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1 www.semtech.com sc1457 150ma ultra low dropout regulator with undervoltage flag power management revision: november 10, 2004 the sc1457 is a low dropout linear regulator that operates from a +2.25v to +6.5v input range and delivers up to 150ma. a pmos pass transistor allows the low 75a supply current to remain independent of load, making these devices ideal for battery operated portable equipment such as cellular phones, cordless phones and personal digital assistants. the sc1457 has very low dropout voltage (typically 1.1mv at light loads and 150mv at 150ma) with better than 1.5% initial output voltage accuracy. it has a logic compatible enable control input and an internal output undervoltage monitor. designed especially for hand held, battery powered devices, the sc1457 can be switched by a cmos or ttl compatible logic signal. when disabled, power consumption drops nearly to zero. other features include short circuit protection, thermal shutdown protection and reverse battery protection. the sc1457 is available in several fixed voltages in the tiny 5 lead sot-23 package and the ultra low profile 5 lead tsot-23. ? guaranteed 150ma output current ? error flag indicates output undervoltage fault ? 2% output accuracy guaranteed over line, load and temperature ? very small external components - designed to work with ceramic capacitors ? low 110v rms output noise ? very low supply current ? thermal overload protection ? reverse battery protection ? low power shutdown ? full industrial temperature range ? very low profile packaging available (1mm max. height) ? surface mount packaging (sot-23-5 and tsot-23-5) vin vo undervoltage flag c2 1uf c1 1uf u1 sc1457 1 2 3 4 5 in gnd en flg out r1 100k description features applications ? battery powered systems ? cellular telephones ? cordless telephones ? personal digital assistants ? portable instrumentation ? modems ? pcmcia cards typical application circuit
2 ? 2004 semtech corp. www.semtech.com sc1457 power management r e t e m a r a pl o b m y sm u m i x a ms t i n u e g a t l o v y l p p u s t u p n iv n i 7 + o t 6 . 0 -v s e g a t l o v n i p o / iv n e v , g l f v o t 6 . 0 - n i v t n e i b m a o t n o i t c n u j e c n a t s i s e r l a m r e h t a j 6 5 2w / c e s a c o t n o i t c n u j e c n a t s i s e r l a m r e h t c j 1 8w / c e g n a r e r u t a r e p m e t t n e i b m a g n i t a r e p ot a 5 8 + o t 0 4 -c e g n a r e r u t a r e p m e t n o i t c n u j g n i t a r e p ot j 5 2 1 + o t 0 4 -c e g n a r e r u t a r e p m e t e g a r o t st g t s 0 5 1 + o t 0 6 -c s d n o c e s 0 1 ) g n i r e d l o s ( e r u t a r e p m e t d a e lt d a e l 0 0 3c ) l e d o m y d o b n a m u h ( g n i t a r d s ev d s e 2v k unless specified: v in = v out + 1v, v en = v in , i out = 100a, t a = 25c. values in bold apply over full operating ambient temperature range. absolute maximum ratings electrical characteristics r e t e m a r a pl o b m y ss n o i t i d n o cn i mp y tx a ms t i n u n i e g n a r e g a t l o v y l p p u sv n i 5 2 . 20 5 . 6 v t n e r r u c y l p p u si q i t u o a m 0 5 1 o t a m 0 =5 70 3 1a 0 6 1 v n i v , v 5 . 6 = n e v 0 =1 . 00 . 1a 5 . 1 t u o e g a t l o v t u p t u o ) 1 ( v t u o i t u o a m 1 =% 5 . 1 -v t u o % 5 . 1 +v a m 0 i t u o v , a m 0 5 1 t u o v 1 + v n i v 5 . 5 % 0 . 2 -% 0 . 2 + n o i t a l u g e r e n i l ) 2 ( ) 1 ( g e r ) e n i l ( v ( ) m o n ( t u o ) v 1 . 0 + v n i i , v 5 . 5 t u o a m 1 =5 . 20 1v m 2 1 n o i t a l u g e r d a o l ) 1 ( g e r ) d a o l ( i t u o a m 0 5 1 o t a m 1 . 0 =3 -0 1 -v m 0 2 - exceeding the specifications below may result in permanent damage to the device, or device malfunction. operation outside of th e parameters specified in the electrical characteristics section is not implied. exposure to absolute maximum rated conditions for extended periods of time may affect device reliability.
