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december 2011 doc id 022614 rev 1 1/24 24 stod03as dual dc-dc converter for powering amoled displays features step-up and inverter converters operating input voltage range from 2.5 v to 4.5 v synchronous rectification for both dc-dc converters minimum 200 ma output current 4.6 v fixed positive output voltage programmable negative voltage by s wire from -2.4 v to -5.4 v at 100 mv steps typical efficiency: 85% pulse skipping mode in light load condition 1.5 mhz pwm mode control switching frequency enable pin for shutdown mode low quiescent current in shutdown mode soft-start with inrush current protection overtemperature protection temperature range: -40 c to 85 c true-shutdown mode fast discharge outputs of the circuits after shutdown short-circuit protection package dfn12l (3 x 3 mm) 0.6 mm height applications active matrix amoled power supply cellular phones camcorders and di gital still cameras multimedia players description the stod03as is a dual dc-dc converter with short-circuit protection for amoled display panels. it integrates a step-up and an inverting dc-dc converter making it particularly suitable for battery operated products, in which the major concern is overall system efficiency. it works in pulse skipping mode during light load conditions and pwm-mode at 1.5 mhz frequency for medium/high load conditions. the high frequency allows the value and size of external components to be reduced. the enable pin allows the device to be turned off, therefore reducing the current consumption to less than 1 a. the negative output voltage can be programmed by an mcu through a dedicated pin which implements single- wire protocol. soft-start with controlled inrush current limit and thermal shutdown are integrated functions of the device. dfn12l (3 x 3 mm) table 1. device summary order code positive voltage negative voltage package packaging STOD03ASTPUR 4.6v -2.4v to -5.4v dfn12l (3 x 3 mm) 3000 parts per reel www.st.com
contents stod03as 2/24 doc id 022614 rev 1 contents 1 schematic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 5 typical performance characteristi cs . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6 detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1 s wire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1.1 s wire features and benefits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1.2 s wire protocol . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.1.3 s wire basic operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 6.2 negative output voltage levels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7 application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1 external passive components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1.1 inductor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.1.2 input and output capacitor selection . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.2 recommended pcb layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 8 detailed description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1 general description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1.1 multiple operation modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1.2 pulse skipping operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1.3 discontinuous conduction mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1.4 continuous conduction mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1.5 enable pin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1.6 soft-start and inrush current limiting . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1.7 undervoltage lockout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1.8 overtemperature protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 8.1.9 short-circuit protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
stod03as contents doc id 022614 rev 1 3/24 8.1.10 fast discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 9 package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 10 revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
