FSP3100

FSP3100 FOSLINK | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 11

Technical content

1.5 MHZ, 600MA SYNC HRONOUS STEP-DOWN CONVERTER

„ A P P L I C A T I O N S z Cellular and Smart Phones z PDAs z MP3 Player z Digital Still and Video Cameras z Portable instruments z Microprocessors and DSP Core Supplies z Wireless and DSL Modems „ PIN CONFIGURATION (Top View) „ PIN DESCRIPTION Pin Number Pin Name Pin Function

1 RUN

Regulator Enable control input. Drive R UN above 1.5V to turn on the part. Drive RUN below 0.3V to turn it off. In shutdown, all functions are disable drawing ＜1uA supply current. Do not leave RUN floating.

2 GND Ground

3 SW Power Switch Output. It is the Switch node connection to inductor. This pin connects to the drains of the internal P-CH and N-CH MOSFET switches. 4 IN Supply Input Pin. Must be closely decou pled to GND, pin2, with a 2.2uF or greater ceramic capacitor.

5 FB/VOUT

VFB (FSP3100): Feedback Input Pin. Conn ected FB to the center point of the external resistor divider. The feedback threshold voltage is 0.6V. VOUT (FSP3100-1.2/1.5/1.8): Output Voltage Feedback Pin. An internal resistive divider divides the output voltage down for comparison to the internal reference voltage. „ FEATURES z High Efficiency : Up to 96% z 1.5MHz Constant Switching Frequency z 600mA Output Current at V IN=3.0V z Integrated Main switch and synchronous rectifier. No Schottky Diode Required z 2.5V to 5.5V Input Voltage Range z Output Voltage as low as 0.6V z 100% Duty Cycle in Dropout z Low Quiescent Current : 300uA z ＜1uA Shutdown Current z Slope Compensated Current Mode Control for Excellent Line and Load Transient Response z Short Circuit and Thermal Fault Protection z Space Saving 5-pin SOT23 packages

3 VIN

„ GENERAL DESCRIPTION The FSP3100 is a 1.5MHz constant frequency; slope compensated current mode PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. It is ideal for powering portable equipment that runs from a single cell lithium-Ion (Li+) battery. The FSP3100 can supply 600mA of load current from a 2.5V to 5.5V input voltage. The output voltage can be regulated as low as 0.6V. The FSP3100 can also run at 100% duty cycle for low dropout operation, extending battery life in portable system. Idle mode operation at light loads provides very low output ripple voltage for noise sensitive applications. The FSP3100 is offered in a low profile (1mm) 5-pin, SOT package, and is available in an adjustable version and fixed output voltage of 1.2V, 1.5V and 1.8V.

„ BLOCK DIAGRAM For Adjustable Output R1+R2 is external. „ THERMAL RESISTANCE (NOTE 1) Package θJA (℃/W) θJC (℃/W) SOT23-5L 250 110 Note 1: Thermal Resistance is specified with approximately 1 square of 1 oz cooper. „ ABSOLUTE MAXIMUM RATINGS (NOTE 2) Parameter Rating Unit Input Supply Voltage -0.3 to +6 V RUN, VFB Voltages -0.3 to V IN +0.3 V SW，Vout Voltages -0.3 to VIN+0.3 V Peak SW Sink and Source Current 1.5 A Operating Temperature Range -40 to +85 ℃ Junction Temperature (Note 3) +125 ℃ Storage Temperature Range -65 to 150 ℃ Lead Temperature ( solding, 10 sec.) +300 ℃ Note 2: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 3: TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ=TA+PD×θJA

