RT9185 Triple, Ultra-Fast CMOS LDO Regulator General Description The RT9185 series are an efficient, precise triplechannel CMOS LDO regulator specifically designed for mother-board application. The device is intended to powering the standby voltage in which 3.3V_PCI, 2.5V_Clock and 1.8V_ICH2 or 1.5V_ICH4 core voltage of the PC based computer system. Moreover, it is also optimized for CD/DVD-ROM, CD/RW, XDSL Router or IA equipments applications. The regulator outputs are capable of sourcing 1.5A, 0.8A and 0.3A of output current respectively. The RT9185 also works with low-ESR ceramic capacitors, reducing the amount of board space necessary for power applications. The other features include faster transient response, low dropout voltage, high output accuracy, current limiting and thermal shutdown protections. The RT9185 regulators are available in fused SOP-8, 5-lead TO-252 and 5-lead TO-263 packages. Features Fixed Output Voltages: 3.35V at 1.5A, 2.55V at 0.8A and 1.5V or 1.8V at 0.3A Low Quiescent Current (Typically 0.4mA) Operating Voltage Ranges: 3.5V~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 Applications Mother-board Power Supply CD/DVD-ROM, CD/RW XDSL Router IA Equipments Cable Modems Pin Configurations Ordering Information Part Number Pin Configurations RT9185 RT9185 CS (Plastic SOP-8) VOUT1 1 8 GND VDD 2 7 GND VOUT2 3 6 GND VOUT3 4 5 GND Package Type S : SOP-8 L5 : TO-252-5 M5 : TO-263-5 Operating Temperature Range C: Commercial Standard VOUT3 A : 1.8V B : 1.5V TOP VIEW RT9185 CL5 (Plastic TO-252-5) Other voltage versions please contact RichTek for detail. 1 2 3 4 5 VOUT1 VDD GND (TAB) VOUT2 5. VOUT3 TOP VIEW RT9185 CM5 (Plastic TO-263-5) 1 2 3 4 5 DS9185-02 July 2003 1. 2. 3. 4. 1. 2. 3. 4. 5. VOUT1 VDD GND (TAB) VOUT2 VOUT3 www.richtek.com 1 RT9185 Typical Application Circuit VOUT1 (3.35V / 1.5A) VOUT1 C2 4.7µF VOUT3 (1.5V or 1.8V / 0.3A) VOUT3 C4 1µF RT9185 VDD (5VSB) VDD GND VOUT2 (2.55V / 0.8A) VOUT2 C3 4.7µF C1 2.2µF Pin Description Pin Name Pin Function VOUT1 Channel 1 Output Voltage VDD Supply Input GND Common Ground VOUT2 Channel 2 Output Voltage VOUT3 Channel 3 Output Voltage Function Block Diagram Current Limiting Thermal VDD + _ Sensor _ + Error Amp VOUT1 Ref erence VDD + _ Current Limiting Current Limiting VDD + _ _ VOUT3 + Error Amp _ + Error Amp VOUT2 GND www.richtek.com 2 DS9185-02 July 2003 RT9185 Absolute Maximum Ratings (Note 1) Supply Input Voltage Package Thermal Resistance SOP-8, θJC TO-252-5, θJC TO-263-5, θJC Lead Temperature (Soldering, 10 sec.) Junction Temperature Storage Temperature Range ESD Susceptibility (Note 2) HBM MM 7V 20°C/W 10°C/W 5.5°C/W 260°C 150°C −65°C to 150°C 2kV 200V Recommended Operating Conditions (Note 3) Supply Input Voltage Junction Temperature Range 3.5V to 5.5V −40°C to 125°C Electrical Characteristics (VDD = 5V, CIN = 1µF, TA = 25°C, for each LDO unless otherwise specified) Parameter Output Voltage Accuracy Symbol Line Regulation (triple LDOs) Load Regulation (Note 4) Typ Max Units IOUT = 1mA 3.315 3.35 3.415 VOUT2 IOUT = 1mA 2.525 2.55 2.60 RT9185A 1.782 1.8 1.836 1.485 1.5 1.530 RT9185B IOUT = 1mA V ILIM1 RLOAD = 1Ω 1.5 1.9 -- ILIM2 RLOAD = 1Ω 0.8 1.3 -- ILIM3 RLOAD = 1Ω 0.3 0.5 -- IOUT = 0mA -- 0.4 0.8 mA ∆VDROP1 IOUT = 1.0A -- 600 1085 mV ∆VDROP2 IOUT = 0.8A -- 700 -- mV ∆VLINE IOUT = 1mA, VDD = 4V to 6V -- 2 10 mV ∆VLOAD1 VOUT1, 1mA < IOUT <1.0A -- 30 55 ∆VLOAD2 VOUT2, 1mA < IOUT <0.8A -- 30 55 ∆VLOAD3 VOUT3, 1mA < IOUT < 0.3A -- 20 45 Quiescent Current (triple LDOs) IDD (Note 5) Dropout Voltage Min VOUT1 VOUT3 Current Limiting Test Conditions A mV Temperature Coefficient TC -- 30 -- PPM Thermal Shutdown TSD 125 165 -- °C DS9185-02 July 2003 www.richtek.com 3 RT9185 Note 1. Stresses beyond 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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Note 2. Devices are ESD sensitive. Handling precaution recommended. The human body model is a 100pF capacitor discharged through a 1.5KΩ resistor into each pin. