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at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 1 features ? 95% efficient possible dc/dc converter ? bulit-in led driver and open led overvoltage protection ? transformerless inverting controller for ccd bias ? 2 channel built-in mosfet current- mode pwm and 4 channel extra pwm controllers (ch-3 synchronous output) ? up to 1mhz operating frequency ? shutdown current <1ua ? built-in soft-start function built-in short-circuit protection function ? qfn48 package applications ? dsc power supply general description the at1397a/b provide a complete power supply solution for digital cameras. they improve performance, component count, and size compared to other multi-channel controllers in 1-cell li-ion designs. on-chip mosfets provide up to 92~95% efficiency for critical power supplies, while additional channels operate with external fets for optimum design flexibility. all channels dc/dc operate at one fixed frequency settable from 100khz to 1mhz to optimize size, cost, and efficiency. pin assignment at1397 11 10 9 8 7 6 5 4 3 2 1 34 35 36 37 38 39 40 41 42 43 44 21 20 19 18 17 16 15 14 13 12 22 23 24 25 26 27 28 29 30 31 32 33 45 46 47 48 ch1 synchronous rectified current mode step-down on-chip mosfet ch1 synchronous rectified current mode step-down on-chip mosfet ch2 synchronous rectified current mode step-down on-chip mosfet ch2 synchronous rectified current mode step-down on-chip mosfet ch3 synchronous rectified voltage mode step-down ch3 synchronous rectified voltage mode step-down ch4 seletable voltage mode step-up/down/inverting ch4 seletable voltage mode step-up/down/inverting ch5 voltage mode pwm led driver ch5 voltage mode pwm step-up ch6 voltage mode step-up ch6 voltage mode step-up AT1397AN at1397bn ordering information part number package marking at1397 n qfn48,green a:1397an b:1397bn date code * for more marking information, contac t our sales representative directly. aimtron reserves the right without notice to change this circuitry and specifications.
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 2 block diagram ramp1 0.8v fb1 ctl3 - + - + comp1 ss1 ctl1 pvcc1 lx1 pgnd1 ramp2 0.8v fb2 step- down pre- driver current sense - + - + comp2 ss2 pvcc2 lx2 pgnd2 power good /sdok osc1 0.8v fb3 step- down pre- driver - + + - comp3 ss3 pvcc3 out3s out3m pgnd3 osc2 in4 step- up/ down pre- driver - + + - ss4 pvcc4 out4 sel4 comp4 ip4 ctl4 *selectable p-ch or n-ch driver for step-down/up/ inverting converter osc1 fb5 step- up pre- driver - + + - ss5 out5 ctl5 comp5 vref fb5h + - 1v ovp osc2 fb6 step- up pre- driver - + + - ss6 out6 0.8v comp6 ctl6 short-circuit protection cscp scp3 scp4 scp5 scp6 ovp vrgen vbgen ldo 2.3v osc ctlu ramp gen ct vbg 2v 1.22v vreg vcc gnd ctl2 *metal option led driver (vref=0.2v) or step-up(vref=0.8v) ramp2 ramp1 osc2 osc1 - - + + + + step- down pre- driver current sense ss1ok ss1ok ss1ok ss1ok ss1ok ss1ok uvlo 0.8v
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 3 pin description symbol pin no. descript ss1 1 ch1 soft-start input ctl5 2 ch5 enable input ctl6 3 ch6 enable input lx1 4 ch1 converter switching node ctl1 5 ch1 enable and chip enable input pgnd1 6 power ground pgnd2 7 power ground ctl2 8 ch2 enable input lx2 9 ch2 converter switching node ctl3 10 ch3 enable input ctl4 11 ch4 enable input ss2 12 ch2 soft-start input /sdok 13 open-drain, active low, power good for ch2 cscp 14 short circuit protection input pvcc2 15 ch2 converter input comp2 16 ch2 controller compensation node fb2 17 ch2 converter feedback input ss3 18 ch3 soft-start input comp3 19 