RT9184A Dual, Ultra-Fast Transient Response, 500mA LDO Regulator General Description Features The RT9184A series are an efficient, precise dual-channel CMOS LDO regulator optimized for ultra-low-quiescent applications. Both regulator outputs are capable of sourcing 500mA of output current. z The RT9184A's performance is optimized for CD/DVD-ROM, CD/RW or wireless communication supply applications. The RT9184A regulators are stable with output capacitors as low as 1μF. The other features include ultra low dropout voltage, high output accuracy, current limiting protection, and high ripple rejection ratio. z z z z z z z z z The RT9184A regulators are available in fused SOP-8 package. Key features include current limit, thermal shutdown, fast transient response, low dropout voltage, high output accuracy, current limiting protection, and high ripple rejection ratio. z μA) Low Quiescent Current (Typically 440μ Guaranteed 500mA Output Current Low Dropout Voltage : 600mV at 500mA Wide Operating Voltage Ranges : 2.8V to 5.5V Ultra-Fast Transient Response Tight Load and Line Regulation Current Limiting Protection Thermal Shutdown Protection Only low-ESR Ceramic Capacitors Required for Stability Custom Voltage Available RoHS Compliant and 100% Lead (Pb)-Free Ordering Information RT9184APackage Type S : SOP-8 Applications z z z z CD/DVD-ROM, CD/RW Wireless LAN Card/Keyboard/Mouse Battery-Powered Equipment XDSL Router Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) Note : z Pin Configurations (TOP VIEW) VOUT1 8 GND VIN1 2 7 GND VOUT2 3 6 GND VIN2 4 5 GND Output 2 Output 1 The output 2 is designated to larger than or equal to output 1 in voltage code order below, i.e. VOUT2 ≥ VOUT1. For example, the part number of RT9184A-FNCS is assigned for 2.5VOUT1/3.3VOUT2, contrary to the part number of RT9184A-NFCS is opposite to the rule and doesn't exist in the system. Voltage Code for Both Outputs : 2: 1.2V A: 2.0V K: 3.0V U: 4.0V 3: 1.3V B: 2.1V L: 3.1V V: 4.1V 4: 1.4V C: 2.2V M: 3.2V W: 4.2V SOP-8 : : 9: 1.9V J: 2.9V : T: 3.9V : Z: 4.5V RichTek products are : ` RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020. ` DS9184A-09 April 2011 Suitable for use in SnPb or Pb-free soldering processes. www.richtek.com 1 RT9184A Typical Application Circuit VOUT2 VOUT2 VOUT1 1uF VOUT1 1uF VIN2 1uF dielectric is strongly recommended if ceramics are used as input/output capacitors. When using the Y5V dielectric, RT9184A VIN2 μF minimum X7R or X5R Note: To prevent oscillation, a 1μ the minimum value of the input/output capacitance that VIN1 VIN1 can be used for stable over full operating temperature 1uF GND range is 3.3μ μF. (see Application Information Section for further details) Function Block Diagram VIN1 VOUT1 Error Amplifier - + Current Limiting Sensor Thermal Shutdown 1.2V Reference VOUT2 VIN2 Error Amplifier - + Current Limiting Sensor Thermal Shutdown 1.2V Reference GND Functional Pin Description Pin No. Pin Name Pin Function 1 VOUT1 Channel 1 Output Voltage 2 VIN1 Channel 1 Supply Input 5,6,7,8 GND Common Ground 3 VOUT2 Channel 2 Output Voltage 4 VIN2 Channel 2 Supply Input www.richtek.com 2 DS9184A-09 April 2011 RT9184A Absolute Maximum Ratings z z z z z z z (Note 1) Supply Input Voltage ------------------------------------------------------------------------------------------------ 6.5V Power Dissipation, PD @ TA = 25°C SOP-8 ------------------------------------------------------------------------------------------------------------------ 0.625W Package Thermal Resistance (Note 2) SOP-8, θJA ------------------------------------------------------------------------------------------------------------ 160°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 (Note 4) Supply Input Voltage ------------------------------------------------------------------------------------------------ 2.8V to 5.5V Junction Temperature Range -------------------------------------------------------------------------------------- −40°Cto 125°C Electrical Characteristics (VIN = VOUT + 1V, or VIN = 2.8V whichever is greater, CIN = 1μF, COUT = 1μF, TA = 25°C, for each LDO unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Output Voltage Accuracy ΔV OUT IOUT = 1mA −1 -- 3 % Current Limit ILIM RLOAD = 1Ω 500 -- -- mA Quiescent Current (both LDOs) (Note 5) IQ IOUT = 0mA -- 440 600 μA Dropout Voltage VDROP IOUT = 500mA -- 600 -- mV ΔV LINE VIN = (VOUT + 0.3V) to 5.5V, -- 0.2 -- %/V (Note 6) Line Regulation IOUT = 1mA ΔV LOAD 1mA < IOUT < 500mA -- 30 -- mV Power Supply Rejection Rate PSRR f = 1kHz, C OUT = 1μF -- −55 -- dB Thermal Shutdown Protection TSD -- 170 -- °C Thermal Shutdown Hysteresis ΔT SD -- 40 -- °C Load Regulation (Note 7) DS9184A-09 April 2011 www.richtek.com 3 RT9184A 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. θ JA is measured in the natural convection at TA = 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 recommended. Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Regulation is measured at constant junction temperature by using a 20ms current pulse. Devices are tested for load regulation in the load range from 1mA to 500mA. Note 6. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) − 100mV. Note 7. 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. www.richtek.com 4 DS9184A-09 April 2011 RT9184A Typical Operating Characteristics Output Voltage vs. Temperature Quiescent Current vs. Temperature 500 3.35 VIN1 = VIN2 = 5V CIN1 = CIN2 = 1uF COUT1 = COUT2 = 1uF RL1 = RL2 = ∞ A VIN1 = 5V CIN1 = 1uF COUT1 = 1uF RL1 = ∞ Quiescent Current (uA) Output Voltage (V) 3.4 3.3 3.25 3.2 450 400 350 300 -50 -40 -25 0 25 50 75 100 125 -50 -40 -25 0 Temperature (°C) 75 100 125 Current Limit vs. Temperature Current Limit vs. Input Voltage 900 VIN1 = 5V CIN1 = 1uF COUT1 = 1uF RL1 = 0.5Ω 850 Current Limit (mA) Current Limit (mA) 50 Temperature (°C) 900 800 750 VIN1 = 5V CIN1 = 1uF COUT1 = 1uF RL1 = 0.5Ω 850 800 750 700 700 3 3.5 4 4.5 5 -50 -40 5.5 Input Voltage (V) ≈ ≈ ≈ IOUT2 VOUT2 VOUT1 (20mV/Div) (20mV/Div) (100mA/Div) ≈ DS9184A-09 April 2011 0 25 50 75 100 125 Load Transient Regulation VIN1 = VIN2 = 5V, CIN1 = CIN2 = 1uF(X7R) COUT1 = COUT2 = 1uF(X7R), IOUT2 = 0A Time (1ms/Div) -25 Temperature (°C) Load Transient Regulation IOUT1 VOUT2 VOUT1 (20mV/Div) (20mV/Div) (100mA/Div) 25 VIN1 = VIN2 = 5V, CIN1 = CIN2 = 1uF(X7R) COUT1 = COUT2 = 1uF(X7R), IOUT1 = 0A ≈ ≈ ≈ ≈ Time (1ms/Div) www.richtek.com 5 RT9184A Dropout Voltage vs. Output Current Power Supply Rejection Ratio 0 800 CIN1 = 10uF COUT1 = 10uF 700 -10 TJ = 125°C PSRR (dB) Dropout Voltage (mA) 600 500 TJ = 25°C 400 TJ = -40°C 300 VIN1 = 5V CIN1 = 10uF COUT1 = 10uF -20 -30 -40 100mA 1mA 200 -50 100 -60 0 0 100 200 300 400 10 500 100 1k 1000 10k 10000 100k 100000 1M 1000000 Frequency (Hz) Output Current (mA) Range of Stable ESR Line Transient Regulation Input Voltage Deviation (V) 10 10uF Unstable Range Output Voltage Deviation (mV) Output Capacitor ESR ( Ω ) 100 1 Stable Range 1uF 0.1 VIN1 = 3 to 4V VIN2 = 5V CIN1 = 10uF COUT1 = 10uF 4 3 ≈ ≈ 2 0 -2 0.01 0 100 200 300 400 500 Time (1ms/Div) Output Current (mA) Output Noise Output Noise Signal (uV) VIN1 = 5V ILOAD = 100mA CIN1 = 1uF COUT1 = 1uF 4 3 2 0 -2 F = 10Hz to 100kHz Time (1ms/Div) www.richtek.com 6 DS9184A-09 April 2011 RT9184A Application Information Like any low-dropout regulator, the RT9184A requires input and output decoupling capacitors. The device is specifically designed for portable applications requiring minimum board space and smallest components. 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. 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 1cm 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 RT9184A is designed specifically to work with very small ceramic output capacitors. The recommended minimum capacitance (temperature characteristics X7R or X5R) are 1μF to 4.7μF range with 10mΩ to 50mΩ range ceramic capacitors between each 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.) DS9184A-09 April 2011 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) Voltage 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-tosource on-resistance, RDS(ON), multiplied by the load current : VDROPOUT = VIN − VOUT = RDS(ON) × IOUT Current Limit The RT9184A monitors and controls the PMOS' gate voltage, limiting the output current to 500mA (min.). 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. Capacitor Characteristics 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). Aluminum electrolytics also typically have large temperature variation of capacitance value. www.richtek.com 7 RT9184A 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. Tantalum : 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. Tantalums also have good temperature stability: a good quality tantalum will typically show a capacitance value that varies less than 10~15% 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. www.richtek.com 8 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. PCB 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”. DS9184A-09 April 2011 RT9184A 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. 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 : GND + + VOUT1 VIN2 + GND + VIN1 VOUT2 GND SOP-8 Board Layout DS9184A-09 April 2011 www.richtek.com 9 RT9184A Outline Dimension H A M J 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 3.988 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.508 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.050 0.254 0.002 0.010 J 5.791 6.200 0.228 0.244 M 0.400 1.270 0.016 0.050 8-Lead SOP Plastic 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 DS9184A-09 April 2011