CM3718 1.5a l ow -n oise pwm s tep -d own r egulator general description features the CM3718 is a low-noise, pulse-width-modulated (pwm), dc-dc step-down converter. it powers logic and transmitters in small wireless systems such as cellular phones, communicating pdas, and handy-terminals. the device features an internal synchronous rectifier for high efficiency; it requires no external schottky diode. excellent noise characteristics and fixed-frequ ency operation provide easy post-filtering. the CM3718 is ideally suited for li-lon battery applications. it is also useful for +3v or +5v fixed input applications. the device operates in one of four modes. forced pwm mode operates at a fixed freq uency regardless of the load. shutdown mode places the device in standby, reducing quiescent supply current to under 0.1 a. the CM3718 can deliver over 1. 5a. the output voltage can be adjusted from vref to vin. the input range is from 2.0v to 5.0v. other features of the CM3718 include high efficiency, low dropout voltage. it is available in a space-saving 8-pin sop package. ? patent number #6,452,366 ? 1.2mhz switching and synchronization ? dynamic output-voltage adjustment from vref to vin ? 1.5a guaranteed output current ? 95% efficiency ? no schottky diode required ? external soft start ? 8-pin psop power packages applications pin configuration ? cellular phone ? cordless phone ? pdas and handy-terminals ? cpu i/o supplies ? notebook chipset supplies ? battery operated devices psop-8 (pt-08) top view 1 2 3 4 8 7 6 5 vin gnd sd vref pvin lx pgnd vfb 2006/10/11 rev. 1.6 champion microelectronic corporation page 1
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator pin description pin no. symbol description operating rating CM3718 min. typ. max. uni t 1 vin voltage supply for internal circuits 2 2.5 5.5 v 2 gnd ground for internal reference voltage divider shutdown level 0.75 x vin vin + 0.3 3 sd cmos input level enable level 0 2.0 v 4 vref v out set voltage 1.1 vin v 5 vfb feedback node for the v out vref v 6 pgnd ground for output power transistors 7 lx inductor connection to the drains of the internal power mosfets 5.5 v 8 pvin voltage supply for output power transistors 2 2.5 5.5 v ordering information part number temperature range package CM3718is -40 to 85 8-pin psop (ps08) CM3718gis* -40 to 85 8-pin psop (ps08) *note: g : suffix for pb free product block diagram pwm controller oscillator ramp generator error amp thermal protection mos vref gnd 4 2 vfb 5 pgnd 6 lx 7 pvin 8 vin1 1 sd 3 2006/10/11 rev. 1.6 champion microelectronic corporation page 2
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator absolute maximum ratings junction temperature ...???????? ????150c absolute maximum ratings are those values beyond which the device could be permanently damaged. storage temperature ??................??. -65c to 125c pvin/vin ????.............. ................. ......?.......-0.3v to 6.0v lead temper ature (soldering, 5 sec)??????.. 260c voltage on any other pin ???... gnd ? 0.3v to vin + 0.3v thermal dissipation ?( jc )?.. ???????.. .50c/w output current, source or sink ??......????........?...1.5a operating conditions temperature range ............................. -40c to 85c p vin operating range .........................2.0v to 4.0v electrical characteristics (unless otherwise stated, these specifications apply t a =25 c ; vin=+3.3v and pvin=+3.3v) maximum ratings are stress ratings only and functional device operation is not implied. (note 1) CM3718 symbol parameter test conditions min. typ. max. unit switching regulator v ref adjustable output vo ltage vref vin v fsw switching frequency CM3718 1.2 mhz i out(rms) maximum output rms current CM3718 1.5 a i out(peak) maximum output peak current CM3718 3 a mosfets rds (on) drain to source on-state resistance pvin=5v 250 m supply i vin quiescent current vfb = 1.4v lc unconnected 220 a i pvin vfb = 1.4v lc unconnected 500 a 2006/10/11 rev. 1.6 champion microelectronic corporation page 3