3 ? 2004 semtech corp. www.semtech.com sc1457 power management unless specified: v in = v out + 1v, v en = v in , i out = 100a, t a = 25c. values in bold apply over full operating ambient temperature range. electrical characteristics (cont.) r e t e m a r a pl o b m y ss n o i t i d n o cn i mp y tx a ms t i n u ) . t n o c ( t u o t i m i l t n e r r u ci m i l 0 0 4 a m e g a t l o v t u o p o r d ) 3 ( ) 1 ( v d i t u o a m 1 =1v m i t u o a m 0 5 =0 55 6v m 5 7 i t u o a m 0 0 1 =0 0 15 2 1v m 5 5 1 i t u o a m 0 5 1 =0 5 10 9 1v m 0 3 2 e s i o n e g a t l o v t u p t u oe n i , z h k 0 0 1 o t z h 0 1 t u o c , a m 0 5 = t u o f 1 =5 3 1v s m r i , z h k 0 0 1 o t z h 0 1 t u o c , a m 0 5 = t u o f 0 0 1 =0 1 1 o i t a r n o i t c e j e r y l p p u s r e w o pr r s pz h 0 2 1 = f0 6b d n e d l o h s e r h t t u p n i e l b a n ev h i v 5 2 . 2 v n i v 5 . 6 6 . 1 v v l i v 5 2 . 2 v n i v 5 . 6 4 . 0 t n e r r u c s a i b t u p n i e l b a n e ) 4 ( i n e v 0 v n e v n i 5 . 0 - 0 5 . 0 + a g l f d l o h s e r h t g a l fv ) g l f ( h t ) l a n i m o n w o l e b ( n o i t i d n o c e g a t l o v r e d n u4 -6 -8 -% 4 -2 1 - e g a t l o v w o l c i g o l t u p t u ov g l f i g l f n o i t i d n o c e g a t l o v r e d n u , a m 1 = 4 . 0 v t n e r r u c e g a k a e l g a l fi g l f v , f f o g a l f g l f v 5 . 6 o t v 0 = 1 - 1 . 0 1 + a n o i t c e t o r p e r u t a r e p m e t r e v o l e v e l p i r t h g i ht i h 0 5 1c s i s e r e t s y ht t s y h 0 2c notes: (1) low duty cycle pulse testing with kelvin connections required. (2) v in(min) = 2.25v. (3) defined as the input to output differential at which the output voltage drops 100mv below the value measured at a differential of 1v. not measurable on 1.5v and 1.8v parts due to minimum v in constraints. (4) guaranteed by design .
4 ? 2004 semtech corp. www.semtech.com sc1457 power management notes: (1) where x.x or xx denotes voltage options. available voltages are: 1.5v (1.5 or 15), 1.8v (1.8 or 18), 2.5v (2.5 or 25), 2.7v (2.7 or 27), 2.8v (2.8 or 28), 2.9v (2.9 or 29), 3.0v (3.0 or 30), 3.1v (3.1 or 31), 3.2v (3.2 or 32) and 3.3v (3.3 or 33). (2) only available in tape and reel packaging. a reel contains 3000 devices. (3) evaluation board for sc1457. specify output voltage option when ordering. (4) lead free product. this product is fully weee and rohs compliant. r e b m u n t r a pe g a k c a p r t x . x - k s i 7 5 4 1 c s ) 1 ( 5 - 3 2 - t o s ) 2 ( t r t x . x k s i 7 5 4 1 c s ) 4 ( ) 1 ( r t x x - k s t i 7 5 4 1 c s ) 1 ( 5 - 3 2 - t o s t ) 2 ( t r t x x k s t i 7 5 4 1 c s ) 4 ( ) 1 ( b v e 7 5 4 1 c s ) 3 ( a / n pin configuration top view (sot-23-5 & tsot-23-5) ordering information block diagram n i pe m a n n i pn o i t c n u f n i p 1n in i p t u p n i 2d n g. d e d e e n f i g n i k n i s t a e h r o f d e s u e b n a c . n i p d n u o r g 3n ev t c e n n o c . n i p e l b a n e h g i h e v i t c a n i . d e s u g n i e b t o n f i 4g l f . n o i t i d n o c e g a t l o v r e d n u t u p t u o n a s e t a c i d n i w o l e v i t c a . t u p t u o n i a r d n e p o . g a l f r o r r e 5t u o. a m 0 5 1 o t p u g n i c r u o s t u p t u o r o t a l u g e r pin descriptions
5 ? 2004 semtech corp. www.semtech.com sc1457 power management top mark bottom mark yyww = date code (example: 0008 for week 8 of 2000) marking information applications information theory of operation the sc1457 is intended for applications where very low dropout voltage, low supply current and output voltage monitoring are critical. it provides a very simple, low cost solution that uses very little pcb real estate. only two external capacitors and one resistor are required for operation. the sc1457 contains a bandgap reference trimmed for optimal temperature coefficient which is fed into the inverting input of an error amplifier. the