ch3 compensation node fb3 20 ch3 feedback input ss4 21 ch4 soft-start input comp4 22 ch4 compensation node in4 23 ch4 negative feedback input ip4 24 ch4 positive feedback input pvcc3 25 ch3 power input out3m 26 ch3 master output driver out3s 27 ch3 slave output driver pgnd3 28 power ground out4 29 ch4 output driver out5 30 ch5 output driver out6 31 ch6 output driver pvcc4 32 ch4, ch5 and ch6 power input gnd 33 power ground fb5h 34 ch5 controller over voltage protection input fb5 35 ch5 controller voltage feedback/current feedback comp5 36 ch5 compensation node vbg 37 reference bypass ss5 38 ch5 soft-start input fb6 39 ch6 feedback input comp6 40 ch6 compensation node ct 41 oscillator control vreg 42 reference output fb1 43 ch1 converter feedback input comp1 44 ch1 controller compensation node vcc 45 ic power input pvcc1 46 ch1 converter input ss6 47 ch6 soft-start input sel4 48 configures the ch4 as a step-up or step-down
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 4 absolute maximum ratings * 1 rated value parameter symbol min. max. units storage temperature t stg -55 150 operating temperature t a t opr -35 85 pvcc1,pvcc2,pvcc3,pvcc4 input voltage - -0.3 6.0 v lx1,lx2, out3m,out3s input voltage v lx/out -0.3 6.0 v other input pin - -0.3 6.0 v lx1, lx2 current - - 2.25 a out3m,out3s current - - 200 ma hbm - 2 kv esd susceptibility*2 mm - 200 v power consumption pd - 1000 mw 1. stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability . 2. device are esd sensitive. handling precaution recommended. the human body model is a 100pf capacitor discharged through a 1.5k ? resistor into each pin. recommended operating conditions (ta=+25 0 c) value parameter symbol min typ max unit startup power supply voltage vcc 2.5 -- 5.5 v power supply voltage pvcc 2.5 -- 5.5 v feedback input voltage v in 0 -- vcc-2 v control input voltage v ctl 0 -- vcc v soft start capacitor c ss -- 0.1 1.0 f short circuit protection capacitor c scp -- 0.1 1.0 f vreg pin capacitor c vreg 0.082 0.1 -- f operating ambient temperature* t a -20 25 85 * using x5r or x7r input capacitors.
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 5 electrical characteristics (pvcc1=pvcc2=pvcc3=pvcc4=vcc=3.6v, ta=+25 0 c) values parameter symbol condition min. typ. max. unit general input voltage range vcc ic power input 2.5 - 5.5 v vcc under voltage lockout v uv - 2.35 2.4 2.45 v uvlo hysteresis v hy - - 100 - mv ch1,ch2 switch- off input current i in1 no switching, fb1=fb2=0.9v ctl1=ctl2=3.6v, other disable - 1.1 1.2 ma ch1,ch2, ch3(or 4,5,6) switch- off input current i in2 no switching, fb1=fb2=fb3=0.9v ctl1=ctl2=ctl3=3.6v, other disable - 1.3 1.4 ma shutdown current i cc all ctl disable, vcc=3.6v - 1 10 a reference reference output voltage v reg i reg =1ma 2.25 2.30 2.35 v reference load regulation ? v reg1 1ma< i reg <5ma - 5 10 mv reference line regulation ? v reg2 2.5 at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 6 lx leakage current i lx1/2 v lx1/2 =0~3.6v - 1 5 a r n n-channel - 200 250 m ? switch on-resistance r p p-channel - 250 300 m ? p-channel current limit i limit2 - 1.0 1.2 1.4 a n-channel turn-off current i rev2 - - 20 - ma /sdok output low voltage v sdok 0.1ma into /sdok - 0.01 0.1 v /sdok leakage current i l_sdok ctl2=0v, /sdok=5.5v - 0.1 1 a channel 3 input voltage range pvcc3 - 2.5 - 5.5 v normal operating soft-start charge current i ss3 v cc =2.5v~5.5v 0.7 1 1.3 a fb3 input current i fb3 fb3=0.8v - - 100 na fb3 regulation voltage v fb3 t a =-20 c ~+85 c, fb3=comp3 0.784 0.8 0.816 v error amplifier voltage gain av dc 80 - - db error amplifier frequency bandwidth