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1/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. high-performance regulat or ic series for pcs ultra low dropout linear regulators for pc chipsets BD3508MUV, bd3509muv description the BD3508MUV / bd3509muv ultra low-dropout linear chipset regul ator operates from a very low input supply, and offers ideal performance in low input voltage to low output voltage ap plications. it incorporates a built-in n-mosfet power transistor to minimize the input-to-output vo ltage differential to the on resistance (r on max =100m /50m ) level. by lowering the dropout voltage in this way, the regulator r ealizes high current output (i omax=3.0a/4.0a) with reduced conversion loss, and thereby obviates the switching regulator and its power transistor, choke coil, and rectifier diode. thus, the BD3508MUV / bd3509muv are designed to enable signif icant package profile downsizing and cost reduction. an external resistor allows the entire range of output voltage co nfigurations between 0.65 and 2.7v, while the nrcs (soft start) function enables a controlled output vo ltage ramp-up, which can be programmed to whatever power supply sequence is required. features 1) internal high-precision reference voltage circuit (0.65v 1%) 2) built-in vcc under voltage lock out circuit (vcc=3.80v) 3) nrcs (soft start) function reduces the magnitude of in-rush current 4) internal nch mosfet driver offers low on resistance (65m /28m typ) 5) built-in current limit circuit (3.0a/4.0a min) 6) built-in thermal shutdown (tsd) circuit 7) variable output (0.65 2.7v) 8) incorporates high-powe r vqfn020v4040 package: 4.0 4.0 1.0(mm) 9) tracking function applications notebook computers, desktop computer s, lcd-tv, dvd, digital appliances model lineup maximum output current package vcc=5v 3a vqfn020v4040 BD3508MUV 4a bd3509muv no.09030eat22
2/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note absolute maximum ratings (ta=100 ) BD3508MUV / bd3509muv parameter symbol limit unit BD3508MUV bd3509muv input voltage 1 vcc 6.0 * 1 v input voltage 2 vin 6.0 * 1 v input voltage 3 vdd - 6.0* 1 v enable input voltage ven 6.0 v power good input voltage v pgood - 6.0 v power dissipation 1 pd1 0.34 *2 w power dissipation 2 pd2 0.70 *3 w power dissipation 3 pd3 1.21 *4 w power dissipation 4 pd4 3.56 *5 w operating temperature range topr -10 +100 storage temperature range tstg -55 +125 maximum junction temperature tjmax +150 * 1 should not exceed pd. * 2 reduced by 4mw/ for each increase in ta R 25 (no heat sink) * 3 1 layer, mounted on a board 74.2mm 74.2mm 1.6mm glass-epoxy pcb (copper foil area : 10.29mm 2 ) * 4 4 layers, mounted on a board 74.2mm 74.2mm 1.6mm glass-epoxy pcb (copper foil area : 10.29mm 2 ) , copper foil in each layers. * 5 4 layers, mounted on a board 74.2mm 74.2mm 1.6mm glass-epoxy pcb (copper foil area : 5505mm 2 ) , copper foil in each layers. operating conditions(ta=25 ) parameter symbol BD3508MUV bd3509muv unit min max min max input voltage 1 vcc 4.3 5.5 4.3 5.5 v input voltage 2 vin 0.75 vcc-1 * 6 0.7 vcc-1 * 6 v input voltage 3 vdd - - 2.7 5.5 v output voltage setting range vo vfb 2.7 vfb 2.7 v enable input voltage ven -0.3 5.5 -0.3 5.5 v nrcs capacity cnrcs 0.001 1 0.001 1 uf * 6 vcc and vin do not have to be implemented in the order listed. this product is not designed for use in radioactive environments.
