SC189 2.5MHz, 1.5A Synchronous Step Down Regulator POWER MANAGEMENT Features Description VIN Range: 2.9 – 5.5V VOUT Options: 1.0 - 3.3V Up to 1.5A Output Current Ultra-Small Footprint, <1mm Height Solution 2.5MHz Switching Frequency Efficiency Up to 93% Low Output Noise Across Load Range Excellent Transient Response Start Up into Pre-Bias Output 100% Duty-Cycle Low Dropout Operation <1µA Shutdown Current Internal Soft Start Input Under-Voltage Lockout Output Over-Voltage, Current Limit Protection Over-Temperature Protection Adjustable Output Voltage Available in SOT23-5 package and 2mm x 2mm x 0.6mm thermally enhanced MLPD-UT6 package -40 to +85°C Temperature Range Fully WEEE and RoHS Compliant The SC189 is a high efficiency, synchronous step-down regulator providing up to 1.5A output current in either an ultra-small 2mm x 2mm, low profile package or a low cost SOT23-5 package. The device requires only three external filter components for a complete step down regulator solution. The input voltage range is 2.9 to 5.5V with either factory programmed outputs from 1.0 to 3.3V or adjustable output via an external resistor divider. The converter operates at fixed 2.5MHz switching frequency allowing small L/C filtering components. The voltage mode architecture is compatible with chip inductors and capacitors for minimum PCB footprint and lowest overall system cost. Total footprint of 25mm2 can be achieved - making the SC189 the ideal solution for high density systems. Solution height of <1mm is also possible. Up to 93% efficiency is achieved with low RDS(ON) internal switches. PWM constant frequency operation ensures low output ripple across the load range. 100% duty-cycle provides 360mV dropout voltage at 1.5A which extends the minimum input voltage for 2.5V and 3.3V outputs. Excellent transient response is achieved with no external compensation components. The SC189 provides input under-voltage, output overvoltage, output short circuit and over-temperature protection to safeguard the device and system under fault conditions. The regulator provides integrated soft-start to minimize inrush currents. Standby quiescient current is less than 1µA. Applications Bluetooth Radios DSC and PMPs GPS Devices xDSL Systems POL Regulators Portable HDD Wireless LAN The SC189 is available in SOT23-5 and a thermally enhanced 2mm x 2mm x 0.6mm MLPD-UT6 package rated from -40 to +85°C. Typical Application Circuit Total PCB Area ~25mm2 SC189C VIN 2.9V to 5.5V CIN 10µF VIN LX EN VOUT L 1µH L Chip VOUT 1.20V/1.5A COUT 22µF COUT 0805 GND SC189 CIN 0603 Actual Size June 01, 2009 www.semtech.com SC189 Pin Configuration NC 1 EN 2 VIN 3 Ordering Information TOP VIEW T 6 VOUT 5 GND 4 LX 2mm x 2mm x 0.6mm MLPD-UT6 θJA = 60°C/W(1) VIN 1 GND 2 EN 3 5 LX Device Package & Description SC189xULTRT(2)(3)(4) 2mm x 2mm x 0.6mm MLPD-UT6 SC189xSKTRT2)(3)(4) SOT23-5 SC189xEVB(5) Evaluation Board for MLPD-UT6 - Standard Size (i.e., Wire Wound Inductor) SC189xEVB-1(5) Evaluation Board for MLPD-UT6 - Small Size (i.e., Chip Inductor) SC189xEVB-2(5) Evaluation Board for SOT23-5 - Standard Size (i.e., Wire Wound Inductor) SC189xEVB-3(5) Evaluation Board for SOT23-5 - Small Size (i.e., Chip Inductor) TOP VIEW 4 VOUT Notes: (1) Measured in free convection, mounted on 10mm x 10mm, 2 layer FR4 PCB shown in figure 7 ( for MLPD-UT6 package) and figure 8 ( for SOT23-5 package) with copper of 1oz for each layer. (2) Available in tape and reel only. A reel contains 3,000 devices. (3) Available in lead-free package only. Device is WEEE and RoHS compliant. (4) “x” is the code of the output voltage. See Table 1 for the code. For example, the device number for VOUT= 1.20V is SC189CULTRT. (5) “x” is the code of the output voltage. See Table 1 for the code. For example, the EVB for MLPD-UT6 package with VOUT= 1.20V is SC189CEVB (Standard Size) or SC189CEVB-1 (Small Size). SOT23-5 θJA = 90°C/W(1) Marking Information FLx Table 1: Available Output Voltages Marking for 2mm x 2mm MLPD-UT 6 Lead Package: x = Code of the output voltage (Example: C for VOUT=1.20V) oyw = Pin 1 and Datecode (Reference Package Marking Design Guidelines, Appendix A) Top Mark Bottom Mark 189 x Marking for SOT23, 5 Lead Package: x = Code of the output voltage (Example: C for VOUT=1.20V) yyww = Datecode (Example: 0852) © 2009 Semtech Corp. Code for MLPD-UT6 Code for SOT23-5 VOUT(1) A A 1.00 B B 1.10 C C 1.20 E Not Available 1.28 F Not Available 1.30 H H 1.50 L L 1.80 N Not Available 2.00 T Y 2.50 Not Available V 2.70 Z Z 3.30 Notes: (1) Contact factory for unavaliable output voltage options. www.semtech.com SC189 Recommended Operating Conditions Absolute Maximum Ratings VIN Supply Voltage ……………………………… -0.3 to 6.0V VIN Supply Voltage ……………………………… 2.9 to 5.5V LX Voltage Maximum Output Current(3) …………………………… 1.5A ………….. -1 to VIN+1V, -3V (20ns Max), 6V Max VOUT Voltage Temperature Range …………………………… -40 to +85˚C ……………………………… -0.3 to VIN+0.3V EN Voltage …………………………………. -0.3 to VIN+0.3V Thermal Information Peak IR Reflow temperature …………………………. 