RT9182 Preliminary Dual, Low-Noise, 200mA LDO Regulator General Description The RT9182 is a dual-channel, low noise, and low 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 operating from a +2.7V to +5.5V input. The RT9182 uses an internal PMOS as the pass device, which consumes 165µA supply current (both LDOs on) independent of load current and dropout conditions. The SHDN1 and SHDN2 pins control each output respectively. When both outputs shutdown simultaneously, the chip will be turn off and consumes nearly zero operation current which is suitable for battery-power devices. Other features include a current limiting, and over temperature protection. Features • • • • • • • Up to 200mA Output Current (Each LDO) Dual Shutdown Pins Control Each Output 124µVRMS Low Noise Output Current Limiting and Thermal Protection Short Circuit Protection 120mV Dropout at 100mA Load Two LDOs in SOT-26 Package Applications Cellular Phones Laptop, Notebook, and Palmtop Computers Battery-powered Equipment Hand-held Equipment Wireless LAN Pin Configurations Part Number Ordering Information RT9182 RT9182 CES (Plastic SOT-26) Pin Configurations TOP VIEW 6 5 4 1 2 3 1. 2. 3. 4. 5. 6. Package type ES : SOT-26 Operating temperature range C : Commercial standard VOUT2 GND SHDN2 SHDN1 VIN VOUT1 Output voltage A : 2.8V (Output1), 2.8V (Output2) B : 3.0V (Output1), 3.0V (Output2) C : 2.8V (Output1), 3.0V (Output2) 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. DS9182-05 February 2003 Typical Application Circuit ON OFF VOUT2 2.2µF ON SHDN2 SHDN1 VO UT2 VO UT1 RT9182 GND VIN OFF VOUT1 2.2µF VIN 2.2µF www.richtek.com 1 RT9182 Preliminary Pin Description Pin No. Pin Name Pin Function 1 VOUT2 Channel 2 Output Voltage 2 GND Common Ground 3 SHDN2 Note Channel 2 Shutdown Input Logic, Active Low. If the shutdown feature is not required, connect SHDN2 to VIN. SHDN1 Note Channel 1 Shutdown Input Logic, Active Low. If the shutdown feature is not required, connect SHDN1 to VIN. 4 5 VIN Supply Input 6 VOUT1 Channel 1 Output Voltage Note: Active Low shutdown. If SHDN1 and SHDN2 are both low, both regulators and the reference turn off. Function Block Diagram Current Limit Thermal Protection Vref + + _ Current Limit _ VIN VOUT1 VOUT2 GND SHDN1 Bias SHDN2 www.richtek.com 2 DS9182-05 February 2003 RT9182 Preliminary Absolute Maximum Ratings Supply Input Voltage Power Dissipation, PD @ TA = 25°C SOT-26 Lead Temperature (Soldering, 10 sec.) Junction Temperature Storage Temperature Range 6.5V 748mW 260°C 125°C −65°C to 150°C Recommended Operating Conditions (Note 1) Supply Input Voltage Shutdown Input Voltage Junction Temperature Range 2.7V to 5.5V 0V to 5.5V −40°C to 85°C Electrical Characteristics (VIN = 3.6V, CIN = COUT = 2.2µF, SHDN = SHDN1 = SHDN2 = VIN, typical values at TA = 25°C, for each LDO unless otherwise specified.) Parameter Symbol Test Conditions Min Typ Max Units -2 -- +2 % Output Voltage Accuracy (Load Regulation) ∆VOUT IL = 1mA to 200mA Maximum Output Current IMAX Continuous 200 -- -- mA Current Limit ILIMIT RLOAD = 1Ω 500 -- 1000 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 2) VDROP Line Regulation ∆VLINE VIN = (VOUT +0.4V or 2.7V) to 5.5V IOUT = 1mA -0.2 -- +0.2 %/V SHDN Input High Threshold VIH VIN = 2.7V to 5.5V 1.6 -- -- V SHDN Input Low Threshold VIL VIN = 2.7V to 5.5V -- -- 0.4 V SHDN Input Bias Current ISD SHDN = GND or VIN -- -- 100 nA Shutdown Supply Current IGSD SHDN1 = SHDN2 = GND -- 0.01 2 µA Thermal Shutdown Temperature TSD -- 140 -- °C Thermal Shutdown Hysteresis ∆TSD -- 10 -- °C Output Voltage Noise eNO 10Hz to 100kHz, COUT = 4.7µF, ILOAD = 1mA -- 124 -- µVRMS 100Hz, COUT = 4.7µF, ILOAD = 100mA -- 62 -- dB Output Voltage AC PSRR Note 1. The device is not guaranteed to function outside its operating conditions Note 2. Dropout voltage definition: VIN – VOUT when VOUT is 50mV below the value of VOUT (normal) DS9182-05 February 2003 www.richtek.com 3 RT9182 Preliminary Typical Operating Characteristics VOUT = 2.8V, ILOAD = 100mA, VIN = 3.6V, COUT = 4.7µF, and CIN = 2.2µF, unless otherwise noted. Quiescent Current vs. Supply Voltage Output Voltage Accuracy vs. Temp. 240 1.0 0.8 No Load 0.6 ILoad = 100mA, both outputs 160 120 80 Output Voltage (%) Quiescent Current (µ A) 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 60 85 300 Both outputs loaded 250 Dropout Voltage (mV) Quiescent Current ((µA) A) 35 Dropout Voltage vs. Temp. Quiescent Current vs. Load Current 180 150 10 Temperature ( °C) Supply Voltage (V) 120 90 60 200 150 100 50 30 ILOAD = 200mA 0 0 0 40 80 120 160 -40 200 -15 200 120 175 60 85 100 150 Channel Isolation (dB) Quiescent Current (µ A) 35 Channel-to-Channel Isolation vs. Frequency Quiescent Current vs. Temp. 125 100 75 50 80 60 40 20 25 RLOAD = 100Ω 0 -40 -15 10 35 Temperature ( °C) www.richtek.com 4 10 Temperature ( °C) Load Current (mA) 60 85 0 100 1K 10K Frequency (Hz) 100K 1M DS9182-05 February 2003 RT9182 Load Transient Response (ILOAD = 0 to 80mA) ≈ 4.5 ≈ TT 3.5 2↓ 50µS/Div Time 50mV/Div 1> T 1> Peak value depends on COUT ESR ≈ ≈ 100mA/Div 20mV/Div T Output Voltage Deviation (AC-Coupled) Line Transient Response Load Current Input Voltage (V) Output Voltage Deviation (AC-Coupled) Preliminary 2> TT 10µS/Div Time COUT = 2.2µF ILOAD = 50mA 1V/Div Output Voltage Shutdown Response T ≈ 5V/Div Shutdown Voltage 1> 2> DS9182-05 February 2003 ≈ TT 1mS/Div Time www.richtek.com 5 RT9182 Preliminary Functional Description The RT9182 is integrated with two low noise, low dropout, and low quiescent current linear regulators designed primarily for battery-powered applications. Output voltages are optional ranging from 1.5V to 3.3V, and each channel can supply current up to 200mA. Shutdown The RT9182 is shutdown by pulling the SHDN input low, and turned on by driving the input high. If this feature is not to be used, the SHDN input should be tied to VIN to keep the regulator on at all times (the SHDN input must not be left floating). 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 Pchannel 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 currents under large loads. The RT9182 does not suffer from these problems and consume only 165µA of quiescent current whether in dropout, light-load, or heavy-load applications. resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overloaded protection is designed to protect the RT9182 in the event of fault conditions. Do not exceed the absolute maximum junction-temperature rating of TJ = +150°C for continuous operation. The output can be shorted to ground for an indefinite amount of time without damaging the part by cooperation of current limit and thermal protection. Operating Region and Power Dissipation The maximum power dissipation of RT9182 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 RT9182 die junction and the surrounding environment, θJA is the thermal resistance from the junction to the surrounding environment. The GND pin of the RT9182 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. Current Limit and Thermal Protection The RT9182 includes two independent current limit structure which monitor and control each pass transistor’s gate voltage limiting the guaranteed 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, www.richtek.com 6 DS9182-05 February 2003 RT9182 Preliminary Applications Information Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9182 must be carefully selected for regulator stability and performance. rating sufficient manufacture. for the application by the Region of Stable COUT ESR vs. Load Current 100 The output capacitor must meet both requirements for minimum amount of capacitance and ESR in all LDO applications (see Fig.1). The RT9182 is designed specifically to work with low ESR ceramic output capacitor in space-saving and performance consideration. Using a ceramic capacitor whose value is at least 1µF with ESR is > 5mΩ on the RT9182 output ensures stability. The RT9182 still works well with output capacitor of other types due to the wide stable ESR range. Output capacitor of larger capacitance can reduce noise and improve loadtransient response, stability, and PSRR. The output capacitor should be located not more than 0.5" from the VOUT pin of the RT9182 and returned to a clean analog ground. 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 maintain capacitance and ESR in the stable region for strict application environment. Tantalum capacitors maybe suffer failure due to surge current when it is connected to a lowimpedance 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 DS9182-05 February 2003 COUT = 4.7µF 10 COUT ESR (mΩ) (Ω) Ω Ω Using a capacitor whose value is > 1µF on the RT9182 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. COUT = 1µF 1 0.1 0.01 0.001 0 40 80 120 160 200 Load Current (mA) Fig. 1 Load-Transient Considerations The RT9182 load-transient response graphs 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 0mA to 50mA is tens mV, depending on the ESR of the output capacitor. Increasing the output capacitor’s value and decreasing the ESR attenuates the overshoot. 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. www.richtek.com 7 RT9182 Preliminary 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.com 8 DS9182-05 February 2003 RT9182 Preliminary Package Information H D L C B b A A1 e Symbol 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 DS9182-05 February 2003 www.richtek.com 9 RT9182 Preliminary 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 10 DS9182-05 February 2003