schematic stod03as 4/24 doc id 022614 rev 1 1 schematic figure 1. application schematic note: all the above components refer to the typical application performance characteristics. operation of the device is not limited to the choice of these external components. inductor values ranging from 3.3 h to 6.8 h can be used together with the stod03as. , , # -)$ # / # 2%& , 8 6 / 6 -)$ 0'.$ !'.$ # ). 6 "!4 , 8 6 ).! 6 ).0 %. 3 7)2% 6 2%& 34/$!3 3 7ire %. !-v table 2. typical external components comp. manufacturer part number value size ratings l 1 (1) coilcraft murata semco abco abco lps4012-472ml lqh3npn4r7mj0 cig22b4r7mne lpf2810t-4r7m lpf2807t-4r7m 4.7h 4.0 x 4.0 x 1.2 3.0 x 3.0 x 1.1 2.5 x 2.0 x 1.0 2.8 x 2.8 x 1.0 2.8 x 2.8 x 0.7 20%, i = 1.7 a, r = 0.175 20%, i = 1.1 a, r = 0.156 20%, i = 1.1 a, r = 0.300 20%, i = 0.85 a, r = 0.33 20%, i = 0.70 a, r = 0.44 l 2 (2) coilcraft murata toko abco tdk lps4012-472ml lqh3npn4r7mj0 dfe252012c1239as-h4r7n lpf3510t-4r7m vlf4014at-4r7m1r1 4.7h 4.0 x 4.0 x 1.2 3.0 x 3.0 x 1.1 2.5 x 2.0 x 1.2 3.5 x 3.5 x 1.0 3.7 x 3.5 x 1.4 20%, i = 1.7 a, r = 0.175 20%, i = 1.1 a, r = 0.156 30%, i = 1.2 a, r = 0.252 20%, i = 0.83 a, r = 0.25 20%, i = 1.1 a, r = 0.140 c in murata taiyo yuden grm219r61a106ke44 lmk212bj106kd-t 2 x 10f 0805 0805 10%, x5r, 10v 10%, x5r, 10v c mid murata taiyo yuden grm219r61a106ke44 lmk212bj106kd-t 10f 0805 0805 10%, x5r, 10v 10%, x5r, 10v c o2 murata taiyo yuden grm219r61a106ke44 lmk212bj106kd-t 2 x 10f 0805 0805 10%, x5r, 10v 10%, x5r, 10v c ref murata taiyo yuden grm185r60j105ke26 jmk107bj105kk-t 1f 0603 0603 10%, x5r, 6.3v 10%, x5r, 6.3v 1. a 200 ma load can be provided wi th inductor saturation current as a minimum of 0.5 a. 2. at -5.4 v, a 200 ma load can be pr ovided with inductor saturation cu rrent as a minimum of 1 a. see section 7.1.1 .
stod03as schematic doc id 022614 rev 1 5/24 figure 2. block schematic 34%0 50 #/.42/, ).6%24).' #/.42/, $)3#(!2'% &!3 4 $)3#(!2'% &!3 4 62%& ,/')##/.42/, /40 3 7)2% 6).0 2).' +),,%2 /3 # 3 wire control $-$ $-$ 62%& 56,/ , 8 6 / 6 -) $ 0'.$ !'.$ , 8 6 ).! 6 ).0 %. 3 7) 2% 6 2%& . 0! 0" 0 . !-v
pin configuration stod03as 6/24 doc id 022614 rev 1 2 pin configuration figure 3. pin configuration (top view) table 3. pin description pin name pin n description lx 1 1 switching node of the step-up converter pgnd 2 power ground pin v mid 3 step-up converter output voltage (4.6v) nc 4 not internally connected agnd 5 signal ground pin. this pin must be connected to the power ground pin v ref 6 voltage reference output. 1f bypa ss capacitor must be connected between this pin and agnd s wire 7 negative voltage setting pin en 8 enable control pin. on = v ina . when pulled low it puts the device in shutdown mode v o2 9 inverting converter output voltage (default - 4.9v) lx 2 10 switching node of the inverting converter v in a 11 analogic input supply voltage v in p 12 power input supply voltage exposed pad internally connected to agnd. exposed pad must be connected to agnd and pgnd in the pcb layout in order to guarantee proper operation of the device
stod03as maximum ratings doc id 022614 rev 1 7/24 3 maximum ratings note: absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these conditions is not implied. table 4. absolute maximum ratings symbol parameter value unit v ina , v inp dc supply voltage -0.3 to 6 v en, s wire logic input pins -0.3 to 4.6 v il x2 inverting converter switching current internally limited a l x2 inverting converter switching node voltage - 10 to v inp + 0.3 v v o2 inverting converter output voltage - 10 to agnd + 0.3 v v mid step-up converter and ldo output voltage -0.3 to 6 v l x1 step-up converter switching node voltage -0.3 to v mid + 0.3 v il x1 step-up converter switching current internally limited a v ref reference voltage -0.3 to 3 v p d power dissipation internally limited mw t stg storage temperature range -65 to 150 c t j maximum junction temperature 150 c esd esd protection hbm 2 kv table 5. thermal data symbol parameter value unit r thja thermal resistance junction-ambient 33 c/w r thjc thermal resistance junction-case (fr-4 pcb) (1) 2.12 c/w 1. the package is mounted on a 4-layer (2s2p) jedec board as per jesd51-7.