output voltage of the regulator is divided down internally using a resistor divider and compared to the bandgap voltage. the error amplifier drives the gate of a low r ds(on) p-channel mosfet pass device. an active high enable pin (en) allows the regulator to be shut down. pulling this pin low causes the device to enter a very low power shutdown mode, where it will draw typically 0.1a from the input supply. an open drain flag pin (flg) is provided to signal whenever the output voltage is 6% (typically) below nominal. a tap is taken from the internal resistor divider and compared to the bandgap voltage to determine if the output voltage is above or below this level. the flag pin pulls low whenever the output is out of specification. an external pullup resistor is required for a high signal when the flag pin is not pulling low. since this circuitry is powered from the input supply, the flg pin will pull low for output voltages all the way down to zero, unlike external devices powered from the ldo output. the regulator has its own current limit circuitry to ensure that the output current will not damage the device during output short, overload or start-up. the current limit is guaranteed to be greater than 400ma to allow fast charging of the output capacitor and high initial currents for dsp initialization. the sc1457 includes thermal shutdown circuitry to turn off the device if t j exceeds 150c (typical), with the device remaining off until t j drops by 20c (typical). reverse battery protection circuitry ensures that the device cannot be damaged if the input supply is accidentally reversed, limiting the reverse current to less than 1.5ma. component selection - general output capacitor - semtech recommends a minimum capacitance of 1f at the output with an equivalent series resistance (esr) of < 1 ? over temperature. while the sc1457 has been designed to be used with ceramic capacitors, it does not have to be used with ceramic capacitors, allowing the designer a choice. increasing the bulk capacitance will further reduce output noise and improve the overall transient response. input capacitor - semtech recommends the use of a 1f ceramic capacitor at the input. this allows for the device being some distance from any bulk capacitance on the rail. additionally, input droop due to load transients is reduced, improving overall load transient response. flag pullup resistor - semtech recommends a maximum value of 100k ? for this resistor to ensure that this pin is high even under worst-case flag pin leakage conditions of 1a when off. x7xx yyww x = package (5 for sot-23-5, t for tsot-23-5) 7 = sc1457 xx = voltage option (examples: 5731 for 3.1v option in sot-23-5, t728 for 2.8v option in tsot-23-5)
6 ? 2004 semtech corp. www.semtech.com sc1457 power management applications information (cont.) with the standard sot-23-5/tsot-23-5 land pattern shown at the end of this datasheet, and minimum trace widths, the thermal impedance junction to ambient for sc1457isk is 256c/w. thus no additional heatsinking is required for this example. the junction temperature can be reduced further (or higher power dissipation can be allowed) by the use of larger trace widths and connecting pcb copper to the gnd pin (pin 2), which connects directly to the device substrate. adding approximately one square inch of pcb copper to pin 2 will reduce ja to approximately 130c/w and t j(max) for the example above to approximately 100c for the sot-23-5 package. the use of multi layer boards with internal ground/power planes will lower the junction temperature and improve overall output voltage accuracy. layout considerations while layout for linear devices is generally not as critical as for a switching application, careful attention to detail will ensure reliable operation. 