„ ELECTRICAL CHARACTERISTICS (NOTE 4) (VIN=VRUN=3.6V, TA=25℃, Unless otherwise noted) Parameter Condition Min. Typ. Max. Unit Input Voltage Range 2.5 5.5 V Input DC Supply Current Active Mode Shutdown Mode VFB=0.5V VFB=0V, VIN=4.2V 270 0.08 400 1.0 uA TA=+25℃ 0.5880 0.6000 0.6120 V TA=0℃≤TA≤85℃ 0.5865 0.6000 0.6135 V Regulated Feedback Voltage TA=-40℃≤TA≤85℃ 0.5850 0.6000 0.6150 V VFB Input Bias Current V FB=0.65V ±30 nA Reference Voltage Line Regulation V IN=2.5V to 5.5V, VOUT=VFB (R2=0) 0.11 0.40 %/V FSP3100C12AD: -40℃≤TA≤85℃ 1.164 1.200 1.236 V FSP3100C15AD: -40℃≤TA≤85℃ 1.455 1.500 1.545 V Regulated Output Voltage FSP3100C18AD: -40℃≤TA≤85℃ 1.746 1.800 1.854 V Output Voltage Line Regulation V IN=2.5V to 5.5V, IOUT=10mA 0.11 0.40 %/V Output Voltage Load Regulation I OUT from 0 to 600mA 0.0015 %/mA Maximum Output Current V IN=3.0V 600 mA Oscillator Frequency V FB=0.6V or VOUT=100% 1.2 1.5 1.8 MHz RDS(ON) of P-CH MOSFET I SW=300mA 0.30 0.50 Ω RDS(ON) of N-CH MOSFET I SW=-300mA 0.20 0.45 Ω Peak Inductor Current VIN=3V, VFB=0.5V or VOUT=90%, Duty Cycle＜35% 1.20 A SW Leakage V RUN=0V, VSW=0V or 5V, VIN=5V ±0.01 ±1 uA Output over voltage lockout ΔVOVL=VOVL-VFB 60 mV RUN Threshold -40℃≤TA≤85℃ 0.3 0.45 1.30 V RUN Leakage Current ±0. 1 ±1 uA Note 4: 100% production test at +25 ℃. Specifications over the temperatur e range are guaranteed by design and characterization.

„ TYPICAL PERFORMANCE CHARACTERISTICS (Test Figure 1 below unless otherwise specified)

„ TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) Output Voltage (V)

„ TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) Frequency (MHz) RDS(ON) (OHM)

„ TYPICAL PERFORMANCE CHARACTERISTICS (CONTINUED) L o a d T r a n s i e n t R e s p o n s e P W M M o d e O n l y Load Transient Response Idle Mode to PWM Mode Idle Mode PWM Input Current (mA) Supply Current (µA)

„ OPERATION FSP3100 is a monolithic switching mode Step-Down DC-DC converter. It utilizes internal MOSFETs to achieve high efficiency and can generate very low output voltage by usi ng internal reference at 0. 6V. It operates at a fixed switching frequency, and uses the slope compensated current mode architecture. This Step-Down DC-DC Converter suppliers 600mA output current at VIN=3V with input voltage range from 2.5V to 5.5V. „ CURRENT MODE PWM CONTROL Slope compensated current mode PWM control provides st able switching and cycle-by-cycle current limit for excellent load and line responses and protection of the internal main switch (P-Ch MOSFET) and synchronous rectifier (N-Ch MOSFET). During normal operation, the inte rnal P-Ch MOSFET is turned on for a certain time to ramp the inductor current at each rising edge of the in ternal oscillator, and switched off when the peak inductor current is above the error voltage. The current comparator, I COMP, limits the peak inductor current. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the inductor current starts to reverse, as indicated by the current reversal comparator, IZERO, or the beginning of the next clock cycle. The OVDET comparator controls output tran sient overshoots by turning the main switch off and keeping it off until the faults is no longer present. „ IDLE MODE OPERATION At very light loads, the FSP3100 automatically enters Idle Mode. In the Idle mode, the inductor current may reach zero or reverse on each pulse. The PWM control loop will automatically skip pulses to maintain output regulation. The bottom MOSFET is turned off by the current reversal comparator, IZERO, and the switch voltage will ring. This is discontinuous mode operation, and is normal behavior for the switching regulator. „ DROPOUT OPERATION When the input voltage decreases toward the value of t he output voltage, the FSP3100 allows the main switch to remain on for more than one switching cycle and increases the duty cycle until it reaches 100%. The duty cycle D of a step-down converter is defined as: OUT ON OSC IN Where TON is the main switch on time and fOSC is the oscillator frequency (1.5MHz). The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. At low input supply voltage, the RDS(ON) of the P-Channel MOSFET increase, and the efficiency of the converter decreases. Caution must be exercised to ensure the heat dissipated not to exceed the maximum junction temperature of the IC. „ MAXIMUM LOAD CURRENT The FSP3100 will operate with input supply voltages as low as 2.5V, however, the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases.

