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step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 1 o f 15 5j15n - rev.f 001 general description the EC9215 is a single pwm, step \ up dc \ dc controller with low operating voltage application integrating softstart and short circuit detection function. the oscillator switching frequency on chip can be o perated by terminating osc pin to connect capacitor and resistor for adjustable operating frequency. soft \ start is adjusted with the external capacitor, which sets the input current ramp. besides, the external compensation fb pin will apply the flexibility in the dynamic loop status, which allows using small and low equivalent series resistance (esr) ceramic output capacitors. the EC9215 is available in a pb \ free, sop \ 8 l and tssop - 8l package. featur e s 2.5 to 5. 5v input voltage range adjustable frequency: maximum 1mhz incorporates soft \ start function built \ in short \ circuit detection circuit (scp) low operating current: maximum to 1ma low shutdown current: maximum to 1a under \ voltage lockout package: sop \ 8 and tssop \ 8 lead free and green devices available (rohs compliant) applications lcd display power source pda, pmp, mp3 digital camera pin assignments figure1 pin configuration of EC9215 (top view) pin description pin number pin name description 1 inv internal 0.5v reference voltage. use a resistor divider to set the output voltage 2 scp soft \ start and short \ circuit detection, connects a capacitor from the pin to ground. 3 vdd power supply input pin for ic voltage 4 ctl output control pin. low = operating mode; high = shutdown mode. 5 out external mosfet driving pin. 6 gnd gnd 7 osc setting capacitor and resister to provide oscillation switching frequency adjustment. 8 fb error amplifier output pin. setting circuit for ic compensation.
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 2 o f 15 5j15n - rev.f 001 orderi n g information function block figure 2 function block diagram of EC9215 part number package marking marking information EC9215 nnm1r sop - 8l EC9215 lllll yywwt 1. llll last four number of lot no 2. yyww date code 3. t internal tracking code EC9215 nne1r tssop - 8l
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 3 o f 15 5j15n - rev.f 001 absolute maximum ratings recommended operating conditions symbol parameter rating unit v dd supply voltage \ 0.3 to 7 v v io input/output pins \ 0.3 to 7 v t a operating ambient temperature range \ 40 to 85 t j junction temperature range \ 40 to 150 t stg storage temperature range \ 60 to 150 t sdr maximum lead soldering temperature, 10 seconds 260 symbol parameter rating unit min. typ. max. v dd supply voltage 2.5 \ 5.5 v v inv error amplifier invert input voltage - 0.2 1 v v ctl control pin input voltage - 0.2 v dd v c scp scp pin capacitor 0.1 uf r t timing resistance 1.0 3.3 10 k c t timing capacitor 100 270 pf f sw oscillator frequency 200 600 1000 khz
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 4 o f 15 5j15n - rev.f 001 electrical characteristics (vdd = 3.3v, ta = 25c unless otherwise specified) parameters symbol test condition min. typ. max. unit entire device supply voltage v dd 2.5 \ 5.5 v supply current i dd v dd =2.5v to 5.5v \ 0.7 1 ma shutdown current i sd ctl pin open or vdd \ 0.1 1 a maximum duty cycle d max r t =3.3k, c t =270pf 80 85 92 % under \ voltage lockout protection vdd startup threshold voltage v th \ 2.0 \ 2.4 v hysteresis voltage v r \ \ 150 \ mv soft \ start voltage at soft \ start completion v ss \ 0.7 0.8 0.9 v soft \ start charge current i cs v scp =0v \ 0.7 \ 1.0 \ 1.5 a vol tage at soft \ start completion v ss \ 0.7 0.8 0.9 v soft \ start charge current i cs v scp =0v \ 0.7 \ 1.0 \ 1.5 a short circuit protection (scp) threshold voltage v scp 0.7 0.8 0.9 v charge current i scp v scp =0v \ 0.7 \ 1.0 \ 1.5 a sawtooth waveform oscillator (osc) oscillator frequency f osc rt =3.3k, c t =270pf 500 600 700 khz frequency stability for voltage f dv v dd =2.5v to 5.5v \ 2 5 % frequency stability for temperature f dt t a = \ 40c to 85c \ 5 \ % error amplifier reference voltage v ref v fb =inv 0.490 0.5 0.510 v vref stability v dd = 2.5v to 5.5v 5 20 mv vref variation with temperature ta= - 40 to 85 1 % transconductance gm 1000 1300 1600 ua/v input bias current i b inv=0v 1 ua output voltage ra nge v oh 1.6 1.8 v v ol 0.01 v
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 5 o f 15 5j15n - rev.f 001 parameters symbol test condition min. typ. max. unit output source current inv=0v,fb=0.5v - 150 - 180 \ - 210 ua output sink current inv=1v,fb=0.5v 140 170 200 ua pwm controller driver output source current i source duty<5%,out=0v - 150 - 200 ma output sink current i sink duty>5%,out=5v 150 200 ma c ontrol block control voltage v il active mode 0.2v dd v ih switch - off mode 0.8v dd
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 6 o f 15 5j15n - rev.f 001 typical application circuit
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 7 o f 15 5j15n - rev.f 001 typical application circuit
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 8 o f 15 5j15n - rev.f 001 timing diagram
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 9 o f 15 5j15n - rev.f 001 typical perf or man ce characteristics (t a =25,v dd =3.3v,unless otherwise specified)
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 10 o f 15 5j15n - rev.f 001 typical perf or man ce characteristics(cont.) (t a =25,v dd =3.3v,unless otherwise specified)
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 11 o f 15 5j15n - rev.f 001 typical perf or man ce characteristics(cont.)
