1 ltc1262 12v, 30ma flash memory programming supply s f ea t u re d u escriptio u a o pp l ic at i ty p i ca l n regulated 12v 5% output voltage n no inductors n supply voltage range: 4.75v to 5.5v n guaranteed 30ma output n low power: i cc = 500 m a n i cc in shutdown: 0.5 m a n 8-pin pdip or so-8 package the ltc ? 1262 is a regulated 12v, 30ma output dc/dc converter. it is designed to provide the 12v 5% output necessary to program byte-wide flash memories. the output will provide up to 30ma from input voltages as low as 4.75v without using any inductors. only four external capacitors are required to complete an extremely small surface mountable circuit. the ttl compatible shutdown pin can be directly con- nected to a microprocessor and reduces the supply cur- rent to less than 0.5 m a. the ltc1262 offers improved shutdown current performance and requires fewer exter- nal components than competing solutions. the ltc1262 is available in an 8-pin pdip or so-8 package. 1
2
3
4 8
7
6
5
0.22 m f 4.7 m f from mpu 4.7 m f v cc vpp ltc1262 ?ta01 v cc
4.75v to 5.5v flash
memory 0.22 m f c1
c1 +
c2
c2 + shdn
gnd
v out
v cc ltc1262 + + u s a o pp l ic at i n 12v flash memory programming supplies n compact 12v op amp supplies n battery-powered systems 5v 0v shdn 5v/div 5v 0v 12v v out 5v/div 1ms/div 1262 ta01a in/out of shutdown , ltc and lt are registered trademarks of linear technology corporation.
2 ltc1262 a u g w a w u w a r b s o lu t exi t i s wu u package / o rder i for atio (note 1) supply voltage (v cc ) ................................................ 6v input voltage (shdn) ................... C 0.3v to v cc + 0.3v output current (i out ) ........................................... 50ma operating temperature range ltc1262c................................................ 0 c to 70 c ltc1262i ........................................... C 40 c to 85 c storage temperature range ................ C 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c electrical characteristics consult factory for military grade parts. 1
2
3
4 8
7
6
5
top view c1
c1 +
c2
c2 + shdn
gnd
v out
v cc n8 package
8-lead pdip s8 package
8-lead plastic so t jmax = 150 c, q ja = 100 c/w (n8) t jmax = 150 c, q ja = 150 c/w (s8) v cc = 4.75v to 5.5v, t a = C 40 c to 85 c, (notes 2, 3), unless otherwise noted. symbol parameter conditions min typ max units v out output voltage 0ma i out 30ma, v shdn = 0v, 0 c t a 70 c l 11.4 12.6 v 0ma i out 30ma, v shdn = 0v, C 40 c t a 85 c l 11.2 12.6 v i cc supply current no load, v shdn = 0v, 0 c t a 70 c l 0.5 1.0 ma no load, v shdn = 0v, C 40 c t a 85 c l 0.5 1.3 ma i shdn shutdown supply current no load, v shdn = v cc l 0.5 10 m a f osc oscillator frequency v cc = 5v, i out = 30ma l 300 khz power efficiency v cc = 5v, i out = 30ma l 74 % r sw v cc to v out switch impedance v cc = v shdn = 5v, i out = 0ma l 0.18 2 k w v ih shdn input high voltage l 2.4 v v il shdn input low voltage l 0.8 v shdn input current v cc = 5v, v shdn = 0v, 0 c t a 70 c l C20 C10 C5 m a v cc = 5v, v shdn = 0v, C 40 c t a 85 c l C35 C10 C5 m a v cc = 5v, v shdn = 5v l 0.06 10 m a t on turn-on time c1 = c2 = 0.22 m f, c in = c out = 4.7 m f, (figures 1, 2) 500 m s t off turn-off time c1 = c2 = 0.22 m f, c in = c out = 4.7 m f, (figures 1, 2) 3.3 ms note 2: all currents into device pins are positive; all currents out of device pins are negative. all voltages are referenced to ground unless otherwise specified. note 3: all typicals are given at v cc = 5v, t a = 25 c. the l denotes specifications which apply over the full operating temperature range. note 1: absolute maximum ratings are those values beyond which the life of the device may be impaired. order part number ltc1262cn8 ltc1262cs8 ltc1262is8 s8 part marking 1262 1262i
3 ltc1262 typical perfor m a n ce characteristics u w pi fu ctio s u uu v out (pin 6): 12v output. connect a 4.7 m f bypass capaci- tor c out to ground. when in the shutdown mode v out = v cc . gnd (pin 7): ground. shdn (pin 8): logic level shutdown pin. application of a logic low at shdn pin will place the regulator in normal operation. with no external connection, or with shdn tied to v cc , the device will be put into shutdown mode. connect to gnd for normal operation. in shutdown mode the charge pump is turned off and v out = v cc . efficiency vs output current shutdown supply current vs temperature output voltage vs output current c1 C (pin 1): c1 negative input. connect a 0.22 m f capaci- tor c1 between c1 + and c1 C . c1 + (pin 2): c1 positive input. connect a 0.22 m f capaci- tor c1 between c1 + and c1 C . c2 C (pin 3): c2 negative input. connect a 0.22 m f capaci- tor c2 between c2 + and c2 C . c2 + (pin 4): c2 positive input. connect a 0.22 m f capaci- tor c2 between c2 + and c2 C . v cc (pin 5): positive supply input where 4.75v v cc 5.5v. connect a 4.7 m f bypass capacitor c in to ground. supply current vs supply voltage supply voltage (v) 4.5 480 supply current ( m a) 500 520 540 560 600 4.75 5.0 5.25 5.5 ltc1262 g03 5.75 6.0 580 t a = 70 c i out = 0 t a = 25 c t a = 0 c output current (ma) 0 55 efficiency (%) 60 65 70 75 85 10 20 30 40 ltc1262 g01 50 80 v cc = 4.75v v cc = 5v v cc = 5.5v temperature ( c) ?0 0 shutdown supply current ( m a) 0.6 1.2 1.8 2.4 3.6 ?5 02550 ltc1262 g02 75 100 3.0 v cc = 5v output current (ma) 0 5 10 15 20 25 30 35 40 45 50 output voltage (v) 12.2
12.0
11.8
11.6
11.4
11.2
11.0
10.8
10.6
10.4
10.2
1262 g04
v cc = 4.75v v cc = 5.5v v cc = 5v
4 ltc1262 block diagra m w ti i g diagra s ww u figure 2. ltc1262 timing circuit + s3b s3d s3a s4a s4b s1 and s2 shown with shdn pin low.
