RT9182 Preliminary Dual, Low-Noise, 200mA LDO Regulator General Description Features The RT9182 is a dual-channel, low noise, and low • Up to 200mA Output Current (Each LDO) dropout regulator supplying up to 200mA current at each channel. The output voltage ranges from 1.5V to 3.3V in 100mV increments and 2% accuracy by • Shutdown Function • 29µ µVRMS Low Noise Output • Current Limiting and Thermal Protection operating from a +2.7V to +6.5V input. • Short Circuit Protection The RT9182 uses an internal PMOS as the pass • Two LDOs in SOT-26 Package device, which consumes 165µA supply current (both LDOs on) independent of load current and dropout • 120mV Dropout at 100mA Load Applications conditions. The SHDN pin controls both outputs z Cellular Phones simultaneously and consumes nearly zero operation z Laptop, Notebook, and Palmtop Computers current in the disable mode making the IC suitable z Battery-powered Equipment for battery-power devices. Other features include a z Hand-held Equipment reference voltage bypass pin to improve low noise performance, current limiting, and over temperature Pin Configurations Part Number protection. Pin Configurations TOP VIEW RT9182 CE Ordering Information (Plastic SOT-26) 6 5 4 1 2 3 1. 2. 3. 4. 5. 6. RT9182 Package type E : SOT-26 Operating temperature range C : Commercial standard Output voltage A : 2.8V (Output1), 2.8V (Output2) B : 3.0V (Output1), 3.0V (Output2) VOUT2 GND BP SHDN VIN VOUT1 Typical Application Circuit ON OFF VOUT2 Marking Information VOUT2 VOUT1 2.2µF Part Number Marking RT9182ACE 2M RT9182BCE 2Q DS9182-02 April 2002 SHDN RT9182 BP GND 10nF VIN VOUT1 2.2µF VIN 2.2µF www.richtek-ic.com.tw 1 RT9182 Preliminary Pin Description Pin Name Pin Function VOUT2 Output2 Voltage GND Ground BP Reference Noise Bypass SHDN Active Low Shutdown Input VIN Power Input VOUT1 Output1 Voltage Function Block Diagram Current Limit Thermal Protection Vref + VOUT1 + _ Current Limit _ VIN VOUT2 Bias BP www.richtek-ic.com.tw 2 Start-Up GND SHDN DS9182-02 April 2002 RT9182 Preliminary Absolute Maximum Ratings z Input Voltage z Power Dissipation, PD @ TA = 25°C 7V SOT-26 748mW z Junction Temperature Range -40°C ~ 125°C z Storage Temperature Range -65°C ~ 150°C z Operating Temperature Range -40°C ~ 85°C z Lead Temperature (Soldering, 10 sec.) 260°C Electrical Characteristics (VIN = 3.6V, CIN = COUT = 2.2µF, SHDN = VIN, typical values at TA = 25°C, for each LDO unless otherwise specified.) Parameter Symbol Test Conditions Min Typ Max Units 2.7 -- 6.5 V -2 -- +2 % Input Voltage Range VIN Output Voltage Accuracy (Load Regulation) ∆VOUT IL = 1mA to 200mA Maximum Output Current IMAX Continuous 200 -- -- mA Current Limit ILIMIT RLOAD = 1Ω 200 -- 550 mA GND Pin Current IG No Load -- 165 260 µA IOUT = 100mA (Both LDOs) -- 165 260 µA IOUT = 1mA -- 1.2 -- mV IOUT = 100mA -- 120 -- mV IOUT = 200mA -- 255 -- mV Dropout Voltage (Note) VDROP Line Regulation ∆VLINE VIN = (VOUT +0.4V or 2.7V) to 6.5V IOUT = 1mA -0.2 -- +0.2 %/V SHDN Input High Threshold VIH VIN = 2.7V to 6.5V 1.6 -- -- V SHDN Input Low Threshold VIL VIN = 2.7V to 6.5V -- -- 0.4 V SHDN Input Bias Current ISD SHDN = GND or VIN -- -- 100 nA Shutdown Supply Current IGSD SHDN = GND -- 0.01 1 µA -- 140 -- °C -- 10 -- °C 10Hz to 100kHz, CBP = 10nF COUT = 4.7µF, ILOAD = 1mA -- 29 -- µVRMS 100Hz, CBP = 10nF, COUT = 4.7µF ILOAD = 100mA -- 62 -- dB Thermal Shutdown Temperature Thermal Shutdown Hysteresis TSD Output Voltage Noise eNO Output Voltage AC PSRR Note : Dropout voltage definition: VIN – VOUT when VOUT is 50mV below the value of VOUT (normal) DS9182-02 April 2002 www.richtek-ic.com.tw 3 RT9182 Preliminary Typical Operating Characteristics VOUT = 2.8V, ILOAD = 100mA, VIN = 3.6V, COUT = 4.7µF, CBP = 10nF, and CIN = 2.2µF, unless otherwise noted. Quiescent Current vs. Supply Voltage Output Voltage Accuracy vs. Temp. 240 1.0 No Load 160 ILoad = 100mA, both outputs 0.6 120 80 Output Voltage (%) Quiescent Current (µ A) 0.8 200 0.4 0.2 0.0 -0.2 -0.4 -0.6 40 -0.8 -1.0 0 2.5 3.5 4.5 5.5 -40 6.5 -15 Both outputs loaded Dropout Voltage (mV) Quiescent Current (µ A) 90 60 200 150 100 30 50 0 0 120 160 ILOAD = 200mA -40 200 -15 Quiescent Current vs. Temp. 200 70 175 60 150 35 60 85 PSRR vs. Frequency ILOAD = 1mA 50 125 PSRR (dB) Quiescent Current ( µ A) 10 Temperature ( ° C) Load Current (mA) 100 75 40 30 20 50 10 25 0 0 -40 -15 10 35 Temperature ( °C) www.richtek-ic.com.tw 4 85 250 120 80 60 300 150 40 35 Dropout Voltage vs. Temp. Quiescent Current vs. Load Current 180 0 10 Temperature ( ° C) Supply Voltage (V) 60 85 10 100 1K 10K 100K 1M Frequency (Hz) DS9182-02 April 2002 RT9182 Preliminary Channel-to-Channel Isolation vs. Frequency 120 Noise Density vs. Frequency 10K Noise Density (nV/ Hz) Channel Isolation (dB) 100 80 60 40 1K 100 20 RLOAD = 100Ω Frequency (Hz) 100K Line Transient Response 20mV/Div T 1> ≈ 4.5 10 10 1M ≈ TT 3.5 2↓ Peak value depends on COUT ESR ≈ ≈ 2> TT 10µS/Div Time ILOAD = 1mA DS9182-02 April 2002 TT 1mS/Div Time 100µV/Div ≈ Output Voltage (AC-Coupled) 1V/Div 5V/Div 2> COUT = 2.2µF Output Noise (10Hz to 100kHz) T ≈ 100K T ILOAD = 50mA 1> 10K 1> Shutdown Response Output Voltage 1K Load Transient Response (ILOAD = 0 to 80mA) 50µS/Div Time Shutdown Voltage 100 Frequency (Hz) 50mV/Div 10K 100mA/Div 1K Output Voltage Deviation (AC-Coupled) 100 Load Current Input Voltage (V) Output Voltage Deviation (AC-Coupled) 0 T 1> 1mS/Div Time www.richtek-ic.com.tw 5 RT9182 Preliminary Functional Description The RT9182 is integrated with two low noise, low event of fault conditions. Do not exceed the absolute dropout, and low quiescent current linear regulators maximum junction-temperature rating of TJ = +150°C designed primarily for battery-powered applications. for continuous operation. The output can be shorted Output voltages are optional ranging from 1.5V to to ground for an indefinite amount of time without 3.3V, and each channel can supply current up to damaging the part by cooperation of current limit and 200mA. thermal protection. Shutdown Operating Region and Power Dissipation The RT9182 is shutdown by pulling the SHDN input The maximum power dissipation of RT9182 depends low, and turned on by driving the input high. If this on the thermal resistance of the case and circuit feature is not to be used, the SHDN input should be board, the temperature difference between the die tied to VIN to keep the regulator on at all times (the junction and ambient air, and the rate of airflow. The SHDN input must not be left floating). power dissipation across the device is P = IOUT (VIN - VOUT). Internal P-Channel Pass Transistor The RT9182 features double typical 1.5Ω P-channel MOSFET pass transistors. It provides several advantages over similar designs using PNP pass transistors, including longer battery life. The P- The maximum power dissipation is: PMAX = (TJ - TA) / θJA where TJ - TA is the temperature difference between the RT9182 die junction and the surrounding channel MOSFET requires no base drive, which environment, θJA is the thermal resistance from the reduces quiescent current considerably. PNP-based junction to the surrounding environment. The GND regulators waste considerable current in dropout pin of the RT9182 performs the dual function of when the pass transistor saturates. They also use providing an electrical connection to ground and high base-drive currents under large loads. The channeling heat away. Connect the GND pin to RT9182 does not suffer from these problems and ground using a large pad or ground plane. consume only 165µA of quiescent current whether in dropout, light-load, or heavy-load applications. Low-Noise Operation An external 10nF bypass capacitor at BP, in Current Limit and Thermal Protection conjunction with an internal resistor, creates a The RT9182 includes two independent current limit lowpass filter. The RT9182 exhibits 29µVRMS of structure which monitor and control each pass output voltage noise with CBP = 10nF and COUT = transistor’s gate voltage limiting the guaranteed 2.2µF. maximum output current to 200mA minimum. Thermal-overload protection limits total power dissipation in the RT9182. When the junction temperature exceeds TJ = +140°C, the thermal sensor signals the shutdown logic turning off the pass transistor and allowing the IC to cool. The thermal sensor will turn the pass transistor on again after the IC’s junction temperature cools by 10°C, resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overloaded protection is designed to protect the RT9182 in the www.richtek-ic.com.tw 6 DS9182-02 April 2002 RT9182 Preliminary Applications Information Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external rating sufficient for the application by the manufacture. capacitors used with