260°C ESD Protection Level (2) …………………………………. Thermal Resistance, Junction to Ambient(1) 3kV MLPD-UT6 Package ……………………………… 60°C/W SOT23-5 Package ……………………………… 90°C/W Maximum Junction Temperature …………………… +150°C Storage Temperature Range ………………… -65 to +150 °C Exceeding the absolute maximum ratings may result in permanent damage to the device and/or device malfunction. Operation outside of the parameters specified in the Electrical Characteristics section is not recommended. NOTES: (1) Measured in free convection, mounted on 10mm x 10mm, 2 layer FR4 PCB shown in figure 7 ( for MLPD-UT6 package) and figure 8 ( for SOT235 package) with copper of 1oz for each layer. (2) Tested according to JEDEC standard JESD22-A114-B. (3) For SOT23-5 package, the limit of the maximum power dissiption shown in figure 2 may reduce the maximum output current. Electrical Characteristics Unless specified: VIN = 5.0V, CIN=10µF, COUT=10µF; L=2.2µH; -40°C<TA<+85 °C; TJ(MAX)=125°C; Unless otherwise noted typical values are TA=+25 °C. Parameter Symbol Conditions Min Typ Max Units Rising VIN 2.60 2.70 2.80 V Under-Voltage Lockout UVLO Output Voltage Tolerance(1) ΔVOUT VIN=3.6V to 5.0V; No Load -2.5 ILIMIT Peak inductor current 2.0 IQ EN= VIN, No Load 7.5 ISHDN EN= GND 1 ILX= 100mA, for MLPD-UT6 0.13 ILX= -100mA, for SOT23-5 0.15 ILX= -100mA, for MLPD-UT6 0.10 ILX= -100mA, for SOT23-5 0.125 VIN=5.5V; LX=0V; EN=GND 1 Current Limit VIN Supply Current VIN Shutdown Current High Side Switch Resistance Low Side Switch Resistance LX Leakage Current RDSON_P RDSON_N ILK(LX) Hysteresis VIN=5.5V; LX=5.0V; EN=GND 250 -10 mV +2.5 % A mA 10 µA Ω 10 -1 µA Line Regulation ΔVLINE-REG VIN= 3.6 – 5.0V; IOUT=0A ±1.0 % Load Regulation(2) ΔVLOAD-REG VIN= 5.0V; IOUT=10mA – 1.5A ±1.0 % Oscillator Frequency FOSC Soft-Start Time(2) TSS EN Input High Current © 2009 Semtech Corp. 2.0 2.5 3.0 100 IEN_HI EN=VIN -2.0 MHz µs 2.0 µA www.semtech.com SC189 Electrical Characteristics (continued) Unless specified: VIN = 5.0V, CIN=10µF, COUT=10µF; L=2.2µH; -40°C<TA<+85 °C; TJ(MAX)=125°C; Unless otherwise noted typical values are TA=+25 °C. Parameter Symbol Conditions Min EN Input Low Current IEN_LO EN=GND -2.0 EN Input High Threshold VEN_HI EN Input Low Threshold VEN_LO VOUT Over Voltage Protection(2) VOVP Thermal Shutdown Temperature (2) TSD TSD_HYS Thermal Shutdown Hysteresis (2) Typ Max Units 2.0 µA 1.2 V 0.4 V 115 % Junction Temperature +160 °C Junction Temperature 10 °C Notes: (1) The “Output Voltage Tolerance” includes output voltage accuracy, voltage drift over temperature and the line regulation. (2) Guaranteed by design. © 2009 Semtech Corp. www.semtech.com SC189 Typical Characteristics Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package. Efficiency Efficiency vs. Load Current (VOUT=3.3V) 100% 100% 95% 95% VIN= 4.0V VIN= 5.0V 90% 90% 85% 85% Efficiency (%) Efficiency (%) Efficiency vs. Load Current (VOUT=1.5V) Efficiency 80% 75% VIN= 3.3V 75% 70% 70% VOUT= 1.50V TA=25°C 65% VIN= 5.0V 80% VOUT= 3.30V TA=25°C 65% 60% 60% 0.0 0.3 0.6 0.9 1.2 0.0 1.5 0.3 0.6 0.9 1.2 1.5 Output Current (A) Output Current (A) Efficiency vs. Load Current (VIN=5.0V, VOUT=3.3V) Efficiency Efficiency Efficiency vs. Load Current (VIN=5.0V, VOUT=1.0V) 100% 100% L=1071AS-2R2N (50m_typ) L=1071AS-2R2N (50m_typ) 95% 95% L=1071AS-1R0N (33m_typ) 90% L=MDT2520-CR1R0M (60m_typ) 85% Efficiency (%) Efficiency (%) 90% 80% 75% 70% L=1071AS-1R0N (33m_typ) 80% L=MDT2520-CR1R0M (60m_typ) 75% 70% VIN= 5.0V VOUT= 1.0V TA=25°C L=LQM2HPN1R0MG0 (55m_typ) 65% 85% VIN= 5.0V VOUT= 3.3V TA=25°C 65% 60% 0.0 0.3 0.6 0.9 1.2 1.5 0.0 0.3 Output Current (A) 0.6 0.9 1.2 1.5 Output Current (A) Total Loss vs. LoadLosses Current (VOUT=3.3V) Total Loss vs. LoadLosses Current (VOUT=1.5V) 800 800 VOUT= 3.30V TA=25°C VOUT= 1.50V TA=25°C VIN= 3.3V 600 Loss (mW) 600 Loss (mW) L=LQM2HP1R0MG0 (55m_typ) 60% 400 VIN= 5.0V 400 200 200 VIN= 5.0V VIN= 4.0V 0 0 0.0 0.3 0.6 0.9 1.2 0.0 1.5 © 2009 Semtech Corp. 0.3 0.6 0.9 1.2 1.5 Output Current (A) Output Current (A) www.semtech.com SC189 Typical Characteristics (continued) Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package. Efficiency Efficiency vs. Load Current (VOUT=1.5V, SOT23-5) Efficiency Efficiency vs. Load Current (VOUT=3.3V, SOT23-5) 100% 100% VIN= 4.0V 95% VIN= 5.0V 90% 90% 85% 85% Efficiency (%) Efficiency (%) 95% 80% 75% VIN= 3.3V 75% 70% 70% VOUT= 1.50V TA=25°C 65% VIN= 5.0V 80% VOUT= 3.30V TA=25°C 65% 60% 60% 0.0 0.3 0.6 0.9 1.2 0.0 1.5 0.3 0.6 0.9 1.2 1.5 Output Current (A) Output Current (A) Efficiency Efficiency vs. Load Current (SOT23-5) Efficiency Efficiency vs. Load Current (SOT23-5) 100% 