s3a, s3b, s3c, s3d, s4a and s4b shown with oscillator output low and v div < v bgap ?v hyst .
comparator hysterisis is v hyst . c1 c1 + c1 c2 c2 + c2 charge
pump s3c d2 d1 v bgap s1 ltc1262 ?bd s2 r3 r1 r2 v out v cc shdn gnd c out bandgap
reference oscillator c in v div + + figure 1. ltc1262 timing diagram 1
2
3
4 8
7
6
5
c1
0.22 m f c2
0.22 m f c out
4.7 m f v shutdown v out ltc1262 ?f02 v cc
4.75v to 5v c in
4.7 m f c1
c1 +
c2
c2 + shdn
gnd
v out
v cc ltc1262 + + 1.4v 5.1v 1.4v v shdn v out v cc v cc v out 11.4v 0v ltc1262 ?f01 t off t on
5 ltc1262 applicatio n s i n for m atio n wu u u operation the ltc1262 uses a charge pump tripler to generate 12v from a v cc of 5v. the charge pump operates when clocked by a 300khz oscillator. when the oscillator output is low, c1 and c2 are connected between v cc and gnd, charging them to v cc . when the oscillator output goes high, c1 and c2 are stacked in series with the bottom plate of c1 pulled to v cc . the top plate of c2 is switched to charge c out and v out rises. v out is regulated to within 5% of 12v by an oscillator pulse gating scheme. a resistor divider senses v out . when the output of the divider (v div ) is less than the output of a bandgap (v bgap ) by the hysteresis voltage (v hyst ) of the comparator, oscillator pulses are applied to the charge pump to raise v out . when v div is above v bgap by v hyst , the oscillator pulses are prevented from clock- ing the charge pump. v out drops until v div is below v bgap by v hyst again. the gates of all internal switches are driven between v out and gnd. an internal diode ensures that the ltc1262 will start up under load by charging c out to one diode drop below v cc . to reduce supply current the ltc1262 may be put into shutdown mode by floating the shdn pin or taking it to v cc . in this mode the bandgap, comparator, oscillator and resistor divider are switched off to reduce supply current to typically 0.5 m a. at the same time an internal switch shorts v out to v cc ; v out takes 3.3ms to reach 5.1v (see t off in figure 1). when the shdn pin is low, the ltc1262 exits shutdown and the charge pump operates to raise v out to 12v. v out takes 500 m s to reach the lower regula- tion limit of 11.4v (see t on in figure 1). choice of capacitors the ltc1262 is tested with the capacitors shown in figure 2. c1 and c2 are 0.22 m f ceramic capacitors and c in and c out are 4.7 m f tantalum capacitors. refer to table 1 if other choices are desired. table 1. recommended capacitor types and values capacitor ceramic tantalum aluminum c1, c2 0.22 m f to 1 m f not not recommended recommended c out 2 m f (min) 4.7 m f (min) 10 m f (min) c in 1 m f (min) 4.7 m f (min) 10 m f (min) c1 and c2 should be ceramic capacitors with values in the range of 0.22 m f to 1 m f. higher values provide better load regulation. tantalum capacitors are not recommended as the higher esr of these capacitors degrades performance when the load current is above 25ma with v cc = 4.75v. c in and c out can be ceramic, tantalum or electrolytic capacitors. the esr of c out introduces steps in the v out waveform whenever the charge pump charges c out . this tends to increase v out ripple. ceramic or tantalum capaci- tors are recommended for c out if minimum ripple is desired. the ltc1262 does not require a 0.1 m f capacitor between v cc and v out for stability. maximum load current the ltc1262 will source up to 50ma continuously without any damage to itself. do not short the v out pin to ground . if the v out pin is shorted to ground, irreversible damage to the device will result.