bw av=0db - 5 - mhz v oh - - 1.0 - v error amplifier output voltage v ol - - 10 - mv i source comp=0.8v - 1 - ma error amplifier output source/sink current i sink comp=0.8v - 60 - a maximum duty cycle d max fb3=0.7v - 100 - % i source duty=90%,out=1/2vc c - -130 -80 ma output source/sink current i sink duty=0%,out=1/2vcc 65 100 - ma r oh out=-15ma - 18 30 ? output on-resistor r ol out=15ma - 16 25 ? channel 4, 5, 6 input voltage range pvcc4 ch4, 5, 6 2.5 - 5.5 v normal operating soft-start charge current i ss4/5/6 v cc =2.5v~5.5v 0.7 1 1.3 a fb4/5/6 regulation voltage v fb4/5/6 t a =-20 c ~+85 c, fb_=comp_ 0.784 0.8 0.816 v fb5 regulation voltage for led driver v fb5 t a =-20 c ~+85 c, fb5=comp5 0.19 0.20 0.21 v
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 7 fb5h ovp trip level v fb5h t a =-20 c ~+85 c, 0.98 1.00 1.02 v error amplifier voltage gain av dc 80 - - db error amplifier frequency bandwidth bw av=0db - 5 - mhz v oh - - 1.0 - v error amplifier output voltage v ol - - 10 - mv i source comp=0.8v - 1 - ma error amplifier output source/sink current i sink comp=0.8v - 60 - a d max fb_=0.7v 85 90 95 % maximum duty cycle d max fb5=0.1v 85 90 95 % i source duty=90%,out=1/2vc c - -130 -80 ma output source/sink current i sink duty=0%,out=1/2vcc 65 100 - ma r oh out=-15ma - 18 30 ? output on-resistor r ol out=15ma - 16 25 ? short circuit protection threshold voltage v th ch3,ch4,ch5,ch6 - 0.9 - v v cscp detect voltage v th ch3,ch4,ch5,ch6 - 0.7 - v cscp charge current i cscp ch3,ch4,ch5,ch6 0.7 1 1.3 a control block v ih active mode 1.5 - vcc v ctl input voltage v il standby mode 0 - 0.5 v ctl hysteresis v h - - 100 - mv v ih step-up type 1.5 - vcc v sel4 input voltage v il step-down type 0 - 0.5 v sel4 hysteresis v h - - 100 - mv
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 8 typical characteristics ch1,2 efficiency vs. load current 50 60 70 80 90 100 10 100 1000 load current(ma) efficiency(%) vbat=4.2v vbat=3.8v vbat=3.6v vbat=3.3v vbat=3.0v vbat=2.5v ch1,2 efficiency vs. load current 50 60 70 80 90 100 10 100 1000 load current(ma) efficiency(%) vbat=4.2v vbat=3.8v vbat=3.6v ch3 efficiency vs. load current 50 60 70 80 90 100 10 100 1000 load curre nt(ma) efficiency(%) vbat=4.2v vbat=3.8v vbat=3.6v vbat=3.3v ch4,5,6 efficiency vs. load current 50 60 70 80 90 100 10 100 1000 load curre nt(ma) efficiency(%) vbat=4.2v vbat=3.8v vbat=3.6v vbat=3.3v vbat=3.0v vbat=2.5v ch4,5,6 efficiency vs. load current 0 10 20 30 40 50 60 70 80 90 100 110100 load current(ma) efficiency(%) vbat=4.2v vbat=3.8v vbat=3.6v vbat=3.3v vbat=3.0v vbat=2.5v ch4 efficiency vs. load current 0 10 20 30 40 50 60 70 80 90 100 110100 load current(ma) efficiency(%) vbat=4.2v vbat=3.8v vbat=3.6v vbat=3.3v vbat=3.0v vbat=2.5v vout =1.8v vo u t =3 . 3 v vout =3.0v vo u t =5 . 0 v vout=15v vout =-7.5v
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 9 typical characteri stics (continued ) efficiency vs. input voltage 80 85 90 95 100 2.53.03.54.04.5 input voltage-vin (v) efficiency(%) no-load input current vs. input voltage 0.6 0.8 1.0 1.2 1.4 1.6 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 input voltage-vin (v) input current(ma) ch1 ch1+ch2 reference voltage vs. temperature 2.275 2.280 2.285 2.290 2.295 2.300 2.305 -20 0 20 40 60 80 100 temperature reference voltage(v) switching frequency vs. temperature 460 470 480 490 500 510 520 -20 0 20 40 60 80 100 temperature switching frequency(khz) maximum duty vs. temperature 87 88 89 90 91 92 93 94 95 96 -20 0 20 40 60 80 100 tempe rature maximum duty(% ) p-mos n-mos fb regulation voltage vs. temperature 0.785 0.790 0.795 0.800 0.805 -20 0 20 40 60 80 100 te mpe rature fb regulation voltage(v ) vout1,2=1.8v iout1,2=300ma vout4=5.0v iout4=50ma vout1,2=3.3v iout1,2=300ma vout3=3.0v iout3=300ma