100% VIN= 5.0V VOUT= 1.0V TA=25°C 95% 90% L=1071AS-2R2N (50m_typ) L=1071AS-2R2 (50m_typ) 95% 90% Efficiency (%) Efficiency (%) L=1071AS-1R0 (33m_typ) 85% 80% 75% 85% L=1071AS-1R0N (33m_typ) 80% L=MDT2520-CR1R0M (60m_typ) 75% 70% 70% VIN= 5.0V VOUT= 3.3V TA=25°C L=LQM2HPN1R0MG0 (55m_typ) 65% 65% L=MDT2520-CR1R0 (60m_typ) 60% 60% 0.0 0.3 0.6 0.9 Output Current (A) 1.2 0.0 1.5 0.3 0.6 0.9 Output Current (A) 1.2 1.5 Total Loss vs. Load Current (VOUT=3.3V, SOT23-5) Losses Losses Total Loss vs. Load Current (VOUT=1.5V, SOT23-5) 800 800 VOUT= 3.30V TA=25°C VOUT= 1.50V TA=25°C VIN= 3.3V 600 Loss (mW) 600 Loss (mW) L=LQM2HP1R0MG0 (55m_typ) 400 VIN= 5.0V 400 200 200 VIN= 5.0V VIN= 4.0V 0 0 0.0 0.3 0.6 0.9 1.2 0.0 1.5 © 2009 Semtech Corp. 0.3 0.6 0.9 1.2 1.5 Output Current (A) Output Current (A) www.semtech.com SC189 Typical Characteristics (continued) Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package. RDSON (P & N) Variation Over Temperature RDS(ON) Variation vs. Temperature (P & N) Variation over Line RDS(ON)RDSON Variation vs. Input Voltage 30% 20% 25% 15% P-Channel 20% 10% 15% 5% Variation Variation VIN= 5.0V ILX= ±100mA 10% 5% N-Channel 0% -5% 0% -10% ILX= ±100mA TA= 25°C -5% N-Channel P-Channel -15% -10% -20% 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 -15 Input Voltage (V) 5% 60 85 1.0% 4% 0.8% VOUT= 3.3V 3% 0.6% 2% 0.4% 1% 0.2% Variation Variation 35 Frequency Variation SwitchingSwitching Frequency vs. Temperature Switching Frequency vs. Variation over Line Switching Frequency Input Voltage 0% -1% -2% -0.2% -0.6% IOUT= 0A TA= 25°C -4% 0.0% -0.4% VOUT= 1.5V -3% VIN= 5.0V IOUT= 0A -0.8% -5% -1.0% 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 -15 Input Voltage (V) 10 35 60 85 Ambient Temperature (°C) Line Regulationvs. over Temperature Line Regulation Temperature Line Regulation ove Line Line Regulation 1.0% 1.0% 0.8% 0.8% 0.6% 0.6% VOUT= 1.5V 0.4% 0.4% 0.2% Regulation Regulation 10 Ambient Temperature (°C) 0.0% -0.2% 0.2% 0.0% -0.2% -0.4% -0.4% VOUT= 3.3V -0.6% -0.6% IOUT= 0A TA= 25°C -0.8% VOUT= 1.5V IOUT= 0A -0.8% -1.0% -1.0% 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 Input Voltage (V) © 2009 Semtech Corp. -15 10 35 60 85 Ambient Temperature (°C) www.semtech.com SC189 Typical Characteristics (continued) Circuit Conditions: CIN= 10uF/6.3V; COUT= 10uF/6.3V for L=2.2uH; COUT= 22uF/6.3V for L=1uH. Unless otherwise noted, L= 2.2uH (TOKO: 1071AS-2R2M) and SC189 in MLPD-UT6 package. Load Regulation Load Regulation (VOUT=3.3V) Load Regulation Load Regulation (VOUT=1.5V) 1.0% 1.0% VOUT= 1.50V TA=25°C 0.8% 0.6% 0.6% 0.4% 0.4% VIN= 3.3V Load Regulation Load Regulation VOUT= 3.30V TA=25°C 0.8% 0.2% 0.0% -0.2% VIN= 4.0V 0.2% 0.0% -0.2% -0.4% -0.4% VIN= 5.0V -0.6% -0.6% VIN= 5.0V -0.8% -0.8% -1.0% -1.0% 0.0 0.3 0.6 0.9 1.2 0.0 1.5 0.3 0.6 5% 0.8% 4% 0.6% 3% 0.4% 2% 0.2% 1% Variation Variation 1.0% 0.0% -0.2% 1.5 60 85 0% -1% -0.4% -2% -0.6% -3% -4% IOUT= 0A -1.0% IOUT= 0A -5% -40 -15 10 35 60 85 -40 -15 Ambient Temperature (°C) 10 35 Ambient Temperature (°C) Dropout Voltage in 100% Duty Cycle Operation Dropout Voltage of 100% Duty Cycle Operation (MLP) Dropout Voltage in 100% Duty Cycle Operation Dropout Voltage of 100% Duty Cycle Operation (SOT23-5) 500 500 Package: MLPD-UT6 TA= 25°C 450 Package: SOT23-5 TA= 25°C 450 400 400 L= MDT2520-CR1R0M (DCR= 80m_max) 350 Dropout Voltage (mV) Dropout Voltage (mV) 1.2 HysteresisVariation Variation UVLOUVLO Hysteresis Rising Threshold Variation UVLOUVLO Rising Threshold Variation -0.8% 0.9 Output Current (A) Output Current (A) 300 250 200 150 100 300 250 200 150 100 L= 1071AS-1R0 (DCR=40m_max) 50 L= MDT2520-CR1R0M (DCR= 80m_max) 350 L= 1071AS-2R2 (DCR=60m_max) 50 0 0 0.0 0.3 0.6 0.9 1.2 0.0 1.5 Output Current (A) © 2009 Semtech Corp. 0.3 0.6 0.9 1.2 1.5 Output Current (A) www.semtech.com SC189 Typical Waveforms Circuit Conditions: VOUT=1.5V (SC189HULTRT); L= 2.2uH (TOKO: 1071AS-2R2M); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K). Output Voltage Ripple (V=1.5V) OUT=1.5V) Output Voltage Ripple (VOUT Output Voltage Ripple (V=1.5V) OUT=1.5V) Output Voltage Ripple (VOUT VOUT 10mV/div ILX VOUT 500mA/div 10mV/div ILX 500mA/div VLX VLX 2V/div 2V/div VIN=5.0V IOUT=0A VIN=5.0V IOUT=1.5A 500ns/div Output Voltage Ripple (V=1.5V) OUT=1.5V) Output Voltage Ripple (VOUT 500ns/div Output Voltage Ripple (V=1.5V) OUT=1.5V) Output Voltage Ripple (VOUT VOUT 10mV/div VOUT 10mV/div ILX ILX 500mA/div 500mA/div VLX VLX 2V/div 2V/div VIN=3.3V IOUT=0A VIN=3.3V IOUT=1.5A 500ns/div (VOUT TransientTransient ResponseResponse (VOUT=1.5V; 0A=1.5V) to 0.5A) 500ns/div Transient Response OUT=1.5V) Transient Response (VOUT=1.5V;(V0.5A to 1.0A) VOUT VOUT 100mV/div 100mV/div IOUT IOUT 500mA/div 500mA/div VIN=5.0V IOUT=0A to 0.5A © 2009 Semtech Corp. VIN=5.0V IOUT=0.5A to 1A 50µs/div 50µs/div www.semtech.com SC189 