RT9181 Preliminary 150mA LDO Regulator with POG General Description Features The RT9181 is a low dropout voltage regulator with z Low Dropout Voltage Regulator, Output 1.2V an output 2% accuracy and supply a continuous z Up to 150mA Output Current 150mA current within operating range from a +3V to z Power Good (POG) Function +5.5V input. The power good function monitors the z Chip Enable/Shutdown Function output voltage and indicates by pulling low the power z Load Independent, Low Ground Current, 160µ µA good output (open drain). z Current Limiting and Thermal Protection The RT9181 requires a small output capacitor with z Under Voltage Lockout (UVLO) low ESR for stabilizing output voltage. The device z Low Variation Due to Load and Line Regulation also minimizes output overshoot during power up. z Output Stable with Low ESR Capacitors z SOT-25 Package The RT9181 uses an internal PMOS as the pass device, which consumes 160µA supply current independent of load and dropout conditions. The CE pin controls the output and consumes no input bias current. Other features include current limiting, over temperature protection, and under voltage lockout. Pin Configurations Part Number Pin Configurations RT9181CB TOP VIEW (Plastic SOT-25) 5 Applications z Processor Power-Up Sequencing z Laptop, Notebook, and Palmtop Computers Ordering Information 1 4 2 1. 2. 3. 4. 5. 3 VIN GND CE POG VOUT Typical Application Circuit RT9181 Package type B : SOT-25 Operating temperature range C: Commercial standard 10K VIN VIN POG CE VOUT POG C IN 1µF ON GND VOUT C OUT 1µF OFF DS9181-00 February 2002 www.richtek-ic.com.tw 1 RT9181 Preliminary Pin Description Pin Name Pin Function VIN Input Pin GND Power Ground Pin CE Enable/Shutdown Input (Active High) POG Power Good Indicator VOUT Output Pin Function Block Diagram VIN CE Shutdown Control Undervoltage Lockout Current Limit Thermal Sensor Gate Control VOUT + _ Verf Output Voltage Detection GOOD Delay Timer Fault POG Power Good Control GND www.richtek-ic.com.tw 2 DS9181-00 February 2002 RT9181 Preliminary Absolute Maximum Ratings z Input Voltage, VIN 7V z CE Input Voltage 7V z Power Good Output Voltage 7V z Power Dissipation, PD @ TA = 25°C SOT-25 570mW z Junction Temperature Range -40°C ~ 125°C z Storage Temperature Range -65°C ~ 150°C z Operating Temperature Range 0°C ~ 70°C z Lead Temperature (Soldering, 10 sec.) 260°C Electrical Characteristics (VIN = 5V, CIN = COUT = 1µF, TA = 25°C, unless otherwise specified) Parameter Symbol Input Voltage Range VIN Output Voltage Accuracy ∆VOUT Output Load Current Test Conditions Min Typ Max Units 3 -- 5.5 V 1.182 1.2 1.218 -2 -- +2 Continuous 150 -- -- mA IL = 25mA IL = 0.1mA, TA = 0°C to 70°C (Note) % Current Limit ILIMIT RLOAD = 1Ω 160 300 -- mA GND Current IG No Load 90 160 250 µA Line Regulation ∆VLINE VIN = 3 to 5.5V, IOUT = 0.1mA -0.3 -- +0.3 % Load Regulation ∆VLOAD IL = 0.1mA to 150mA -- -- +3 % Dropout Voltage VDROP IL = 150mA -- 1 -- V CE Input High Threshold VIN = 3 to 5.5V 2 -- -- V CE Input Low Threshold VIN = 3 to 5.5V -- -- 0.8 V CE Input Bias Current CE = GND or VIN -- -- 100 nA CE Supply Current CE = GND -- 0.01 -- µA 85 -- -- % -- -- 90 % Output falls % of VOUT (power NOT VPOGH Power Good Low Threshold timer (Power good)) Output reaches % of VOUT, start VPOGH Power Good High Threshold delay timer (power good) VOL Power Good Output Logic Low Fault condition, IOL = 100µA -- -- 0.4 V td(POG) Delay Time to Power Good See timing diagram 1 2 5 mS -- 1 -- % -- 150 -- °C -- 20 -- °C -- 62 -- dB Maximum voltage overshoot allowed Power Up Overshoot Thermal Shutdown Temperature on output during power-up TSD Thermal Shutdown Hysteresis Output Voltage AC PSRR 100Hz, COUT = 1µF, RLOAD = 100Ω Note: Assured by design, not tested in production DS9181-00 February 2002 www.richtek-ic.com.tw 3 RT9181 Preliminary Typical Operating Charateristics Output Voltage vs. Supply Voltage 1.210 1.205 1.205 Output Voltage (V) Output Voltage (V) Output Voltage vs. Temperature 1.210 1.200 1.195 VIN = 5V ILOAD = 0.1mA 1.190 -20 0 20 40 60 1.200 1.195 ILOAD = 0.1mA 1.190 80 3.0 Temperature ( °C) 400 350 350 Current Limit (mA) Current Limit (mA) Current Limit vs. Temperature 300 250 VIN = 5V -20 0 20 40 60 3 3.5 Quiescent Current ( µ A) Quiescent Current ( µ A) 170 165 160 155 VIN = 5V www.richtek-ic.com.tw 4 4.5 5 5.5 6 Quiescent Current vs. Supply Voltage 175 Temperature ( °C) 4 Supply Voltage (V) 175 40 6.0 200 180 20 5.5 250 80 Quiescent Current vs. Temperature 0 5.0 300 180 -20 4.5 Current Limit vs. Supply Voltage Temperature ( °C) 150 4.0 Supply Voltage (V) 400 200 3.5 60 80 170 165 160 155 150 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Supply Voltage (V) DS9181-00 February 2002 RT9181 Preliminary POG Delay Time vs. Supply Voltage 3.00 2.5 2.50 POG Delay Time (mS) POG Delay Time (mS) POG Delay Time vs. Temperature 3.0 2.0 1.5 1.0 2.00 1.50 1.00 0.50 0.5 VIN = 5V 0.0 -20 0 20 40 Temperature ( ° C) 60 0.00 3.0 80 3.5 4.0 4.5 5.0 5.5 6.0 Supply Voltage (V) POG Response at Power Down Under Voltage Lock Out T POG 1> VIN T 1> 1.2V VOUT VOUT TT 2> 1) Ch 1: 2) Ch 2: TT VIN = 5V COUT = 1µF 2> COUT = 1µF 2 Volt 5 ms 500 mVolt 5 ms 1) Ch 1: 2) Ch 2: 5 Volt 25 us 500 mVolt 25 us Time Time POG Response vs. VOUT T POG 1> 2ms delay TT VOUT 2> 1) Ch 1: 2) Ch 2: VIN = 5V 5 Volt 1 ms 500 mVolt 1 ms Time DS9181-00 February 2002 www.richtek-ic.com.tw 5 RT9181 Preliminary Timing Diagram 90% max of VOUT (normal) VPOGL VPOGH 85% min t d(POG) 2.0ms typ. VOUT POG Application Guides CE/Shutdown The RT9181 is enabled by driving the CE input high, and shutdown by pulling the input low. If this feature is not to be used, the CE input should be tied to VIN to keep the regulator enabled at all times (the CE input must not be left floating). The RT9181 features a P-channel MOSFET pass transistors. It provides several advantages over similar designs using PNP pass transistors, including longer battery life. The P-channel MOSFET requires no base drive, which reduces quiescent current PNP-based Because at shutdown mode, a fault condition occurs by pulling the POG output low, it will sink a current from the open drain and the external power. Selecting a suitable pulling resistance will be well to control this dissipated power. Internal P-Channel Pass Transistor considerably. drives the open drain transistor to indicate a fault. regulators waste considerable current in dropout when the pass Current Limit and Thermal Protection The RT9181 includes a current limit structure which monitor and control the pass transistor’s gate voltage limiting the guaranteed maximum output current to 150mA minimum. Thermal-overload protection limits total power dissipation in the RT9181. When the junction transistor saturates, They also use high base-drive temperature exceeds TJ = +150°C, the thermal currents under large loads. The RT9181 does not sensor signals the shutdown logic turning off the suffer from these problems and consume only 160µA pass transistor and allowing the IC to cool. The of quiescent current whether in dropout, light-load, or thermal sensor will turn the pass transistor on again heavy-load applications. after the IC’s junction temperature cools by 20°C, Power Good The power good output is an open-drain output. It is designed essentially to work as a power-on reset generator once the regulated voltage was up or a fault condition. The output of the power good drives low when a fault condition occurs. The power good output come back up once the output has reached 90% of its nominal value and a 2.0ms (typ.) delay has passed. See Timing Diagram. The output voltage resulting in a pulsed output during continuous thermal-overload conditions. Thermal-overloaded protection is designed to protect the RT9181 in the event of fault conditions. Do not exceed the absolute maximum junction-temperature rating of TJ = +125°C for continuous operation. The output can be shorted to ground for and indefinite amount of time without damaging the part by cooperation of current limit and thermal protection. level will be drooped at the fault conditions including Operating Region and Power Dissipation current limit, thermal shutdown, or shutdown and The