NCT3705U-25 TR

Nuvoton 500mA Linear Regulator NCT3705U Series NCT3705U -Table of Content1. GENERAL DESCRIPTION .............................................................................................................. 1 2. FEATURES ...................................................................................................................................... 1 3. BLOCK DIAGRAM ........................................................................................................................... 2 4. PIN CONFIGURATION AND TYPICAL APPLICATION CIRCUIT .................................................. 4 5. PIN DESCRIPTION.......................................................................................................................... 5 6. FUNCTIONAL DESCRIPTION ........................................................................................................ 6 6.1 OUTPUT VOLTAGE AND DROPOUT VOLTAGE ................................................................... 6 6.2 NOISE ....................................................................................................................................... 6 6.3 PSRR ........................................................................................................................................ 6 6.4 LOAD REGULATION CONSIDERATION ................................................................................ 7 6.5 CURRENT LIMIT PROTECTION ............................................................................................. 8 6.6 VIN & VOUT CAPACITOR SELECTION ...................................................................................... 8 6.7 OVER TEMPERATURE PROTECTION................................................................................... 8 6.8 LAYOUT NOTE......................................................................................................................... 9 6.9 THERMAL CONSIDERATION.................................................................................................. 9 7. ELECTRICAL CHARACTERISTIC ................................................................................................ 10 7.1 ABSOLUTE MAXIMUM RATINGS ......................................................................................... 10 7.2 THERMAL INFORMATION .................................................................................................... 11 7.3 RECOMMENDED OPERATING CONDITIONS..................................................................... 11 7.4 ELECTRICAL CHARACTERISTICS....................................................................................... 11 8. TYPICAL OPERATING WAVEFORMS ......................................................................................... 13 9. PACKAGE DIMENSION ................................................................................................................ 17 　 TAPING SPECIFICATION.......................................................................................................... 17 10. ORDERING INFORMATION ...................................................................................................... 18 11. TOP MARKING SPECIFICATION.............................................................................................. 18 12. REVISION HISTORY ................................................................................................................. 