FT441AA

Fremont Micro Devices FT441 1.5MHz, 900mA Synchronous Step-Down Converter FEATURES DESCRIPTION ¾ High Efficiency - Up to 95% The FT441 is a 1.5MHz constant frequency, slope ¾ Guaranteed 900mA Output Current compensated current mode step down converter. It is ¾ 2.5V to 5.5V Input Voltage Range ideal for portable equipment requiring very high ¾ 1.5MHz Constant Frequency Operation current up to 0.9A from single-cell Lithium-ion ¾ No external Schottky Diode Needed batteries while still achieving over 90% efficiency ¾ Adjustable Output Voltages From 0.6V to VIN during peak load conditions. ¾ Fixed Output Voltage Options Available ¾ 100% Duty Cycle Low-Dropout Operation The FT441 integrates a main switch and a ¾ 0.1ȝA Shutdown Current synchronous rectifier for high efficiency without an ¾ SOT23-5 Package external Schottky diode. The FT441 automatically turns off the synchronous rectifier to increase TYPICAL APPLICATIONS efficiency while enters discontinuous PWM mode. ¾ Cellular phones The FT441 can run at 100% duty cycle for low ¾ DSP Core Supplies dropout operation, maximizing battery life in portable ¾ XDSL Applications application. FT441 consumes less than 1uA when ¾ USB Powered Modems enter shutdown mode. ¾ Digital Still Cameras ¾ Portable Instruments The FT441 is available in a fixed output voltages of ¾ PC Cards and Notebooks 1.2V, 1.5V, and 1.8V, and is also available in an adjustable output voltage version capable of generating output voltages from 0.6V to VIN .The FT441 is available in a 5-pin SOT23-5 package. www.fremontmicro.com Page 1 of 10 DS441-A2 Fremont Micro Devices FT441 TYPICAL APPLICATION CIRCUIT VIN 2.7~4.2V 4 SW VIN 3 1 EN Vout 1.8V C2 22pF FT441 C1 10uF L1 2.2uH VFB 5 GND 2 R2 200K C3 10u F R1 100K Figure 1: Typical Application Circuit ABSOLUTE MAXIMUM RATINGS VIN to GND……………………………….……………………………………………………………-0.3V to 6V EN to GND..…………………………………………….……………………………….. ……-0.3V to (VIN+0.3) VFB to GND..…………………………………………………………………………………. -0.3V to (VIN+0.3) SW to GND………………….…………………………………………………………….……-0.3V to (VIN+0.3) Peak SW Sink and Source Current……………...……………………………………………….Internally Limited Junction to Ambient Thermal Resistance (©JA).…………………….……………………………………250ć/W Operating Temperature Range……………….……………………………………………………...-40ć to +85ć Junction Temperature………………………………………………………………………..….... -40ć to +150ć Storage Temperature Range …………………………..……………………………………….….-55ć to +150ć Lead Temperature (Soldering, 10sec) …………………………………………………………………...…...300ć Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. www.fremontmicro.com Page 2 of 10 DS441-A2 Fremont Micro Devices FT441 PIN COMFIGURATION Figure 2: Package Top View TERMINAL DEFINITION Pin Name Description Enable control input 1 EN 2 GND 3 SW Switching node, connecting to inductor 4 VIN Power input 5 VFB/Vout Ground Feedback node. VFB for adjustable version, and Vout for fixed output version Table 1 www.fremontmicro.com Page 3 of 10 DS441-A2 Fremont Micro Devices FT441 ORDERING INFORMATION FT441ķĸ Designator Symbol ķ Output Voltage A ADJ B 1.5V C 1.8V D 2.5V E 1.2V F 2.8V G 3.3V Designator Symbol ĸ Package Type a SOT23-5 Table 2 MARKING RULE 4 5 . ķĸĹĺĻ 1 2 3 Figure 3 ķ Represent Product Series Symbol  Product Series )7[[ Table 3 ĸ Represent Output Voltage Ĺ Represent Package Tape ĺĻ For internal reference www.fremontmicro.com Page 4 of 10 DS441-A2 Fremont Micro Devices FT441 BLOCK DIAGRAM Figure 4: FT441 Block Diagram www.fremontmicro.com Page 5 of 10 DS441-A2 Fremont Micro Devices FT441 ELECTRICAL CHARACTERISTICS (VIN = VEN = 3.6V, TA = 