Typical Waveforms (continued) Circuit Conditions: VOUT=1.5V (SC189HULTRT); L= 2.2uH (TOKO: 1071AS-2R2); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K). Up (VOUT=1.5V) Start UpStart (Enable)(V =1.5V) OUT Up (VOUT=1.5V) Start UpStart (Enable)(V =1.5V) OUT VIN VIN 2V/div 2V/div VEN VEN 2V/div 2V/div VOUT VOUT 1V/div 1V/div VIN=5.0V ROUT=1k VIN=5.0V ROUT=1 100µs/div Start Up (Vup =1.5V), OUTV Start Up (Power ) (VOUTEN=VIN =1.5V) IN 100µs/div Start Up (Vup =1.5V), OUTV Start Up (Power ) (VOUTEN=VIN =1.5V) IN VIN VIN 2V/div 2V/div VOUT VOUT 500mV/div 500mV/div VIN=5.0V ROUT=1k VIN=5.0V ROUT=1 200µs/div Start UpUp intointo Pre-Biased OUT=1.5V) Enable Start Pre-Bias Output Output(V(Enable) 200µs/div ShutdownShutdown-Disable (Disable) (VOUT=1.5V) VIN 2V/div VIN 2V/div VEN 2V/div VEN 2V/div VOUT VOUT 500mV/div 500mV/div VIN=5.0V ROUT=1k © 2009 Semtech Corp. VIN=5.0V ROUT=1.5 200µs/div 10 50µs/div www.semtech.com SC189 Typical Waveforms (continued) Circuit Conditions: VOUT=3.3V (SC189ZULTRT); L= 2.2uH (TOKO: 1071AS-2R2); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K). Output Voltage Ripple (V=3.3V) OUT=3.3V) Output Voltage Ripple (VOUT Output Voltage Ripple (V=3.3V) OUT=3.3V) Output Voltage Ripple (VOUT VOUT 10mV/div VOUT ILX 10mV/div 500mA/div ILX 500mA/div VLX VLX 2V/div 2V/div VIN=5.0V IOUT=0A VIN=5.0V IOUT=1.5A 500ns/div (VOUT TransientTransient ResponseResponse (VOUT=3.3V; 0A=3.3V) to 0.5A) 500ns/div Transient Response OUT=3.3V) Transient Response (VOUT=3.3V;(V0.5A to 1.0A) VOUT VOUT 100mV/div 100mV/div IOUT IOUT 500mA/div 500mA/div VIN=5.0V IOUT=0A to 0.5A VIN=5.0V IOUT=0.5A to 1A 50µs/div Up (VOUT=3.3V) Start UpStart (Enable)(V =3.3V) OUT 50µs/div Up (VOUT=3.3V) Start UpStart (Enable)(V =3.3V) OUT VIN VIN 5V/div 5V/div VEN VEN 2V/div 2V/div VOUT VOUT 1V/div 1V/div VIN=5.0V ROUT=1k © 2009 Semtech Corp. VIN=5.0V ROUT=2.2 200µs/div 11 200µs/div www.semtech.com SC189 Typical Waveforms (continued) Circuit Conditions: VOUT=3.3V (SC189ZULTRT); L= 2.2uH (TOKO: 1071AS-2R2); CIN= COUT= 10uF/6.3V (Murata: GRM21BR60J106K). Start Up (Vup =3.3V), OUTV Start Up (Power ) (VOUTEN=VIN =3.3V) IN Start Up (Vup =3.3V), OUTV Start Up (Power ) (VOUTEN=VIN =3.3V) IN VIN VIN 2V/div 2V/div VOUT VOUT 1V/div 1V/div VIN=5.0V ROUT=1k VIN=5.0V ROUT=2.2 200µs/div Start Up Up intointo Pre-Biased OUT=3.3V)(Enable) Start Pre-BiasOutput Output(V(Enable) VIN 200µs/div Start Pre-Biased Output (Power (VOUT=3.3V)(Power Up) StartUp Upinto into Pre-Bias Output Up V ) IN VIN 2V/div 2V/div VEN 2V/div VOUT VOUT 1V/div 1V/div VIN=5.0V ROUT=1k VIN=5.0V ROUT=1k 200µs/div Shutdown-Disable (VOUT =3.3V) Shutdown (Disable) (VOUT =3.3V) 200µs/div Shutdown-Disable (VOUT =3.3V) Shutdown (Disable) (VOUT =3.3V) VIN VIN 5V/div 5V/div VEN VEN 2V/div 2V/div VOUT VOUT 2V/div 2V/div VIN=5.0V ROUT=33 © 2009 Semtech Corp. VIN=5.0V ROUT=3.3 500µs/div 12 100µs/div www.semtech.com SC189 Typical Waveforms (continued) Circuit Conditions: VOUT=1.0V (SC189AULTRT); L= 1uH (Murata: LQM2HPN1R0NG0L); CIN= 10uF/6.3V; COUT= 22uF/6.3V (Murata: GRM21BR60J226M). Output Voltage Ripple (V=1.0V) OUT=1.0V) Output Voltage Ripple (VOUT Output Voltage Ripple (V=1.0V) OUT=1.0V) Output Voltage Ripple (VOUT VOUT VOUT 10mV/div 10mV/div ILX ILX 500mA/div Offset: 0A 1A/div VLX VLX 2V/div 2V/div VIN=3.3V IOUT=0A VIN=3.3V IOUT=1.5A 500ns/div Output Voltage Ripple (V=1.0V) OUT=1.0V) Output Voltage Ripple (VOUT 500ns/div Output Voltage Ripple (V=1.0V) OUT=1.0V) Output Voltage Ripple (VOUT VOUT VOUT 10mV/div 10mV/div ILX ILX 500mA/div 1A/div VLX VLX 2V/div 2V/div VIN=5.0V IOUT=0A VIN=5.0V IOUT=1.5A 500ns/div Transient Response (V=1.0V) OUT=1.0V) Transient Response (VOUT 500ns/div Transient Response (V=1.0V) OUT=1.0V) Transient Response (VOUT VOUT VOUT 20mV/div 20mV/div IOUT IOUT 500mA/div 500mA/div VIN=5.0V IOUT=0A to 0.5A © 2009 Semtech Corp. VIN=5.0V IOUT=0.5A to 1A 50µs/div 13 50µs/div www.semtech.com SC189 Pin Descriptions Pin # (MPLD-UT6) Pin # (SOT23-5) Pin Name Pin Function 1 Not Available NC No connection. 2 3 EN Enable pin. When connected to logic high or tied to VIN pin, the SC189 is on. When connected to logic low, the device enters shutdown and consumes less than 1µA of current. The enable pin has a 1 MΩ internal pulldown resistor. This resistor is switched in circuit whenever the EN pin is below the enable input high threshold, or when the part is in undervoltage lockout. 3 1 VIN Input power supplies. Powers the internal circuitry and is connected to the source of highside P channel MOSFET. 4 5 LX Switching node - connect an inductor between this pin and the output capacitor. 5 2 GND Ground connection. 6 4 VOUT Output voltage sense pin. T Not Available Thermal Pad © 2009 Semtech Corp. Thermal pad for heatsinking purposes. This pad is not connected internally. Connect it to GND plane. 