3/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note electrical characteristics (unless otherwise specified, ta=25 vcc=5v ven=3v vin=1.8v vdd=3.3v r1=3.9k r2=3.3k ) BD3508MUV parameter symbol limit unit condition min. typ. max. bias current icc - 0.7 1.4 ma vcc shutdown mode current ist - 0 10 ua ven=0v output voltage vo - 1.200 - v maximum output current io 3.0 - - a output short circuit current iost 3.0 - - a vo=0v output voltage temperature coefficient tcvo - 0.01 - %/ feedback voltage 1 vfb1 0.643 0.650 0.657 v feedback voltage 2 vfb2 0.630 0.650 0.670 v io=0 to 3a tj=-10 to 100 * 7 line regulation 1 reg.l1 - 0.1 0.5 %/v vcc=4.3v to 5.5v line regulation 2 reg.l2 - 0.1 0.5 %/v vin=1.2v to 3.3v load regulation reg.l - 0.5 10 mv io=0 to 3a minimum input-output voltage differential dvo - 65 100 mv io=1a,vin=1.2v tj=-10 to 100 * 7 standby discharge current iden 1 - - ma ven=0v, vo=1v [enable] enable pin input voltage high enhi 2 - - v enable pin input voltage low enlow -0.2 - 0.8 v enable input bias current ien - 7 10 ua ven=3v [feedback] feedback pin bias current ifb -100 0 100 na [nrcs] nrcs charge current inrcs 14 20 26 ua vnrcs=0.5v nrcs standby voltage vstb - 0 50 mv ven=0v [uvlo] vcc under voltage lock out threshold voltage vccuvlo 3.5 3.8 4.1 v vcc:sweep-up vcc under voltage lock out hysteresis voltage vcchys 100 160 220 mv vcc:sweep-down [amp] gate source current i gso - 1.6 - ma v fb =0, v gate =2.5v gate sink current i gsi - 4.7 - ma v fb =vcc, v gate =2.5v *7 design guarantee
4/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note electrical characteristics (unless otherwise specified, ta=25 vcc=5v ven=3v vin=1.5v vdd=3.3v r1=3.9k r2=3.6k ) bd3509muv parameter symbol limit unit condition min. typ. max. bias current icc - 1.1 2.0 ma vcc shutdown mode current ist - 0 10 ua ven=0v output voltage vo - 1.25 - v maximum output current io 4.0 - - a output voltage temperature coefficient tcvo - 0.01 - %/ feedback voltage 1 vfb1 0.643 0.650 0.657 v feedback voltage 2 vfb2 0.637 0.650 0.663 v io=0 to 4a tj=-10 to 100 * 7 line regulation 1 reg.l1 - 0.1 0.5 %/v vcc=4.3v to 5.5v line regulation 2 reg.l2 - 0.1 0.5 %/v vin=1.2v to 3.3v load regulation reg.l - 0.5 10 mv io=0 to 4a minimum input-output voltage differential dvo - 28 50 mv io=1a,vin=1.25v tj=-10 to 100 * 7 standby discharge current iden 1 - - ma ven=0v, vo=1v [enable] enable pin input voltage high enhi 2 - - v enable pin input voltage low enlow -0.2 - 0.8 v enable input bias current ien - 7 10 ua ven=3v [feedback] feedback pin bias current ifb -100 0 100 na [nrcs] nrcs charge current inrcs 14 20 26 ua vnrcs=0.5v nrcs standby voltage vstb - 0 50 mv ven=0v [uvlo] vcc under voltage lock out threshold voltage vccuvlo 3.5 3.8 4.1 v vcc:sweep-up vcc under voltage lock out hysteresis voltage vcchys 100 160 220 mv vcc:sweep-down [amp] gate source current i gso - 10 - ma v fb =0, v gate =2.5v gate sink current i gsi - 18 - ma v fb =vcc, v gate =2.5v [pgood block] threshold voltage v thpg - 0.585 - v fb voltage ron r pg - 0.1 - k *7 design guarantee
5/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note reference data BD3508MUV fig.1 transient response (0 3a) co=150 f 2, c fb =0.01uf fig.2 transient response (0 3a) co=150 f fig.4 transient response (3 0a) co=150 2 fig.5 transient response (3 0a) co=150 f fig.6 transient response (3 0a) co=47 3a/3 sec t(5 sec/div) io=0a 3a/3 sec t(5 sec/div) fig.3 transient response (0 3a) co=47 f, c fb =0.01uf 91mv 3a vo 100mv/di v io 2a/di v io=0a 3a/3 sec t(5 sec/div) io=3a 0a/3 sec t(5 sec/div) vo 50mv/di v io 2a/di v 79mv 3.0a io=3a 0a/3 sec t(5 sec/div) vo 100mv/di v io 2a/di v 87mv 3a io=3a 0a/3 sec t(5 sec/div) vcc ven vin vo vcc ven vin vo vcc ven vin vo vcc ven vin vo vcc vin ven vin vcc ven ven vcc vin vcc ven vin fig.7: waveform at output star t fig.8 waveform at output off ven 2v/di v vnrcs 2v/di v vo 1v/di v ven 2v/di v t(200 sec/div) t(2msec/div) vnrcs 2v/di v vo 1v/di v
