View AIC2323_8550237.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AIC2323 3.2a 550k/1.1mhz synchronous pwm step-down converter analog integrations corporation si-soft research center ds-2323g-03 20121212 3a1, no.1, li-hsin rd. i , science park , hsinchu 300, taiwan , r.o.c. tel: 886-3-5772500 fax: 886-3-5772510 www. analog.com.tw 1 ? features ? 2.5v to 6v input voltage range ? adjustable output voltage from 0.8v to vin ? 3.2a guaranteed output current ? up to 95% efficiency ? low r ds(on) internal switches: 110m ? ? no schottky diode required ? 100% duty cycle in low dropout operation ? fixed 550k/1.1mhz operating frequency ? optional soft-start internal fixed 1ms soft- start (in sop-8) ? applications ? lcd tv ? portable products ? wireless and dsl modems ? solid-state drives ? battery-operated devices (1 li-ion or 3 nimh/ nicd) ? description the AIC2323 is a low-noise, pulse-width- modulated (pwm), dc-dc step-down converter. the device features an internal synchronous rectifier for high efficiency; it requires no external schottky diode. shutdown mode places the device in standby, reducing supply current to under 2a. other features of the AIC2323 include high efficiency for all load range, low dropout voltage, short circuit protection, and over temperature protection.
AIC2323 2 ? applications circuit 10 ? r1 50k ? r2 16k ? r3 0.1uf c2 10uf c1 2.2uh l1 22uf c3 100k ? r4 0.22uf c5 5v 0.1uf c4 vin vou t pg lx 10 vin 1 fb 5 en 8 ref 3 pgood 7 vcc 2 ss 6 pgnd 9 gnd 4 AIC2323 on off 3.3v fig. 1 typical application circuit for dfn-10 package vin 8 vcc 1 en 5 pgnd 6 gnd 3 ref 2 fb 4 lx 7 AIC2323 10? r1 50k ? r2 16k ? r3 2.2uh l1 0.1uf c4 22uf c3 10uf c1 0.1uf c2 vout vin on off 5v 3.3v fig. 2 typical application circuit for sop-8 package
AIC2323 3 ? pin configuration exposed p ad packing type tr: tape & reel tb: tube(for sop-8 package) bg: bag(for dfn-10 package) package type r8: sop-8 with exposed pad dc: dfn-10 with exposed pad g: green package a: 1.1mhz b: 550khz example: AIC2323-agdctr ? fixed 1.1mhz operating frequency in green dfn-10 with exposed pad package and tape & reel packing type pin configuration dfn-10 (3x3) with exposed pad (heat sink) top view 1 3 2 5 4 vin vcc ref gnd fb 10 8 9 6 7 pgood ss lx pgnd en exposed pad pgnd vin lx en gnd ref fb vcc 1 3 4 2 8 6 5 7 sop-8 with exposed pad (heat sink) top view AIC2323-xxxxxx note: th e exp osed pa d must be con ne cted with gnd pin. note: th e exp ose d pa d mu st b e con ne cte d with g nd pi n.
AIC2323 4 ? absolute maximum ratings supply input volatge, vcc, vin -0.3v to 6.5v lx pin switch voltage -0.3v to (vin + 0.3v) other i/o pin voltage -0.3v to (vcc + 0.3v) pgnd to gnd +/-0.3 v operating ambient temperature range t a -40? c to 85 ? c operating maximum junction temperature t j 150 ? c storage temperature range t stg -65? c to 150 ? c lead temperature (soldering 10 sec.) 260 ? c thermal resistance junction to case sop-8 (exposed pad)* 15? c/w thermal resistance junction to case dfn 10l (exposed pad)* 20 ? c/w thermal resistance junction to ambient sop-8 (exposed pad)* 60 ? c/w thermal resistance junction to ambient dfn 10l (exposed pad)* 50 ? c/w latch-up 200ma hbm (human body mode) 4kv (assume no ambient airflow) absolute maximum ratings are those values beyond which the life of a device may be impaired. * the package is placed on a two layers pcb with 2 ounces copper and 2 square in ch, connected by 8 vias.