19 -I- Publication Date: Dec., 2008 Revision A1 NCT3705U 1. GENERAL DESCRIPTION The NCT3705U is a low supply current and low dropout linear regulator which provides 500mA power for battery-powered application such as notebook computers, cellular phones, and handheld devices. An over current protection and an over-temperature protection circuit were built-in the chip to prevent current and thermal overload. Featured low noise, high PSRR and low dropout make it ideal for audio codec and handheld devices. It comes in a space saving SOT-23-5 package and suitable for handheld applications. The NCT3705U has two versions for different operation circuits. In fixed mode, the SET pin is connected to ground. The output voltage is a preset value. There is no external component required. When an output other than the preset value is needed, two external resistors should be used as an output voltage divider and operates in adjustable mode. The output voltage can be adjusted by the resistor ratio and regulates from 1.25V to 5.0V. 2. FEATURES 2.1. 2.2. General z Guaranteed 500mA Output Current z Low Ground Current 90uA @ No Load (Typical) z 70dB PSRR @ 10mA, 100Hz z Low Dropout Voltage 145mV @ 150mA (VOUT = 5V) z Low Output Noise 28u Vrms @ 1mA with Bypass Capacitor z Excellent Load Regulation & Line Regulation z Short Circuit Protection & Over Current Protection z Over Temperature Protection z Stable with Low ESR Capacitor z 0℃ to 70℃ Ambient Operating Temperature Range Package z SOT23-5 Green Package (Lead Free and Halogen Free) -1- Publication Date: Dec., 2008 Revision A1 NCT3705U 2.3. Application z Desktop PCs, Notebooks, and Workstations z Graphics Card or Add-on Card Low Power Applications z Set Top Boxes, Digital TVs and Printers z Digital Still Camera and Camcorders z Mobile or handheld Devices 3. BLOCK DIAGRAM IN Short Circuit Protection Over Current Protection VREF Over Temperature SHDN# Shut Down Protection OUT SET VCOMP GND Figure1. Adjustable Mode -2- Publication Date: Nov., 2008 Revision A1 NCT3705U IN Short Circuit Protection Over Current Protection VREF Over Temperature SHDN# Shut Down Protection OUT BYP GND Figure2. Fixed Mode -3- Publication Date: Dec., 2008 Revision A1 NCT3705U 4. PIN CONFIGURATION AND TYPICAL APPLICATION CIRCUIT IN 1 GND 2 SHDN# 3 5 OUT 4 BYP IN 1 GND 2 SHDN# 3 5 OUT 4 SET Fixed Mode Adjustable Mode NCT3705U -XXX NCT3705U -A (Top View) (Top View) Figure3. Pin Configuration IN + VOUT OUT COUT IN + COUT 4.7uF - CIN 1uF - SHDN# BYP R1 CIN 1uF CBYP VOUT OUT GND 4.7uF SHDN# SET GND R2 10nF Fixed Mode Adjustable Mode NCT3705U -XXX NCT3705U -A (Top View) (Top View) Figure4. Typical Application Circuits -4- Publication Date: Nov., 2008 Revision A1 NCT3705U 5. PIN DESCRIPTION PIN NAME NCT3705 NCT3705 U-A U-XXX I/O IN 1 I GND 2 SHDN# 3 FUNCTION Regulator input voltage. Supply voltage can range from 2.5V to 6.0V. Ground Active-Low shutdown input pin. I 4 BYP O A logic low reduces the supply current to 1uA. Connect to IN for normal operation. This is a reference bypass pin. It should connect an external capacitor to GND to reduce output noise. Feedback input for setting the output voltage. SET OUT 4 I 5 Connect to GND to set the output voltage to the preset output voltage. Connect to an external resistor divider for adjustable-output operation. Regulator output. Fixed or adjustable from 1.25V to 5.0V with sourcing current which up to 500mA. -5- Publication Date: Dec., 2008 Revision A1 NCT3705U 6. FUNCTIONAL DESCRIPTION 6.1 Output Voltage and Dropout voltage The output voltage of NCT3705U-A can be adjusted by the resistive divider between OUT, SET and GND pins. The internal VREF is 1.25V and the output voltage is given by the following equation: VOUT = VREF (1+R1/R2) =1.25(1+R1/R2) For the reasons of reducing power dissipation and loop stability, R2 is chosen to be 120KΩ. Alternatively, the relationship between R1 and R2 is given by: R1 = R2 (VOUT /1.25 - 1) A regulator's minimum input-output voltage differential (or dropout voltage) determines the lowest usable supply voltage. NCT3705U uses a P-channel MOSFET pass transistor, it’s dropout voltage is a function of RDS(ON) multiplied by the load current. Dropout voltage is defined as the input-output voltage differential at which output 100mV below the standard of output voltage. The NCT3705U has a very low dropout voltage 280 mV (typical at VOUT = 5V) with 500mA of output current. 