|
If you can't view the Datasheet, Please click here to try to view without PDF Reader . |
|
Datasheet File OCR Text: |
RT9179 Adjustable, 300mA LDO Regulator with Enable General Description 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. 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. Features 300mV Dropout @ 300mA 150A Low Ground Pin Current Excellent Line and Load Regulation <1A Standby Current in Shutdown Mode Guaranteed 300mA Output Current Stable with 1F 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 Applications Battery-Powered Equipment Graphic Card Peripheral Cards PCMCIA Card Ordering Information RT9179 Package Type B : SOT-23-5 Operating Temperature Range P : Pb Free with Commercial Standard G : Green (Halogen Free with Commercial Standard) Marking Information For marking information, contact our sales representative directly or through a RichTek distributor located in your area, otherwise visit our website for detail. Note : RichTek Pb-free and Green 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. 100% matte tin (Sn) plating. Pin Configurations (TOP VIEW) VIN GND EN 1 2 3 4 ADJ 5 VOUT SOT-23-5 DS9179-08 March 2007 www.richtek.com 1 RT9179 Typical Application Circuit RT9179CB VIN Chip Enable C3 0.1uF C1 1uF EN GND ADJ R2 VIN VOUT R1 C2 1uF VOUT VOUT = 1.175 x ( 1+ 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 1 2 3 VIN GND EN Power Input Voltage Ground Chip Enable (Active High) Adjust Output Voltage. The output voltage is set by the internal feedback resistors when 4 5 ADJ VOUT this pin grounded. If external feedback resistors are applied, the output voltage will be: VOUT = 1.175 x (1 + Output Voltage R1 ) Volts R2 Pin Function Function Block Diagram Current-Limit and Thermal Protection Thermal SHDN + _ Error Amplifier MOS Driver VOUT ADJ GND EN Shutdown and Logic Control VIN 1.175V VREF www.richtek.com 2 DS9179-08 March 2007 RT9179 Absolute Maximum Ratings (Note 1) Supply Input Voltage -------------------------------------------------------------------------------------------------- 6V Power Dissipation, PD @ TA = 25C SOT-23-5 ---------------------------------------------------------------------------------------------------------------- 0.4W Package Thermal Resistance (Note 7) SOT-23-5, JA ----------------------------------------------------------------------------------------------------------- 250C/W Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260C Junction Temperature ------------------------------------------------------------------------------------------------- 150C Storage Temperature Range ---------------------------------------------------------------------------------------- -65C to 150C ESD Susceptibility (Note 2) HBM (Human Body Mode) ------------------------------------------------------------------------------------------ 2kV MM (Machine Mode) -------------------------------------------------------------------------------------------------- 200V Recommended Operating Conditions (Note 3) Supply Input Voltage -------------------------------------------------------------------------------------------------- 3V to 5.5V Enable Input Voltage -------------------------------------------------------------------------------------------------- 0V to 5.5V Junction Temperature Range ---------------------------------------------------------------------------------------- -40Cto 125C Electrical Characteristics (VIN = VOUT + 0.7V, IOUT = 10A, CIN = COUT = 1F (Ceramic), TA = 25C unless otherwise specified) Parameter Reference Voltage Tolerance Adjust Pin Current Output Voltage Range Quiescent Current Standby Current Current Limit Dropout Voltage Line Regulation Thermal Shutdown Temperature Thermal Shutdown Hysteresis EN Threshold EN Current Logic-Low Voltage Logic-High Voltage (Note 4) (Note 5) (Note 6) Symbol VREF IADJ VOUT IQ ISTBY ILIM VDROP VLINE TSD TSD VIL VIH IEN Test Conditions Min 1.163 -1.175 Typ 1.175 --150 --10 300 0.001 170 40 ---- Max 1.187 10 4.5 -1 -----0.4 -10 Units V nA V A A A mV %/V C C V nA Enabled, IOUT = 0mA VIN = 5.5V, Shutdown IOUT = 10mA IOUT = 300mA VOUT + 0.7V < VIN < 5.5V --0.5 ------ VIN = 3.3V, Shutdown VIN = 3.3V, Enable VIN = 5.5V, Enable -2.0 -- DS9179-08 March 2007 www.richtek.com 3 RT9179 Note 1. Stresses listed as the abovez "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. Devices are ESD sensitive. Handling precaution recommended. Note 3. The device is not guaranteed to function outside its operating conditions. Note 4. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) - 100mV. 