AIC2323 5 ? electrical characteristics (t a =25 ? c, v in =3.3v, unless otherwise specified.) (note1) parameter conditions symbol min typ max units input voltage range v in 2.5 6 v v cc rising v uvlo(r) 2.3 v under voltage lockout thresh- old v cc falling v uvlo(f) 2.1 v output adjustment range v out 0.8 v in v shutdown current v en = 0v i sd 1 2 ? a quiescent current i out = 0a, v fb = 1v no switching i q 550 ? a standby current i out = 0a, switching i sb 600 900 ? a feedback reference voltage v ref 0.784 0.8 0.816 v vout line regulation v in = 2.5v to 5.5v v out -2 2 % fb leakage current i fb 0.1 0.2 ? a en supply current i en 3.5 ? a en logic high 1.5 v cc v en logic low 0 0.5 v p-channel on-resistance i lx = 0.2a r dsh(on) 110 m ? n-channel on-resistance i lx = 0.2a r dsl(on) 80 m ? switch leakage current v en = 0v, v in = 5.5v 0.1 1 ? a peak inductor current i pk 4 5 a oscillator frequency (a version) f osca 920 1100 1280 khz oscillator frequency (b version) f oscb 468 550 632 khz maximum duty cycle d max 100 % thermal shutdown trip point t otp 150 c thermal shutdown hysteresis t otp_hys 25 c pgood leakage current pgood=5v i pgood 1 ? a pgood voltage low i pgood =1ma v pgl 0.2 v pgood high window with respect to nominal output, t a =t j =25c 8 10 15 % pgood delay time vout rising or vout fal- ling 1024 clks soft-start charge current i ss 4 ? a note 1: specifications are production tested at t a =25 ? c. specifications over the -40 ? c to 85 ? c operating tem- perature range are assured by design, characteriza tion and correlation with statistical quality con- trols (sqc).
AIC2323 6 ? typical performance characteristics (c1=10 f,c3=22 f,l1=2.2 h,t a =25 ,unless otherwise noted) 50.00 55.00 60.00 65.00 70.00 75.00 80.00 85.00 90.00 95.00 100.00 0 500 1000 1500 2000 2500 3000 y( ) fig. 3 efficiency vs load current fig. 4 output voltage deviation vs input voltage fig. 5 switching waveform fig. 6 soft start waveform fig. 7 soft start waveform fig. 8 shoutdown waveform vin=vcc=3.3v,vout=1.8v,iload=1.5a vin=vcc=3.3v,vout=1.8v,iload=1.5a vin=vcc=3.3v,vout=0.8v,iload=1.5a ven vout ven out ripple ilx vlx vlx vout ven (vcc=vin=5v) vout 3.3v out 1.8v out
AIC2323 7 ? typical performance characteristics (continued) fig. 9 load transient response fig. 10 load transient response fig. 11 switching frequence vs input voltage fig. 12 output voltage deviation vs load current out ripple out ripple vin=vcc=5v,vout=2.5v,iload=0.5a to 1a vin=vcc=5v,vout=1.5v,iload=0.5a to 1a iload iload
AIC2323 8 ? block diagram functional block diagram of AIC2323
AIC2323 9 ? pin descriptions (for dfn-10 package) pin no. pin name pin function 1 vin power input supply. decouple this pin to pgnd with a capacitor. 2 vcc signal input supply. decouple this pin to gnd with a capacitor. normally vcc is equal to vin. 3 ref internal reference voltage. decouple this pin to gnd with a capacitor. 4 gnd signal ground. all small-signal co mponents and compensation components should connect to this ground, which in tu rn connects to pgnd at one point. 5 fb feedback pin. this pin receives the f eedback voltage from a resistive divider connect across the output. 6 ss soft-start control input. ss controls the so ft-start period. connect a capacitor from ss to gnd to set the soft-start period. 7 pgood power good indicator. it is an open drain out put. low when the output is out of the power good high window. 8 en enable pin. connect to logic high in norma l operation. forcing this ping to gnd cause the device to be shutdown. 9 pgnd power ground. connect this pin to the negative terminal of c in and c out. 10 lx internal power mosfet switches ou tput. connect this pin to the inductor. (for sop-8 package) pin no. pin name pin function 1 vcc signal input supply. decouple this pin to gnd with a capacitor. normally vcc is equal to vin. 2 ref internal reference voltage. decouple this pin to gnd with a capacitor. 3 gnd signal ground. all small-signal co mponents and compensation components should connect to this ground, which in tu rn connects to pgnd at one point. 4 fb feedback pin. this pin receives the f eedback voltage from a resistive divider connect across the output. 5 en enable pin. connect to logic high in normal operation. forcing this pin to gnd cause the device to be shutdown. 6 pgnd power ground. connect this pin to the negative terminal of c in and c out . 7 lx internal power mosfet switches ou tput. connect this pin to the inductor. 8 vin power input supply. decouple this pin to pgnd with a capacitor.