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. 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 1.5A, 0.8A and 0.3A for each LDO respectively. 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. www.richtek.com 4 DS9185-02 July 2003 RT9185 Typical Operating Characteristics Temperature Stability 600 4.2 VOUT1 = 3.3V VDD = 5V VOUT2 500 3.4 VOUT1 3 Iq (µA) Output Voltage (V) 3.8 Quiescent Current VOUT2 = 2.5V 2.6 2.2 400 VOUT3 300 VOUT3 = 1.8V/1.5V 1.8 1.4 -40 -35 -15 5 25 45 65 85 105 200 -40 -35 125 -15 Current Limit vs. Temperature -10 2.5 VOUT1 -20 VOUT2 -30 PSRR (dB) Current Limit (A) 2 1.5 1 VOUT3 85 105 125 TA=25°C VDD = 5V C1 =2.2µF, C2 = 4.7µF C3 =4.7µF, C4 = 1µF IO1, IO2, IO3 = 10mA -50 VOUT3 VOUT2 VOUT1 -80 -15 5 25 45 65 85 105 10 10 125 100 100 Dropout Valtage vs. Temperature 10K 10000 100K 100000 1M 10000 Short Thermal Shutdown VDD = 5V 3 VOUT2 = 2.5V 0.8 1K 1000 Frequency (Hz) Temperature(°C) ( C) VDD = 5V C1 = 2.2µF TA = 25°C 2.5 VOUT1 = 3.3V ILoad1 (A) Dropout Valtage (V) 65 PSRR -70 0 -35 -40 45 -40 -60 0.5 1 25 Temperature (°C) Temperature (°C C) VDD = 5V 5 0.6 0.4 2 1.5 1 0.5 0 0.2 -35 -40 -15 5 25 45 65 Temperature (°C) ( C) DS9185-02 July 2003 85 105 125 Time 25mS/Div www.richtek.com 5 RT9185 TA = 25°C 0 -50 0 ≈ 1 0 Line Transient Response Output Voltage Deviation (mV) C1=2.2µF C4=1µF 0 -50 ≈ 400 200 0 Input Voltage Deviation (V) Load Current (mA) Output Voltage Deviation (mV) Input Voltage Deviation (V) -50 Load Transient Response ≈ C1 = 2.2µF C2 = 4.7µF IOUT1 = 500mA VDD = 4.5V to 5.5V 10 VOUT1 = 3.3V 5 TA = 25°C 0 -5 ≈ ≈ 5.5 4.5 Time 500µS/Div Time 100µS/Div Line Transient Response Line Transient Response VDD = 4.5V to 5.5V 20 VOUT2 = 2.5V TA = 25°C C1 = 2.2µF C3 = 4.7µF IOUT1 = 400mA 0 -10 ≈ ≈ 5.5 4.5 Time 100µS/Div 6 0 Time 500µS/Div 50 www.richtek.com TA = 25°C Time 500µS/Div VDD=5V 100 VOUT3=1.5V TA=25°C 10 50 ≈ Load Current (A) 1 C1 = 2.2µF C3 = 4.7µF VDD = 5V 100 VOUT2 = 2.5V ≈ Output Voltage Deviation (mV) Load Current (A) ≈ Output Voltage Deviation (mV) Output Voltage Deviation (mV) C1 = 2.2µF C2 = 4.7µF VDD = 5V 100 VOUT1 = 3.3V 50 Load Transient Response Input Voltage Deviation (V) Output Voltage Deviation (mV) Load Transient Response C1 = 2.2µF C4 = 4.7µF IOUT1 = 150mA VDD = 4.5V to 5.5V 20 VOUT1 = 1.5V 10 TA = 25°C 0 -10 ≈ ≈ 5.5 4.5 Time 100µS/Div DS9185-02 July 2003 RT9185 Power Dissipation vs. Copper Area Power Dissipation vs. Copper Area 500 500 TJ = 125°C 2 Copper Area (mm ) 2 Copper Area (mm ) TJ = 125°C 400 300 200 TA = 65°C 100 400 300 200 TA = 25°C TA = 50°C TA = 50°C 100 TA = 65°C SOP-8 0 TA = 25°C TO-252 0 1 1.5 2 2.5 3 Power Dissipation (W) 2 2.5 3 3.5 4 4.5 5 Power Dissipation (W) Power Dissipation vs. Copper Area 2 Copper Area (mm ) 300 TJ = 125°C 250 TA = 65°C TA = 50°C TA = 25°C 200 150 TO-263-5 100 2.5 3.5 4.5 5.5 6.5 7.5 8.5 Power Dissipation (W) DS9185-02 July 2003 www.richtek.com 7 RT9185 Applications Information Like any low-dropout regulator, the RT9185 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 ≅2.2µF 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 ≅2.2µF over the entire operating temperature range. OUTPUT CAPACITOR The RT9185 is designed specifically to work with very small ceramic output capacitors. The recommended minimum capacitance (temperature characteristics X7R, X5R, Z5U, or Y5V) are 2.2µF 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. www.richtek.com 8 The output capacitor’s ESR is critical because it forms a zero to provide phase lead which is required for loop stability. 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-to-source on-resistance, RDS(ON), multiplied by the load current: VDROUPOUT = VDD – VOUT = RDS(ON) × IOUT CURRENT LIMIT The RT9185 monitors and controls the PMOS’ gate voltage, limiting the output current to 1.9A, 1.3A and 0.5A (typ) respectively. The outputs 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, DS9185-02 July 2003 RT9185 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. 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. 