electrical characteristics stod03as 8/24 doc id 022614 rev 1 4 electrical characteristics t j = 25 c, v ina = v inp = 3.7 v, i mid,o2 = 30 ma, c in = 2 x 10 f, c mid = 10 f, c o2 = 2 x 10 f, c ref = 1 f, l1 = l2 = 4.7 h, v en = 2 v, v mid = 4.6 v, v o2 = -4.9 v unless otherwise specified. table 6. electrical characteristics symbol parameter test conditions min. typ. max. unit general section v ina, v inp supply input voltage 2.3 3.7 4.5 v uvlo_h undervoltage lockout high v ina rising 2.22 2.25 v uvlo_l undervoltage lockout low v ina falling 1.9 2.18 v i_v i input current no load condition 1.7 2.1 ma i q_sh shutdown current v en =gnd t j =-40c to +85c 1a v en h enable high threshold v ina =2.5v to 4.5v, t j =-40c to +85c 1.2 v v en l enable low threshold 0.4 i en enable input current v en =v ina =4.5v t j =-40c to +85c 1a f s switching frequency pwm mode 1.2 1.5 1.7 mhz d1 max step-up maximum duty cycle no load 87 % d2 max inverting maximum duty cycle no load 87 % total system efficiency i mid,o2 =10 to 30ma, v mid =4.6v, v o2 =-4.9v 80 % i mid,o2 =30 to 150ma, v mid =4.6v, v o2 =-4.9v 85 % v ref voltage reference i ref =10a 1.216 1.228 1.240 v i ref voltage reference current capability at 98.5% of no load reference voltage 100 a step-up converter section v mid positive voltage total variation v ina =v inp =2.5v to 4.5v; i mid =5ma to 150ma, i o2 no load, t j =25c 4.55 4.6 4.65 v temperature accuracy v ina =v inp =3.7v; i mid =5ma; i o2 no load; t j =-40c to +85c 0.5 % v mid lt line transient v ina,p =3.5v to 3.0v, i mid =100ma; t r =t f =50s -12 mv
stod03as electrical characteristics doc id 022614 rev 1 9/24 symbol parameter test conditions min. typ. max. unit v midt load transient regulation i mid =3 to 30ma and i mid =30 to 3ma, t r =t f =30s 20 mv i mid =10 to 100ma and i mid =100 to 10ma, t r =t f =30s 25 mv v mid-pp tdma noise line transient regulation i mid =5 to 100ma; v ina,p =2.9v to 3.4v; f=200hz; t r =t f =50s; i o2 no load 20 mv i mid max max. step-up load current v ina,p =2.9v to 4.5v 200 ma i-l 1max step-up inductor peak current v mid 10% below of nominal value 0.9 1.1 a r dson p1 p-channel static drain-source on resistance v ina,p =3.7v, i sw =100ma 1.0 2.0 r dson n1 n-channel static drain-source on resistance v ina,p =3.7v, i sw =100ma 0.4 1.0 inverting converter section v o2 output negative voltage range 31 different values set by the s wire pin (see section 6.1.2 ) -5.4 -2.4 v output negative voltage total variation on default value v ina =v inp =2.5v to 4.5v; i o2 =5ma to 150ma, i mid no load, t j =25c -4.97 -4.9 -4.83 v temperature accuracy v ina =v inp =3.7v; i o2 =5ma, i mid no load, t j =-40c to +85c 0.5 % v o2 lt line transient v ina,p =3.5v to 3.0v, i o2 =100ma, t r =t f =50s +12 mv v o2t load transient regulation i o2 =3 to 30ma and i o2 =30 to 3ma, t r =t f =100s 20 mv load transient regulation i o2 =10 to 100ma and i o2 =100 to 10ma, t r =t f =100s 25 mv v o2-pp tdma noise line transient regulation i o2 =5 to 100ma; v ina,p =2.9v to 3.4v; f=200hz; t r =t f =50s; i mid no load 25 mv i o2 maximum inverting output current v ina,p =2.9v to 4.5v -200 ma i-l 2max inverting peak current v o2 below 10% of nominal value -1.2 -0.9 a r dson p2 p-channel static drain-source on resistance v ina,p =3.7v, i sw =100ma 0.42 r dson n2 n-channel static drain-source on resistance v ina,p =3.7v, i sw =100ma 0.43 table 6. electrical characteristics (continued)