AIC2323 10 ? application information operation the AIC2323 is a low-noise step-down dc/dc converter with current-mode pwm control architecture. it features an internal synchronous rectifier, which eliminates the external schottky diode and increases efficiency. during normal operation, the AIC2323 can regulate its output voltage through a feedback control circuit, which is composed of an error amplifier; a current comparator and several control signal generators. by comparing the feedback voltage to the reference voltage of 0.8v, the error amplifier varies its output voltage. the output volt age of the error amplifier is compared with the summing signal of current sensing signal and slope compensation signal to determine the duty cycle of internal main power switch (p-channel mosfet). while the main power switch is turned on, the synchronous power switch (n-channel mosfet) will be turned off through anti-short-through block. similarly, when the main power switch is turned off, the synchronous power switch will be turned on until the inductor current starts to reverse or the beginning of the next switching cycle. current limitation the AIC2323 provides current limit function by using an internal sensing resistor. when the main power switch turns on, current follows through the internal sensing resistor. and current amplifier senses the voltage, which crosses the resistor, and amplifies it. while the sensed voltage gets higher than reference voltage, the current limitation function is activated. while the current limitation function is activated, the duty cycle will be reduced to limit the output power to protect the internal power switches. short circuit protection while the output is short ed to ground, the switching frequency of AIC2323 will be reduced to one fourth of the normal switching frequency. this lower switching frequency ensures the inductor current has more time to discharge, thereby pr eventing inductor current runaway. the switching frequency will automatically return to its designed value while short circuit condition is released. shutdown by connecting the en pin to gnd, the AIC2323 can be shut down to reduce the supply current to 2 ? a (typical). at this operation mode, the output voltage of step- down converter is equal to 0v. 100% duty cycle operation when the input voltage approac hes the output voltage, the AIC2323 smoothly transits to 100% duty cycle operation. this allows AIC2323 to regulate the output voltage until AIC2323 completely enters 100% duty cycle operation. in 100% dut y cycle mode, the output voltage is equal to the input voltage minus the voltage, which is the drop across the main power switch. the AIC2323 achieves 100% duty cycle operation by extending the turn-on time of the main power switch. if the summing signal of curr ent sensing signal and slope compensation signal does not reach the output voltage level of the error amplifier at the end of 90% switching period, the main power switch is continuously turned on and the oscillator remains off until the summing signal of current sensing signal and slope compensation signal reaches the output voltage level of the error amplifier. after the summing signal of current sensing signal and slope compensation signal reaches the output voltage leve l of the error amplifier, the main power switch is turned off and the synchronous power switch is turned on for a constant off time. at the end of the constant off time, the next switching cycle is begun. while the input voltage approaches the output voltage, the switching frequency decreases gradually to smoothly transit to 100% duty cycle operation.
