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preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 1 vfm step-up dc/dc converter general description the rt9261 series are vfm step-up dc/dc ics with ultra low supply current by cmos process and suitable for use with battery-powered instruments. the rt9261 ic consists of an oscillator, a vfm control circuit, a driver transistor (lx switch), a reference voltage unit, an error amplifier, resistors for voltage detection, and a lx switch protection circuit. a low ripple and high efficiency step-up dc/dc converter can be constructed of this rt9261 ic with only three external components. the rt9261a ic provides with a drive pin (ext) for an external transistor, so that a power transistor can be externally applied. therefore, the rt9261a ic is recommended for applications where large currents are required. ce pin enables circuit to set the standby supply current at a maximum of 0.5 a. ordering information rt9261a- ?? ? ? features z minimal number of external components ( only an inductor, a diode, and a capacitor) z ultra low input current ( 5 a at switch off) z 2% high output voltage accuracy z low ripple and low noise z low start-up voltage, 0.85v at 1ma z 75% efficiency with low cost inductor z +50 ppm/ c low temperature-drift z sot-89 and sot-25 small packages applications z power source for battery-powered equipment z power source for cameras, camcorders, vcrs, pdas, pagers, electronic data banks, and hand- held communication equipment z power source for applications, which require higher voltage than that of batteries used in the appliances pin configurations part number pin configurations rt9261- ?? cx (plastic sot-89) top view 1. gnd 2. vout (tab) 3. lx rt9261a- ?? cx (plastic sot-89) top view 1. gnd 2. vout (tab) 3. ext rt9261- ?? cb (plastic sot-25) top view 1. ce 2. vout 3. nc 4. gnd 5. lx rt9261a- ?? cb (plastic sot-25) top view 1. ce 2. vout 3. nc 4. gnd 5. ext operating temperature range c: commercial standard package type b : sot-25 x : sot-89 output voltage 15 : 1.5v 16 : 1.6v : 49 : 4.9v 50 : 5.0v a : use external switch use internal switch 123 123 54 3 2 1 54 3 2 1
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 2 absolute maximum ratings z output voltage 8v z lx pin voltage (1) 8v z ext pin voltage (2) -0.3 to v out +0.3v z ce pin voltage (3) -0.3 to v out +0.3v z lx pin output current (1) 250ma z ext pin current (2) 50ma z power dissipation, p d @ t a = 25 c z sot-89 0.5w sot-25 0.25w z package thermal resistance sot-89, jc 100 c/w sot-89, ja 300 c/w sot-25, ja 250 c/w z operating temperature range -20 to +85 c z storage temperature range 165 c z lead temperature (soldering, 10 sec.) 260 c notes: (1) applicable to rt9261- ?? cx and rt9261- ?? cb (2) applicable to rt9261a- ?? cx and rt9261a- ?? cb (3) applicable to rt9261- ?? cb and rt9261a- ?? cb electrical characteristics (refer to fig. 1) parameter symbol test conditions min typ max units output voltage accuracy ? v out -2 -- +2 % input voltage v in -- -- 7 v start-up voltage v st i out = 1ma, v in : 0 2v -- 0.85 1.0 v hold-on voltage v ho i out = 1ma, v in : 2 0v 0.7 -- -- v v out 3.5v (1) -- 15 18 input current 1 3.5v < v out 5v (2) to be measured at v in at no load -- 18 24 a input current 2 to be measured at v out in switch off condition -- 5 8 a v out 3.5v (1) 60 -- -- lx switching current 3.5v < v out 5v (2) i switching v lx = 0.4v 80 -- -- ma lx leakage current i leakage v lx = 6v -- -- 0.5 a maximum oscillator f max 80 120 160 khz oscillator duty cycle d osc on ( v lx ? l ? ) side 65 75 85 % efficiency -- 75 -- % v lx voltage limit l x switch on 0.65 0.8 1.0 v notes: (1) v in = 1.8v, vss = 0v, i out = 10ma, t opt = 25 c, and external circuit of typical application (2) v in = 3v, vss = 0v, i out = 10ma, t opt = 25 c, and external circuit of typical application
preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 3 electrical characteristics (refer to fig. 2) parameter symbol test conditions min typ max units output voltage accuracy ? v out -2 -- +2 % input voltage v in -- -- 7 v start-up voltage v st i out = 1ma, v in : 0 2v -- 0.85 1.0 v v out 3.5v (1) -- 30 50 input current 1 3.5v < v out 5v (2) to be measured at v in at no load -- 60 90 a v out 3.5v (1) input current 2 3.5v < v out 5v (2) to be measured at v out in switch off condition -- 6 10 a v out 3.5v (1) -1.5 -- -- ext ?h? output current 3.5v < v out 5v (2) v ext = v out ? 0.4v -2 -- -- ma v out 3.5v (1) 1.5 -- -- ext ?l? output current 3.5v < v out 5v (2) v ext = 0.4v 2---- ma maximum oscillator frequency f max 80 120 160 khz oscillator duty cycle d osc v ext ? h ? side 65 75 85 % notes: (1) unless otherwise provided, v in = 1.8v, vss = 0v, i out = 10ma, t opt = 25 c, and use external circuit of typical application (2) unless otherwise provided, v in = 3v, vss = 0v, i out = 10ma, t opt = 25 c, and external circuit of typical application
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 4 electrical characteristics (refer to fig. 3) parameter symbol test conditions min typ max units output voltage accuracy ? v out -2 -- +2 % input voltage v in -- -- 7 v start-up voltage v st i out = 1ma, v in : 0 2v -- 0.85 1.0 v hold-on voltage v ho i out = 1ma, v in : 2 0v 0.7 -- -- v v out 3.5v (1) -- 75 -- efficiency 3.5v < v out 5v (2) -- 85 -- % v out 3.5v (1) -- 15 18 input current 1 3.5v < v out 5v (2) to be measured at v in at no load -- 18 24 a v out 3.5v (1) -- 5 8 input current 2 3.5v < v out 5v (2) to be measured at v out in switch off condition -- 6 10 a v out 3.5v (1) 60 -- -- lx switching current 3.5v < v out 5v (2) i switching v lx = 0.4v 80 -- -- ma lx leakage current i leakage v lx = 6v -- -- 0.5 a ce ?h? level v in = v out 0.9 0.4 v out -- -- v ce ? l? level v in = v out 0.9 -- -- 0.2 v ce ? h? input current ce = v out -- -- 0.5 a ce ? l? input current ce = 0v -0.5 -- -- a maximum oscillator frequency f max 80 120 160 khz oscillator duty cycle d osc on (v lx ? l? ) side 65 75 85 % v lx voltage limit lx switch on 0.65 0.8 1.0 v notes: (1) unless otherwise provided, v in = 1.8v, vss = 0v, i out = 10ma, t opt = 25 c, and use external circuit of typical application (2) unless otherwise provided, v in = 3v, vss = 0v, i out = 10ma, t opt = 25 c, and external circuit of typical application
preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 5 electrical characteristics (refer to fig. 4) parameter symbol test conditions min typ max units output voltage accuracy ? v out -2 -- +2 % input voltage v in -- -- 7 v start-up voltage v st i out = 1ma, v in : 0 2v -- 0.85 1.0 v v out 3.5v (1) -- 75 -- efficiency 3.5v < v out 5v (2) -- 85 -- % v out 3.5v (1) -- 30 50 input current 1 3.5v < v out 5v (2) to be measured at v in at no load -- 60 90 a v out 3.5v (1) input current 2 3.5v < v out 5v (2) to be measured at v out in switch off condition -- 6 10 a v out 3.5v (1) -1.5 -- -- ext ?h? output current 3.5v < v out 5v (2) v ext = v out ? 0.4v -2 -- -- ma v out 3.5v (1) 1.5 -- -- ext ?l? output current 3.5v < v out 5v (2) v ext = 0.4v 2---- ma ce ?h? level v in = v out 0.9 0.4 v out -- -- v ce ? l? level v in = v out 0.9 -- -- 0.2 v ce ? h? input current ce = v out -- -- 0.5 a ce ? l? input current ce = 0v -0.5 -- -- a maximum oscillator frequency f max 80 120 160 khz oscillator duty cycle d osc on (v lx ? l? ) side 65 75 85 % v lx voltage limit lx switch on 0.65 0.8 1.0 v notes: (1) unless otherwise provided, v in = 1.8v, vss = 0v, i out = 10ma, t opt = 25 c, and use external circuit of typical application (2) unless otherwise provided, v in = 3v, vss = 0v, i out = 10ma, t opt = 25 c, and external circuit of typical application
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 6 function block diagram notes: (1) lx pin .?? only for 9261- ?? cx and 9261- ?? cb (2) ext pin ?? only for 9261a- ?? cx and 9261a- ?? cb (3) ce pin ?? only for 9261- ?? cb and 9261a- ?? cb pin description pin no. -xxcx a-xxcx -xxcb a-xxcb pin name pin function 1 1 4 4 gnd ground 2 2 2 2 vout output voltage 3 -- 5 -- lx pin for switching -- 3 -- 5 ext drive external device -- -- 1 1 ce chip enable (active high) -- -- 3 3 nc no connected vout vref chip enable osc 100khz vfm control buffer v lx limiter error amp. ce lxsw + _ ext gnd lx
preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 7 typical application circuit fig. 1 v out co l1 v in lx vout gnd d1 + _ 22 f 100 h 1n5819 rt9261cx fig. 2 v out co l1 v in ext vout gnd d1 + _ 22 f 27 h 1n5819 0. 01 f cb rb 300 ? tr ztx 650 rt9261acx fig. 3 v out co l1 v in lx gnd d1 + _ 22 f 100 h 1n5819 ext vout ce nc rt9261cb
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 8 fig. 4 v out co l1 v in ext vout gnd d1 + _ 22 f 27 h 1n5819 0. 01 f cb rb 300 ? tr ztx 650 ce lx nc rt9261acb fig. 5 v out co l1 v in lx gnd d1 + _ 22 f 27 h 1n5819 ext vout ce nc ce rt9261cb
preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 9 typical operating charateristics rt9261(2.7v) start-up/hold-on voltage vs. output current 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 1020304050 output current (ma) start-up/hold-on voltage vstart/vhold (v) v start v hold rt9261 v out = 2.7v rt9261(2.7v) output current vs. ripple voltage 0 20 40 60 80 100 120 0 20406080100 output current (ma) ripple voltage (mv p-p) 0.9v 1.5v 2.0v 2.5v rt9261 v out = 2.7v rt9261(2.7v) output voltage vs. output current 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 20406080100 output current (ma) output voltage (v) 0.9v 1. 0v 1.5v 2.0v 2.5v rt9261 v out = 2.7v output voltage vs. temperature 2.60 2.65 2.70 2.75 2.80 2.85 2.90 -40 -20 0 20 40 60 80 temperature ( c) output voltage (v) rt9261 v out = 2.7v rt9261(2.7v) efficiency vs. output current 0 10 20 30 40 50 60 70 80 90 020406080100 output current (ma) efficiency (%) 0.9v 1.0v 1.5v 2.0v 2.5v rt9261 v out = 2.7v supply current vs. temperature 0 10 20 30 40 50 60 70 -40-20 0 20406080 temperature ( c) supply current ( a) input current 1 input current 2 rt9261 v out = 2.7v
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 10 maximum oscillator frequency vs. temp. 0 20 40 60 80 100 120 140 160 -40-20 0 20406080 temperature ( c) maximum oscillator frequency (khz) rt9261 v out = 2.7v rt9261a (2.7v) output voltage vs. output current 0.0 0.5 1.0 1.5 2.0 2.5 3.0 0 306090120150 output current (ma) output voltage (v) 0.9v 1.0v 1.5v 2.0v 2.5v rt9261a v out = 2.7v oscillator duty cycle vs. temperatrue 50 60 70 80 90 100 -40 -20 0 20 40 60 80 temperature ( c) oscillator duty cycle (%) rt9261 v out = 2.7v rt9261a (2.7v) efficiency vs. output current 0 10 20 30 40 50 60 70 80 0 30 60 90 120 150 output current (ma) efficiency (%) 1.0v 0.9v 1.5v 2.0v 2.5v rt9261a v out = 2.7v start-up/hold-on voltage vs. output current 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0306090120150 output current (ma) start-up/hold-on voltage vstart/vhold (v) v start v hold rt9261a v out = 2.7v rt9261a (2.7v) output current vs. ripple voltage 0 20 40 60 80 100 120 0 30 60 90 120 150 output current (ma) ripple voltage (mv p-p) 0.9v 1.5v 2.0v 2.5v rt9261a v out = 2.7v
preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 11 package information dimensions in millimeters dimensions in inches symbol min max min max a 1.397 1.600 0.055 0.063 b 0.356 0.483 0.014 0.019 b 2.388 2.591 0.094 0.102 b1 0.406 0.533 0.016 0.021 c -- 4.242 -- 0.167 c1 0.787 1.194 0.031 0.047 d 4.394 4.597 0.173 0.181 d1 1.397 1.753 0.055 0.069 e 1.448 1.549 0.057 0.061 h 0.355 0.432 0.014 0.017 3-lead sot-89 surface mount d d1 c c1 b e e a b b1 b a h
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 12 dimensions in millimeters dimensions in inches symbol min max min max a 0.889 1.295 0.035 0.051 a1 0.000 0.152 0.000 0.006 b 1.397 1.803 0.055 0.071 b 0.356 0.559 0.014 0.022 c 2.591 2.997 0.102 0.118 d 2.692 3.099 0.106 0.122 e 0.838 1.041 0.033 0.041 h 0.102 0.254 0.004 0.010 l 0.356 0.610 0.014 0.024 sot- 25 surface mount package b 4 5 b c d 3 1 l h a1 e a
preliminary rt9261/a ds9261/a-03 january 2002 www.richtek-ic.com.tw 13
rt9261/a preliminary www.richtek-ic.com.tw ds9261/a-03 january 2002 14 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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