25ÛC unless otherwise specified.) Parameter Symbol Input Voltage Range VIN Under Voltage Lockout Threshold VUVLO Test Conditions Min Typ Max Unit 5.5 V 2.35 2.5 V 2.5 VIN rising 2.2 Operating Supply Current VFB=0.5 or Vout=90% 300 450 uA Shutdown Supply Current VEN = 0V, VIN = 4.2V 0.1 1 uA Adjustable Version Regulation Voltage Fixed Output Regulation Voltage VFB VOUT TA = 25°C 0.588 0.6 0.612 0 < TA < 85°C 0.585 0.6 0.615 -40°C < TA < 85°C 0.582 0.6 0.618 FT441Ba 1.455 1.5 1.545 FT441Ca 1.746 1.8 1.854 FT441Da 2.425 2.5 2.575 FT441Ea 1.164 1.2 1.236 FT441Fa 2.716 2.8 2.884 FT441Ga 3.2 3.3 3.4 0.5 Output Voltage Line Regulation VIN = 2.5V to 5.5V 0.1 Output Voltage Load Regulation IOUT = 0mA to 900mA 0.5 Inductor Current Limit ILIM Oscillator Frequency fSW VIN = 3.6V, VFB =0.5V or Vout=90% VFB=0.6 or Vout=100% V %/V % 1.15 1.5 1.8 A 1.2 1.5 1.8 MHz VFB=0 or Vout=0 400 KHz PMOS On Resistance RONP ISW = -100mA 0.28 0.4 ȍ NMOS On Resistance RONN ISW = 100mA 0.22 0.35 ȍ 1 uA 1 1.5 V 0.01 1 uA EN = 0, VIN = 5.5V, SW Leakage Current VSW = 5.5V or 0V EN Threshold VIH VIN = 2.5V to 5.5V EN Leakage Current IEN VIN = 5.5V, EN = VIN 0.3 Table 4 www.fremontmicro.com Page 6 of 10 DS441-A2 Fremont Micro Devices FT441 TYPICAL PERFORMANCE CHARACTERISTICS Efficiency vs Output Current @Vout=2.5V 100 100 90 90 80 80 Efficiency(%) Efficiency(%) Efficiency vs Output Current @Vout=1.8V 70 60 70 60 50 50 Vcc=2.7 Vcc=3.6 Vcc=4.2 40 Vcc=2.7 Vcc=3.6 Vcc=4.2 Vcc=5 40 30 30 0.1 1 10 100 1 1000 10 100 1000 Output Current(mA) Output Current(mA) Efficiency vs Output Current @Vout=3.3V Efficiency vs Output Current @Vout=1.8V 100 100 90 90 Efficiency(%) Efficiency(%) 80 70 60 80 50 Iout=10mA Iout=200mA Iout=500mA Iout=1A 70 Vcc=3.7 Vcc=4.2 Vcc=5.0 40 60 30 1 10 100 1000 Output Current(mA) www.fremontmicro.com 2 3 4 5 6 Output Current(mA) Page 7 of 10 DS441-A2 Fremont Micro Devices FT441 Load Regulation @Vout=1.8V 1.79 Vout(V) 1.785 1.78 1.775 Vcc=2.7 Vcc=3.6 Vcc=4.2 Vcc=5 1.77 1 10 100 1000 Iout(mA) www.fremontmicro.com Page 8 of 10 DS441-A2 Fremont Micro Devices FT441 APPLICATION INFORMATION Figure4 below shows the typical application circuit with FT441 fixed output versions. VIN 2.7~4.2V 4 SW VIN L1 2.2uH 3 Vout 1.8V FT441 C1 10uF 1 EN Vout C2 5 10uF GND 2 Figure 4 Typical Application Circuit with fixed output versions Inductor Selection Under normal operation, the inductor maintains continuous current to the output. Its value is chosen based on the desired ripple current. Large value inductors lower ripple current, and small value inductors result in higher ripple currents. The inductor value can be derived from the following equation: L Vout u (V IN  Vout ) , Where ̲IL is inductor ripple current. V IN u 'I L u f osc Input Capacitor Selection The input capacitor reduces input voltage ripple to the converter; a 10uF ceramic capacitor is recommended for most applications. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. The output ripple ̲Vout approximately: 'VOUT # 'I L u ( ESR  1 ) 8 fC OUT Output Voltage Programming Figure1 above shows the typical application with FT4412 adjustable version. The external resistor sets the output voltage according to following equation: VOUT www.fremontmicro.com 0.6V u (1  Page 9 of 10 R2 ) R1 DS441-A2 Fremont Micro Devices FT441 SOT23-5 PACKAGE Symbol Dimensions In Millimeters Dimensions In Inches Min Max 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 0.95 (BSC) 0.037 (BSC) e1 1.800 2.000 0.071 0.079 L 0.300 0.600 0.012 0.024 ș 0° 8° 0° 6° www.fremontmicro.com Page 10 of 10 DS441-A2