electrical characteristics stod03as 10/24 doc id 022614 rev 1 symbol parameter test conditions min. typ. max. unit thermal shutdown otp overtemperature protection 140 c otp hyst overtemperature protection hysteresis 15 c discharge resistor r dis resistor value no load 400 t dis discharge time no load, v mid -v o2 at 10% of nominal value 8ms table 6. electrical characteristics (continued)
stod03as typical performance characteristics doc id 022614 rev 1 11/24 5 typical performance characteristics v o2 = - 4.9 v; t a = 25 c; see ta bl e 1 for external components used in the tests below. figure 4. efficiency vs. input voltage f igure 5. efficiency vs. output current figure 6. input current vs. v in no load figure 7. max. power output vs. v in, t a = 25 c figure 8. fast discharge v in = 3.7 v, no load figure 9. startup and inrush v in = 3.7 v, no load 66 % 6 8% 70 % 72 % 74 % 76 % 7 8% 8 0 % 8 2 % 8 4 % 8 6 % 88% 90 % 2.5 2.7 2.9 3 .1 3 . 33 .5 3 .7 3 .9 4.1 4. 3 4.5 efficiency [%] v in [v] io=50ma io=100ma io=150ma io=200ma 50 % 55 % 60 % 65 % 70 % 75 % 8 0 % 8 5 % 90 % 0204060 8 0 100 120 140 160 1 8 0200 efficiency [ % ] i out [ma] vin=2.7v vin= 3 .2v vin= 3 .7v vin=4.2v 100 150 200 250 300 350 400 450 500 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 v in [v] i out [ma] 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 p out [w] max i out at v o2 = -4.9v max p out en v mid v o2 i in
typical performance characteristics stod03as 12/24 doc id 022614 rev 1 figure 10. step-up ccm operation figure 11. inverting ccm operation v en = v ina = v inp = 3.7 v, i mid = 100 ma, t a = 25 c v en = v ina = v inp = 3.7 v, i o2 = 100 ma, t a = 25 c figure 12. line transient figure 13. output voltage vs. input voltage i o = 200 ma, v o2 = - 4.9 v v ina = v inp = 2.9 to 3.4 v, i mid,o2 = 100 ma, t r = t f = 50 s v in v mid v o2 0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00 10.00 1.6 1.8 2 2.2 2.4 2.6 2.8 3 v in [v] v o1 +v o2 [v] -40 c 25 c 85 c
stod03as detailed description doc id 022614 rev 1 13/24 6 detailed description 6.1 s wire protocol: to digitally communicate over a single cable with single-wire components single-wire's 3 components: 1. an external mcu 2. wiring and associated connectors 3. the stod03as device with a dedicated single-wire pin. 6.1.1 s wire features and benefits fully digital signal no handshake needed protection against glitches and spikes though an internal low pass filter acting on falling edges uses a single wire (plus analog ground) to accomplish both communication and power control transmission simplified design with an interface protocol that supplies control and signaling over a single-wire connection to set the output voltages. 6.1.2 s wire protocol single-wire protocol uses conventional cmos/ttl logic levels (maximum 0.6 v for logic ?zero? and a minimum 1.2 v for logic ?one?) with operation specified over a supply voltage range of 2.5 v to 4.5 v both master (mcu) and slave (stod03as) are configured to permit bit sequential data to flow only in one direction at a time; master initiates and controls the device data is bit-sequential with a start bit and a stop bit signal is transferred in real time system clock is not required; each single-w ire pulse is self-clocked by the oscillator integrated in the master and is asserted valid within a frequency range of 250 khz (maximum). 6.1.3 s wire basic operations the negative output voltage levels are selectable within a wide range (steps of 100 mv) the device can be enabled / disabled via s wire in combination with the enable pin.