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 10 typical characteri stics (continued ) vbat=3.8v ch1 ctl1 ch2 vout1 ch3 iout1 ch4 iin vbat=4.2v ch1 ctl ch2 vout1 ch3 vout2 ch4 vout3 vbat=3.8v ch2 vout2 ch3 iout2 vbat=3.8v ch1 ctl2 ch2 vout2 ch3 iout2 ch4 iin vbat=3.8v ch2 vout1 ch3 iout1 vbat=3.8v ch2 vout3 ch3 iout3
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 11 typical application circuits out5 ss6 fb6 out6 pgnd3 pvcc4 pvcc4 vbat 1-cell li-ion 3.4v~4.2v fb5h fb5 ss5 led+ 2~4cell 20ma vbat out4 ip4 ss4 vreg pvcc3 vbat fb3 ss3 sel4 pgnd1 lx1 pvcc1 fb1 ss1 pvcc4 pgnd2 lx2 pvcc2 fb2 ss2 vdsp_core +1v8/200ma vbg vcc gnd comp1 comp2 ct ctl1 ctl3 ctl4 ctl5 ctl6 /sdok out3m out3s ch6 voltage-mode step-up pwm ch4 voltage-mode inverting pwm in4 ch5 voltage-mode pwm led driver ch3 voltage-mode synchronous step-down pvcc4 ch1 current-mode synchronous step-down pwm ch2 current-mode synchronous step-down pwm cscp comp6 comp5 comp4 comp3 vbat vdsp_io +3v3/200ma ccd bias -6v3/50ma short-circuit protection power on lens on ccd on led on at1397a 6.8uh vbat 1uf 0.1uf 22uf 10uf 125k 100k 1uf 0.1uf 6.8uh 100k 312.5k 22uf 0.1uf mbr140ws 10uh 0.1uf 0.1uf 10k 100k 275k 10uf 1uf upm2032bn upm2031an 22uf 0.1uf 10k 0.1uf 10k 140k 10uf mbr140ws upm2031an 10uf 10uh upm2031an mbr140ws 1k 0.1uf 10r 1uf 10k 150k 0.22uf 1uf 0.22uf 10k 0.1uf 10uf /6v3 mbr140ws 10uh upm2032bn 10uf led- 10k 10k 10k 64.9k 1500pf 51k 51k 1500pf 82pf ctl2 0.47uf 10k vbat 10uf mbr140ws mbr140ws vlens +3v/300ma 10uh 10uf ccd bias +12v/50ma 33pf 33pf pvcc3 1-li battery application 1
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 12 typical application circuits ( continued ) out5 ss6 fb6 out6 pgnd3 pvcc4 pvcc4 vbat 1-cell li-ion 3.4v~4.2v fb5h fb5 ss5 lcd +12v/50ma vbat out4 ip4 ss4 vreg pvcc3 vbat fb3 ss3 sel4 pgnd1 lx1 pvcc1 fb1 ss1 pvcc4 pgnd2 lx2 pvcc2 fb2 ss2 vdsp_core +1v8/200ma vbg vcc gnd comp1 comp2 ct ctl1 ctl3 ctl4 ctl5 ctl6 /sdok out3m out3s ch6 voltage-mode step-up pwm ch4 voltage-mode inverting pwm in4 ch5 voltage-mode step-up pwm ch3 voltage-mode synchronous step-down pvcc4 ch1 current-mode synchronous step-down pwm ch2 current-mode synchronous step-down pwm cscp comp6 comp5 comp4 comp3 vbat vdsp_io +3v3/200ma ccd bias -6v3/50ma short-circuit protection power on lens on ccd on led on at1397b 6.8uh vbat 1uf 0.1uf 22uf 10uf 125k 100k 1uf 0.1uf 6.8uh 100k 312.5k 22uf 0.1uf mbr140ws 10uh 0.1uf 0.1uf 10k 100k 275k 10uf 1uf upm2032bn upm2031an 22uf 0.1uf 10k 0.1uf 10k 140k 10uf mbr140ws upm2031an 10uf 10uh upm2031an mbr140ws 1k 0.1uf 10uf 10k 140k 0.1uf 1uf 0.22uf 10k 0.1uf 10uf /6v3 mbr140ws 10uh upm2032bn 10uf 10k 10k 10k 64.9k 1500pf 51k 51k 1500pf 82pf ctl2 0.47uf vbat 10uf mbr140ws mbr140ws vlens +3v/300ma 10uh 10uf ccd bias +12v/50ma 33pf 33pf pvcc3 1- li battery application 2
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 13 application information the at1397a/b includ 6 channels dc/dc to generate a multip le-output digital camera power-supply system. it include : z step-down dc/dc converter with on-ch ip synchronous mosfets.(ch1, ch2) z main synchronous dc/dc controller for step-down converter.(ch3) z selectable dc/dc controller for boost/fly back/buck/inverting converters.(ch4) z white led driver with open led pr otection or boost controller.(ch5) z boost/flyback controller.