6/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note reference data 1.15 1.17 1.19 1.21 1.23 1.25 -101030507090 ta( ) vo(v) fig.13 input sequence fig.14 input sequence vcc ven vin vo vcc ven vin vo vin ven vcc ven vin vcc fig.15 tj-vo (io=0ma) fig.16 tj-icc 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 0.95 1.00 -101030507090 ta( ) icc(ma) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 -60 -30 0 30 60 90 120 150 ta( ) icc(ua) fig.17 tj-istb 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 -101030507090 ta( ) iin(ma) fig.18 tj-iin fig.19 tj-iinstb 0 5 10 15 20 25 30 -60 -30 0 30 60 90 120 150 ta( ) iin(ua) 15 16 17 18 19 20 21 22 23 24 25 -101030507090 ta( ) inrcs(ua) fig.20 tj-inrcs -20 -15 -10 -5 0 5 10 15 20 -101030507090 ta( ) ifb(na) fig.21 tj-ifb fig.22 tj-ien 0 1 2 3 4 5 6 7 8 9 10 -101030507090 ta( ) ien(ua) fig.23 tj-ron (vcc=5v/vo=1.2v) fig.24 vcc-ron 100 100 100 100 100 100 25 30 35 40 45 50 55 60 2468 vcc(v) ron(m ) 0 10 20 30 40 50 60 -101030507090 ta( ) ron(m ) 2.5v 100 1.8v 1.2v
7/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note reference data bd3509muv fig.25 transient response (0 4a) co=22 f fig.26 transient response (0 4a) co=100 f fig.28 transient response (4 0a) co=22 f, c fb =0.01 f fig.29 transient response (4 0a) co=100 f fig.30 transient response (4 0a) co=47 f, c fb =0.01 f fig.33 input sequence fig.34 input sequence fig.35 input sequence fig.36 input sequence 39mv vo 50mv/di v io 2a/di v 51mv 4.0a vo 50mv/di v io 2a/di v vo 50mv/di v io 2a/di v 37mv 4.0a io=0a 4a/4 sec t(10 sec/div) io=0a 4a/4 sec t(10 sec/div) fig.27 transient response (0 4a) co=47 f 41mv 4.0a vo 100mv/di v io 2a/di v io=0a 4a/4 sec t(10 sec/div) io=4a 0a/4 sec t(100 sec/div) vo 50mv/di v io 2a/di v 41mv 4.0a io=4a 0a/4 sec t(100 sec/div) vo 50mv/di v io 2a/di v 39mv 4.0a io=4a 0a/4 sec t(100 sec/div) ven vcc vin vo ven vcc vin vo ven vcc vin vo vcc vin ven vin vcc ven ven vcc vin vcc ven vin fig.31: waveform at output start fig.32 waveform at output off t(200 sec/div) t(2msec/div) 4.0a ven 2v/di v vnrcs 1v/di v vo 1v/di v pgood 2v/di v ven 2v/di v vnrcs 1v/di v vo 1v/di v pgood 2v/di v ven vcc vin vo
8/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note reference data fig.37 input sequence fig.38 input sequence ven vcc vin vo vin ven vcc fig.39 tj-vo (io=0ma) fig.40 tj-icc fig.41 tj-istb fig.44 tj-iin fig.45 tj-iinstb fig.46 tj-inrcs fig.47 tj-ifb fig.48 tj-ien -10 -8 -6 -4 -2 0 2 4 6 8 10 -50 -25 0 25 50 75 100 125 150 ta( ) ifb(na) 0 1 2 3 4 5 6 7 8 9 10 -50 -25 0 25 50 75 100 125 150 ta( ) ien(ua) 15 16 17 18 19 20 21 22 23 24 25 -50 -25 0 25 50 75 100 125 150 ta( ) inrcs(ua) 0 0.3 0.6 0.9 1.2 1.5 -50 -25 0 25 50 75 100 125 150 ta( ) icc(ma) 1 1.2 1.4 1.6 1.8 2 -50 -25 0 25 50 75 100 125 150 ta( ) iin(ma) 1.2 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29 1.3 -50 -25 0 25 50 75 100 125 150 ta( ) vo(v) 0 5 10 15 20 25 30 35 40 45 50 -50 -25 0 25 50 75 100 125 150 ta( ) idd(ua) fig.42 tj-idd fig.43 tj-iddstb ven vcc vin vo ven vin vcc 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -50 -25 0 25 50 75 100 125 150 ta( ) istb(ua) 0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 0.1 -50 -25 0 25 50 75 100 125 150 ta( ) iddstb(ua) 0 5 10 15 20 25 30 35 40 45 50 -50 -25 0 25 50 75 100 125 150 ta( ) iin(ua)
