RT9177 Preliminary Ultra-Low-Noise 200mA LDO Regulator General Description Features The RT9177 is a 200mA low dropout and low noise z micro-power regulator suitable for portable RF z Ultra-Low-Noise(150nV/ Hz ) for RF Application 1µ µF Ceramic COUT Stable applications. The output voltage accuracy within z Low Dropout Voltage(220mV @ 200mA) ±2% and range from 2.4V to 3.2V in 100mV z Low Operation Current - 80µ µA Typical increments could be selected. It is designed for z Shutdown Function using very low ESR output capacitor. Its output z Low Temperature Coefficient remains stable even in using 1µF ceramic as its z Current and Thermal Limiting output capacitor. z Custom Voltage Available z SOT-25 Package Using an internal PMOS as the pass device cause that don’t need extra GND current in heavy load and Applications dropout conditions. In shutdown mode, nearly zero z Cellular Telephones operation current cause the IC is suitable for z Laptop, Notebook, and Palmtop Computers battery-power devices. Other features including z Battery-powered Equipment current limiting, over temperature protection and z Hand-held Equipment adding a capacitor in bypass pin to improve its noise performance are functional. Pin Configurations Ordering Information Part Number RT9177- RT9177- CB Package type B : SOT-25 Type I BR : SOT-25 Type II Operating temperature range C: Commercial standard Output voltage 24 : 2.4V 25 : 2.5V : : 31 : 3.1V 32 : 3.2V Pin Configurations 4 5 (Plastic SOT-25) TOP VIEW 1 RT9177- CBR 2 4 5 (Plastic SOT-25) 3 TOP VIEW 1 2 3 1. 2. 3. 4. 5. IN GND SHDN BP OUT 1. 2. 3. 4. 5. OUT GND IN SHDN BP Typical Application Circuit RT9177 VIN IN CIN 1µF ON OFF DS9177-00 Feb. 2001 VOUT OUT GND COUT 1µF SHDN CBP 10nF www.richtek-ic.com.tw 1 RT9177 Preliminary Marking Infromation Part Number Marking Part Number Marking RT9177-24CB H9 RT9177-24CBR P9 RT9177-25CB HA RT9177-25CBR PA RT9177-26CB HB RT9177-26CBR PB RT9177-27CB HC RT9177-27CBR PC RT9177-28CB HD RT9177-28CBR PD RT9177-29CB HE RT9177-29CBR PE RT9177-30CB HF RT9177-30CBR PF RT9177-31CB HG RT9177-31CBR PG RT9177-32CB HH RT9177-32CBR PH Pin Description Pin Name Pin Function IN IC Power Pin GND IC GND SHDN Active Low Shutdown Input BP Reference Noise Bypass OUT Regulator Output Function Block Diagram Shutdown and Logic Control SHDN BP IN VREF + _ Error Amp MOS Driver Current-Limit and OUT Thermal Protection GND www.richtek-ic.com.tw 2 DS9177-00 Feb. 2001 RT9177 Preliminary Absolute Maximum Ratings z Input Voltage VIN z Power Dissipation 7V SOT-25 0.25W z Operating Junction Temperature Range −40°C to 125°C z Storage Temperature Range −65°C to 150°C z Thermal Resistance RθJA z 250°C/W Lead Temperature (Soldering 5 sec.) 260°C Electrical Characteristics (VIN = 5.0V, CIN = 1µF, COUT = 1µF, TA = 25°C, unless otherwise specified) Parameter Symbol Input Voltage VIN Output Voltage Accuracy ∆VOUT Maximum Output Current IMAX Current Limit ILIMIT GND Pin Current IG (Note) Test Conditions Min Typ Max Units 2.5 -- 6 V -2 -- +2 % 200 -- -- mA RLOAD = 1 Ohm -- 300 -- mA No Load -- 80 150 IOUT = 200mA -- 90 150 IOUT = 1mA -- 1.1 5 IOUT = 50mA -- 55 100 IOUT = 200mA -- 220 300 -0.2 -- +0.2 %/V -- 0.01 0.04 %/mA IL = 1mA µA Dropout Voltage (VOUT(Nominal)≥3.0V Version) VDROP Line Regulation ∆VLINE Load Regulation ∆VLOAD IOUT = 0mA to 200mA SHDN Input High Threshold VIH VIN = 3V to 5.5V 1.0 -- -- V SHDN Input Low Threshold VIL VIN = 3V to 5.5V -- -- 0.4 V SHDN Bias Current ISD -- -- 100 nA Shutdown Supply Current IGSD -- 0.01 1 µA Thermal Shutdown Temperature TSD -- 150 -- °C Output Noise eno CBP = 10nF, COUT = 10µF -- 150 -- nV/ Hz Ripple Rejection PSRR F = 100Hz, CBP = 10nF, COUT = 10µF -- 68 -- dB VIN = (VOUT+0.15) to 6V, IOUT = 1mA VOUT = 0V mV Notes: Dropout voltage definition: VIN - VOUT when VOUT is 50 mV below the value