maximum power dissipation of RT9181 depends triggers the POG detector to alarm a fault condition. on the thermal resistance of the case and circuit This output is fed into an on-board delay circuitry that board, the temperature difference between the die junction and ambient air, and the rate of air flow. The www.richtek-ic.com.tw 6 DS9181-00 February 2002 RT9181 Preliminary large capacitor). If a tantalum capacitor is used at the power dissipation across the device is input, it must be guaranteed to have a surge current P = IOUT (VIN – VOUT) The GND pin of the RT9181 performs the dual function of providing an electrical connection to rating sufficient for the application by the manufacture. ground and channeling heat away, Connect the GND Load-Transient Considerations pin to ground using a large pad or ground plane. The RT9181 load-transient response graphs show Capacitor Selection and Regulator Stability Like any low-dropout regulator, the external capacitors used with the RT9181 must be carefully selected for regulator stability and performance. Using a capacitor whose value is ≥ 1µF on the 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 RT9181 input and the amount of capacitance can be mV, depending on the ESR and ESL of the output increased without limit. The input capacitor must be capacitor. Increasing the output capacitor’s value and located a distance of not more than 0.5” from the decreasing the ESR and ESL attenuates the input pin of the IC and returned to a clean analog overshoot. 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. Reverse Current Path The power transistor used in the RT9181 has an inherent diode connected between each regulator input and output (see Fig.1). If the output is forced The output capacitor must meet both requirements above the input by more than a diode-drop, this diode for minimum amount of capacitance and ESR in all will become forward biased and current will flow from LDO designed the VOUT terminal to VIN. This diode will also be specifically to work with low ESR ceramic output turned on by abruptly stepping the input voltage to a capacitor performance value below the output voltage. To prevent regulator consideration. Using a ceramic capacitor whose mis-operation, a Schottky diode could be used in the applications. in The RT9181 space-saving and is value is at least 1µF with ESR is > 5mΩ on the applications where input/output voltage conditions RT9181 output ensures stability. The RT9181 still can cause the internal diode to be turned on (see works well with output capacitor of other types due to Fig.2). As shown, the Schottky diode is connected in the wide stable ESR range. Output capacitor of larger parallel with the internal parasitic diode and prevents capacitance can reduce noise and improve load- it from being turned on by limiting the voltage drop transient response, stability, and PSRR. The output across it to about 0.3V < 100mA to prevent damage capacitor should be located not more than 0.5” from to the part. the VOUT pin of the RT9181 and returned to a clean analog ground. Note that some ceramic dielectrics exhibit large capacitance and ESR variation with temperature. It Fig. 1 may be necessary to use 2.2µF or more to ensure stability at temperatures below -10°C in this case. Also, tantalum capacitors, 2.2µ or more may be needed to maintain capacitance and ESR in the stable region for strict application environment. VOUT VIN Tantalum capacitors maybe suffer failure due to surge current when it is connected to a lowimpedance source of power (like a battery or very DS9181-00 February 2002 Fig. 2 www.richtek-ic.com.tw 7 RT9181 Preliminary Package Information D C B b H A e Symbol L A1 Dimensions In Millimeters Dimensions In Inches Min Max Min Max A 0.889 1.295 0.035 0.051 A1 0.000 0.152 0.000 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- 25 Surface Mount Package www.richtek-ic.com.tw 8 DS9181-00 February 2002 Preliminary DS9181-00 February 2002 RT9181 www.richtek-ic.com.tw 9 RT9181 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 DS9181-00 February 2002