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features applications general description n n n n n n n n n 2a maximum output current tiny 1.0uh chip inductor excellent transient response input voltage: 2.7v to 5.5v ultra-small, low profile 8-pin 2mm x 2mm tdfn package fixed or adjustable output voltage - adjustable output voltage: 1.0v to 3.3v high efficiency with 2.5mhz switching frequency 1ua shutdown current -40c to 85c temperature range pb-free/halogen free package rohs/reach compliant cellular phone digital cameras hard disk drives mp3 players pdas and handheld computers por table media players usb devices wireless network cards the pam2316 is a 2a step-down sync converter. the 2.5mhz switching frequency enables the use of small external components. the ultra-small 2mm x 2mm footprint and high efficiency make the pa m 2 3 1 6 a n i d e a l c h o i c e f o r p o r t a b l e applications. the pam2316 delivers a maximum output current while consuming only 55ua no load quiescent current. low r integrated mosfets and 100 duty cycle operation make the pam2316 the ideal choice for high output voltage, high current applications whi ch require a low dropout threshold t he pam 23 16 p r ov id es ex c el le nt tr an s ie nt r es p o n s e a n d o u tp ut a c c ur a c y a c r o s s th e operating range. t h e pa m 2 3 1 6 m a i n t a i n s h i g h e f f i c i e n c y th r ou g h o u t th e l o a d r a n g e . t h e pa m 2 3 1 6 automatically optimizes efficiency during light l oa d m o de ( p s m) an d m a i nt a i n s c o n s ta n t frequency and low output ripple during pwm mode. over-temperature and short circuit protection safeguard the pam2316 and system components from damage. the pam2316 is available in a pb-free, ultra- small, low pr ofile, 8-pin 2mm x 2mm tdfn package. the product is rated over a temperature range of -40c to 85c. n n n n n n n n n n n n n n 55ua no load quiescent current 100% duty cycle low-dropout operation internal soft start over-temperature and current limit protection < - % . 2 ds( on) typical application 1 www.poweranalog.com pam2316 2.5mhz,fast transient 2a step-down converter 12/2011 rev1.1 , power analog microelectronics inc c2 1.0f pvin en vin agnd pgnd fb sw sw vin=3.3v l1 1.0uh c1 10f c3 10f vout=1.2v c4 100pf r1 150k vout=0.6* (1+r1/r2) r2 150k
block diagram 2 pin configuration & marking information top view tdfn22-8 ch: product code of pam2316 v: output voltage y: year w: week , power analog microelectronics inc www.poweranalog.com p i n n o . n a m e f u n c t i o n 1 p g n d m a i n p o w e r g r o u n d r e t u r n p i n . c o n n e c t t o t h e o u t p u t a n d i n p u t c a p a c i t o r r e t u r n . 2 p v i n i n p u t p o w e r s u p p l y t i e d t o t h e s o u r c e o f t h e h i g h s i d e p - c h a n n e l m o s f e t . 3 v i n p o w e r s u p p l y ; s u p p l i e s p o w e r f o r t h e i n t e r n a l c i r c u i t r y . 4 f b f e e d b a c k i n p u t p i n . f e e d b a c k v o l t a g e t o i n t e r n a l e r r o r a m p l i f i e r , t h e t h r e s h o l d v o l t a g e i s 0 . 6 v . 5 a g n d a n a l o g g r o u n d . t h i s p i n i s i n t e r n a l l y c o n n e c t e d t o t h e a n a l o g g r o u n d o f t h e c o n t r o l c i r c u i t r y . 6 e n e n a b l e p i n . a l o g i c l o w d i s a b l e s t h e c o n v e r t e r a n d i t c o n s u m e s l e s s t h a n 1 a o f c u r r e n t . w h e n c o n n e c t e d h i g h , i t r e s u m e s n o r m a l o p e r a t i o n . 7 , 8 s w s w i t c h i n g n o d e . c o n n e c t t h e i n d u c t o r t o t h i s p i n . i t i s i n t e r n a l l y c o n n e c t e d t o t h e d r a i n o f b o t h h i g h a n d l o w s i d e m o s f e t s . pin description 12/2011 rev1.1 en r1 r2 fb + - iamp + - ircmp sw pgnd synchronous rectifier nch ( ) main switch pch ( ) pvin comp vin shutdown osc rs latch 0.6vref freq shift - + ea s q r q switching logic and blanking circuit slope comp 2.5m osc anti shoot thru - - vin gnd pam2316 2.5mhz,fast transient 2a step-down converter 1 2 3 4 8 7 6 5 pgnd pvin vin fb agnd en sw sw exposed pad (gnd)