6 ltc1262 burst mode is a trademark of linear technology corporation. 1
2
3
4 8
7
6
5
c1
c1 +
c2
c2 + shdn
gnd
v out
v cc pdrive
sense +
sense
ndrive
pgnd 3
10
6
4
11 1
8
7
14
12 v in
shdn
i th
c t
sgnd c7
0.22 m f shutdown c9
1 m f ltc1262 ?ta02 panasonic
ecgcokb220r u2
ltc1262 u1
ltc1148-3.3 c8
0.22 m f + v out
3.3v
10a v in
5v c2
150pf c3
1000pf c4
220 m f
8v
3 c5
330 m f
6.3v
2
os-con q3
si9410 d1
mbrs120t3 q5
si9410 r6
22k burst mode tm defeat;
use if required
q2
vn7002 r2
100 w r3
100 w r4
0.01 w
2w l2
3 m h/10a q1
tp0610 q4
si9410 c1
3300pf r1
510 w c6
10 m f
25v + + + + + + 5v to 3.3v/10a converter u a o pp l ic at i ty p i ca l
7 ltc1262 package descriptio n u dimensions in inches (millimeters) unless otherwise noted. information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. s8 package 8-lead plastic small outline (narrow 0.150) (ltc dwg # 05-08-1610) n8 package 8-lead pdip (narrow 0.300) (ltc dwg # 05-08-1510) n8 1197 0.100 0.010
(2.540 0.254) 0.065
(1.651)
typ 0.045 ?0.065
(1.143 ?1.651) 0.130 0.005
(3.302 0.127) 0.020
(0.508)
min 0.018 0.003
(0.457 0.076) 0.125
(3.175)
min
12 3 4 87 6 5 0.255 0.015*
(6.477 0.381)
0.400*
(10.160)
max 0.009 ?0.015
(0.229 ?0.381) 0.300 ?0.325
(7.620 ?8.255) 0.325 +0.035
0.015 +0.889
0.381 8.255 () *these dimensions do not include mold flash or protrusions.
mold flash or protrusions shall not exceed 0.010 inch (0.254mm) 1 2 3 4 0.150 ?0.157**
(3.810 ?3.988) 8 7 6 5 0.189 ?0.197*
(4.801 ?5.004) 0.228 ?0.244
(5.791 ?6.197) 0.016 ?0.050
0.406 ?1.270 0.010 ?0.020
(0.254 ?0.508) 45 0 ?8 typ 0.008 ?0.010
(0.203 ?0.254) so8 0996 0.053 ?0.069
(1.346 ?1.752) 0.014 ?0.019
(0.355 ?0.483) 0.004 ?0.010
(0.101 ?0.254) 0.050
(1.270)
typ dimension does not include mold flash. mold flash
shall not exceed 0.006" (0.152mm) per side
dimension does not include interlead flash. interlead
flash shall not exceed 0.010" (0.254mm) per side
*
**
8 ltc1262 ? linear technology corporation 1994 lt/tp 0298 rev a 2k ? printed in usa output current (ma) 0 102030405060 70 80 90 100 output voltage (v) 12.4
12.2
12.0
11.8
11.6
11.4
11.2
11.0
10.8
10.6
10.4 1262 ta04
v cc = 4.75v v cc = 5.5v v cc = 5v 1
2
3
4 8
7
6
5
0.22 m f 10 m f 10 m f tie to v cc or float
to shutdown both
devices ltc1262 ?ta03 v cc
4.75v to
5.5v 0.22 m f 1
2
3
4 8
7
6
5
0.22 m f 12v output 0.22 m f note: keep devices close together or use separate 4.7 m f tantalum capacitors if this is not possbile. c1
c1 +
c2
c2 + shdn
gnd
v out
v cc ltc1262 c1
c1 +
c2
c2 + shdn
gnd
v out
v cc ltc1262 + + paralleling devices see figure at left. u a o pp l ic at i ty p i ca l related parts part number description comments lt1106* micropower step-up dc/dc converter for pcmcia card flash memory pcmcia card power control, 9 m a i shdn , small smt components, requires external inductor lt1109-12 micropower low cost dc/dc converter adjustable and fixed 12v three-lead z package, requires external inductor lt1109a-12 micropower dc/dc converter flash memory vpp generator requires external inductor adjustable and fixed 12v lt1301 micropower high efficiency 5v/12v step-up dc/dc 7 m a i shdn , smt inductor and capacitors converter for flash memory lt1309 500khz micropower dc/dc converter for flash memory small smt inductor and capacitors, 6 m a i shdn * see also lt1312/lt1313 pcmcia vpp drivers/regulators, lt1314/lt1315 pcmcia switch matrix and the ltc1470/ltc1471/ltc1472 protected v cc and vpp switching matrices output voltage vs output current for two paralleled devices linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 l (408) 432-1900 fax: (408) 434-0507 l telex: 499-3977 l www.linear-tech.com
|
