description gm3326 is step-up/down dc/dc converter controller ics with fast, and low on resistance drivers built-in. a versatile step-up/ down dc/dc converter can be realised by using with large output current only 4 basic external components - transistors, coils, diodes, and capacitors. output voltage is selectable in 0.1v steps within a 2.4v ~ 6.0v ( 2.5% accuracy) range, and switching frequency is set at or 300khz. gm3326 switches from pwm to pfm control during light loads, and the series offers high efficiencies from light loads through to large output currents. soft-start time is internally set to 10 msec, which offers protection against rush currents when the power is switched on and also against voltage overshoot. during shutdown (ce pin = l), consumption current can be reduced to as little as 0.5a or less. application mobile phones pdas palmtop computers typical applica tion circuits features input voltage range : 2.0v ~ 10v output voltage range : 2.4v ~ 6.0v ( 2.5% accuracy) (selectable in 0.1v steps) oscillation frequency : 300khz ( 15% accuracy) output current : more than 250ma (v =2.4v, in v =3.3v) out efficiency : 81% (typ) at 5.0v, 78% (typ) at 3.3v stand-by : istb = 0.5a (max) output voltage internal set-up sot-25 package g m 3 3 2 6 v 0 . 1 1 www.gammamicro.com portable audio equipment various power supplies c in + + c l v out v in 3l colis smtspr5d5047c-220 youth coils ycdh57-220 nch fdn339an mosfet ce pch mosfet fdn338p gm3326 v out schottky mbrs140 schottky mbrs140 ext v dd gnd l 68f/ 10v chemi_con pt- series 100f/ 10v chemi_con pt- series
marking information & pin configura tions g m 3 3 2 6 2 * for detail ordering number identification, please see last page. oa: device code v : output voltage y : y ear w : weekly oav yw 1 3 2 5 4 gnd sot-25 (sot-23-5) ext v dd v out ce package shipping ordering number output v oltage suffix ordering information sot-25 sot-25 sot-25 sot-25 sot-25 sot-25 sot-25 sot-25 sot-25 sot-25 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel 3,000 units/ t ape & reel gm3326 -2.5st25r gm3326 -2.8st25r gm3326 -3.0st25r gm3326 -3.3st25r gm3326 -3.5st25r gm3326 -4.0st25r gm3326 -4.5st25r gm3326 -5.0st25r gm3326 -5.5st25r gm3326 -6.0st25r 2.5 2.8 3.0 3.3 3.5 4.0 4.5 5.0 5.5 6.0 b e g j l q v a f k absolute maximum ratings parameter units v pin voltage dd v pin voltage out ce pin voltage ext/ pin voltage ext/ pin current power dissipation operating ambient temp. storage t emp. v v v v mw c c symbol v dd v out v ce v ext/ i ext/ pd t opr tstg ratings -0.3 ~ 12 -0.3 ~ 12 -0.3 ~ 12 -0.3 ~ v +0.3 dd 100 150 -40 ~ +85 -40 ~ +125 ma
g m 3 3 2 6 3 block diagram v out ce error amp. + - phase compensation + - v with ref soft start ce pwm/ pfm controller pwm/ pfm comparator ramp wave generator, osc buffer, driver v dd ext/ gnd block diagram explanation the error amplifier is used as an output voltage monitor. it compares the reference voltage with the feedback from the voltage divided by the internal resistor. should a voltage higher than the reference voltage be fedback, the output of the error amp will increase. the pwm comparator compares the output of the error amp with the ramp wave. when the voltage at the output of the error amp is low, the ext/ pin will be low level (switching on time). the ramp wave generator, as the name suggests, generates the switching frequency's ramp wave. with the gm3326 series, control is automatically switched between pwm and pfm according to the size of the load. the start up of the vref voltage at the error amp's input is gradual due to the internal capacitor and low current circuit. because of this soft-start function, the operations of the error amp's 2 inputs are balanced and the ext/ pin's on time can be manipulated to produce longer on times. further, with the uvlo function, the signal will be such so as not to turn the mos switch on until any instability in the internal circuit stabilizes during soft-start time. even in cases where input voltage is so low as to produce instability in the ic, the uvlo function will operate and the mos switch will be turned off.