3 absolute maximum ratings these are stress ratings only and functional operation is not implied exposure to absolute maximum ratings for prolonged time periods may affect device reliability all voltages are with respect to ground . . . input voltage..................................-0.3v to 6.5v en, fb pin voltage.............................- sw pi n voltage.....................- 0.3v to v 0.3v to v +0.3v junction temperature................................150c storage temperature range........-65c to 150c soldering temperature......................300c 5sec ( ) in in , recommended operating conditions supply voltage................................2.7v to 5.5v c c c c operation temperature range.........-40 to 85 junction temperature range........-40 to 125 thermal information p a r a m e t e r p a c k a g e s y m b o l m a x i m u m u n i t t h e r m a l r e s i s t a n c e ( j u n c t i o n t o c a s e ) t d f n 2 2 - 8 j c 2 3 . 4 t h e r m a l r e s i s t a n c e ( j u n c t i o n t o a m b i e n t ) t d f n 2 2 - 8 j a 7 0 c / w i n t e r n a l p o w e r d i s s i p a t i o n t d f n 2 2 - 8 p d 1 . 4 w , power analog microelectronics inc www.poweranalog.com 12/2011 rev1.1 pam2316 2.5mhz,fast transient 2a step-down converter
electrical characteristic t =25 , v =3.3v, vout=1.2v,c =10f, c =10f, l=1.0h, unless otherwise noted. a in in o c 4 , power analog microelectronics inc www.poweranalog.com p a r a m e t e r s y m b o l t e s t c o n d i t i o n s m i n t y p m a x u n i t s i n p u t v o l t a g e r a n g e v i n 2 . 7 3 . 3 5 . 5 v v i n r i s i n g 2 . 6 2 . 7 v h y s t e r e s i s 2 5 0 m v u v l o t h r e s h o l d v u v l o v i n f a l l i n g 2 v o u t p u t v o l t a g e r a n g e v o u t 1 1 . 2 3 . 3 v o u t p u t v o l t a g e a c c u a r y v o u t i o = 0 t o 2 a - 3 . 0 + 3 . 0 % r e g u l a t e d f e e d b a c k v o l t a g e v f b n o l o a d 0 . 5 9 1 0 . 6 0 0 . 6 0 9 v p m o s c u r r e n t l i m i t i l i m 3 . 0 a o u t p u t v o l t a g e l i n e r e g u l a t i o n l n r v i n = 3 . 3 v t o 4 v 0 . 3 % / v o u t p u t v o l t a g e l o a d r e g u l a t i o n l d r i o = 1 m a t o 2 a - 2 2 % q u i e s c e n t c u r r e n t i q n o l o a d 5 5 9 0 a s h u t d o w n c u r r e n t i s d v e n = 0 v 1 a o s c i l l a t o r f r e q u e n c y f o s c 2 . 5 m h z p m o s f e t 1 0 5 m d r a i n - s o u r c e o n - s t a t e r e s i s t a n c e r d s ( o n ) i d s = 1 0 0 m a n m o s f e t 7 0 m s w l e a k a g e c u r r e n t i l s w 1 a s t a r t - u p t i m e t s 2 5 0 u s p s m t h r e s h o l d i t h v i n = 3 . 3 v , v o = 1 . 2 v 2 5 0 4 5 0 m a e n t h r e s h o l d h i g h v e h 1 . 4 v e n t h r e s h o l d l o w v e l 0 . 4 v e n l e a k a g e c u r r e n t i e n 0 . 0 1 a o v e r t e m p e r a t u r e p r o t e c t i o n o t p 1 5 0 c o t p h y s t e r e s i s o t h 3 0 c 12/2011 rev1.1 pam2316 2.5mhz,fast transient 2a step-down converter
0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 o u t p u t c u r r e n t ( m a ) v i n = 3 . 3 v v i n = 4 . 2 v v i n = 5 v - 1 . 0 0 - 0 . 8 0 - 0 . 6 0 - 0 . 4 0 - 0 . 2 0 0 . 0 0 0 . 2 0 0 . 4 0 0 . 6 0 0 . 8 0 1 . 0 0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 o u t p u t c u r r e n t ( m a ) v i n = 3 . 3 v v i n = 4 . 2 v v i n = 5 . 0 v 5 , power analog microelectronics inc www.poweranalog.com efficiency vs output current(vo=1.5v) efficiency vs output current (vo=1.8v) efficiency vs output current(vo=2.5v) efficiency vs output current (vo=3.3v) load regulation efficiency vs output current(vo=1.2v) typical performance characteristics c t =25 , c =10 f, c =10 f,l=1.0h, unless otherwise noted. a in o 12/2011 rev1.1 pam2316 2.5mhz,fast transient 2a step-down converter vo=1.2v l=1.0uh 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 o u t p u t c u r r e n t ( m a ) v i n = 3 . 3 v v i n = 4 . 2 v v i n = 5 v 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 o u t p u t c u r r e n t ( m a ) v i n = 3 . 3 v v i n = 4 . 2 v v i n = 5 v 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 o u t p u t c u r r e n t ( m a ) v i n = 3 . 3 v v i n = 4 . 2 v v i n = 5 v 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 1 0 0 1 1 0 1 0 0 1 0 0 0 1 0 0 0 0 o u t p u t c u r r e n t ( m a ) v i n = 4 . 2 v v i n = 5 . 0 v v i n = 5 . 5 v