6.2 Noise Noise is specified in two–spot noise or output noise density is the RMS (root means square) sum of all noise source, measured at the regulator output , at a specific frequency from 10Hz~100KHz,this type of frequency. Total output noise or Broad-Band Noise is the RMS sum of spot noise over specified bandwidth, usually several decades of frequencies. Total output noise is measured in μV (rms). With the 10nF capacitor at the BYP pin can reduce the noise significantly and is required for loop stability. The bandgap is noise source in the NCT3705U LDO that will generates 32uVrms in the 10HZ to 100KHZ bandwidth. It will be increased following the loop gain as below equation: Vnoise = 32uVrms *(VO/VREF) μV 6.3 PSRR PSRR (Power Supply Rejection Ratio) can be improved by CBYP capacitor selection. It’s the key of LDO anti-interference capability. With the increasing value of CBYP, the PSRR will be better. -6- Publication Date: Nov., 2008 Revision A1 NCT3705U Figure5. Select a CBYP for NCT3705 Circuits 6.4 Load Regulation Consideration Load regulation will be affected by the length of trace. The impendence of the trace (RLine1 & RLine2) will have influence on the VOUT. The output voltage is given by the following equation: VOUT = VOUT -[ ILoad * (RLine1 +RLine2) ] (Figure 6) The best method/layout is making terminals of VOUT & R1, R2 & GND as close as possible to reduce the trace impedance. It will have the better load regulation of the circuits. (Figure7) RLine1 RLine1 VOUT OUT IN OUT IN COUT COUT R1 R1 CIN 1uF 4.7uF SHDN# SET GND VOUT CIN 1uF R2 4.7uF SHDN# SET GND RLine2 Figure6. Equivalent Trace Impedance Circuits -7- R2 RLine2 Figure7. Recommended Circuits Publication Date: Dec., 2008 Revision A1 NCT3705U 6.5 Current Limit Protection The NCT3705U uses a current sense-resistor to monitor the output current. Once the output current exceeds limit threshold, NCT3705U would be protected with a limited output current. Further more, when the output is short to ground ( 10 inches) between the input source and the LDO, some input capacitance is recommended. A minimum of 1.0μF to 4.7μF is recommended for most applications. For applications that have output step load requirements, the input capacitance of the LDO is very important. The input capacitance provides the LDO with a good local low-impedance source to pull the transient currents from in order to respond quickly to the output load step. For good step response performance, the output capacitor value should be equivalent or higher than the input capacitor. The capacitor should be placed as close to the LDO as possible. Larger input capacitors will also help reduce any high-frequency noise on the input and output of the LDO and reduce the effects of any inductance that exists between the input source voltage and the input capacitance of the LDO. The recommended value of output capacitor is at least 1uF with low ESR. 6.7 Over Temperature Protection The NCT3705U LDO has temperature-sensing circuitry to prevent the junction temperature from exceeding approximately 150°C. If the LDO junction temperature does reach 150°C, the LDO output will be turned off until the junction temperature cools to approximately 110°C, at which point the LDO output will automatically resume normal operation. If the internal power dissipation continues to be