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. 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. 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. DS9185-02 July 2003 www.richtek.com 9 RT9185 THERMAL CONSIDERATIONS The RT9185 is a triple channel CMOS regulator designed to provide two output voltage from one package. Each output pin the RT9185 can deliver a current of up to 1.5A, 0.8A and 0.3A respectively 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. Each regulator contributes power dissipation to the overall power dissipation of the package. Power dissipation can be calculated based on the output current and the voltage drop across each regulator. PD = (VDD –VOUT1) IOUT1 + (VDD – VOUT2) IOUT2 + (VDD – VOUT3) IOUT3 + VIN IGND Although the device is rated for 1.5A, 0.8A and 0.3A of output current, the application may limit the amount of output current based on the total power dissipation and the ambient temperature. The final operating junction temperature for any set of conditions can be estimated by the following thermal equation: PD (MAX) = ( TJ (MAX) − TA ) / θJA Where TJ (MAX) is the maximum junction temperature of the die (125°C) and TA is the maximum ambient temperature. θJA is the thermal resistance from the junction to the surrounding environment which is combined with θJC + θCA. Where θJC is junction to case thermal resistance which for fused SOP-8 is 20°C/W, TO-252-5 is 10°C/W and TO-263-5 is 5.5°C/W, θCA is case to ambient thermal resistance which depend on PCB board area and air flow. PCB LAYOUT The RT9185 is a fixed output voltage regulator which the voltage are sensed at the output pin. A long PCB trace to load will cause a voltage drop between load and RT9185. Be careful with PCB layout which minimum the output trace length and maximum the trace width. www.richtek.com 10 RT9185 VDD + VOUT1 VOUT3 VOUT2 GND TRACE RESISTANCE RP IO DROP = I O * RP + LOAD GND PLANE The GND pin of the RT9185 performs the dual function of providing an electrical connection to ground and channeling heat away. Connect the GND pin to ground using a large pad or ground plane. 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 VDD, 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. 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: DS9185-02 July 2003 RT9185 GND + + VOUT3 VOUT1 + GND + VDD VOUT2 GND SOP-8 Board Layout GND + + VOUT1 VOUT3 + GND + VDD VOUT2 GND TO-252-5/TO-263-5 Board Layout DS9185-02 July 2003 www.richtek.com 11 RT9185 Package Information H A M J B F C I D Symbol Dimensions In Millimeters Dimensions In Inches 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 0.178 0.254 0.007 0.010 I 0.102 0.254 0.004 0.010 J 5.791 6.198 0.228 0.244 M 0.406 1.270 0.016 0.050 8–Lead SOP Plastic Package www.richtek.com 12 DS9185-02 July 2003 RT9185 E C2 b3 L3 V D H L b P L2 A Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 2.184 2.388 0.086 0.094 b 0.381 0.889 0.015 0.035 b3 4.953 5.461 0.195 0.215 C2 0.457 0.889 0.018 0.035 D 5.334 6.223 0.210 0.245 E 6.350 6.731 0.250 0.265 H 9.000 10.414 0.354 0.410 L 0.508 1.780 0.020 0.070 L2 L3 P V 0.020 Ref. 0.508 Ref. 0.889 2.032 0.035 1.270 Ref. 4.572 0.080 0.050 Ref. -- 0.180 -- 5-Lead TO-252 Plastic Package DS9185-02 July 2003 www.richtek.com 13 RT9185 C D U B V E L1 L2 b e b2 A Symbol Dimensions In Millimeters Dimensions In Inches Min Max Min Max D 9.652 10.668 0.380 0.420 B 1.143 1.676 0.045 0.066 E 8.128 9.652 0.320 0.380 A 4.064 4.826 0.160 0.190 C 1.143 1.397 0.045 0.055 U 6.223 Ref. 0.245 Ref. V 7.620 Ref. 0.300 Ref. L1 14.605 15.875 0.575 0.625 L2 2.286 2.794 0.090 0.110 b 0.660 0.914 0.026 0.036 b2 0.305 0.584 0.012 0.023 e 1.524 1.829 0.060 0.072 5-Lead TO-263 Plastic Surface Mount Package www.richtek.com 14 DS9185-02 July 2003 RT9185 DS9185-02 July 2003 www.richtek.com 15 RT9185 RICHTEK TECHNOLOGY CORP. RICHTEK TECHNOLOGY CORP. Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)89191466 Fax: (8862)89191465 Email: [email protected] www.richtek.com 16 DS9185-02 July 2003