liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 1/7 pin assignment (top view) pin description pin number pin name pin description 1 fb feedback pin 2 en power-off pin h: normal operation(step-down operation) l: step-down operation stopped(all circuits deactivated) 3 ocset add an external resistor to set max output current 4 vcc ic power supply pin 5,6 output switch pin. connect external inductor/diode here. minimize trace area at this pin to reduce emi. 7,8 vss gnd pin typical application pc motherboard lcd monitor graphic card dvd-video player telecom equipment adsl modem printer and other peripheral equipment microprocessor core supply networking power supply vcc vss vss output output 8 7 6 5 1 2 3 4 fb en ocset general description lsp3130 consists of step-down switching regulator with pwm control. these devices include a reference voltage source, oscillation circuit, error amplifier, internal pmos and etc. lsp3130 provides low-ripple power, high efficiency, and excellent transient characteristics. the pwm control circuit is able to vary the duty ratio linearly from 0 up to 100%. this converter also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. an enable function, an over current protect function and a short circuit protect function are built inside, and when ocp or scp happens, the operation frequency will be reduced from 300khz to 50khz. also, an internal compensation block is built in to minimum external component count. with the addition of an internal p-channel power mos, a coil, capacitors, and a diode connected externally, these ics can function as step-down switching regulators. they serve as ideal power supply units for portable devices when coupled with the sop8l mini-package, providing such outstanding features as low current consumption. since this converter can accommodate an input voltage up to 18v, it is also suitable for the operation via an ac adapter. features input voltage: 3.6v to 18v. output voltage: 0.8v to vcc. duty ratio: 0% to 100% pwm control oscillation frequency: 300khz typ. soft-start, current limit, enable function thermal shutdown function built-in internal sw p-channel mosfet sop8l package.
liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 2/7 absolute maximum ratings (note) parameter value unit vcc pin voltage, v cc v ss -0.3 to v ss +20 v feedback pin voltage, v fb v ss -0.3 to v cc v en pin voltage, v en v ss -0.3 to v in + 0.3 v switch pin voltage, v output v ss -0.3 to v in + 0.3 v power dissipation, p d internally limited mw operating temperature range, t opr -20 to +125 c storage temperature range, t stg -40 to +150 c note: do not exceed these limits to prevent damage to t he device. exposure to absolute maximum rating conditions for long periods may affect device reliability. recommended operating conditions symbol parameter min max unit v in input voltage 3.6 18 v t j operating junction te mperature range -20 125 o c electrical characteristics (v in = 12v, t a = 25c, unless otherwise specified.) parameter symbol test conditions min. typ. max. unit input voltage v in 3.6 18 v feedback voltage v fb i iout = 0.1a 0.784 0.8 0.816 v feedback bias current i fb i iout = 0.1a 0.1 0.5 a switch current i sw 2.5 a current consumption during power off i sss v en = 0 10 a line regulation v out /v out v in =5v~18v 1 2 % load regulation v out /v out i iout = 0.1a~2a 0.2 0.5 % oscillation frequency fosc measure waveform at sw pin 240 300 360 khz frequency of current limit or short circuit protect fosc1 measure waveform at sw pin 30 50 70 khz v sh evaluate oscillation at sw pin 2.0 enable pin input voltage v sl evaluate oscillation stop at sw pin 0.8 v i sh 20 enable pin input leakage current i sl -10 a ocset pin bias current i ocset 75 90 105 a soft-start time t ss 0.3 2 5 ms v in =5v, v fb = 0 110 150 internal mosfet rdson r dson v in =12v, v fb = 0 70 100 m ? efficiency effi v in =12v, v out =5v, i iout = 2a 92 % thermal resistance junction to ambient ja 150 c/w
liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 3/7 thermal resistance junction to case jc 60 c/w over temperature shutdown t sd 150 c over temperature shutdown hysteresis t hys 25 c functional block diagram functional descroption pwm control the lsp3130 consists of dc/dc converters that employ a pulse-width modulation (pwm) system. in converters of the lsp3130, the pulse width varies in a range from 0 to 100%, according to the load current. the ripple voltage produced by the switching can easily be removed through a f ilter because the switching frequency remains constant. therefore, these converters provide a low-ripple pow er over broad ranges of input voltage and load current. under voltage lockout the under voltage lockout circuit of the lsp3130 assures that the high-side mosfet driver outputs remain in the off state whenever the supply voltage drops below 3.3v. normal operation resumes once vcc rises above 3.5v. r ds(on) current limiting the current limit threshold is setting by the external resi stor connecting from vcc supply to ocset. the internal 100ua sink current crossing the resistor sets the voltage at the pin of ocset. when the pwm voltage is less than the voltage at ocset, an over-cu rrent condition is triggered. i peak r ds(on) = i ocset r ocset see above formula for setting the current limit value
liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 4/7 typical application circuit note1:c in/ c out can be electro capacitor or tan capacitor; the typical c in electro capacitor is 470uf/35v,the typical c in tan capacitor is 100uf/35v; the typical c out electro capacitor is 470uf/16v,the typical c out tan capacitor is 22uf/16v; note2: v out =v fb *(1+r a /r b ) r b =0.7k ? ~5k ? v in =12v, i max =2a v out 2.5v 3.3v 5v l1 value 22uh 27uh 33uh test circuits 1) enable function test 2) feedback function test 3) operation function test typical characteristics
liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 5/7
liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 6/7 typical characteristics (continued) ordering information marking information
liteon semiconductor corporation lsp3130 pwm control 2a step-down converter rev1.2 7/7 package information dimensions in millimeters dimensions in inches symbol min. nom. max. min. nom. max. a 1.35 1.6 1.75 0.053 0.063 0.069 a1 0.1 0.25 0.004 0.01 a2 1.25 1.45 1.55 0.049 0.057 0.061 b 0.31 0.41 0.51 0.012 0.016 0.02 c 0.1 0.2 0.25 0.0039 0.008 0.01 d 4.8 4.9 5 0.192 0.196 0.2 e 3.8 3.9 4 0.148 0.154 0.16 e 1.27 bsc 0.050 bsc h 5.7 6 6.3 0.224 0.236 0.248 l 0.4 0.71 1.27 0.015 0.028 0.05 0 8 0 8
|