9/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note reference data block diagram BD3508MUV bd3509muv fig.49 tj-ron (vcc=5v/vo=1.2v) fig.50 vcc-ron 0 5 10 15 20 25 30 35 40 45 50 -50 -25 0 25 50 75 100 125 150 ta( ) ron(m ) 25 30 35 40 45 50 4 4.3 5 5.5 vcc[v] ron[m ] 2.5v 1.8v 1.25v 1.0v reference block thermal shutdown nrcs current limit cl uvlo tsd en vcc uvlo vcc cl en vcc vcc vin1 vin2 vin3 vo1 vo2 vo3 fb gate gnd nrcs vo vin tsd 7 6 20 12 11 8 9 10 16 17 18 19 reference block thermal shutdown nrcs current limit 7 6 9 10 12 14 15 16 19 11 2 1 20 cl uvlo tsd en vcc uvlo vcc cl en vcc vcc vin1 vin2 vin3 vo1 vo2 vo3 fb gate gnd nrcs vo vin tsd 13 8 vin4 vin5 17 18 vo4 vo5 4 power good pgood vcc 5 vdd
10/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note pin layout pin function table pin no. pin name pin function 1 gnd1 ground pin 1 2 gnd2 ground pin 2 3 n.c. no connection (empty) pin * 4 pgood power good pin 5 vdd power supply pin 6 vcc power supply pin 7 en enable input pin 8 vin1 input pin 1 9 vin2 input pin 2 10 vin3 input pin 3 11 gate gate pin 12 vin4 input pin 4 13 vin5 input pin 5 14 vo1 output voltage pin 1 15 vo2 output voltage pin 2 16 vo3 output voltage pin 3 17 vo4 output voltage pin 4 18 vo5 output voltage pin 5 19 fb reference voltage feedback pin 20 nrcs in-rush current protection (nrcs) capacitor connection pin rever se fin connected to heatsink and gnd pin no. pin name pin function 1 gnd1 ground pin 1 2 gnd2 ground pin 2 3 n.c. no connection (empty) pin * 4 n.c. no connection (empty) pin * 5 n.c. no connection (empty) pin * 6 vcc power supply pin 7 en enable input pin 8 vin1 input pin 1 9 vin2 input pin 2 10 vin3 input pin 3 11 gate gate pin 12 n.c. no connection (empty) pin * 13 n.c. no connection (empty) pin * 14 n.c. no connection (empty) pin * 15 n.c. no connection (empty) pin * 16 vo1 output voltage pin 1 17 vo2 output voltage pin 2 18 vo3 output voltage pin 3 19 fb reference voltage feedback pin 20 nrcs in-rush current protection (nrcs) capacitor connection pin rever se fin connected to heatsink and gnd 16 17 18 19 20 1 2 3 4 5 10 9 8 7 6 15 14 13 12 11 vo2 vo1 vin5 vin4 gate vdd pgood n.c gnd2 gnd1 vin3 vin2 vin1 en vcc vo3 vo4 vo5 fb nrcs fin 16 17 18 19 20 1 2 3 4 5 10 9 8 7 6 15 14 13 12 11 n.c n.c n.c n.c gate n.c n.c n.c gnd2 gnd1 vin3 vin2 vin1 en vcc vo1 vo2 vo3 fb nrcs fin BD3508MUV bd3509muv BD3508MUV bd3509muv * please short n.c to the gnd * please short n.c to the gnd
11/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note operation of each block ? amp this is an error amp that functions by comparing the refere nce voltage (0.65v) with vo to drive the output nch fet (ron=50m ). frequency optimization helps to rea lize rapid transit response, and to support the use of functional polymer output capacitors. amp input voltage ranges from gnd to 2.7v , while the amp output ranges from gnd to vcc. when en is off, or when uvlo is active, output goes low and the output nchfet switches off. ? en the en block controls the regulator on/off pin by means of the logic input pin. in off position, circuit voltage is maintained at 0 a, thus minimizing current consum ption at standby. the fet is switched on to enable discharge of the nrcs pin vo, thereby draining the excess charge and preventing the load ic from malfunctioning. since no electrical connection is required (such as between the vcc pin