(ch6) step-down dc/dc converter (ch1, ch2) the step-down dc/dc is optimized for generating dsp voltage (down to 0.8v) at high efficiency. it runs from the voltage at pvcc1/pvcc2. this pin can be connected directly to the battery if sufficie nt headroom exists to avoid dropout. the ch2 also features an open-drain /sdok out put that goes low when the ch2 is in regulation. /sdok may be used to drive an external p-mosfet that gates 3v power to the lens after the dsp_io voltage is in regulation (figure 1). the r1,r2 and c1 is for mosfet soft-start function to avoid the more inrush current . step-down dc/dc converter (ch3) the ch3 is step-down voltage mode pw m converter. an external mosfet and synchronous rectifier allow conversion effi ciencies as high as 93%. step-down operation can be direct from li-ion cell if the minimum input voltage exceeds the desired output by a pproximately 200mv.
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 14 pgnd3 pvcc3 pgnd1 lx1 pvcc1 fb1 ss1 pgnd2 lx2 pvcc2 fb2 ss2 vdsp_io +3v3 vbg vcc gnd /sdok out3m out3s ch3 voltage-mode synchronous step-down ch1 current-mode synchronous step-down pwm ch2 current-mode synchronous step-down pwm vlens +3v vbat vbat ss3 r1 c1 r2 comp3 fb3 vbat vdsp_core +1v8 vbat comp1 comp2 figure 1. using /sdok to drive external p-mosfet that gates 3v power to lens after 3.3v i/o voltage is in regulation
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 15 auxiliary controller (ch4, ch5, ch6) the three auxiliary controllers operate as fixed-frequency voltage-mode pwm controllers. they use the external mosfet s, so output power is determined by external components. all of auxiliary cont rollers have a guaranteed duty cycle of maximum duty cycle of 85% (boost-type) or 100%(buck/inverting type). in boost designs that employ continuous current (ccm), the maximum duty cycle limits the boost ratio so: with discontinuous inductor current (dcm), no such limit exists for the input/output ratio since the inductor has time to fully di scharge before the next cycle begins. the discontinuous conduction mode boost voltage conversion relationship is given by: where k is defined as: the ch4 is selectable dc/dc controller for drive n-channel mosfets (sel=high) or p-channel mosfets (sel=low). it can be configure as the inverting circuit (figure 2), typically for ccd and lcd bias. this is useful in height-limited designs where transformers may not be desired. the efficiency is more than the charge-pump inversion for some load conditions. the ch5 can be configure as a switching- mode boost current source for white leds, fb5 (0.2v) provides current-sensing feedbac k, while fb5h (1.0v) provides (optional) open-led over-voltage protection (figure 3). if used as a boost converter, fb5h is grounded and fb5 (0.8v) is used as the feedback input. in this case, ch5 behaves exactly like ch4 and ch6. the ch6 can be used for conventional dc/dc boost and flyback designs.(figure 4 ,figure 5 and figure 6) % 85 1 ? out in v v s t r l k = 2 i o v v m = 2 4 1 1 2 k d v v i o + + = ) 1 ( ? = m m k d
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 16 vbat out4 ip4 ss4 vreg sel4 ch4 voltage-mode inverting pwm in4 pvcc4 comp4 -7.5v ccd bias figure 2. regulated ?7.5v negative ccd bias. out5 pvcc4 fb5h fb5 ss5 led+ 2~4cell 20ma ch5 voltage-mode pwm led driver comp5 vbat led- figure 3. led drive with open led over-voltage protection
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 17 ss6 fb6 out6 pvcc4 vbat ch6 voltage-mode step-up pwm comp6 -7.5v 15v figure 4. +15v and ?7.5v ccd bias with transformer ss6 fb6 out6 pvcc4 vbat ch6 voltage-mode step-up pwm comp6 15v -7.5v figure 5. +15v and ?7.5v ccd bias with charge-pump inversion