- 0 . 5 - 0 . 4 - 0 . 3 - 0 . 2 - 0 . 1 0 . 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 2 . 7 3 . 1 3 . 5 3 . 9 4 . 3 4 . 7 5 . 1 5 . 5 i n p u t v o l t a g e ( v ) i o = 1 0 0 m a i o = 1 0 0 0 m a i o = 2 0 0 0 m a 6 , power analog microelectronics inc www.poweranalog.com typical performance characteristics c t =25 , c =10 f, c =10 f,l=1.0h,unless otherwise noted. a in o line regulation rdson vs input voltage (vo=1.2v) quiescent current vs input voltage 12/2011 rev1.1 pam2316 2.5mhz,fast transient 2a step-down converter vo=1.2v l=1.0uh 3 6 4 1 4 6 5 1 5 6 6 1 2 . 7 3 . 1 3 . 5 3 . 9 4 . 3 4 . 7 5 . 1 5 . 5 i n p u t v o t a g e ( v ) 0 2 0 4 0 6 0 8 0 1 0 0 1 2 0 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) p m o s n m o s vo=1.2v l=1.0uh start-up io=2a, vo=1.2v, vin=3.3v load transient io=0~2a, vo=1.2v, vin=3.3v load transient io=0~2a, vo=3.3v, vin=5v
7 , power analog microelectronics inc www.poweranalog.com application information the basic pam2316 application circuit is shown on page 1. external component selection is determined by the load requirement, selecting l first and then cin and cout. for most applications, the value of the inductor will fall in the range of 0.47h to 2h. its value is chosen based on the desired ripple current. large value inductors lower ripple current and small value inductors result in higher ripple currents. higher v or vout also increases the ripple current as shown in equation 2.0a reasonab le starting point for setting ripple current is i = 800ma (40% of 2a). (1) the dc current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. thus, a 2.8a rated inductor should be enough for most applications (2a + 800ma). for better efficiency, choose a low dc-resis tance inductor. in continuous mode, the source current of the top mosfet is a square wave of duty cycle vout/vin. to prevent large voltage transients, a low esr input capacitor sized for the maximum rms current must be used. the maximum rms capacitor current is given by: this formula has a maximum at v =2vout, w h e r e i = i / 2 . t h i s s i m p l e w o r s t - c a s e condition is com monly used for design because even significant deviations do not offer much relief. note that the capacitor manufacturer's ripple current ratings are often based on 2000 hours of life. this makes it advisable to fu rther derate the capacitor, or choose a capacitor rated at a higher temperature than required. consult the manufac turer if there is any question. the selection of cout is driven by the required effective series resistance (esr). typically, once the esr requirement for cout has been met, the rms current rating generally far exceeds the i (p-p) requirement. the output ripple vout is determined by: where f = operating frequency, c =output capacitance and i = ripple current in the inductor. for a fixed o utput voltage, the output ripple is highest at maximum input voltage since i increases with input voltage. higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. their high ripple current, high voltage rating and low esr make them ideal for switching regulator applications. using ceramic capacitors can achieve very low output ripple and small circuit size. when choosing the input and output ceramic capacitors, choose the x5r or x7r dielectric formulations. th ese dielectrics have the best temperature and voltage charac teristics of all the ceramics for a given value and size. inductor selection c and c selection using ceramic input and output capacitors in l in r m s o u t ripple out l l in out = vout i thermal protection limits power dissipation in the pam2316. when the junction temperature exceeds 150c, the otp (over temperature protection) starts the thermal shutdown and turns the pass transistor off. the pass transistor r e s u m e s o p e r a t i o n a f t e r t h e j u n c t i o n temperature drops below 120c. f o r c o n t i n u o u s o p e r a t i o n , t h e j u n c t i o n temperature should be maintained below 125c. the power dissipation is defined as: i is the step-down converter quiescent current. the term tsw is used to estimate the full load step-down converter switching losses. for the condition where the step-down converter is in dropout at 100% duty cycle, the total device dis sipation reduces to: since r , quiescent current, and switching l out (esr+1/8fc ) thermal consideration q ds(on) ( ) 1 2 o u t i n o u t i n r m s o m a x i n v v v c r e q u i r e d i i v - ? ? ? ? @ ( ) ( ) ? ? d ? ? ? ? o u t o u t l i n 1 v i = v 1 - f l v ( ) ( ) o d s o n h i n o d s o n l 2 d o s w s o q i n i n v r + v - v r p = i + t f i + i v v 12/2011 rev1.1 pam2316 2.5mhz,fast transient 2a step-down converter 2 d o d s o n h q i n p = i r + i v
