preliminary RT9264 ds9264-00 december 2001 www.richtek-ic.com.tw 1 high frequency, high efficiency, step-up dc/dc converter general description the RT9264 is a compact, high efficient, step-up dc/dc converter with current mode pwm control loop, providing stable and high efficient operations without external compensation. the RT9264 suitable for 1 to 4 battery cells as well as usb power applications providing up to 400ma output current. the high switching rate minimized the size of external components. a 300ma ldo is included in RT9264 to provide a secondary low noise output as well as an output current stop in the shutdown mode. RT9264 is provided in sop-8 packages. ordering information RT9264 ? ? typical application circuit features z 400ma high supply capability z 90% efficiency z switching rate higher than 1.4mhz z providing flexibility for using internal and external power switches z built-in 300ma ldo, also for the zero-output- current shutdown mode z boost dc-dc integrating ldo for up-down regulation z 8-pin sop package applications z portable instrument z adsl modem z usb devices pin configurations part number pin configurations RT9264cs (plastic sop-8) top view fig. 1 RT9264 typical application for portable instruments operating temperature range c: commercial standard package type s : sop-8 c1 47 f vdd ce RT9264 ext ldoo lx lfb gnd fb + 3. 3v v ou t1 c2 1 f d1 1n5819 l1 2. 2 h r1 36k r2 22k r4 42k r3 22k c3 10 f 2. 5v v ou t2 v in + 47 f gnd ext lf b ldoo ce lx vdd fb 1 2 3 4 8 7 6 5
RT9264 preliminary www.richtek-ic.com.tw ds9264-00 december 2001 2 fig. 2 application circuit with zero-output-current shutdown mode control fig. 3 high voltage application c1 47 f vdd ce RT9264 ext ldoo lx lfb gnd fb + c2 1 f d1 1n5819 l1 2. 2 h r1 36k r2 22k c3 10 f 3. 3v v ou t v in chip enable i nput + 47 f c1 47 f vdd ce RT9264 ext ldoo lx lfb gnd fb + 15v v ou t1 c2 1 f d1 1n5819 l1 3. 3 h q1 nmos r2 20k r4 42k r3 22k c3 10 f 2. 5v v ou t2 3. 3v/5v v in + r1 220k c4 47 f + r5 100 ? c5 22 f
preliminary RT9264 ds9264-00 december 2001 www.richtek-ic.com.tw 3 pin description pin no. pin name pin function 1gnd ground 2ext output pin for driving external nmos or npn when driving an npn, a resistor should be added for limiting base current. 3lfb feedback pin of the built-in ldo (internal vref = 0.86v) 4ldoo voltage output pin of the built-in ldo 5fb feedback input pin internal reference voltage for the error amplifier is 1.25v. 6vdd input positive power pin of RT9264 7lx pin for switching 8ce chip enable RT9264 gets into shutdown mode when ce pin set to low. function block diagram ext ldoo loop control circuit over temp. detect or lx gnd shut down 1. 25 v 1. 25v RT9264 vdd lf b fb ce vdd r2 q3 nmos vdd q2 pmos r1 q1 nmos + _ + _
RT9264 preliminary www.richtek-ic.com.tw ds9264-00 december 2001 4 absolute maximum ratings z supply voltage -0.3v to 6v z lx pin switch voltage -0.3v to (vdd + 0.8v) z ldo output voltage -0.3v to (vdd + 0.3v) z other i/o pin voltages -0.3v to (vdd + 0.3v) z lx pin switch current 2.5a z ext pin driver current 30ma z power dissipation, p d @ t a = 25 c sop-8 0.625w ? package thermal resistance sop-8, ja 160 c/w z operating junction temperature 150 c z storage temperature range -65 c ~ +150 c electrical characteristics (v in = 3.3v, vdd set to 5v, load current = 0, t a = 25 c, unless otherwise specified) parameter symbol test conditions min typ max units operating vdd range v dd 1--6 v no load current i (v in ) i no load v in = 3.3v, v out = 5v -- 3 -- ma switch-off current i (vdd) i switch off v in = 6v -- 1 -- ma shutdown current i (v in ) i off ce pin = 0v, v in = 4.5v -- 0.1 1 a feedback reference voltage v ref close loop, vdd = 3.3v 1.225 1.25 1.275 v feedback reference voltage for ldo v ref close loop, vdd = 3.3v 0.843 0.86 0.877 v switching rate f s vdd = 5v 1.4 -- 2.8 mhz maximum duty d max vdd = 5v -- 80 -- % lx on resistance vdd = 5v -- 0.25 -- ? current limit setting i limit vdd = 5v -- 2 -- a ext on resistance to vdd vdd = 5v -- 30 -- ? ext on resistance to gnd vdd = 5v -- 20 -- ? line regulation ? v line v in = 3 ~ 4v, i l = 1ma -- 20 -- mv/v load regulation ? v load v in = 3.3v, i l = 1 ~ 50ma -- 0.5 -- mv/ma ldo pmos on resistance vdd = 5v -- 1 1.5 ? ldo drop out voltage v drop vdd = 5v, il = 100ma -- 70 -- mv ce pin trip level vdd = 5v 0.2 0.8 1.4 v temperature stability for fb, lfb, lbi t s guaranteed by design -- 50 -- ppm/ c thermal shutdown t sd guaranteed by design -- 165 -- c thermal shutdown hysterises ? t sd guaranteed by design -- 10 -- c
preliminary RT9264 ds9264-00 december 2001 www.richtek-ic.com.tw 5 application note output voltage setting referring to application circuits fig.1 to fig.3, the output voltage of the switching regulator (v out1 ) can be set with eq.1. the ldo output voltage can be set with eq.2. layout guide ? a full gnd plane without gap break. ? v out1 to gnd noise bypass ? short and wide connection for c2 to pin1 and pin6. ? v in to gnd noise bypass ? add a 100 f capacitor close to l1 inductor, when vin is not an idea voltage source. ? minimized fb/lfb node copper area and keep far away from noise sources. ? minimized parasitic capacitance connecting to lx and ext nodes, which may cause additional switching loss. ? the following diagram is an example of 2-layer board layout for application circuits fig.1 and fig.2. first layer second layer (full gnd plane) RT9264 v 25 . 1 ) 2 r 1 r 1 ( v 1 out + = eq.1 v 86 . 0 ) 3 r 4 r 1 ( v 2 out + = eq.2
RT9264 preliminary www.richtek-ic.com.tw ds9264-00 december 2001 6 package information dimensions in millimeters dimensions in inches symbol min max min max a 4.801 5.004 0.189 0.197 b 3.810 3.988 0.150 0.157 c 1.346 1.753 0.053 0.069 d 0.330 0.508 0.013 0.020 f 1.194 1.346 0.047 0.053 h 0.178 0.254 0.007 0.010 i 0.102 0.254 0.004 0.010 j 5.791 6.198 0.228 0.244 m 0.406 1.270 0.016 0.050 8?lead sop plastic package f a j b d i c m h
preliminary RT9264 ds9264-00 december 2001 www.richtek-ic.com.tw 7
RT9264 preliminary www.richtek-ic.com.tw ds9264-00 december 2001 8 richtek technology corp. headquarter 6f, no. 35, hsintai road, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5510047 fax: (8863)5537749 richtek technology corp. taipei office (marketing) 8f-1, no. 137, lane 235, paochiao road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)89191466 fax: (8862)89191465 email: marketing@richtek-ic.com.tw
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