and the esd prevention di), module oper ation is independent of the input sequence. ? uvlo to prevent malfunctions that can occur when there is a momentary decrease in vcc supply voltage, the uvlo circuit switches output off, and, like the en block, discharges the nrcs vo. once the uvlo threshold voltage (typ3.80v) is exceeded, the power-on reset is triggered and output begins. ? current limit with output on, the current lim it function monitors internal ic output curr ent against the parameter value. when current exceeds this level, the current limit module lowers the output current to protect the load ic. when the overcurrent state is eliminated, output voltage is re stored at the parameter value. ? nrcs the soft start function is realized by connecting an nrcs pin external capacitor to the target ground. output ramp-up can be set for any period up to the time the nrcs pin reaches vf b (0.65v). during startup, the nrcs pin serves as the 20 a (typ) constant current source and charges the externally connected capacitor. ? tsd (thermal shut down) the shutdown (tsd) circuit automatically switches output off when the chip tem perature gets too high, thus serving to protect the ic against ?thermal runaway? and heat damage. because the tsd circuit is provided to shut down the ic in the presence of extreme heat, in order to avoi d potential problems with the tsd, it is cr ucial that the tj (max) parameter not be exceeded in the thermal design. ? vin the vin line is the major current supply line, and is connected to the output nchfet drain. since no electrical connection (such as between the vcc pin and an esd protective di) is necessary, vin operates indepen dent of the input sequence. however, since there is an output nchfet body di between vin and vo, a vin-vo elec tric (di) connection is present. note, therefore, that when output is switched on or of f, reverse current may flow to the vin from vo. ? pgood (bd3509muv) this is the monitor pin for output voltage (vo). it is used through the pull-up resistance (100k ). pgood pin judges the voltage high or low (fb voltage 0.585v typ. : threshold voltage).
12/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note timing chart vcc on/off 0.65v(typ) vin vcc en nrcs vo t start up 0.65v(typ) vo 0.9v(typ) 80 s(typ) pgood (bd3509muv) vin vcc en nrcs vo t hysteresis uvlo start up 0.65v(typ) vo 0.9v(typ) 80 s(typ) pgood (bd3509muv)
13/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note evaluation board component rating manufacturer product name component rating manufacturer product name u1 - rohm bd3509muv r4 100k rohm mcr03ezpf1003 c5 0.1uf murata grm155f11e104zd r7 0 - jumper c6 1uf murata grm188b11a105kd r8 3.6k rohm mcr03ezpf3601 c8 10uf murata grm21bb10j106kd r9 3.9k rohm mcr03ezpf3901 c16 22uf kyocera cm316w5r226k06at jp13 0 - jumper c20 0.01uf murata grm188b11h103kd jp14 0 - jumper bd3509muv evaluation board schematic bd3509muv evaluation board standard component list
14/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note recommended circuit example silk screen (bottom) bottom layer silk screen (top) middle layer_1 middle layer_2 top layer c16 c20 r19 r18 vo (1.25v/4a) 16 17 18 19 20 1 2 3 4 5 15 14 13 12 11 10 9 8 7 6 c8 vin c6 vcc ven r4 vpgood vdd c5 c18 bd3509muv evaluation board layout