g m 3 3 2 6 4 [ step-up&down dc/dc converter] set output voltage obtained as a result of the automatic switching operations of the ic regardless of the difference between input voltage and set output voltage. the above graph shows that over a wide input voltage range, the efficiency of the gm3326 is more or less constant. in applications that use either a standard dry 3 cell battery or a cell lithium ion battery to obtain an output of 3.3v, for example, the efficiency of gm3326 is again much better. due to gm3326 does not have a series regulator output, we recommend a test with samples for use in applications where ripple voltage is a problem. external components selection (notes) the performance of the dc/dc converter ic circuit is heavily reliant upon the performance of the surrounding circuitry and components. in particular, since the v voltage of the schottky diode used will have a direct effect upon efficiency , the f smaller the diode, the better the efficiency obtainable. (refer to the graph below) it is also recommended that a switching mosfet with a small on resistance be used. with gm3326, an on resistance of 500m w or less is recommended. i = 10ma out 100ma 200ma figure 1. input voltage vs. efficiency 90 85 80 75 70 65 60 55 50 45 40 2 3 4 5 6 7 8 input voltage (v) e f f i c i e n c y ( % ) 85 80 75 70 65 0.2 0.4 e f f i c i e n c y ( % ) figure 2. v = 3.3v, i = 100ma out out v voltage (v) f v = 2.4v in v = 3.0v in v = 4.5v in set output voltage +0.4v s te p -u p m o d e step-down mode
g m 3 3 2 6 5 electrical characteristics (gm3326- 3.3v) min typ max unit parameter conditions min v = 3.3v, f = 300khz out osc t = 25c a symbol output voltage supply voltage supply current 1 supply current 2 stand- by current oscillation frequency max. duty ratio pfm duty ratio efficiency note 1 soft- start time ce 'h' voltage ce 'l' voltage ext/ 'h' on resistance ext/ 'l' on resistance v out v dd i dd 1 i dd 2 i stb f osc maxdty pfmdty effi t ss v ceh v cel r extbh r extbl 3.218 2.0 - - - 255 78 15 - 5.0 0.65 - - - 3.300 - 130 20 - 300 85 25 78 10.0 - - 29 19 3.383 10.0 200 35 0.5 345 92 35 - 20.0 - 0.20 43 27 v v a a a khz % % % ms v v w w v out = ce: set output voltage x 0.95 applied v out = ce: set output voltage + 0.5 applied v out = set output voltage x 0.95 applied, ce= 0v v dd =v = ce: set output voltage x 0.95 applied out v dd =v = ce: set output voltage x 0.95 applied out no load v dd =v = ce: set output voltage x 0.95 applied in v : set output voltage x 0.95 applied out v : set output voltage x 0.95 applied out same as i 1, v / = v - 0.4v dd ext out same as i 1, v / = 0.4v dd ext measuring condition: unless otherwise stated, v = 3.3v , i = 130ma dd out note 1: effi= {[(output voltage) x (output current)] [(input voltage) x (input current)]} x100 gm3326 is pwm (pwm/ pfm switching) step-up/down dc/dc converter controller ics. gm3326 switches to pfm operations during light loads and is very efficient over a wide range in relation to load. further, the efficiency can be maintained over a wide input voltage range as both step-up & step-down operations are pwm controlled. output voltage settings are laser trimmed. [ on time] p-ch mosfet = on, n-ch mosfet = on : current flows from v via pch moseft , l, nch fet to gnd : l is charged. in [off time] p-ch mosfet (psw) = off , n-ch mosfet (nsw) = off : current flows from gnd via schottky 1, l, schottky 2, to v : v rises due to the charge stored at l. by comparing v with the internal reference voltage, the on time vs out out out off time ratio can be regulated & output stability can be protected. operational explanation c in + + c l v out v in l schottky nch mosfet ce pch mosfet v out ext ce gnd v in schottky
g m 3 3 2 6 6 ordering number gm 3326 2.5 st25 r gamma micro. circuit type package st25: sot-25 shipping r: t ape & reel sot-25(sot -23-5) p ackage outline dimensions pad layout 2.9 0.1 0.074 1.9 0.037 0.95 0.037 0.95 0.094 2.4 0.028 0.7 inches mm ( ) 1.9 0.05 2.8 0.1 1.5 0.05 0.65 0.05 0.35 0.03 0.13 0~0.1 0.8 0.05 1.10 0.1 5 5 unit: mm output voltage 1.5: 1.5v 0.039 1.0 0.95 0.038
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