1) attaching the part to a larger copper footprint will enable better heat transfer from the device, especially on pcbs where there are internal ground and power planes. 2) place the input, output and bypass capacitors close to the device for optimal transient response and device behaviour. 3) connect all ground connections directly to the ground plane. if there is no ground plane, connect to a common local ground point before connecting to board ground. thermal considerations the worst-case power dissipation for this part is given by: () ) max ( q ) max ( in ) max ( out ) min ( out ) max ( in ) max ( d i v i v v p ? + ? ? = (1) for all practical purposes, equation (1) can be reduced to the following expression: () ) max ( out ) min ( out ) max ( in ) max ( d i v v p ? ? = (2) looking at a typical application, 3.3v to 2.8v at 150ma: v in(max) = 3.3 + 5% = 3.465v v out(min) = 2.8v - 2% = 2.744v i out = 150ma t a = 85c inserting these values into equation (2) gives us: () mw 108 150 . 0 744 . 2 465 . 3 p ) max ( d = ? ? = using this figure, we can calculate the maximum thermal impedance allowable to maintain t j 125c: () () w / c 370 108 . 0 85 125 p t t ) max ( d ) max ( a ) max ( j ) max ( ja = ? = ? =
7 ? 2004 semtech corp. www.semtech.com sc1457 power management quiescent current vs. junction temperature vs. input voltage off-state quiescent current vs. junction temperature typical characteristics output voltage vs. junction temperature vs. output current line regulation vs. junction temperature vs. input voltage change load regulation vs. junction temperature current limit vs. junction temperature vs. input voltage 0 20 40 60 80 100 120 -50 -25 0 25 50 75 100 125 t j (c) i q (a) i out = 150ma v in = 3.8v v in = 6.5v 0 25 50 75 100 125 150 175 200 -50 -25 0 25 50 75 100 125 t j (c) i q(off) (na) v in = 6.5v v en = 0v -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 -50 -25 0 25 50 75 100 125 t j (c) v out deviation (%) v in = v out + 1v i out = 1ma i out = 50ma 100ma i out 150ma 0 2 4 6 8 10 12 -50 -25 0 25 50 75 100 125 t j (c) reg line (mv) v in = v out + 1v to 5.5v v in = v out + 1v to 6.5v i out = 1ma 0 1 2 3 4 5 6 7 8 9 10 -50 -25 0 25 50 75 100 125 t j (c) reg load (mv) v in = v out + 1v i out = 0.1ma to 150ma 0.40 0.45 0.50 0.55 0.60 0.65 0.70 0.75 0.80 0.85 0.90 -50 -25 0 25 50 75 100 125 t j (c) i lim (a) v in = 6.5v v in = 3.8v
8 ? 2004 semtech corp. www.semtech.com sc1457 power management dropout voltage vs. junction temperature vs. output current dropout voltage vs. output current vs. junction temperature typical characteristics (cont.) flag threshold voltage vs. input voltage vs. output voltage 0 25 50 75 100 125 150 175 200 -50 -25 0 25 50 75 100 125 t j (c) v d (mv) i out = 150ma i out = 50ma 0 25 50 75 100 125 150 175 200 0 25 50 75 100 125 150 i out (ma) v d (mv) top to bottom: t j = 125c t j = 25c t j = -40c enable input threshold voltage vs. junction temperature vs. input voltage 0.4 0.6 0.8 1.0 1.2 1.4 1.6 -50 -25 0 25 50 75 100 125 t j (c) v en (v) v ih @ v in = 6.5v v ih @ v in = 3.8v v il @ v in = 6.5v v il @ v in = 3.8v -8.0 -7.5 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 v in (v) v th(flg) (% below v out(nom) ) v out = 3.3v v out = 1.5v flag voltage vs. junction temperature vs. flag current flag threshold voltage vs. junction temperature vs. output voltage -8.0 -7.5 -7.0 -6.5 -6.0 -5.5 -5.0 -4.5 -4.0 -50 -25 0 25 50 75 100 125 t j (c) v th(flg) (% below v out(nom) ) v out = 1.5v v out = 3.3v 0 25 50 75 100 125 150 175 200 -50 -25 0 25 50 75 100 125 t j (c) v flg (mv) v in = 4.3v i flg = 10ma i flg = 1ma
9 ? 2004 semtech corp. www.semtech.com sc1457 power management reverse battery protection vs. junction temperature 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -50 -25 0 25 50 75 100 125 t j (c) i (rev bat) (ma) v in = v en = -6.5v typical characteristics (cont.)