of VOUT at VIN = VOUT + 0.5V DS9177-00 Feb. 2001 www.richtek-ic.com.tw 3 RT9177 Preliminary Typical Operating Characteristics GND Current vs. Load 75 Output Voltage Variation vs. Load 0.2 TA = 25°C 74 0.0 73 -0.2 71 ∆VOUT (%) IG (uA) 72 70 69 68 -0.4 -0.6 -0.8 67 -1.0 66 TA = 25°C 65 0 50 100 150 200 -1.2 250 0 IOUT (mA) VOUT vs. VIN 50 100 150 200 IOUT (mA) 250 Dropout Voltage vs. Output Current 3.10 250 80°C Dropout Voltage (mV) 3.00 VOUT (V) 2.90 2.80 2.70 20mA 50mA 100mA 2.60 2.50 2.5 200 25°C 150 100 50 VOUT = 3V TA = 25°C 200mA 3.0 3.5 4.0 4.5 VOUT = 3V 0 20 5.0 50 80 110 140 170 200 Output Current (mA) VIN (V) Output Voltage Variation vs. Temperature GND Current vs. Temperature 0.4 72 No Load 0.3 71 0.2 70 200mA 0.0 69 IG (uA) ∆VOUT (%) 0.1 -0.1 -0.2 68 67 -0.3 66 -0.4 65 -0.5 -0.6 64 -10 www.richtek-ic.com.tw 4 20 50 80 Temperature ( °C) 110 140 -40 -10 20 50 80 Temperature ( C) 110 140 ° -40 DS9177-00 Feb. 2001 RT9177 Preliminary 0 -30 -10 -40 -20 -50 10mA PSRR (dB) PSRR (dB) PSRR -20 -60 -70 100mA -80 -100 10 100 1K 10K 100K -30 -40 -50 10mA -60 -70 VOUT = 3V TA = 25°C CBP = 470pF -90 PSRR -90 1M Frequency (Hz) 100mA 10 8 0 10 1 40 50 5 -50 30 - 20 CIN = 1uF TAN 10 COUT = 4.7uF TAN - CBP = 10nF Load = 10mA Sampling Rate = 250KHz - 0 0 25 50 75 Frequency (KHz) 100 125 6 8 CIN = 1uF TAN COUT = 4.7uF TAN CBP = 470nF Load = 10mA Sampling Rate = 250KHz 20 0 0 25 DS9177-00 Feb. 2001 50 75 Frequency (KHz) 100 10 -50 30 -50 20 ≈ CIN = 1uF TAN -15 COUT = 4.7uF TAN CBP = 10nF Load = 100mA Sampling Rate = 250KHz 10 -25 0 0 0 -250 40 8 50 10 0 ≈ 6 25 50 75 -35 125 100 Frequency (KHz) Noise Signal & Spectrum Distribution 250 0 80 Time (mS) 4 40 50 -500 -750 -100 125 Noise Signal (uV) 4 100 250 -250 60 Noise Level (uV) 2 2 150 2 Time (mS) 4 6 8 10 100 250 25 80 0 0 -250 60 Noise Level (uV) Noise Signal (uV) 0 1M 50 150 Noise Signal & Spectrum Distribution Time (mS) 100K Noise Signal (uV) 6 50 150 ≈ 10K Noise Signal & Spectrum Distribution Noise Signal (uV) 4 1K Noise Level (uV) Time (mS) Noise Level (uV) 2 100 Frequency (Hz) Noise Signal & Spectrum Distribution 0 VOUT = 3V TA = 25°C CBP = 10nF -80 -25 ≈ CIN = 1uF TAN 40 COUT = 4.7uF TAN CBP = 470nF Load = 100mA Sampling Rate = 250KHz 20 0 0 25 50 75 Frequency (KHz) 100 -50 -75 -10 125 www.richtek-ic.com.tw 5 RT9177 Preliminary Load Transitne Response from 1mA to 100mA Load Transitne Response from 100mA to 1mA 3 2 4 100mA Load CIN = 1µF COUT = 1µF VIN = 5V TA = 25°C 1mA Load 1 0 -1 -2 -10 10 30 50 Time (uS) www.richtek-ic.com.tw 6 70 90 Output Voltage Variation (%) Output Voltage Variation (%) 4 3 100mA Load 1mA Load 2 CIN = 1µF COUT = 1µF VIN = 5V TA = 25°C 1 0 -1 -2 -10 10 30 50 70 90 Time (uS) DS9177-00 Feb. 2001 RT9177 Preliminary Application Guides Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors COUT = 4.7µF used with the RT9177 must be carefully selected for regulator stability and performance. Using a capacitor whose value is >1µF on the RT9177 Ω COUT = 1µF input and the amount of capacitance can be increased without limit. The input capacitor must be located a distance of not more than 0.5" from the input pin of the IC and returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor. The capacitor with larger value and lower ESR (equivalent series resistance) provides better PSRR and line-transient response. Fig. 1 The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all LDOs application. The RT9177 is designed specifically to work with low ESR ceramic output capacitor in spacesaving and performance consideration. Using a ceramic capacitor whose value is at least 1µF with ESR is > 5mΩ on the RT9177 output ensures stability. The RT9177 still works well with output capacitor of other types due to the wide stable ESR range. Fig.1 Tantalum capacitors maybe suffer failure due to surge