lx3005 p roduction d atasheet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 800-8776458, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2010 rev.1.0, 2010-02-05 2a s tep -d own c onverter tm ? w w w . m i c r o s e m i . c o m l l x x 3 3 0 0 0 0 5 5 d e s c r i p t i o n k e y f e a t u r e s ? 2a constant output current ? 130m ? r dson internal power mosfet ? up to 94% efficiency ? fixed 420khz frequency ? wide 4.75v to 25v input voltage range ? output voltage adjustable from 0.8v to 21v ? built-in thermal shutdown function ? built-in current limit function ? built-in soft-start function ? support ceramic or electrolytic capacitors ? pb-free and rohs compliant a p p l i c a t i o n s the lx3005 is a 420khz fixed frequency pwm buck (step-down) dc-dc converter, capable of driving a 2a load with high efficiency, low ripple and excellent line and load regulation. the device operates over a wide input voltage range of 4.75v to 25v, and the output voltage can be externally set from 0.8v to a voltage near vin, as the pwm control circuit is able to adjust the duty ratio linearly from 0% to close to 100%. the lx3005 device integrates a high-side low rds on pmos for a low cost and high efficiency solution. an internal transconductance error amplifier is used in the control loop allowing flexibility to compensate the system using an all ceramic capacitor system. the lx3005 also features an enable function, internal circuitry for soft start, and protection schemes such as thermal shutdown, over-current protection, and short-circuit protection. when ocp or scp is triggered, the device operating frequency will be reduced from typically 420khz to typically 40khz, limiting the output power capability. the lx3005 serves as an ideal power supply device for portable devices, especially for chipset power in portable systems. it?s widely used for pdvd, lcd monitor and dpf chipset power sources. the lx3005 is available in soic8 package and is functional from an ambient t e m p e r a t u r e r a n g e o f 0 ? c t o 8 5 ? c . ? portable dvd ? lcd monitor/lcd tv ? digital photo frame ? adsl ? set-top box important: : for the most current data, consult microsemi ?s website: http://www.microsemi.com patents pending p r o d u c t h i g h l i g h t on off l1 c o r2 r1 lx3005 vin en gnd fb sw c in c c v out @ 2a v in c1 r c comp d1 package order info t h e r m a l d a t a dm plastic soic 8-pin ? j a = 100 ? c/w t a ( ? c) rohs compliant / pb-free thermal resistance - junction to ambient 0 to 85 lx3005cdm note: available in tape & reel. append the letters ?tr? to the part number. (i.e. LX3005CDM-TR) junction temperature calculation: t j = t a + (p d x ? ja ). the ? ja numbers are guidelines for the thermal performance of the device/pc-board system. all of the above assume no ambient airflow.
lx3005 p roduction d atasheet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 800-8776458, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2010 rev.1.0, 2010-02-05 2a s tep -d own c onverter tm ? w w w . m i c r o s e m i . c o m l l x x 3 3 0 0 0 0 5 5 a b s o l u t e m a x i m u m r a t i n g s p a c k a g e p i n o u t supply input voltage (v in )................................................................-0.3v to 30v fb pin voltage (v fb )...........................................................................-0.3v to 6v en pin voltage (v en ) ......................................................................... -0.3v to v in comp pin voltage (v comp ) ................................................................-0.3v to 6v sw pin voltage (v sw )........................................................................ -0.3v to v in power dissipation (p d ) ............................................................... internally limited maximum operating junction temperature.................................................150 ? c storage temperature range .......................................................... -65 ? c to 150 ? c lead temperature (soldering, 10 seconds) ..................................................260 ? c note: exceeding these ratings could cause damage to the device. all voltages are with respect to ground. currents are positive into, negative out of specified terminal. m s c 3 0 0 5 c d m x x x x 1 2 3 4 5 6 7 8 nc vin sw gnd fb nc en comp dm p ackage (top view) xxxx = date/lot code rohs / pb-free 100% matte tin pin finish f u n c t i o n a l p i n d e s c r i p t i o n name pin # description nc 1 pin not used. vin 2 supply voltage pin. the lx3005 operates from a 4.75v to 25v dc voltage. bypass vin to gnd with a suitable large capacitor to eliminate noise on the input. sw 3 power switch output pin. sw is the switch node that supplies power to the output. gnd 4 ground for ic. fb 5 feedback pin. through an external resistor divider network, fb senses the output voltage and regulates it. to prevent current limit run away in a short circuit fault condition, the frequency feedback comparator lowers the oscillator frequency to 40khz when the fb voltage is below 0.52v. the feedback threshold voltage is 0.8v. comp 6 compensation pin. this pin is the output of the error amplifier. frequency compensation is done at this pin by connecting a series rc to ground(parallel a capacitor if necessary) en 7 enable pin. drive en pin high to turn on the device, drive it low to turn off. default of this pin is high level. nc 8 pin not used.
lx3005 p roduction d atasheet microsemi analog mixed signal group 11861 western avenue, garden grove, ca. 92841, 800-8776458, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2010 rev.1.0, 2010-02-05 2a s tep -d own c onverter tm ? w w w . m i c r o s e m i . c o m l l x x 3 3 0 0 0 0 5 5 thank you for your interest in microsemi ? analog mixed signal products. the full data sheet for this device contains proprietary information. to obtain a copy, please contact your local microsemi sales representative. the name of your local representative can be obtained at the following link http://www.microsemi.com/contact/contactfind.asp or contact us directly by sending an email to: ipgdatasheets@microsemi.com be sure to specify the data sheet you are requesting and include your company name and contact information and or vcard. we look forward to hearing from you.
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