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator functional description the CM3718 step-down, pulse-width-modulated (pwm), dc-dc converter has an adjustable output range from vref to the input voltage (vin). an internal synchronous rectifier improves efficiency and eliminates an external schottky diode. fixed-frequency operation enables easy post-filtering, thereby providing excellent noise characteristics. as a result, the CM3718 is an ideal choice for many small wireless systems. vref the reference voltage could be ranged from 1.1v to vin. ouputs the output voltage pins (lx) are tied to the rf power amp, via an external inductor. output voltage is determined by the vref inputs. inputs the input voltage reference pin, vref determine the output voltages (lx). if a specific voltage is forced at the vref pin, the output voltage follows the voltage at the vref pin. other supply voltages several inputs are provided for the supply voltages: pvin and vin. the pvin provide the power supply to the power mosfets. vin provides the voltage supply to the logic section and internal error amplifiers. feedback the vfb pin is an input that can be used for closed loop compensation. this input is derived from the voltage output. agnd pin is a contact node of internal resistor divider for remote sense. application circuit tp1 bnc 1 2 3 4 5 vcc r4 470 2 1 l1 3.3uh/2a c2 105 r5 0 r3 100k 2 1 u3 CM3718-8pin 2 1 3 4 5 6 7 8 gnd vin sd vref vfb pgnd lx pvin vdd jp1 jumper c3 470 d1 sk12 vcc jp2 jumper j3 vref-out 1 2 r7 0 2 1 jp3---->useing external voltage seting board (pin 1,2 short) c4105 vdd j2 vtt 1 2 note: j1 pwr/in 1 2 r1 100k 2 1 c7 104 c6 47uf/6.3v c5 104p jp3 con3 3 2 1 jp4 on/off sw u2 cm-431 1 3 2 r2 1k 2 1 c1 100uf/6.3v d2 sk12 r8 5.1 2 1 2006/10/11 rev. 1.6 champion microelectronic corporation page 4
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator load regulation vin=5v, vref input=1.09v CM3718 0 1 2 0. 05 0. 2 0. 4 0. 6 0. 8 1 iout(a) vout(v) vin=5v, vref input=4.04v CM3718 3 4 5 0.05 0.2 0.4 0.6 0.8 1 iout(a) vout(v) load transient response CM3718 transient response vref=1v, (i out from 1.5a- 0a) CM3718 transient response vref=1v, (i out from 0a- 1.5a) CM3718 transient response vref=4v (i out from 1.5a- 0a) CM3718 transient response vref=4v (i out from 0a- 1.5a) 2006/10/11 rev. 1.6 champion microelectronic corporation page 5
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator v out outout ripple and noise CM3718 vref=1v, load=0.5a CM3718 vref=1v, load=1.0a CM3718 vref=1v, load=1.5a CM3718 vref=4v, load=0.5a CM3718 vref=4v, load=1.0a CM3718 vref=4v, load=1.5a voltage setting step response CM3718 (vref from 1v- 4v), load=0.5a CM3718 vref=1v-4v, load=1.0a CM3718 vref=1v-4v, load=1.5a CM3718 vref=4v-1v, load=0.5a CM3718 vref=4v-1v, load=1.0a CM3718 vref=4v-1v, load=1.5a 2006/10/11 rev. 1.6 champion microelectronic corporation page 6
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator in-rush current CM3718 vin=5v, vref=1v, load=1.5a, ip-p=1.81a CM3718 vin=5v, vref=4v, load=1.5a, ip-p=1.81a efficiency CM3718 efficiency (v out =1v, load from 0.05a~1.5a) CM3718 60.0% 65.0% 70.0% 75.0% 80.0% 85.0% 90.0% 95.0% 100.0% 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.5 iout(a) efficiency CM3718 efficiency (v out =4v, load from 0.05a~1.5a) CM3718 80.0% 82.0% 84.0% 86.0% 88.0% 90.0% 92.0% 94.0% 96.0% 98.0% 100.0% 0.05 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.5 iout(a) efficiency 2006/10/11 rev. 1.6 champion microelectronic corporation page 7
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator pcb layout top layer bottom layer silkscreen top sold-mask top sold-mask bottom 2006/10/11 rev. 1.6 champion microelectronic corporation page 8
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator package dimension 8-pin psop (ps08) 2006/10/11 rev. 1.6 champion microelectronic corporation page 9
CM3718 1.5a l ow -n oise pwm s tep -d own r egulator important notice champion microelectronic corporation (cmc) reserves the ri ght to make changes to its products or to discontinue any integrated circuit product or serv ice without notice, and advis es its customers to obtain the latest version of relevant information to verify, before placing orders , that the information being relied on is current. a few applications using integrated circuit products may in volve potential risks of death, personal injury, or severe property or environmental damage. cmc integrated circui t products are not designed, intended, authorized, or warranted to be suitable for use in life-s upport applications, devices or systems or other critic al applications. use of cmc products in such applications is un derstood to be fully at the risk of the customer. in order to minimize risks associated with the customer?s applications, the cu stomer should provide adequate design and operating safeguards. hsinchu headquarter sales & marketing 5f, no. 11, park avenue ii, science-based industrial park, hsinchu city, taiwan 300 7f-6, no.32, sec. 1, chenggong rd., nangang district, taipei city 115, taiwan t e l : +886-3-567 9979 t e l : +886-2-2788 0558 f a x : +886-3-567 9909 f a x : +886-2-2788 2985 http://www.champion-micro.com 2006/10/11 rev. 1.6 champion microelectronic corporation page 10
|