detailed description stod03as 14/24 doc id 022614 rev 1 6.2 negative output voltage levels table 7. negative output voltage levels pulse v o2 pulse v o2 pulse v o2 1 -5.411-4.421-3.4 2 -5.312-4.322-3.3 3 -5.213-4.223-3.2 4 -5.114-4.124-3.1 5 -5.015-4.025-3.0 6 (1) -4.9 16 -3.9 26 -2.9 7 -4.817-3.827-2.8 8 -4.718-3.728-2.7 9 -4.619-3.629-2.6 10 -4.5 20 -3.5 30 -2.5 31 -2.4 1. default output voltage. table 8. enable and s wire operation table (1) enable s wire action low low device off low high negative output set by s wire high low default negative output voltage high high default negative output voltage 1. the enable pin must be set to agnd while using the s wire function.
stod03as application information doc id 022614 rev 1 15/24 7 application information 7.1 external passive components 7.1.1 inductor selection magnetic shielded low esr power inductors must be chosen as the key passive components for switching converters. for the step-up converter an inductance between 4.7 h and 6.8 h is recommended. for the inverting stage the suggested inductance ranges from 3.3 h to 4.7 h. it is very important to select the right inductor according to the maximum current the inductor can handle to avoid saturation. the step-up and the inverting peak current can be calculated as follows: equation 1 equation 2 where v mid : step-up output voltage, fixed at 4.6 v; v o2 : inverting output voltage including sign (minimum value is the absolute maximum value); i o : output current for both dc-dc converters; v in : input voltage for the stod03as; f s : switching frequency. use the minimum value of 1.2 mhz for the worst case; 1: efficiency of step-up converter. typical value is 0.85; 2: efficiency of inverting converter. typical value is 0.75. the negative output voltage can be set via s wire at - 5.4 v. accordingly, the inductor peak current, at the maximum load condition, increases. a proper inductor, with a saturation current as a minimum of 1 a, is preferred. 7.1.2 input and output capacitor selection it is recommended to use x5r or x7r low esr ceramic capacitors as input and output capacitors in order to filter any disturbance present in the input line and to obtain stable operation for the two switching converters. a minimum real capacitance value of 6 f must be guaranteed for c mid and c o2 in all conditions. consider ing tolerance, temperature variation and dc polarization, a 10 f, 10 v 10% capacitor as c mid and 2 x 10 f, 10 v 10% as c o2 , can be used to achieve the required 6 f. 1 l fs v 2 ) vin v ( vin vin 1 i v i mid min mid min min out mid boost peak ? + = ? 2 ) 2 ( 2 2 2 ) 2 ( l fs vin vo vo vin vin i vo vin i min min min min min out min min inverting peak x x - x x + x x - = - 2 ) 2 ( 2 2 2 ) 2 ( l fs vin vo vo vin vin i vo vin i min min min min min out min min inverting peak x x - x x + x x - = -
application information stod03as 16/24 doc id 022614 rev 1 7.2 recommended pcb layout the stod03as is high frequency power switching device and therefore requires a proper pcb layout in order to obtain the necessary stab ility and optimize line/load regulation and output voltage ripple. analog input (v ina ) and power input (v inp ) must be kept separated and connected together at the c in pad only. the input capacitor must be as close as possible to the ic. in order to minimize the ground noise, a common ground node for power ground and a different one for analog ground must be used. in the recommended layout, the agnd node is placed close to c ref ground while the pgnd node is centered at c in ground. they are connected by a separated layer routing on the bottom through vias. the exposed pad is connected to agnd through vias. figure 14. top layer and silk-screen (top view, not to scale)
stod03as application information doc id 022614 rev 1 17/24 figure 15. bottom layer and silk-screen (top view, not to scale)
detailed description stod03as 18/24 doc id 022614 rev 1 8 detailed description 8.1 general description the stod03as is a high efficiency dual dc -dc converter which integrates a step-up and inverting power stage suitable for supplying am oled panels. thanks to the high level of integration it needs only 6 external compon ents to operate and it achieves very high efficiency using a synchronous rectification te chnique for each of the two dc-dc converters. the controller uses an average cu rrent mode technique in order to obtain good stability and precise voltage regulation in all possible condit ions of input voltage, output voltage, and output current. in addition, the peak inductor cu rrent is monitored in order to avoid saturation of the coils. the stod03as implements a power saving technique in order to maintain high efficiency at very light load and it switches to pwm operation as the load increases in order to guarantee the best dynamic performances and low noise operation. the stod03as avoids battery leakage thanks to the true-shutdown feature and it is self protected from overtemperature. undervoltage lockout and soft-start guarantee proper operation during startup. 