14 www.semtech.com SC189 Block Diagram VIN + Current Amp Internal Oscillator VOVP VOUT Voltage Select Plimit Comp Plimit Amp Ramp Generator + + + - Control Logic OVP Error Amp LX + PWM Comp 500mV Ref GND EN © 2009 Semtech Corp. 15 www.semtech.com SC189 Applications Information Detailed Description shown above. For programming the output voltage from other standard voltage, the RFB1, RFB2 and CFF need to be adjusted to meet the equation shown above. The SC189 is a synchronous step-down pulse width modulated (PWM) voltage mode DC-DC regulator operating at 2.5MHz fixed-frequency. The switching frequency is chosen to minimize the size of the external inductor and capacitors while maintaining high efficiency. Maximum Power Dissiption of SOT23-5 Package The maximum power dissiption for junction temperature of less than 125°C on SOT23-5 package is shown in figure 2. The curve is drawn based on the ΘJA of 90°C/W which is measured in free convection, mounted on 10mm x 10mm, 2 layer FR4 PCB shown in figure 8 with copper of 1oz for each layer. The maximum power dissiption may limit the maximum output current over temperature. The figure 3 and figure 4 show the typical maximum output current for TJ ≤ 125°C over temperature of VIN=5.0V and VIN=3.3V, respectively. If using inductor with higher loss (i.e., chip inductor), due to the higher board temperature, the ΘJA will be a little bit higher. Operation During normal operation, the internal highside PMOS device is activated on each rising edge of the internal oscillator. The voltage feedback loop uses an internal feedback resistor divider. The period is set by the on board oscillator when in PWM mode at average to high loads. The device has an internal low-side synchronous NMOS device and does not require a Schottky diode on the LX pin. The device operates as a buck converter in PWM mode with a fixed frequency of 2.5MHz. Output Voltage Selection Protection Features The SC189 is designed for fixed output voltage. There are some options for preset output voltage shown in Table 1. If the voltage desired is not shown in the Table 1, it can be programmed via an external resistor divider. There will be typical 1uA current flowing into the VOUT pin. The typical schematic of adjustable output voltage option from the part with standard 1.0V, the SC189A, is shown in Figure 1. The CFF is needed for maintain the performance of the transient response. The proper value of CFF can be calculated by the equation C FF [nF ] = 10 × The SC189 provides the following protection features: Thermal Shutdown Current Limit Over-Voltage Protection Soft-Start Operation • • • • Thermal Shutdown The device has a thermal shutdown feature to protect the SC189 if the junction temperature exceeds 160°C. During thermal shutdown, the on-chip power devices are disabled with the LX output floating. When the die temperature drops by 10°C, the part will initiate a soft start recovery to normal operation. (VOUT − 0.5)2 VOSTD ×( ) RFB1[kΩ] ⋅ (VOUT − VOSTD ) VOSTD − 0.5 ,where the VOSTD is the standard voltage shown in Table 1. To simplify the design, it is recommended to program the Current Limit desired output voltage from 1.0V (Std as shown in Schematic of Adjustable VOUT standard from SC189A VOUT=1.0V) The internal PMOS power device in the switching stage is Figure 1 with a proper CFF calculated from the equation protected by current limit feature. If the output is loaded L above the PMOS current limit for 32 consecutive cycles, V V LX VIN the SC189 enters foldback current limit mode and the C C R GND output current is limited to the current limit holding C R current (ICL_HOLD) of a few hundred milliampere. Under Enable EN VOUT R these conditions the output voltage will be the product RFB1 = (VOUT − 1) × RFB 2 SC189A of I CL_HOLD and the load resistance. The current limit holding current (ICL_HOLD) will be decreased when output Figure 1 — Typical schematic for adjustable output voltage is increased. The load presented must fall below voltage option from standard 1.0V of SC189A OUT IN IN OUT EN FB1 FF FB2 10k Note: (1) REN is optional. (2) R =10k and C © 2009 Semtech Corp. FB2 =10nF for standard design. FF 16 www.semtech.com SC189 Applications Information (continued) Maximum Power Dissiption for T J 125°C SOT23-5 Package the current limit holding current for the SC189 to exit foldback current limit mode. Figure 5 shows the typical current limit holding current decreasing rate over different output voltage. The SC189 is capable of sustaining an indefinite short circuit without damage and will resume normal operation when the fault is removed. The foldback current limit mode will be disabled during the soft-start. 