„ APPLICATION INFORMATION Fig.1 Basic Application Circuit with FSP3100 adjustable version Fig.2 Basic Application Circuit with fixed output versions SETTING THE OUTPUT VOLTAGE Figure 1 above shows the basic application circuit with F SP3100 adjustable output versio n. The external resistor sets the output voltage according to the following equation: OUT R2V0 . 6 V 1 + R1 R1=300kΩ for all outputs; R2=300k Ω for V OUT=1.2V, R2=200kΩ for V OUT=1.5V, R2=150kΩ for V OUT=1.8V and R=95.3kΩ for VOUT=2.5V. INDUCTOR SELECTION For most designs, the FSP3100 operates with inductors of 1uH to 4.7uH. Low inductance values are physically smaller but require faster switching, which results in some efficiency loss. The inductor value can be derived from the following equation: ()OUT IN OUT IN L OSC VV VL VI f Where ∆IL is inductor Ripple Current. Large value inductors lo wer ripple current and small value inductors result in high ripple currents. Choose inductor ripple current approximately 35% of the maximum load current 600mA, or ∆IL=210mA. For output voltages above 2.0V, when light-load efficiency is important, the minimum recommended inductor is 2.2uH. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the 50m Ω to 150mΩ range. For higher efficiency at heavy loads (above 200mA), or minimal load regulation (but some transient overshoot), the resistance should be kept below 100m Ω. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple cu rrent to prevent core saturation (600mA+105mA). Table 1 lists some typical surface mount inductors that meet target applications for the FSP3100. Vin 316K 10uF 4.7uF Vout 1.8V GND VFB Vin 2.7V-4.2V SW Run 2.2uHL1 22pFC2 632K L1Vin 2.5V-5.5V 10uF 3 2.2uH Vout 1.8V SW

4 Vin

4.7uF

Part # L (uH) Max DCR (mΩ) Rated D.C. Current (A) Size W×L×H (mm) Sumida CR43 2.2 3.3 4.7 56.2 71.2 86.2 108.7 2.52 1.75 1.44 1.15 4.5×4.0×3.5 Sumida CDRH4D18 1.5 2.2 3.3 4.7 110 162 1.32 1.04 0.84 4.7×4.7×2.0 Toko D312C 1.5 2.2 3.3 4.7 120 140 180 240 1.29 1.14 0.98 0.79 3.6×3.6×1.2 INPUT CAPACITOR SELECTION The input capacitor reduces the surge current drawn from the input and switch ing noise from the device. The input capacitor impedance at the switching frequency shall be less than input source imp edance to prevent high frequency switching current passing to the input. A low ESR input capacitor sized for minimum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. A 4.7uF ceramic capacitor for most applications is sufficient. OUTPUT CAPACITOR SELECTION The output capacitor is requires to keep the output volt age ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switch ing frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. The output ripple V OUT is determined by: ()OUT IN OUT OUT IN OSC OSC VV V 1VE S R Vf L 8 f C 3 „ ORDERING INFORMATION „ MARKING INFORMATION FSP3100XXXX Package: C: SOT23-5L Output Voltage: Blank: ADJ 12: 1.2V 15: 1.5V 18: 1.8V Packing: A: Tape & Reel Temperature Grade: D: -40~85℃ AXXXX Date code: X: Year (1=2001) X: Week (A~Z,a~z; 0~52) Output Voltage: 1: ADJ 2: 1.5V 3: 1.8V 4: 1.2V Part Number: FSP3100 Internal Code (if needed)

„ PACKAGE INFORMATION Dimensions In Millimeters Dimensions In Inches Symbol Min. Max. Min. Max. A 0.900 1.250 0.036 0.050 A1 0.000 0.100 0.000 0.004 A2 0.900 1.150 0.041 0.045 b 0.300 0.400 0.012 0.016 C 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 2.650 2.950 0.104 0.116 E1 1.500 1.700 0.060 0.068 L 0.300 0.600 0.012 0.024 L1 0.700REF 0.028REF e 0.95 Bsc. 0.038 Bsc. e1 1.90 Bsc. 0.076 Bsc. θ 0 º 8º 0º 8º D e b E 5 4 321 A L θ C