8.1.1 multiple operation modes both the step-up and the inverting stage of the stod03as operate in three different modes: pulse skipping (ps), discontinuous conductio n mode (dcm) and continuous conduction mode (ccm). it switches automatically betwee n the three modes according to input voltage, output current, and output voltage conditions. 8.1.2 pulse skipping operation the stod03as works in pulse skipping mode when the load current is below some tens of ma. the load current level at which this way of operation occurs depends on input voltage only for the step-up converter and on in put voltage and negative output voltage (v o2 ) for the inverting converter. 8.1.3 discontinuous conduction mode when the load increases above a few ma, the stod03as enters dcm operation. in order to obtain this type of operation the controlle r must avoid the inductor current going negative. the discontinuous mode detector (dmd) bloc ks sense the voltage across the synchronous rectifiers (p1b for the step-up and n2 for the inverting) and turn off the switches when the voltage crosses a defined threshold which, in turn, represents a certain current in the inductor. this current can vary according to the slope of the inductor current which depends on input voltage, inductance value, and output voltage. 8.1.4 continuous conduction mode at medium/high output loads, the stod03as enters full ccm at constant switching frequency mode for each of the two dc-dc converters.
stod03as detailed description doc id 022614 rev 1 19/24 8.1.5 enable pin the device operates when the en pin is set hi gh. if the en pin is set low, the device stops switching, and all the internal blocks are turned off. in this condition the current drawn from v inp /v ina is below 1 a in the whole temperature ra nge. in addition, the internal switches are in an off state so the load is electrica lly disconnected from the input, this avoids unwanted current leakage from the input to the load. when the en is pulled high, the p1b switch is turned on for 100 s. in normal operation, during this time, apart of a small drop due to parasitic resistance, v mid reaches v in . if, after this 100 s, v mid stays below v in , the p1b is turned off and stays off until a new pulse is applied to the en. this mechanism av oids the stod03as starting if a short-circuit is present on v mid . 8.1.6 soft-start and in rush current limiting after the en pin is pulled high, or after a suitable voltage is applied to v inp , v ina and en, the device initiates the startup phase. as a first step, the c mid capacitor is charged and the p1b switch implements a current limiting technique in order to keep the charge current below 400 ma. this avoids the battery overloading during startup. after v mid reaches the v inp voltage level, the p1b switch is fully turned on and the soft-start procedure for the step-up is started. after around 2 ms the soft-start for the inverting is started. the positive and negative voltages are under regulation at around 6 ms after the en pin is asserted high. 8.1.7 undervoltage lockout the undervoltage lockout function avoids im proper operation of the stod03as when the input voltage is not high enough. when the input voltage is below the uvlo threshold the device is in shutdown mode. the hysteresis of 50mv avoids unstable operation when the input voltage is close to the uvlo threshold. 8.1.8 overtemperature protection an internal temperature sensor continuously mo nitors the ic junction temperature. if the ic temperature exceeds 140 c, typical, the device stops operating. as soon as the temperature falls below 125 c, typi cal, normal operation is restored. 8.1.9 short-circuit protection when short-circuit occurs, the device is able to detect the voltage difference between v in and v mid . overshoots on lx1 are limited, decreasing the inductor current. after that, the output stages of the device are turned off. this status is maintained, avoiding current flowing to the load. a new enable transition is needed to restart the device. during startup the short-circuit protection is active. 8.1.10 fast discharge when enable turns from high to low level, the device goes into shutdown mode and lx1 and lx2 stop switching. then, the discharge switch between v mid and v in and the switch between v o2 and gnd turn on and discharge the positive output voltage and negative output voltage. when the output voltages are disch arged to 0 v, the switches turn off and the outputs are high impedance.