15/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note component recommended value programming notes and precautions r1/r2 3.6k/3.9k ic output voltage can be set with a conf iguration formula using the values for the internal reference output voltage (v fb ) and the output voltage resistors (r1, r2). select resistance values that will avoid the impact of the v fb current ( 100na). the recommended total resistance value is 10k . r4 100k this is the pull-up resistance for open dr ain pin. it is recommended to set the value about 100k . c16 22uf to assure output voltage stability, please be certain the vo1, vo2, and vo3 pins and the gnd pins are connected. output capacitors play a role in loop gain phase compensation and in mitigating output fluctuation during rapid changes in load level. insufficient capacitance may cause oscillation, while high equivalent seri es reisistance (esr) will exacerbate output voltage fluctuation under rapid load change conditions. while a 47 f ceramic capacitor is recomended, actual stability is highly depen dent on temperature and load conditions. also, note that connecting different types of capacitors in series may result in insufficient total phase compensation, thus causing oscillation. in light of this information, please confirm operation across a variety of temperature and load conditions. c6 1uf the input capacitor reduces the output impe dence of the voltage supply source connected to the vcc. when the output impedence of this power supply increases, the input voltage (vcc) may become unstable. this may result in the output voltage oscillation or lowering ripple rejection. a low esr 1uf capacitor wi th minimal susceptibility to temperature is preferable, but stability depends on power supp ly characteristics and the substrate wiring pattern. please confirm operation across a va riety of temperature and load conditions . c8 10uf input capacitors reduce the output impedance of the voltage supply source connected to the (vin) input pins. if the impedance of this power supply were to increase, input voltage (vin) could become unstable, leading to oscillation or lowered ripple rejection function. while a low-esr 10uf capacitor with minimal susceptibility to temperature is recommended, stability is highly dependent on the input power suppl y characteristics and the substrate wiring pattern. in light of this information, please co nfirm operation across a variety of temperature and load conditions. c5 0.1uf input capacitors reduce the output impedance of the voltage supply source connected to the (vdd) input pins. if the impedance of this powe r supply were to increase, input voltage (vdd) could become unstable, leading to oscillation or lowered ripple rejection function. while a low-esr 0.1uf capacitor with minimal susceptib ility to temperature is recommended, stability is highly dependent on the input power suppl y characteristics and the substrate wiring pattern. in light of this information, please co nfirm operation across a variety of temperature and load conditions. c20 0.01uf the non rush current on startup (nrcs) functi on is built into the ic to prevent rush current from going through the load (vin to vo) and im pacting output capacitors at power supply start-up. constant current comes from the nrcs pin when en is high or the uvlo function is deactivated. the temporary reference voltage is proportionate to time, due to the current charge of the nrcs pin capacitor, and output voltage start-up is proportionate to this reference voltage. capacitors with low susceptibility to temperature are recommended, in order to assure a stable soft-start time. c18 0.01uf this component is employed when the c16 capacitor causes, or may cause, oscillation. it provides more precise internal phase correction.