AIC2323 11 if input voltage is very close to output voltage, the switching mode goes from pure pwm mode to 100% duty cycle operation. duri ng this transient state mentioned above, large output ripple voltage may appear on output terminal. components selection inductor the inductor selection depends on the current ripple of inductor, the input voltage and the output voltage. ? ? ? ? ? ? ? ? ? ?? ? in out l osc out v v 1 if2 v l accepting a large current ripple of inductor allows the use of a smaller inductance. however, higher current ripple of inductor can cause higher output ripple voltage and large core loss. by setting an acceptable current ripple of inductor, a suitable inductance can be obtained from above equation. in addition, it is important to ensure the inductor saturation current exceeds the peak value of inductor current in application to prevent core saturation. the peak value of inductor current can be calculated according to the following equation. ?? ? ? ? ? ? ? ? ? ? ?? ?? in out osc out maxout peak v v 1 lf2 v ii input capacitor and output capacitor to prevent the high input voltage ripple and noise resulted from high frequency switching, the use of low esr ceramic capacitor for the maximum rms current is recommended. the approximated rms current of the input capacitor can be calculated according to the following equation . ?? 12 i v vvv ii 2 l 2 in out inout 2 )max(out cinrms ? ? ? ? ? the selection of output capacitor depends on the required output voltage ripple. the output voltage ripple can be expressed as: l out osc l out iesr cf8 i v ??? ?? ? ?? for lower output voltage ripple, the use of low esr ceramic capacitor is recommended. the tantalum capacitor can also be used well, but its ers is larger than that of ceramic capacitor. when choosing the input and output ceramic capacitors, x5r and x7r types are recommended because they retain their capacitance over wider ranges of voltage and temperature than other types. output voltage programming by connecting a resistive divider r 2 and r 3, the output voltage of AIC2323 step-down converter can be set. v out can be calculated as: ? ? ? ? ? ? ? ? ??? 3 2 out r r 18.0v the resistive divider should sit as close to vfb pin as possible. layout consideration in order to ensure a proper operation of AIC2323, the following points should be managed comprehensively. 1. the input capacitor and v in should be placed as close as possible to each other to reduce the input voltage ripple and noise. 2. the output loop, which is consisted of the inductor, the internal main power switch, the internal synchronous power switch and the output capaci- tor, should be kept as small as possible. 3. the routes with large current should be kept short and wide. 4. logically the large current on the converter should flow at the same direction. 5. the vfb pin should be connected to the feedback resistors directly and the route should be away from the noise sources.
AIC2323 12 ? physical dimensions (unit: mm) ? sop-8 exposed pad (heat sink) note : 1. refer to jedec ms-012e. 2. dimension "d" does not include mold flash, protru sions or gate burrs. mold flash, protrusion or gate bu rrs shall not exceed 6 mil per side . 3. dimension "e" does no t include inter-lead flash o r protrusions. 4. controlling dimension is millimeter, converted in ch dimensions are not necessarily exact. a d ? l view b 0.25 seating plane section a-a base metal gauge plane with plating a1 b c e aa h e d1 e1 exposed thermal pad(heat sink) (bottom center of package) h x 45 see view b
AIC2323 13 ? dfn-10l-3x3 package note : information provided by aic is believed to be accurate and reliabl e. however, we cannot assume responsibility for use of any ci rcuitry other than circuitry entirely embodied in an aic product; nor for any infringement of patents or other rights of third parties that may re sult from its use. we reserve the right to change the circuitr y and specifications without notice. life support policy: aic does not authorize any aic product for us e in life support devices and/or systems. life support device s or systems are devices or systems which, (i) are intended for surgical implant into the body or (ii) support or sustain life, and whose failur e to perform, when properly used in accordance with instructi ons for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 10 pin#1 d 6 e2 e 5 1 b a3 a seating plane l d2 e millimeters min. s y m b o l a3 a0.70 max. 0.20 bsc 0.80 dfn 10l-3x3x0.75-0.5mm e e l e2 0.30 1.40 d2 d b 2.20 0.18 2.90 3.10 0.5 bsc 0.50 1.80 2.90 3.1 0 2.70 0.30 note : 1. dimension and tolerancing conform to asme y14.5m-1994 . 2.controlling dimensionsmillimeterconverted inch dimension are not necessarily exact.

▲Up To Search▲

Price & Availability of AIC2323

	To Download AIC2323 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .