description the AMS1027 is a 5-pin thin sot23 current mode step up converter intended for small, low power applications. the AMS1027 switches at 1.3mhz and allows the use of tiny, low cost capacitors and inductors 2mm or less in height. internal soft start results in small inrush current and extends battery life.the AMS1027 operates from an input voltage as low as 2.5v and can generate 12v at up to 200ma from a 5v supply. the AMS1027 includes under-voltage lockout, current limiting, and thermal overload protection to prevent damage in the event of an output overload. the AMS1027 is available in a small 5-pin sot23 package. features ? on board power mosfet ? uses tiny capacitors and inductors ? 1.3mhz fixed switching frequency ? internally compensated ? internal soft-start ? operates with input voltage as low as 2.5v and output voltage as high as 22v ? 12v at 200ma from 5v input ? uvlo, thermal shutdown ? internal current limit ? available in a sot23-5 package applications ? camera phone flash ? handheld computers and pdas ? digital still and video cameras ? external modems ? small lcd displays ? white led driver typical application v in 5v v out 12v 200ma d1 AMS1027 sw in fb gnd en off on 5 4 3 2 1 ams10 27 advanced monolithic systems http://www.ams-semitech.com 1 vout=1.25(1+r1/r2) (v)
package reference sw gnd fb 1 2 3 5 4 in en top view absolute m ax i mum ratings sw pi n .......................................... . ?0. 5 v to 25v all other pins ................................?0.3v to 6.5v lead temperature ....................................260c storage temperature.............. ?65c to +150c recommended operating conditions supply voltage v in .............................2.5v to 6v output voltage v ou t ........................... . v in to 22v operating temperature............. ?40c to +85c ams10 2 7 advanced monolithic systems http://www.ams-semitech.com 2 pwm comparator error amplifier control logic current sense amplifier sw gnd + - 1 fb 3 2 1.3mhz osc + - - + + 1.25v functional block diagram
electrical characteristics v in = v en = 5v, t a = +25 q c unless otherwise specified. parameters symbol condition min typ max units operating input voltage v in 2.5 6 v undervoltage lockout 2.25 2.45 v undervoltage lockout hysteresis 92 mv supply current (shutdown) v en = 0v 0.1 1 a supply current (quiescent) v fb = 1.3v 635 850 a switching frequency f sw 1.0 1.3 1.5 mhz maximum duty cycle v fb = 0v 85 92 % en threshold v en rising 1.1 1.35 1.6 v en threshold v en rising, v in = 2.5v 0.8 v en hyst e r e s i s 9 0 mv en input bias current v en = 0v, 5 v 1 a fb voltage v fb 1.21 1.25 1.29 v fb input bias current v fb = 1.25v ?100 ?30 na sw on-r e s i s tance r ds (on) 0.5
sw current limit 1.9 a sw leakage v sw = 15v 1 a ther m al shu t down 160 q c ams10 2 7 advanced monolithic systems http://www.ams-semitech.com 3 pin functions pin # name function 1 sw power switch output. sw is the drain of t he internal mosfet switch. connect the power inductor and output rectifier to sw . sw can swing between gnd and 22v. 2 gnd ground. 3 fb feedback input. fb voltage is 1.25v . connect a resistor divider to fb. 4 en regulator on/off control input. a high input at en turns on the converter, and a low input turns it off. when not used, connect en to t he input source for automatic startup. the en pin cannot be left floating. 5 in input supply pin. must be locally bypassed.
typical application circu i ts v out 12v 200ma d1 mbr0520l AMS1027 sw in 51 3 4 2 fb gnd en c3 100pf v in 5v off on v in = 5v, v out = 12v, i out = 200ma boost circuit ams10 2 7 advanced monolithic systems http://www.ams-semitech.com 4
package information sot23-5 0.30 0.50 seating plane 0.95 bsc 0.84 0.90 1.00 max 0.00 0.10 top view front view side view 2.80 3.00 1.50 1.70 2.60 3.00 1 3 4 5 0.09 0.20 note: all dimensions are in millimeters. ams10 2 7 advanced monolithic systems http://www.ams-semitech.com 5
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