excessive, the device will again shut off. The junction temperature of the die is a function of power dissipation, ambient temperature and package thermal resistance. -8- Publication Date: Nov., 2008 Revision A1 NCT3705U 6.8 Layout note Dropout and load regulation will be deteriorated when COUT, CIN and NCT3705U distance is too far. The capacitor must be located a distance of not more than 1 inch from the input and return to a clean analog ground. By putting CBYP close to the NCT3705U, the transient and PSRR will be improved and performs less output noise. NCT3705 NCT3705 Figure8. Fixed Mode Recommended Layout 6.9 Figure9. Adjustable Mode Recommended Layout Thermal Consideration Different (VIN-VOUT) combinations and ambient temperature play important roles in the thermal dissipation. The maximum power dissipation can be calculated by following formula: PD(MAX) = ( TJ-TA ) / θJA Where TJ is the maximum junction temperature.TA is the ambient temperature. θJA is the junction to ambient thermal resistance. For example: NCT3705U at the TA =25℃.it can calculate PD(MAX) = 520mW = (150℃ -25℃) / 240℃/W Differential voltage can to explain below： ( VIN – VOUT ) = PD(MAX) / IOUT NCT3705U occurs Over Temperature Protection if differential voltage surpasses below Figure10 & Figure11 safe operation range. -9- Publication Date: Dec., 2008 Revision A1 NCT3705U Thermal Consideration Area @ Iout=500mA 500 500 450 450 400 400 Ouput Current (mA) Ouput Current (mA) Thermal Consideration Area @ Iout=300mA 350 300 250 50 25 ℃ ℃ 200 150 350 300 50 0 100 75 ℃ ℃ 150 100℃ 50 75℃ 0 0.1 0.4 0.7 1 1.3 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4 4.3 4.6 0.1 0.4 0.7 Vin - Vout Differential Voltage (V) 1 1.3 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4 4.3 4.6 Vin - Vout Differential Voltage (V) Figure10. Safe Operating Area (IOUT=300mA) 7. 25℃ 200 100 100 50℃ 250 Figure11. Safe Operating Area (IOUT=500mA) ELECTRICAL CHARACTERISTIC 7.1 Absolute Maximum Ratings ITEM SYMBOL RATING UNIT Input Voltage VIN -0.3 to 7 V Output Voltage to Ground VOUT -0.3 to 7 V Output Current IOUT Operating Temperature Range Topt 0 to 70 ℃ Human Body Mode ±2 kV Machine Mode ±200 V Latch-Up ±100 mA Electrostatic discharge protection Internally limited Note: Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device and exposure to absolute maximum rating conditions for extended periods may affect device reliability. -10- Publication Date: Nov., 2008 Revision A1 NCT3705U Thermal Information 7.2 ITEM Power Dissipation, PD @ TA=25℃ Package Thermal Resistance, SOT23-5, θ RATING UNIT Internal Limited W 240 ℃/W JA Recommended operating conditions 7.3 ITEM SYMBOL MIN MAX UNIT V Input Voltage VIN 2.5 6.0 Continuous Output Current IOUT 0 500 Peak Output Current IPEAK 0 800 Operating Temperature Range 0 70 ℃ Junction Temperature Range 0 125 ℃ 7.4 mA Electrical Characteristics PARAMETER SYMBOL MIN TYP MAX UNIT 2.5 --- 6.0 V -2 --- 2 % Output Voltage range 1.25 --- 5.0 V Maximum Output Current 500 --- --- mA 500 750 mA 280 mA Input Voltage VIN Output Voltage Accuracy VOUT Current Limit ILIM Shot Circuit Current Isc Ground Pin Current IQ Dropout Voltage VDROP CONDITION Variation from specified VOUT, IOUT=1mA IOUT = 500mA --- 90 120 VOUT =1.25V --- 1.5 1.8 VOUT =1.80V --- 0.9 1.2 VOUT =2.50V --- 0.7 1.0 VOUT =2.80V --- 0.7 1.0 VOUT =3.30V --- 0.6 0.9 VOUT =4.75V --- 0.45 0.75 VOUT =5.00V --- 0.40 0.7 µA V Line Regulation ΔVLNR VIN=V(STD)+0.1V to 6.2V, IOUT=10mA --- 0.05 0.1 %/V Load Regulation ΔVLDR IOUT=10mA to 500mA --- --- 0.02 %/mA Ripple Rejection PSRR Freq. =100Hz, IOUT=10mA --- 70 --- dB --- 32 --- µVRMS Output Voltage Noise en COUT=4.7µF, VOUT =1.25V -11- Publication Date: Dec., 2008 Revision A1 NCT3705U CBYP=10nF, IOUT=1mA (10Hz to 100kHz) Shutdown Supply Current VOUT =1.80V --- 46 --- VOUT =2.50V --- 64 --- VOUT =2.80V --- 72 --- VOUT =3.30V --- 84 --- VOUT =4.75V --- 122 --- VOUT =5.00V --- 128 --- VOUT =0V,TA=+25℃ --- --- 1 µA IOUT =500mA 5m --- 500m Ω VIH Regulator enabled 1.5 --- --- VIL Regulator shutdown --- --- 0.4 ISHDN# VSHDN# = VIN, TA=+25℃ --- --- 0.1 IQSHDN# VSHDN# = GND, TA=+25℃ --- --- 0.1 VSET VIN=2.5V to 5.5V , IOUT=1mA TA=+25℃ 1.225 1.25 1.275 TA=TMIN to TMAX --- 1.25 --- ISET VSET = 1.3V TA=+25℃ --- 5 30 nA I SHDN Stable COUT ESR Range SHUTDOWN SHDN# Input Threshold SHDN# Input Bias Current V µA SET INPUT SET Reference Voltage SET Input current Leakage V THERMAL PROTECTION Thermal Shutdown Temperature TSHDN --- 150 --- ℃ Thermal Shutdown Hysteresis △TSHDN --- 40 ---- ℃ -12- Publication Date: Nov., 2008 Revision A1 NCT3705U 8. TYPICAL OPERATING WAVEFORMS (VOUT=4.75V) Turn – on time Turn – off time Line Transient Load Transient -13- Publication Date: Dec., 2008 Revision A1 NCT3705U Short Circuit Protection Over Current Protection Output Voltage Noise Power Supply Rejection Ratio dB 90 80 70 60 50 40 NCT3705= 4.75V NCT3705 =3.3V NCT3705 =2.8V NCT3705 =2.5V NCT3705 =1.8V 30 20 10 0 10 100 1000 HZ 10000 100000 1000000 -14- Publication Date: Nov., 2008 Revision A1 NCT3705U Quiescent current VS Output Current Dropout voltage VS Output Current 300 200 Iq(uA) Vdrop(mV) 250 150 100 50 0 0 100 200 99 98 97 96 95 94 93 92 91 0 300 300 PSRR VS Output Current 1 100 0.8 80 PSRR(dB) Vout(mV) Line Regulation VS Output Current 0.6 0.4 60 40 0.2 20 0 0 100 200 Iout(mA) Iout(mA) 0 100 200 300 0 Iout(mA) 100 200 Iout(mA) -15- Publication Date: Dec., 2008 Revision A1 300 NCT3705U Dropout VS Temperature Output Voltage VS Temperature 4.75 350 4.7 250 VOUT (mV) Dropout (mV) 300 200 150 4.65 4.6 100 4.55 50 0 4.5 -20 0 20 40 60 80 100 120 -20 0 Temperature (℃) 20 40 60 80 100 120 Temperature (℃) P.S.R.R VS Temperature Quiescent Current VS Temperature 80 120 70 100 P.S.R.R(dB) IQ (mV) 60 80 60 40 20 50 40 30 20 10 0 0 -20 0 20 40 60 80 100 120 -20 0 20 40 60 80 100 120 Temperature (℃) Temperature (℃) -16- Publication Date: Nov., 2008 Revision A1 NCT3705U 9. PACKAGE DIMENSION 5pin SOT23 Package D e1 HE E b e Y L L1 ¾ TAPING SPECIFICATION 5pin SOT23 Package -17- Publication Date: Dec., 2008 Revision A1 NCT3705U 10. ORDERING INFORMATION PART NUMBER MARKING VOUT NCT3705U-A 5A00 ADJ NCT3705U-12 5120 1.2V NCT3705U-15 5150 1.5V NCT3705U-18 5180 1.8V NCT3705U-25 5250 2.5V NCT3705U-28 5250 2.8V NCT3705U-33 5330 3.3V NCT3705U-475 5475 4.75V NCT3705U-50 5500 5.0V SUPPLIED AS PACKAGE TYPE PRODUCTION FLOW T Shape: 5 PIN SOT23 Commercial, 3,000 units/T&R (Green package) 0℃ to +70℃ 11. TOP MARKING SPECIFICATION 5XXX 1st Line: 3XXX z 5: 500mA (NCT3705U) z XXX : Please check ordering information -18- Publication Date: Nov., 2008 Revision A1 NCT3705U 12. REVISION HISTORY VERSION DATE PAGE A1 03/18/2009 All DESCRIPTION New Create Important Notice Nuvoton products are not designed, intended, authorized or warranted for use as components in systems or equipment intended for surgical implantation, atomic energy control instruments, airplane or spaceship instruments, transportation instruments, traffic signal instruments, combustion control instruments, or for other applications intended to support or sustain life. Further more, Nuvoton products are not intended for applications wherein failure of Nuvoton products could result or lead to a situation wherein personal injury, death or severe property or environmental damage could occur. Nuvoton customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Nuvoton for any damages resulting from such improper use or sales. -19- Publication Date: Dec., 2008 Revision A1