16/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note heat loss thermal design should allow operation within the following cond itions. note that the temper atures listed are the allowed temperature limits, and thermal design should allow sufficient margin from the limits. 1. ambient temperature ta can be no higher than 100 . 2. chip junction temperature (tj) can be no higher than 150 . chip junction temperature can be determined as follows: it is recommended to layout the via for heat radiation in the g nd pattern of reverse (of ic) when there is the gnd pattern in the inner layer (in using multiplayer substrat e). this package is so small (size: 4.2mm 4.2mm) that it is not available to layout the via in the bottom of ic. sp reading the pattern and being increased the number of via like the figure below). enable to get the superior heat radiation characteristic. (thi s figure is the image. it is reco mmended that the via size and th e number is designed suitable fo r the actual situation.). most of the heat loss that occurs in t he bd3509muv is generated from the output nch fet. power loss is determined by the total vin-vo voltage and output current. be sure to conf irm the system input and output voltage and the output current conditions in relation to the heat dissip ation characteristics of t he vin and vo in the design. bearing in mind that heat dissipation may vary substantially depending on the substrate employed (due to the power package incorporated in the bd3509muv) make certain to factor conditions such as substrate size into the thermal design. power consumption (w) = input voltage (vin)- output voltage (vo) io (ave) example) vin=1.5v, vo=1.25v, io(ave) = 4a power consumption (w) = 1.5(v)-1.2(v) 4.0(a) = 1.0(w) calculation based on ambient temperature (ta) tj=ta+ j-a w bare (unmounted) ic 4-layer substrate (bottom layer surface copper foil area 10.29mm 2 ) 4-layer substrate (bottom layer surface copper foil area 10.29mm 2 ) 4-layer substrate (top layer copper foil area 5505mm 2 ) substrate size: 74.2 74.2 1.6mm 3 (substrate with thermal via) j-a: vqfn020v4040 367.6 /w 178.6 /w 103.3 /w 35.1 /w reference values
17/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note input-output equival ent circuit diagram vcc vo1 vo2 50k 1k 1k 350k 10k en nrcs vcc 1k 10k 1k 1k 1k 1k vcc 10k 1k vcc fb 1k 100k 100k 20pf vo3 vin1 vin2 vin3 gate vcc vin4 vin5 vo4 vo5 pgood
18/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note operation notes 1. absolute maximum ratings an excess in the absolute maximum ratings, such as supply voltage, temperature range of operating conditions, etc., can break down the devices, thus making impossible to identify br eaking mode, such as a short circuit or an open circuit. if any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices, such as fuses. 2. connecting the power supply connector backward connecting of the power supply in reverse polarity can dam age ic. take precautions when connecting the power supply lines. an external direction diode can be added. 3. output pin in the event that load containing a la rge inductance component is connected to the output terminal, and generation of back-emf at the start-up and when output is turned off is a ssumed, it is requested to insert a protection diode. 4. gnd voltage the potential of gnd pin must be minimu m potential in all operating conditions. 5. thermal design use a thermal design that allows for a sufficient margin in light of the power dissipation (pd) in actual operating conditions. 6. inter-pin shorts and mounting errors use caution when positioning the ic for mounting on print ed circuit boards. the ic may be damaged if there is any connection error or if pins are shorted together. 7. actions in strong electromagnetic field use caution when using the ic in the pr esence of a strong electromagnetic fiel d as doing so may cause the ic to malfunction. 8. aso when using the ic, set the output transistor so that it does not exceed absolute maximum ratings or aso. 9. thermal shutdown circuit the ic incorporates a built-in thermal shutdown circuit (tsd ci rcuit). the thermal shutdown circuit (tsd circuit) is designed only to shut the ic off to prevent thermal runaway. it is not designed to protect the ic or guarantee its operation. do not continue to use the ic after operating this circuit or use the ic in an environment where the operation of this circuit is assumed. tsd on temperature [c] (typ.) hy steresis temperature [c] (typ.) BD3508MUV / bd3509muv 175 15 10. testing on application boards when testing the ic on an application board, connecting a capaci tor to a pin with low impedance subjects the ic to stress. always discharge capacitors after each process or step. always turn the ic's power supply off before connecting it to or removing it from a jig or fixture during the inspection proc ess. ground the ic during assembly steps as an antistatic measure. use similar precaution wh en transporting or storing the ic. output pin (example)