1500 Power Dissiption (mW) 1200 900 600 300 JA= 90°C/W Over-Voltage Protection 0 -40 -25 -10 5 20 35 50 65 80 Ambient Temperature (°C) 95 110 125 In the event of a 15% over-voltage on the output, the PWM drive is disabled with LX pin floating. Figure 2 — Maximum power dissiption of SOT23-5 package over temperature Maximum Output Current for T 125°C J Soft-Start 2.0 1.8 The soft-start mode is activated after VIN reaches its UVLO and EN signal is set high to enable the part. An over temperature shutdown event will also activate the soft start sequence. Soft-start mode controls the maximum current during startup thus limiting in-rush current. The PMOS current limit is stepped through four soft start levels of approximately 20%, 25%, 40%, & 100%. Each step is maintained for 20μs following internal reference start up of 20μs giving the total nominal startup period of 100μs. During startup, the chip operates in controlling the inductor current swings between 0A and current limit. If VOUT reaches 90% of the target within the first 2 current levels, the chip continues in hysteretic mode till the end of the soft-start time period before switching to PWM mode. If VOUT does not reach 90% by the end of the second current limit level, soft start will continue to level 3 or level 4 till the output voltage reaches 96% and will then transition into PWM mode. After the full soft start time period, the SC189 will switch into PWM mode operation regardless of the VOUT level. VOUT=1.2V Output Current (A) 1.6 1.4 1.2 VOUT=2.5V 1.0 0.8 VOUT= 3.3V 0.6 0.4 VIN= 5.0V JA= 90°C/W 0.2 0.0 -40 -25 -10 5 20 35 50 65 80 Ambient Temperature (°C) 95 110 125 Figure 3 — Typical maximum output current over temperature of SOT23-5 package, VIN= 5.0V Maximum Output Current for T 125°C J 2.0 1.8 VOUT=1.2V Output Current (A) 1.6 1.4 1.2 1.0 0.8 VOUT=2.5V 0.6 0.4 VIN= 3.3V JA= 90°C/W 0.2 0.0 -40 -25 -10 5 20 35 50 65 80 Ambient Temperature (°C) 95 110 125 Figure 4 — Typical maximum output current over temperature of SOT23-5 package, VIN= 3.3V The SC189 is capable of starting up into a pre-biased output. When the output is precharged by another supply rail, the SC189 will not discharge the output during the soft start interval. Current Limit Holding Current over Vout 150 Current Limit holding Current (mA) TA= 25°C 120 VIN= 5.0V Shut Down 90 When the EN pin voltage goes low, the SC189 will run in shutdown mode, drawing less than 1μA from the input power supply. The internal switches and bandgap voltage will be immediately turned off. 60 30 VIN= 3.6V 0 1.0 1.5 2.0 2.5 3.0 3.5 Inductor Selection Output Voltage (V) Figure 5 — Current limit holding current decreasing rate vs. output voltage © 2009 Semtech Corp. The SC189 converter has internal loop compensation. The 17 www.semtech.com SC189 Applications Information (continued) Vout Code (Vout) A(1.0V),B(1.1V),C(1.2V),E(1.28V),F(1.3V),H(1.5V) Output Capacitor Inductor Description Vender Part Number 2.2uH, 60m(max) Wire Wound 2.8x3.0x1.5(mm) TOKO 1071AS-2R2N 1.0uH, 40m(max) Wire Wound 2.8x3.0x1.5(mm) TOKO 1071AS-1R0N 1.0uH, 80m(max) Multilayer Chip 2.5x2.0x1.0(mm) 1.0uH, 69m(max) Multilayer Chip 2.5x2.0x1.0(mm) TOKO Murata Description MDT2520-CR1R0M LQM2HPN1R0MG0 Vender Part Number Qty. 10uF,6.3V X5R,0805 Murata GRM21BR60J106K 1 22uF,6.3V X5R,0805 Murata GRM21BR60J226M 1 22uF,6.3V X5R,0805 Murata GRM21BR60J226M 1 10uF,6.3V X5R,0805 Murata GRM219R60J106K 1 22uF,6.3V X5R,0805 Murata GRM21BR60J226M 1 10uF,4.0V X5R,0603 Murata GRM188R60G106M 2 Table 2a – Recommended L and output capacitors for Vout=1.0V to 1.5V Vout Code (Vout) L(1.8V),N(2.0V),T(Y)(2.5V),V(2.7V),Z(3.3V) Inductor Output Capacitor Description Vender Part Number 2.2uH, 60m(max) Wire Wound 2.8x3.0x1.5(mm) TOKO 1071AS-2R2N 1.0uH, 40m(max) Wire Wound 2.8x3.0x1.5(mm) TOKO 1071AS-1R0N 1.0uH, 80m(max) Multilayer Chip 2.5x2.0x1.0(mm) TOKO Description MDT2520-CR1R0M Vender Part Number Qty. 10uF,6.3V X5R,0805 Murata GRM21BR60J106K 1 22uF,6.3V X5R,0805 Murata GRM21BR60J226M 1 22uF,6.3V X5R,0805 Murata GRM21BR60J226M 1 10uF,4.0V X5R,0603 Murata GRM188R60G106M 2 Table 2b – Recommended L and output capacitors for Vout=1.8V to 3.3V © 2009 Semtech Corp. 18 www.semtech.com SC189 Applications Information (continued) compensation is designed to work with a output filter corner frequency of less than 100kHz over any operating condition, tolerance and bias effect. The corner frequency of output filter can be defined by the equation fC minimum gap possible to limit the distance that magnetic fields can radiate from the inductor. However shielded inductors typically have a higher DCR and are thus less efficient than a similar sized non-shielded inductor. 1 2S L COUT The SC189 is compatible with small shielded chip inductors for low cost, low profile applications. The inductance roll off characteristic of chip inductor is worse resulting in high ripple current and increased output voltage ripple at heavy load operation. SC189 has OCP peak inductor current threshold of 2.0A minimum, to support 1.5A DC load current, the inductor ripple current at 1.5A DC load current needs to be less than 1A. Values outside this range may lead to instability, malfunction, or out-of-specification performance. When choosing an inductor, it is important to consider the change in inductance with DC bias current. The inductor saturation current is specified as the current at which the inductance drops a specific percentage from the nominal value. This is approximately 30%. Except for short-circuit or other fault conditions, the peak current must always be less than the saturation current specified by the manufacturer. The peak current is the maximum load current plus one half of the inductor ripple current at the maximum input voltage. Load and/or line transients can cause the peak current to exceed his level for short durations. Maintaining the peak current below the inductor saturation specification keeps the inductor ripple current and the output voltage ripple at acceptable levels. Manufacturers often provide graphs of actual inductance and saturation characteristics versus applied inductor current. The saturation characteristics of the inductor can vary significantly with core temperature. Core and ambient temperatures should be considered when examining the core saturation characteristics. Final inductor selection depends on various design considerations such as efficiency, EMI, size, and cost. Table 2a and 2b list the manufacturers of recommended inductor and output capacitors. Chip inductors provide smaller footprint and height with lower efficiency and increased output voltage ripple. Transient load performance is equivalent to wire wound inductors. Figure 6 shows the typical efficiency curves for different inductors. Efficiency 100% L=1071AS-2R2N (50m_typ) 95% Efficiency (%) 90% L=1071AS-1R0N (33m_typ) 80% L=MDT2520-CR1R0M (60m_typ) 75% 70% VIN= 5.0V VOUT= 3.3V TA=25°C 65% L=LQM2HP1R0MG0 (55m_typ) 60% 0.0 When the inductance has been determined, the DC resistance (DCR) must be examined. The efficiency that can be achieved is dependent on the DCR of the inductor. The lower values give higher efficiency. The RMS DC current rating of the inductor is associated with losses in the copper windings and the resulting temperature rise of the inductor. This is usually specified as the current which produces a 40˚C temperature rise. Most copper windings are rated to accommodate this temperature rise above maximum ambient. 0.3 0.6 0.9 Output Current (A) 1.2 1.5 Figure 6 — Typical efficiency curves (VIN=5.0V, VOUT=3.3V) COUT Selection The internal voltage loop compensation in the SC189 limits the minimum output capacitor value to 10μF if using the inductor of 2.2μH. This is due to its influence on the the loop crossover frequency, phase margin, and gain margin. Increasing the output capacitor above this minimum value will reduce the crossover frequency and provide greater phase margin. A total output capacintance should not exceed 30uF to avoid any start-up problems. For most typical applications, it is recommended to use output capacitance of 10uF to 22uF. When choosing output Magnetic fields associated with the output inductor can interfere with nearby circuitry. This can be minimized by the use of low noise shielded inductors which use the © 2009 Semtech Corp. 85% 19 www.semtech.com SC189 Applications Information (continued) The input capacitor RMS ripple current varies with the input and output voltage. The maximum input capacitor RMS current is found from the equation capacitor’s capacitance, verify the voltage derating effect from the capacitor vendors data sheet. Capacitors with X7R or X5R ceramic dielectric are recommended for their low ESR and superior temperature and voltage characteristics. Y5V capacitors should not be used as their temperature coefficients make them unsuitable for this application. I CIN ( RMS ) = The output capacitor RMS current ripple may be calculated from the equation 1 VOUT ⋅ (VIN ( MAX ) − VOUT ) = L ⋅ f OSC ⋅ VIN 2 3 Table 3 lists the manufacturers of recommended output capacitor options. CIN Selection Type Rated Voltage (VDC) Value at 3.3V (μF) Dimensions LxWxH (mm) 10±10% X5R 10 4.42 2.0x1.25x1.25 (EIA:0805) Murata GRM21BR71A106K 10±10% X7R 10 4.88 2.0x1.25x1.25 (EIA:0805) Murata GRM21BR60J106K 10±10% X5R 6.3 4.05 2.0x1.25x1.25 (EIA:0805) Murata GRM21BR70J106K 10±10% X7R 6.3 4.91 2.0x1.25x1.25 (EIA:0805) Murata GRM21BR60J226M 22±20% X5R 6.3 6.57 2.0x1.25x1.25 (EIA:0805) Manufacturer Part Nunber Value (μF) Murata GRM21BR61A106K Table 3 – Recommended Capacitors The SC189 source input current is a DC supply current with a triangular ripple imposed on it. To prevent large input voltage ripple, a low ESR ceramic capacitor is required. A minimum value of 4.7μF should be used. It is important to consider the DC voltage coefficient characteristics when determining the actual required value. To estimate the required input capacitor, determine the acceptable input ripple voltage and calculate the minimum value required for CIN from the equation C IN The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the PMOS switch. Low ESR/ESL X5R ceramic capacitors are recommended for this function. To minimise stray inductance ,the capacitor should be placed as closely as possible to the VIN and GND pins of the SC189. 