current when it is connected to a low-impedance source of power (like a battery or very large capacitor). If a tantalum capacitor is used at the input, it must be guaranteed to have a surge current rating sufficient for the application by the manufacture. shows the curves of allowable ESR range as a Use a 10nF bypass capacitor at BP for low output function of load current for various output voltages and voltage noise. The capacitor, in conjunction with an capacitor larger internal 200KΩ resistor, which connects bypass pin capacitance can reduce noise and improve load- and the band-gap reference, creates an 80Hz low- transient response, stability, and PSRR. The output pass filter for noise reduction. Increasing the capacitor should be located not more than 0.5" from capacitance will slightly decrease the output noise, the VOUT pin of the RT9177 and returned to a clean but increase the start-up time. The capacitor analog ground. connected to the bypass pin for noise reduction must values. Output capacitor of Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It may be necessary to use 2.2µF or more to ensure stability at temperatures below -10°C in this case. Also, tantalum capacitors, 2.2µF or more may be needed to have very low leakage. This capacitor leakage current causes the output voltage to decline by a proportional amount to the current due to the voltage drop on the internal 200KΩ resistor. Fig. 2 shows the power on response. maintain capacitance and ESR in the stable region for strict application environment. DS9177-00 Feb. 2001 www.richtek-ic.com.tw 7 RT9177 Preliminary Internal P-Channel Pass Transistor T The RT9177 features a typical 1.1Ω P-channel MOSFET CB = 470pF pass transistor. It provides several advantages over similar designs using PNP pass CH1 1> 2.2nF transistors, including longer battery life. The P-channel 10nF MOSFET requires no base drive, which reduces quiescent current considerably. PNP-based regulators waste considerable current in dropout when the pass transistor saturates. They also use high base-drive CH2 2> TT currents under large loads. The RT9177 does not VIN = 3.6V, CIN = 1µF, COUT = 4.7µF suffer from these problems and consume only 80µA of 500µS/Div CH1: 2V/div; CH2 = VOUT, 500mV/div quiescent current whether in dropout, light-load, or heavy-load applications. Fig. 2 Input-Output (Dropout) Voltage Load-Transient Considerations The RT9177 load-transient response graphs (see Typical Operating Characteristics) show two components of the output response: a DC shift from the output impedance due to the load current change, and the transient response. The DC shift is quite small due to the excellent load regulation of the IC. Typical output voltage transient spike for a step change in the load current from 1mA to 100mA is tens mV, depending on the ESR of the output capacitor. Increasing the output capacitor’s value and decreasing the ESR attenuates the overshoot. A regulator’s minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this will determine the useful end-of-life battery voltage. Because the RT9177 uses a Pchannel MOSFET pass transistor, the dropout voltage is a function of drain-to-source on-resistance [Rds (on)] multiplied by the load current. Reverse Current Path The power transistor used in the RT9177 has an inherent diode connected between the regulator Shutdown Input Operation input and output (see Fig.3). If the output is forced The RT9177 is shutdown by pulling the SHDN input above the input by more than a diode-drop, this low, and turned on by driving the input high. If this diode will become forward biased and current will feature is not to be used, the SHDN input should be flow from the VOUT terminal to VIN. This diode will tied to VIN to keep the regulator on at all times (the also be turned on by