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 12 o f 15 5j15n - rev.f 001 function description setting oscillating frequency the oscillator circuit generates a triangular saw tooth wave with a peak of 0.9v and through 0.16v using the timing capacitor (ct) and the timing resistor (rt ) that are connected to osc pin. this oscillator can provide oscillating frequency up to 1mhz set ting output voltage the output voltage is set using t he inv pin and a resistor divider connected to the outpu t is shown in the typical operating circuit. the internal reference voltage is 0.5v with 2% variation, so the ratio of th e feedback resistors sets the output voltage according to the following equation: t o avoid the thermal noise from feedback resistor, the resistance r2 is smaller than 100kw and 1% variation is recommended. error amplifier the error amplifier detects the output voltage of the switching regulator and outpu ts the pwm control signal. the voltage gain is fixed, and connecting a phase comp ensation resistor and capacitor to the fb p in (pin 8) provides stable phase compensation for the system. pwm comparator the voltage comparator has one inverting and three non - inverting inputs. the comparator is a voltage /pulse width converter that controls the on time of the output pulse depending on the input voltage. the output level is high (h) when the saw - tooth wave is lowe r than the error amplifier output voltage, soft \ start setting voltage, and idle period setting voltage
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 13 o f 15 5j15n - rev.f 001 output circuit the output circuit is a typical push \ pull configuration to drive an external nmos transistor di rectly. it can provide a 200ma source/sink to/from out (pin 5). soft - start and short circuit detection soft - start operation is set by co nnecting capacitor cscp to the scp pin (pin 2). soft - start prevents a current spike on start - up. on completion of the soft \ start operation, the scp pin (pin 2) stays low and enters the short circuit detection wait state. when an output short circuit occurs, the error amplifier output is fixed at 1.8v and capacitor cscp starts charging. after charging to approximately 0 .8 v, the output pin (pin5) is set low and the scp pin stays lo w. once the protection circuit operates, the circuit can be resto red by resetting the power supply. short circuit detection time can be calculate as below: under - voltage lock out (uvlo) transients during powering on or instantaneous glitches in the supply voltage can cause sys tem damage or failure. the circuit prevents malfunction a t low input voltage detec ts a low input voltage by comparing the supply voltage with the internal reference voltage. on dete ction, the circuit fixes the output pin to low. the system recovers when the supply voltage rises back above the threshold voltage of the r mal function prevention circuit. layout consideration switching noise decoupling capacitor a 0.1uf ceramic capacitor shou ld be placed close to the vout pin and the gnd pin of the chip to filter the switching spikes in the output voltage mon itored by the vout pin. feedback network the feedback networks should be connected directly to a dedicated analog ground plane and this ground plane must connect to the gnd pin. if no analog ground plane is available, and then this ground must t ie directly to the gnd pin. the feedback network, resis tors r2 and r3, should be kept close to the fb pin, and away from the inductor. input capacitor the input capacitor cin in vin m ust be placed clos e to the ic. this will reduce copper trace res istance which effects input voltage ripple of the ic. for additional input voltage filtering, a 1uf capacitor can be placed in p arallel with c in, close to the vdd pin, to shunt any high frequency noise to the ground.
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 14 o f 15 5j15n - rev.f 001 package information sop - 8l p ack a ge out l ine dimensions
step - up dc/dc controller ec92 15 e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 15 o f 15 5j15n - rev.f 001 package information tssop - 8l p ack a ge out l ine dimensions

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