AMS1302 Features Description Output up to 24V The AMS1302 is a compact, high efficiency, and Internal MOSFET with high switch current up low voltage step-up DC/DC converter including to 3A an error amplifier, ramp generator, comparator, 20µA Quiescent (Switch-off) Supply Current switch pass element and driver in which providing 90% Efficiency a stable and high efficient operation over a wide Up to 450KHz Switching Frequency range of load currents. It operates in stable SOT-23-6L Package waveforms without external compensation. The high switching rate minimized the size of external components. Besides, the low quiescent current together with high efficiency maintains Applications long battery lifetime. The output voltage is set PDA with two external resistors. DSC The output voltage is set with two external LCD Panel resistors. RF-Tags MP3 Portable Instrument Wireless Equipment 1 Advanced Monolithic Systems http://www.ams-semitech.com AMS1302 Typical Applications AMS1302 Figure 1 (1.8V Stat-up input Voltage) ＊ RX can be a Zener Diodes or Resistor: The Ratio of RX/RVDD must to keep VDD voltage less than 5.5V. ＊ The resistor RM can be set to 50mΩ usually. AMS1302 Figure.2 （1.1V Stat-up input Voltage） ＊ The resistor RM can be set to 50mΩ usually 2 Advanced Monolithic Systems http://www.ams-semitech.com AMS1302 Absolute Maximum Ratings (Note 1) Supply Voltage…………………………………………………………………….…−0.3V to 6V SW Pin Switch Voltage……………………………………………………………………−0.3V to 28V Other I/O Pin Voltages……………………………………………………………−0.3V to 6V SW Pin Switch Current ……………………………………………………………...………………..3A Operating Junction Temperature…………………………………………………….……………..125°C Storage Temperature Range ……………………………………………….−65°C ~ +150°C Note 1: Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under any conditions. Moreover, such values for any two items must not be reached simultaneously. Operation above these absolute maximum ratings may cause degradation or permanent damage to the device. These are stress ratings only and do not necessarily imply functional operation below these limits. Pin Assignment 6 5 4 PIN NUMBER PIN NAME FUNCTION 1 GND Ground 2 SW Switch Output 3 SOE Source of the MOSFET 4 FB Feedback 5 VDD Output 6 EN ON/OFF Control(High Enable) SOT-23-6L 1 2 SOT-23-6L 3 3 Advanced Monolithic Systems http://www.ams-semitech.com AMS1302 Electrical Characteristics (VIN = 1.5V, VDD set to 3.3V, Load Current = 0A, TA = 25°C, unless otherwise specified) Parameter Test Conditions Min Typ Max 1.00 Units Start-UP Voltage IL = 1mA V Operating VDD Range VDD pin voltage Switch-off Current I (VIN) VIN = 5V 20 No Load Current I (VIN) VIN = 1.5V, VOUT = 3.3V 40 Feedback Reference Voltage Close Loop, VDD = 3.3V Switching Frequency VDD = 3.3V SW ON Resistance VDD = 3.3V 0.07 Ω Current Limit Setting VDD = 3.3V 3 A Line Regulation VIN = 1.5 ~ 2.5V, IL = 100mA 55 mV/V Load Regulation VIN = 2.5V, IL = 1 ~ 300mA 0.1 mV/mA 2 En Input High 1.182 5.5 1.212 µA µA 1.242 V 450 KHz 1 V En Input Low 0.6 Maximum VRM V 145 4 Advanced Monolithic Systems http://www.ams-semitech.com V mV AMS1302 Typical Performance Characteristics ℃ TA=25 , CIN =10 µF, COUT =20 µF, L=4.7 µH, unless otherwise noted. Refer to Test Circuit Figure 1 Efficiency vs. Output Current (Vout=5V) Output Voltage vs. Load Current (Vout=5V) 100 6 VIN =2V 90 5.5 70 Output Voltage (V) Efficiency(%) 80 VIN=1.5V 60 VIN =1V 50 40 30 20 VIN=1.5V 5 V IN =1V 4.5 VIN =2V 4 3.5 10 3 0 10 100 Output Current (mA) 0 1000 Efficiency vs. Output Current (Vout=5V) 5.5 VIN=3V 60 Output Voltage (V) 70 600 700 6 V IN =4.2V 80 Efficiency(%) 200 300 400 500 Load Current (mA) Output Voltage vs. Load Current (Vout=5V) 100 90 100 VIN =3.6V 50 40 30 20 VIN =4.2V 5 4.5 VIN =3V V IN =3.6V 4 3.5 10 3 0 10 100 1000 Output Current (mA) 10000 0 300 600 900 1200 1500 1800 Load Current (mA) 5 Advanced Monolithic Systems http://www.ams-semitech.com AMS1302 Pin Information GND (Pin 1): Signal and Power Ground. Provide a short direct PCB path between GND and the (–) side of the output capacitor(s). SW (Pin 2): Switch Pin. Connect inductor between SW and VIN. Keep these PCB trace lengths as short and wide as possible to reduce EMI and voltage overshoot. SOE (Pin 3): Source of the MOSFET. Connect resistor to GND FB (Pin 4): Feedback Input to the gm Error Amplifier. Connect resistor divider tap to this pin. The output voltage can be adjusted from 3.3V to 20V by: VOUT = 1.212V • [1 + (R1/R2)] VDD (Pin 5): Input positive power pin. EN (Pin 6): En Control Input. Forcing this pin above 1V enables the part. Forcing this pin below 0.6V shuts down the device. In shutdown, all functions are disabled, drawing <1µA supply current. Do not leave EN floating. Functional Diagram 6 Advanced Monolithic Systems http://www.ams-semitech.com AMS1302 Application Information Output Voltage Setting Referring to Typical Application Circuits, the output voltage of the switching regulator (VOUT) can be set with Equation (1). Feedback Loop Design Referring to the Typical Application Circuits. The selection of R1 and R2 based on the trade-off between quiescent current consumption and interference immunity is stated below: Follow Equation (1) Higher R reduces the quiescent current (Path current = 1.212V/R2), however resistors beyond 5MW are not Recommended. Lower R gives better noise immunity, and is less sensitive to interference, layout parasitics, FB node leakage, and improper probing to FB pin. For applications without standby or suspend modes, lower values of R1 and R2 are preferred. For applications concerning the current consumption in standby or suspend modes, the higher values of R1 and R2 are needed. Such high impedance feedback loop is sensitive to any interference, which requires careful PCB layout and avoid any interference, especially to FB pin. To improve the system stability, a proper value capacitor between FB pin and GND pin is suggested. An empirical suggestion is around 22pF. PCB Layout Guide PCB Layout shall follow these guidelines for better system stability: A full GND plane without gap break. VDD to GND noise bypass - Short and wide connection for the 20-100uF capacitor between Pin 5 and Pin 1. VIN to GND noise bypass - Add a 10uF capacitor close to L1 inductor, when VIN is not an idea voltage source. Minimized FB node copper area and keep far away from noise sources. 7 Advanced Monolithic Systems http://www.ams-semitech.com AMS1302 Packaging Information SOT-23-6L Package Outline Dimension Symbol Dimensions In Millimeters Min Max Dimensions In Inches Min Max A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.500 0.012 0.020 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 e 0.950(BSC) 0.037(BSC) e1 1.800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 0° 8° θ 0° 8° Subject changes without notice. 8 Advanced Monolithic Systems http://www.ams-semitech.com