abruptly stepping the input SHDN input must not be left floating). voltage to a value below the output voltage. To To ensure proper operation, the signal source used to drive the SHDN input must be able to swing above and below the specified turn-on/turn-off voltage thresholds which guarantee an ON or OFF state (see Electrical Characteristics). The ON/OFF signal may come from either CMOS output, or an open-collector output with pull-up resistor to the RT9177 input voltage or another logic supply. The high-level voltage may exceed the prevent regulator mis-operation, a Schottky diode should be used in any applications where input/output voltage conditions can cause the internal diode to be turned on (see Fig.4). As shown, the Schottky diode is connected in parallel with the internal parasitic diode and prevents it from being turned on by limiting the voltage drop across it to about 0.3V. < 100 mA to prevent damage to the part. RT9177 input voltage, but must remain within the absolute maximum ratings for the SHDN pin. www.richtek-ic.com.tw 8 DS9177-00 Feb. 2001 Preliminary RT9177 Current Limit and Thermal Protection The RT9177 is included a current limit circuit used to monitor and control the pass transistor’s gate voltage to limit the output current to 300mA in typical and VIN thermal-overload protection circuit used to limit total VOUT power dissipation. When the junction temperature exceeds TJ = 150°C, the thermal sensor signals the shutdown logic to turn off the pass transistor and allow Fig. 3 the IC to cool down. The thermal sensor will turn on the pass transistor again after the IC’s junction temperature cool down to 120°C. This will cause a pulsing output during continuous thermal-overload conditions. Thermal-overloaded protection is designed VIN to protect the RT9177 in the event of fault conditions. VOUT Do not exceed the absolute maximum junctiontemperature rating of TJ = 125°C for continuous operation. The output can be shorted to ground for an indefinite amount of time without damaging the part by Fig. 4 cooperation of current limit and thermal protection. Operating Region and Power Dissipation The maximum power dissipation of RT9177 depends on the thermal resistance of the case and circuit board, the temperature difference between the die junction and ambient air, and the rate of airflow. The power dissipation across the device is P = IOUT (VIN VOUT). The maximum power dissipation is: PMAX = (TJ - TA) /θja where TJ - TA is the temperature difference between the RT9177 die junction and the surrounding environment, θja is the thermal resistance from the junction to the surrounding environment. The GND pin of the RT9177 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. DS9177-00 Feb. 2001 www.richtek-ic.com.tw 9 RT9177 Preliminary Package Information D 5 4 C B 1 3 b θ1 H A θ3 e Symbols θ2 L A1 Dimensions In Millimeters Dimensions In Inches Min Typ Max Min Typ Max A 1.000 1.100 1.300 0.039 0.043 0.051 A1 0.000 -- 0.100 -- -- 0.004 B 1.400 1.600 1.800 0.055 0.063 0.071 C 2.600 2.800 3.000 0.102 0.110 0.118 D 2.700 2.900 3.100 0.106 0.114 0.122 H 0.100 0.150 0.250 0.004 0.006 0.010 L 0.300 0.450 0.600 0.012 0.018 0.024 b 0.300 0.400 0.500 0.012 0.016 0.020 e -- 0.950 -- -- 0.037 -- θ1 2° -- 8° -- -- -- θ2 5° -- 10° -- -- -- θ3 -- -- 10° -- -- -- 5-Lead SOT- 25 Surface Mount Package www.richtek-ic.com.tw 10 DS9177-00 Feb. 2001 Preliminary DS9177-00 Feb. 2001 RT9177 www.richtek-ic.com.tw 11 RT9177 RichTek Technology Corp. RichTek Technology Corp. Headquarter Taipei Office (Marketing) 6F, No. 35, Hsintai Road, Chupei City 4F-1, No. 127, Lane 235, Paochiao Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5510047 Fax: (8863)5537749 Tel: (8862)89191466 Fax: (8862)89191465 Email: [email protected] www.richtek-ic.com.tw 12 DS9177-00 Jan. 2001