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. JA is measured in the natural convection at T A = 25C on a low effective thermal conductivity test board of JEDEC 51-3 thermal measurement standard. www.richtek.com 4 DS9179-08 March 2007 RT9179 Typical Operating Characteristics Output Voltage vs. Temperature 3.29 ADJ Pin Voltage vs. Temperature 1.2 ADJ Pin Voltage (V) 3.28 VIN = 5V R1 = 1.8K R2 = 1k VIN = 5V 1.19 1.18 1.17 1.16 1.15 1.14 Output Voltage (V) 3.27 3.26 3.25 3.24 -50 -25 0 25 50 75 100 125 -50 -25 0 25 50 75 100 125 Temperature (C) Temperature (C) Quiescent Current vs. Temperature 160 Quiescent Current vs. Input Voltage 150 VIN = 5V 150 Quiescent Current (uA)1 Quiescent Current (uA) 140 140 130 130 120 -50 -25 0 25 50 75 100 125 120 3 3.5 4 4.5 5 5.5 Temperature (C) Input Voltage (V) -20 -30 PSRR Dropout Voltage vs. Io 400 350 VOUT = 3.3V TJ = 125C TJ = 25C -50 -60 -70 -80 -90 Dropout Voltage (mV) -40 300 250 200 150 100 50 0 PSRR (dB) TJ = -40C VIN = 4V IL = 10mA COUT = 1uF (X7R) 10 100 -100 1K 1000 10K 10000 100K 100000 0 50 100 150 200 250 300 Frequency (Hz) DS9179-08 March 2007 Io (mA) www.richtek.com 5 RT9179 Current Limit vs. Temperature 1 VIN = 5V 0.95 4 2 Output Short-Circuit Protection Source Current (A) Current Limit (A) 1 0.8 0.6 0.4 0.2 0 VIN = 5V R1 = 1.8k R2 = 1k CIN = 1uF CO = 1uF 0.9 0.85 0.8 0.75 0.7 -50 -25 0 25 50 75 100 125 Temperature (C) Time (1ms/Div) Line Transient Regulation Input Voltage Deviation(V) 7 6 5 4 20 Load Transient Regulation 60 Output Voltage Deviation(mV) VIN = 4V to 5V ILOAD : 150mA R1=1.8K, R2=1K CIN=1uF(Electrolytic) CO=1uF(Electrolytic) 40 20 0 -20 0.2 0.1 0 -0.1 VIN = 5V, R1 = 1.8K R2 = 1K CIN = 1uF(Ceramic) CO = 2.2uF(Ceramic) Output Voltage Deviation(mV) 10 0 -10 - 20 Load Current(A) Time (100us/Div) Time (100us/Div) Enable Threshold Voltage vs. Temperature 1 Enable Response Enable Voltage(V) 6 4 2 0 VIN =5V R1 =1.8k R2 =1k CIN =1uF CO =1uF Enable Threshold Voltage (V)1 0.9 0.8 VOUT TURN ON 0.7 VOUT TURN OFF Output Voltage Deviation(V) 3 2 1 0 0.6 ILOAD : 150mA 0.5 -50 -25 0 25 50 75 100 125 Temperature (C) www.richtek.com 6 Time (100us/Div) DS9179-08 March 2007 RT9179 Application Information Region of Stable C OUT ESR () C OUT 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. Input Capacitor An input capacitance of 1F 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 1F 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 1F to 4.7F range with 10m to 50m 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 3.3F.) Region of Stable COUT ESR vs. Load Current 100 10 Region of Instable 1 0.1 Region of Stable 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) x 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 DS9179-08 March 2007 RT9179 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. 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 10F to 100F 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 10m). 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 to 15% across the full temperature range of 125C to -40C. 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 25C down to -40C. 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. www.richtek.com 8 DS9179-08 March 2007 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 125C. 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. PD = (VIN - VOUT) IOUT + VIN IGND The final operating junction temperature for any set of conditions can be estimated by the following thermal equation : PD (MAX) = ( TJ (MAX) - TA ) / JA 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 (JA) for SOT-23-5 package at recommended minimum footprint is 250C/W (JA is layout dependent). Visit our website in which "Recommended Footprints for Soldering Surface Mount Packages" for detail. 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". 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. GND EN + VIN + VOUT + 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 GND GND SOT-23-5 Board Layout DS9179-08 March 2007 www.richtek.com 9 RT9179 Outline Dimension H D L C B b A A1 e Symbol A A1 B b C D e H L Dimensions In Millimeters Min 0.889 0.000 1.397 0.356 2.591 2.692 0.838 0.102 0.356 Max 1.295 0.152 1.803 0.559 2.997 3.099 1.041 0.254 0.610 Dimensions In Inches Min 0.035 0.000 0.055 0.014 0.102 0.106 0.033 0.004 0.014 Max 0.051 0.006 0.071 0.022 0.118 0.122 0.041 0.010 0.024 SOT-23-5 Surface Mount Package Richtek Technology Corporation Headquarter 5F, No. 20, Taiyuen Street, Chupei City Hsinchu, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Richtek Technology Corporation Taipei Office (Marketing) 8F, No. 137, Lane 235, Paochiao Road, Hsintien City Taipei County, Taiwan, R.O.C. Tel: (8862)89191466 Fax: (8862)89191465 Email: marketing@richtek.com www.richtek.com 10 DS9179-08 March 2007 |
Price & Availability of RT9179PB |
|
|
All Rights Reserved © IC-ON-LINE 2003 - 2022 |
[Add Bookmark] [Contact Us] [Link exchange] [Privacy policy] |
Mirror Sites : [www.datasheet.hk]
[www.maxim4u.com] [www.ic-on-line.cn]
[www.ic-on-line.com] [www.ic-on-line.net]
[www.alldatasheet.com.cn]
[www.gdcy.com]
[www.gdcy.net] |