package mechanical data stod03as 20/24 doc id 022614 rev 1 9 package mechanical data in order to meet environmental requirements, st offers these devices in different grades of ecopack ? packages, depending on their level of environmental compliance. ecopack specifications, grade definitions an d product status are available at: www.st.com . ecopack is an st trademark.
stod03as package mechanical data doc id 022614 rev 1 21/24 figure 16. dfn12l (3 x 3) drawing table 9. dfn12l (3 x 3) mechanical data dim. mm. inch. min. typ. max. min. typ. typ. a 0.51 0.55 0.60 0.020 0.022 0.024 a1 0 0.02 0.05 0 0.001 0.002 a3 0.20 0.008 b 0.18 0.25 0.30 0.007 0.010 0.012 d 2.85 3 3.15 0.112 0.118 0.124 d2 1.87 2.02 2.12 0.074 0.080 0.083 e 2.85 3 3.15 0.112 0.118 0.124 e2 1.06 1.21 1.31 0.042 0.048 0.052 e 0.45 0.018 l 0.30 0.40 0.50 0.012 0.016 0.020 8085116-a
package mechanical data stod03as 22/24 doc id 022614 rev 1 figure 17. dfn12l (3 x 3 mm) footprint recommended data
stod03as revision history doc id 022614 rev 1 23/24 10 revision history table 10. document revision history date revision changes 20-dec-2011 1 initial release.
stod03as 24/24 doc id 022614 rev 1 please read carefully: information in this document is provided solely in connection with st products. stmicroelectronics nv and its subsidiaries (?st ?) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described he rein at any time, without notice. all st products are sold pursuant to st?s terms and conditions of sale. purchasers are solely responsible for the choice, selection and use of the st products and services described herein, and st as sumes no liability whatsoever relating to the choice, selection or use of the st products and services described herein. no license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted under this document. i f any part of this document refers to any third party products or services it shall not be deemed a license grant by st for the use of such third party products or services, or any intellectual property contained therein or considered as a warranty covering the use in any manner whatsoev er of such third party products or services or any intellectual property contained therein. unless otherwise set forth in st?s terms and conditions of sale st disclaims any express or implied warranty with respect to the use and/or sale of st products including without limitation implied warranties of merchantability, fitness for a parti cular purpose (and their equivalents under the laws of any jurisdiction), or infringement of any patent, copyright or other intellectual property right. unless expressly approved in writing by two authorized st representatives, st products are not recommended, authorized or warranted for use in milita ry, air craft, space, life saving, or life sustaining applications, nor in products or systems where failure or malfunction may result in personal injury, death, or severe property or environmental damage. st products which are not specified as "automotive grade" may only be used in automotive applications at user?s own risk. resale of st products with provisions different from the statements and/or technical features set forth in this document shall immediately void any warranty granted by st for the st product or service described herein and shall not create or extend in any manner whatsoev er, any liability of st. st and the st logo are trademarks or registered trademarks of st in various countries. information in this document supersedes and replaces all information previously supplied. the st logo is a registered trademark of stmicroelectronics. all other names are the property of their respective owners. ? 2011 stmicroelectronics - all rights reserved stmicroelectronics group of companies australia - belgium - brazil - canada - china - czech republic - finland - france - germany - hong kong - india - israel - ital y - japan - malaysia - malta - morocco - philippines - singapore - spain - sweden - switzerland - united kingdom - united states of america www.st.com

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