared by size, the ESR of an aluminum electrolytic is higher than either Tantalum or ceramic, and it also varies greatly with temperature. A typical aluminum electrolytic can exhibit an ESR increase of as much as 50X when going from 25°C down to -40°C. It should also be noted that many aluminum electrolytics only specify impedance at a frequency of 120Hz, which indicates they have poor high frequency performance. Only aluminum electrolytics that have an impedance specified at a higher frequency (between 20kHz and 100kHz) should be used for the device. Derating must be applied to the manufacturer's ESR specification, since it is typically only valid at room temperature. Any applications using aluminum electrolytics should be thoroughly tested at the lowest ambient operating temperature where ESR is maximum. DS9179-11 April 2011 RT9179 Thermal Considerations The RT9179 can deliver a current of up to 300mA over the full operating junction temperature range. However, the maximum output current must be derated at higher ambient temperature to ensure the junction temperature does not exceed 125°C. With all possible conditions, the junction temperature must be within the range specified under operating conditions. Power dissipation can be calculated based on the output current and the voltage drop across regulator. Using a single point ground technique for the regulator and it's capacitors fixed the problem. Since high current flows through the traces going into VIN and coming from VOUT, Kelvin connect the capacitor leads to these pins so there is no voltage drop in series with the input and output capacitors. Optimum performance can only be achieved when the device is mounted on a PC board according to the diagram below: ADJ PD = (VIN - VOUT) IOUT + VIN IGND GND EN + PCB Layout + PD (MAX) = ( TJ (MAX) - TA ) / θJA Where TJ (MAX) is the maximum junction temperature of the die (125° C) and T A is the maximum ambient temperature. The junction to ambient thermal resistance (θJA) for SOT-23-5 package at recommended minimum footprint is 250°C/W (θJA is layout dependent). Visit our website in which “Recommended Footprints for Soldering Surface Mount Packages” for detail. GND VOUT VIN + The final operating junction temperature for any set of conditions can be estimated by the following thermal equation : GND SOT-23-5 Board Layout Good board layout practices must be used or instability can be induced because of ground loops and voltage drops. The input and output capacitors MUST be directly connected to the input, output, and ground pins of the device using traces which have no other currents flowing through them. The best way to do this is to layout CIN and COUT near the device with short traces to the VIN, VOUT, and ground pins. The regulator ground pin should be connected to the external circuit ground so that the regulator and its capacitors have a “single point ground”. It should be noted that stability problems have been seen in applications where “vias” to an internal ground plane were used at the ground points of the device and the input and output capacitors. This was caused by varying ground potentials at these nodes resulting from current flowing through the ground plane. DS9179-11 April 2011 www.richtek.com 9 RT9179 Outline Dimension H D L B C b A A1 e Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.889 1.295 0.035 0.051 A1 0.000 0.152 0.000 0.006 B 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 C 2.591 2.997 0.102 0.118 D 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 H 0.102 0.254 0.004 0.010 L 0.356 0.610 0.014 0.024 SOT-23-5 Surface Mount Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: [email protected] 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. www.richtek.com 10 DS9179-11 April 2011