10 ? 2004 semtech corp. www.semtech.com sc1457 power management evaluation board schematic evaluation board bill of materials y t i t n a u qe c n e r e f e rn o i t p i r c s e d / t r a pr o d n e vs e t o n 35 c , 4 c , 1 cd e c a l p t o n 23 c , 2 cc i m a r e c f 1a t a r u m0 1 k 5 0 1 r 7 x 6 - 2 4 m r g 11 jt e k c o s c n bs u o i r a vv t u o r o t i n o m e l p p i r 34 j - 2 jn i p t s e ts u o i r a vd e r 15 jn i p t s e ts u o i r a ve t i h w 16 jn i p 2 , r e d a e hs u o i r a v 17 jn i p t s e ts u o i r a vw o l l e y 26 1 j , 8 jn i p 3 , r e d a e hs u o i r a v 19 jn i p t s e ts u o i r a ve g n a r o 65 1 j - 0 1 jn i p t s e ts u o i r a vk c a l b 11 q0 1 4 4 i sy a h s i v 11 rk 0 0 1 ? w 0 1 / 1 ,s u o i r a v 12 rd e c a l p t o n 13 re g a p t x e n e e ss u o i r a v 14 rk 0 1 ? w 0 1 / 1 ,s u o i r a v 11 u r o x . x - k s i 7 5 4 1 c s x x - k s t i 7 5 4 1 c s h c e t m e s c3 r1 c4 c1 c5 c2 r4 u1 sc1457 1 2 3 4 5 in gnd en flg out j6 iq mon 1 2 r3 q1 si4410 1 2 3 4 5 6 7 8 s s s gd d d d j3 in j5 en j2 in mon j14 gnd j13 gnd j4 out mon j12 gnd j11 gnd j10 gnd j9 load drv j15 gnd j1 ripple mon j7 flg r2 j16 load drv en 1 2 3 j8 en 1 2 3
11 ? 2004 semtech corp. www.semtech.com sc1457 power management evaluation board gerber plots top copper bottom copper top silk screen ) v ( n o i t p o e g a t l o v t u p t u oe z i s / e u l a v 3 r 5 . 10 1 ? w 5 . 0 / 8 . 12 1 ? w 5 . 0 / 5 . 26 1 ? w 5 . 0 / 7 . 28 1 ? w 5 . 0 / 8 . 28 1 ? w 5 . 0 / 9 . 28 1 ? w 5 . 0 / 0 . 30 2 ? w 5 . 0 / 1 . 30 2 ? w 5 . 0 / 2 . 32 2 ? w 5 . 0 / 3 . 32 2 ? w 5 . 0 /
12 ? 2004 semtech corp. www.semtech.com sc1457 power management outline drawing - sot-23-5 .110 bsc .037 bsc detail aaa c seating plane c ccc c 2x n/2 tips 2x e/2 5 see detail a1 a a2 bxn d a .008 12 n e1 e d .060 .114 .063 .118 .010 - 5 a 0.20 1.60 3.00 2.80 bsc 0.95 bsc .069 1.50 2.90 .020 0.25 1.75 0.50 - ei l (l1) c 01 0.25 plane gage h 2.80 .110 bbb c a-b d a b e 0 .008 - .004 .012 .003 (.024) .018 - .035 .000 .035 - - .045 0.10 0.20 10 0 - 10 1.15 (0.60) 0.45 .024 .009 0.30 0.08 .057 .051 .006 0.00 .90 0.90 0.22 0.60 - 0.15 1.45 1.30 - - 1.90 bsc .075 bsc dimensions "e1" and "d" do not include mold flash, protrusions datums and to be determined at datum plane or gate burrs. controlling dimensions are in millimeters (angles in degrees). notes: 1. 3. 2. -a- -b- -h- dimensions inches l1 aaa bbb ccc 01 n dim e e1 l e e1 c d a a2 b a1 min nom millimeters nom max min max side view outline drawing - tsot-23-5
13 ? 2004 semtech corp. www.semtech.com sc1457 power management semtech corporation power management products division 200 flynn road, camarillo, ca 93012 phone: (805)498-2111 fax (805)498-3804 contact information land pattern - sot-23-5 & tsot-23-5 dimensions inches y z dim g p x c millimeters p (c) z y g .043 .141 .055 (.098) .037 .024 1.40 (2.50) 0.95 0.60 1.10 3.60 x dimensions inches y z dim g p x c millimeters this land pattern is for reference purposes only. consult your manufacturing group to ensure your company's manufacturing guidelines are met. notes: 1.

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