19/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note 11. regarding input pin of the ic this monolithic ic contains p+ isolation and p substrate layers between adjacent el ements in order to keep them isolated. p-n junctions are formed at the intersection of these p layers with the n layers of other elements, creating a parasitic diode or transistor. for example, the relation between each potential is as follows: when gnd > pin a and gnd > pin b, the p-n j unction operates as a parasitic diode. when gnd > pin b, the p-n junction operates as a parasitic transistor. parasitic diodes can occur inevitable in the structure of the ic. the operation of parasitic diodes can result in mutual interference among circuits, operational faults, or physical dama ge. accordingly, methods by which parasitic diodes operate, such as applying a voltage that is lower than the gnd (p substrate) voltage to an input pin, should not be used. 12. ground wiring pattern when using both small signal and large current gnd patterns, it is recommended to isolate the two ground patterns, placing a single ground point at the ground pot ential of application so that the pattern wiring resistance and voltage variations caused by large currents do not cause variations in the sma ll signal ground voltage. be careful not to change the gnd wiring pattern of any external components, either. heat dissipation characteristics resistor transistor (npn) n n n p + p + p p substrate gnd parasitic element pin a n n p + p + p p substrate gnd parasitic element pin b c b e n gnd pin a p aras iti c element pin b other adjacent elements e b c gnd p aras iti c element power dissipation:pd [w] ambient temperature:ta [ ] 0 25 50 75 100 125 150 0 2.0 3.0 4.0 3.56w 1.0 0.70w 4 layers (copper foil area : 5505mm 2 ) copper foil in each layers. j-a=35.1 /w 4 layers (copper foil area : 10.29m 2 ) copper foil in each layers. j-a=103.3 /w 4 layers (copper foil area : 10.29m 2 ) j-a=178.6 /w ic only. 105
20/20 www.rohm.com 2009.05 - rev. a c 2009 rohm co., ltd. all rights reserved. BD3508MUV, bd3509muv technical note ? ordering part number b d 3 5 0 8 m u v - e 2 part no. part no. 3508 3509 package muv: vqfn020v4040 packaging and forming specification e2: embossed tape and reel (unit : mm) vqfn020v4040 2.1 0.1 1 15 11 20 16 5 10 6 1.0 0.5 0.25 +0.05 ?0.04 2.1 0.1 0.4 0.1 c0.2 1.0max 0.02 +0.03 ?0.02 (0.22) 4.0 0.1 4.0 0.1 1pin mark 0.08 s s ? order quantity needs to be multiple of the minimum quantity. embossed carrier tape tape quantity direction of feed the direction is the 1pin of product is at the upper left when you hold reel on the left hand and you pull out the tape on the right hand 2500pcs e2 () direction of feed reel 1pin
r0039 a www.rohm.com ? 2009 rohm co., ltd. all rights reserved. notice rohm customer support system http://www.rohm.com/contact/ thank you for your accessing to rohm product informations. more detail product informations and catalogs are available, please contact us. notes no copying or reproduction of this document, in part or in whole, is permitted without the consent of rohm co.,ltd. the content specified herein is subject to change for improvement without notice. the content specified herein is for the purpose of introducing rohm's products (hereinafter "products"). if you wish to use any such product, please be sure to refer to the specifications, which can be obtained from rohm upon request. examples of application circuits, circuit constants and any other information contained herein illustrate the standard usage and operations of the products. the peripheral conditions must be taken into account when designing circuits for mass production. great care was taken in ensuring the accuracy of the information specified in this document. however, should you incur any damage arising from any inaccuracy or misprint of such information, rohm shall bear no responsibility for such damage. the technical information specified herein is intended only to show the typical functions of and examples of application circuits for the products. rohm does not grant you, explicitly or implicitly, any license to use or exercise intellectual property or other rights held by rohm and other parties. rohm shall bear no responsibility whatsoever for any dispute arising from the use of such technical information. the products specified in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, office-automation equipment, commu- nication devices, electronic appliances and amusement devices). the products specified in this document are not designed to be radiation tolerant. while rohm always makes efforts to enhance the quality and reliability of its products, a product may fail or malfunction for a variety of reasons. please be sure to implement in your equipment using the products safety measures to guard against the possibility of physical injury, fire or any other damage caused in the event of the failure of any product, such as derating, redundancy, fire control and fail-safe designs. rohm shall bear no responsibility whatsoever for your use of any product outside of the prescribed scope or not in accordance with the instruction manual. the products are not designed or manufactured to be used with any equipment, device or system which requires an extremely high level of reliability the failure or malfunction of which may result in a direct threat to human life or create a risk of human injury (such as a medical instrument, transportation equipment, aerospace machinery, nuclear-reactor controller, fuel-controller or other safety device). rohm shall bear no responsibility in any way for use of any of the products for the above special purposes. if a product is intended to be used for any such special purpose, please contact a rohm sales representative before purchasing. if you intend to export or ship overseas any product or technology specified herein that may be controlled under the foreign exchange and the foreign trade law, you will be required to obtain a license or permit under the law.

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