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 18 ss6 fb6 out6 pvcc4 vbat ch6 voltage-mode step-up pwm comp6 15v - + gnd /shdn out fb 1.24v in at1202 figure 6. +15v and ?7.5v ccd bias with charge-pump (using at1202 to regulated the negative output) soft-start setting (ch1~ch6) the at1397a/b all channels feature a soft-sta rt function that limits inrush current and prevents excessive battery loading at start- up by ramping the output voltage of each channel up to the regulation voltage. however that ch2 to ch6 start until the ch1 reaches regulation. consider the input voltage and load current to design the capacitor connected to the ss pin. it can calculate the ch1~6 soft start time ts(s)(valid threshold 0.3~0.8v interval). note : it could be disabled soft start function by floating ss pin. i t v c = ? ? ) ( 5 . 0 ) ( f c s ts =
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 19 scp protection setting (ch3~ch6) the cscp comparator detects ch3, ch4, ch5 and ch6 output voltage while the power converter work at normal condition. at the same time, the voltage level of cscp pin is held at low level. if th e output load of these converters rapidly malfunction or short, causing the output volta ge to drop, the cscp comparator detects that to enable short circuit protection. the time period when short circuit protection show as follow equation. short detection time (t pe (s)) t pe (s) = 0.9 * c cscp (f) note : it could be disabled short circuit protection func tion by connecting cscp pin into the ground. determine the triangular oscillator frequency the triangular oscillator frequency is determined by the timing capacitor (c t ). it is difficult to incorporate these non-linear characteristics into the equation. this difference is caused by characteristics, such as changes in the maximum voltage amplitude of the sawtooth waveform with th e ct value and the circuit delay causing the maximum amplitude to become large in the case of a high oscillating frequency even for the same capacitor. in practical use, therefore, the user should read the ct values from the characteristic curve or shoul d determine an approximate target value by using the equation. ) ( 41000 ) ( pf c khz f t osc =
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 20 package outline: qfn48
at1397a/b preliminary product information 6-channel dc-dc converter for dsc 7f, no.9, park avenue ii, science-based industrial park, hsinchu 300,taiwan, r.o.c. tel: 886-3-563-0878 fax: 886-3-563-0879 www: http://www.aimtron.com.tw 1/10/2006 rev:1.0 email: service@aimtron.com.tw 21 reflow profiles sn-pb eutectic assembly pb-free assembly profile feature large body pkg. thickness 2.5mm or pkg. volume 350mm 3 small body pkg. thickness <2.5mm or pkg. volume <350mm 3 large body pkg. thickness 2.5mm or pkg. volume 350mm 3 small body pkg. thickness 2.5mm or pkg. volume 350mm 3 average ramp-up rate (t l to t p ) 3 c/second max. 3 c/second max. preheat -temperature min(tsmin) -temperature max (tsmax) -time (min to max)(ts) 100 c 150 c 60-120 seconds 150 c 200 c 60-180 seconds tsmax to t l -ramp-up rate - 3 c/second max. time maintained above: -temperature (t l ) -time (t l ) 183 c 60-150 seconds 217 c 60-150 seconds peak temperature(t p ) 225+0/-5 c 240+0/-5 c 245+0/-5 c 250+0/-5 c time within 5 c of actual peak temperature (t p ) 10-30 seconds 10-30 seconds 10-30 seconds 20-40 seconds ramp-down rate 6 c/second max. 3 c/second max. time 25 c to peak temperature 6 minutes max. 8 minutes max. *all temperatures refer to topside of the package , measured on the package body surface.

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