3 ⋅ ∆I LOAD VDROOP ⋅ f OSC I COUT ( RMS ) VOUT 1 − VIN The input voltage ripple and RMS current ripple are at maximum when the input voltage is twice the output voltage or 50% duty cycle. The output voltage droop due to a load transient is determined by the capacitance of the ceramic output capacitor. The ceramic capacitor supplies the load current initially until the loop responds. Within a few switching cycles the loop will respond and the inductor current will increase to match the required load. The output voltage droop during the period prior to the loop responding can be related to the choice of output capacitor by the relationship. COUT = VOUT VIN VOUT 1 − VIN = ∆V − ESR ⋅ f OSC I OUT VOUT VIN © 2009 Semtech Corp. 20 www.semtech.com SC189 Applications Information (continued) PCB Layout Considerations The layout diagram in figure 7 and figure 8 shows a recommended PCB for MLPD-UT6 2x2 and SOT23-5 package, respectively. Fundamental layout rules must be followed since the layout is critical for achieving the performance specified in the Electrical Characteristics table. Poor layout can degrade the performance of the DCDC converter and can contribute to EMI problems, ground bounce, and resistive voltage losses. Poor regulation and instability can result. L CIN COUT VOUT U1 GND VIN GND EN (a) Top layer for MLPD-UT6 2x2 package The following guidelines are recommended when developing a PCB layout: 1. The input capacitor, CIN should be placed as close to the VIN and GND pins as possible. This capacitor provides a low impedance loop for the pulsed currents present at the buck converter’s input. Use short wide traces to connect as closely to the IC as possible. This will minimize EMI and input voltage ripple by localizing the high frequency current pulses. 2. Keep the LX pin traces as short as possible to minimize pickup of high frequency switching edges to other parts of the circuit. COUT and L should be connected as close as possible between the LX and GND pins, with a direct return to the GND pin from COUT. 3. Route the output voltage feedback/sense path away from inductor and LX node to minimize noise and magnetic interference. 4. Use a ground plane referenced to the SC189 GND pin. Use several vias to connect to the component side ground to further reduce noise and interference on sensitive circuit nodes. 5. If possible, minimize the resistance from the VOUT and GND pins to the load. This will reduce the voltage drop on the ground plane and improve the load regulation. And it will also improve the overall efficiency by reducing the copper losses on the output and ground planes. GND GND (b) Bottom layer for MLPD 2x2 package Figure 7 — Recommended PCB Top & Bottom Layer Layout for MLPD-UT6 2x2 Package L VOUT CIN COUT U1 GND VIN (a) Top layer for SOT23-5 package GND EN (b) Bottom layer for SOT23-5 package Figure 8 — Recommended PCB Top & Bottom Layer Layout for SOT23-5 Package © 2009 Semtech Corp. 21 www.semtech.com SC189 Outline Drawing – 2x2 MLPD-UT6 A DIMENSIONS INCHES MILLIMETERS DIM MIN NOM MAX MIN NOM MAX B D A A1 A2 b D D1 E E1 e L N aaa bbb E PIN 1 INDICATOR (LASER MARK) A2 A SEATING PLANE aaa C C A1 .024 .002 (.006) .007 .010 .012 .075 .079 .083 .061 .067 .071 .075 .079 .083 .026 .031 .035 .020 BSC .010 .014 .018 6 .003 .004 .018 .000 0.60 0.05 (0.1524) 0.18 0.25 0.30 1.90 2.00 2.10 1.55 1.70 1.80 1.90 2.00 2.10 0.65 0.80 0.90 0.50 BSC 0.25 0.35 0.45 6 0.08 0.10 0.45 0.00 D1 2 1 LxN E1 N bxN bbb e C A B NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS TERMINALS. Land Pattern – 2x2 MLPD-UT6 H R DIM (C) G K C G H K P R X Y Z Z Y P X DIMENSIONS INCHES MILLIMETERS (.077) .047 .067 .031 .020 .006 .012 .030 .106 (1.95) 1.20 1.70 0.80 0.50 0.15 0.30 0.75 2.70 NOTES: © 2009 Semtech Corp. 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. 3. THERMAL VIAS IN THE LAND PATTERN OF THE EXPOSED PAD SHALL BE CONNECTED TO A SYSTEM GROUND PLANE. FAILURE TO DO SO MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. 22 www.semtech.com SC189 Outline Drawing – SOT23-5 Land Pattern – SOT23-5 X DIMENSIONS DIM (C) G C G P X Y Z Z Y P MILLIMETERS (2.50) 1.40 0.95 0.60 1.10 3.60 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE MET. Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com © 2009 Semtech Corp. 23 www.semtech.com