the RT9182 must be carefully selected for regulator stability and performance. Region of Stable COUT ESR vs. Load Current 100 COUT = 4.7µF Using a capacitor whose value is > 1µF on the RT9182 input and the amount of capacitance can 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 10 COUT ESR (mΩ) (Ω) Ω increased without limit. The input capacitor must be COUT = 1µF 1 0.1 value and lower ESR (equivalent series resistance) provides better PSRR and line-transient response. The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all 0.01 0.001 0 40 80 120 LDO applications (see Fig.1). The RT9182 is Load Current (mA) designed specifically to work with low ESR ceramic Fig. 1 160 200 output capacitor in space-saving and performance consideration. Using a ceramic capacitor whose Use a 10nF bypass capacitor at BP pin for low output value is at least 1µF with ESR is > 5mΩ on the voltage noise. The capacitor, in conjunction with an RT9182 output ensures stability. The RT9182 still internal resistor, which connects bypass pin and the works well with output capacitor of other types due to band-gap reference, creates a low-pass filter for the wide stable ESR range. Output capacitor of larger noise reduction. Increasing the capacitance will capacitance can reduce noise and improve load- slightly decrease the output noise, and it is almost transient response, stability, and PSRR. The output independent of the start-up time. The capacitor capacitor should be located not more than 0.5" connected to the bypass pin for noise reduction must from the VOUT pin of the RT9182 and returned to a have very low leakage. This capacitor leakage clean analog ground. current causes the output voltage to decline by a proportional amount to the current. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It Load-Transient Considerations may be necessary to use 2.2µF or more to ensure The RT9182 load-transient response graphs show stability at temperatures below -10°C in this case. two components of the output response: a DC shift Also, tantalum capacitors, 2.2µF or more may be from the output impedance due to the load current needed to maintain capacitance and ESR in the change, and the transient response. The DC shift is stable region for strict application environment. quite small due to the excellent load regulation of the IC. Typical output voltage transient spike for a step Tantalum capacitors maybe suffer failure due to change in the load current from 0mA to 50mA is tens surge current when it is connected to a low- mV, depending on the ESR of the output capacitor. impedance source of power (like a battery or very Increasing large capacitor). If a tantalum capacitor is used at the decreasing the ESR attenuates the overshoot. the output capacitor’s value and input, it must be guaranteed to have a surge current DS9182-02 April 2002 www.richtek-ic.com.tw 7 RT9182 Preliminary Input-Output (Dropout) Voltage 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 RT9182 uses a P-channel 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 RT9182 has an inherent diode connected between each regulator input and output (see Fig.2). If the output is forced above the input by more than a diode-drop, this diode will become forward biased and current will flow from the VOUT terminal to VIN. This diode will also be turned on by abruptly stepping the input voltage to a value below the output voltage. To prevent regulator mis-operation, a Schottky diode could be used in the applications where input/output voltage conditions can cause the internal diode to be turned on (see Fig.3). 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 < 100mA to prevent damage to the part. VIN VOUT Fig. 2 VIN VOUT Fig. 3 www.richtek-ic.com.tw 8 DS9182-02 April 2002 RT9182 Preliminary Package Information D C B b H A A1 e Symbol L Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.889 1.295 0.035 0.051 A1 -- 0.152 -- 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- 26 Surface Mount Package DS9182-02 April 2002 www.richtek-ic.com.tw 9 RT9182 Preliminary RICHTEK TECHNOLOGY CORP. RICHTEK TECHNOLOGY CORP. Headquarter Taipei Office (Marketing) 6F, No. 35, Hsintai Road, 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)5510047 Fax: (8863)5537749 Tel: (8862)89191466 Fax: (8862)89191465 Email: [email protected] www.richtek-ic.com.tw 10 DS9182-02 April 2002