8 , power analog microelectronics inc www.poweranalog.com losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. the maximum power dissipation de pend s on th e ther ma l r esi sta nc e of ic package, pcb layout, the rate of surrounding airflow and temperature difference between junction and ambient. the maximum power dissipation can be calculated by the following formula: where tj(max) is the maximum allowable junction temperature 125c.t is the ambient temperature and is the thermal resistance from t he junction to the ambient. based on the standard jedec for a two layers thermal test board, the thermal resistance of tdfn2x2 70c/w, respectively. the maximum power dissipation at t = 25c can be calculated by following formula: p =(125c-25c)/70c/w=1.42w the internal reference is 0.6v (typical). the output voltage is calculated as below: the output voltage is given by table 1. resistor selection for output voltage setting when load current decreases, the peak switch current in power-pmos wil l be lower than skip current threshold and the device will enter into pulse skipping mode. in this mode, the device has two states, working state and idle state. first, the device enters into wo rk i ng s ta te c on tr ol l ed b y i nte r nal er r or amplifier.when the feedback voltage gets higher than internal reference voltage, the device will enter into low i idle state with most of internal blocks disabled. the output voltage will be reduced by loading or leakage current. when the feedback voltage gets lowe r than the internal reference voltage, the convertor will start a working state again. as the input voltage approaches the output voltage, the converter turns the p-chan nel transistor continuously on. in this mode the output voltage is equal to the input voltage minus th e voltag e d rop ac ros s the p - c hannel transistor: v = v ?i (r + r ) where r = p-channel switch on resistance, i = o ut pu t c u rr e n t, r = i nd uc t or dc resistance the reference and the circuit remain reset until the vin crosses its uvlo threshold. the pam2316 has an internal soft-start circuit that limits the in-rush current during start-up. this prevents possible voltage drops of the input voltage and eliminates the output voltage overshoot. when the converter output is shorted or the device is overloaded,each high-side mosfet current-limit event (3a typ) turns off the high-side mosfet and turns on the low-side mosfet. a internal counter is used to count the each current-limit event. the counter is reset after consecutive high-side mosfets turn on without re ac h in g c ur r e nt l i mi t. i f the c ur r en t- l im it condition persists, the counter fills up. the control logic then stops both high-side and low- side mosfets and waits for a hiccup period, before attemping a new soft-start sequence. the counter bits is decided by vfb voltage. if vfb 0 2, the counter is 3-bit counter; if vfb>0.2 the counter is 6-bit counter. the typical hicuup made duty cycle is 1.7%. the hicuup mode is disable during soft-start time. when the die temperature exceeds 150c, a reset occurs and the reset remains until the temperature decrease to 120c, at which time the circuit can be restarted. a ja ja a d q out in load dson l dson l o a d l setting the output voltage table 1: pulse skipping mode (psm) description 100% duty cycle operation uvlo and soft-start short circuit protection thermal shutdown . ? ? ? ? ? ? o r 1 v = 0 . 6 1 + r 2 j ( m a x ) a d j a t - t p = 12/2011 rev1.1 v o r 1 r 2 1 . 2 v 1 5 0 k 1 5 0 k 1 . 5 v 1 5 0 k 1 0 0 k 1 . 8 v 3 0 0 k 1 5 0 k 2 . 5 v 3 8 0 k 1 2 0 k 3 . 3 v 6 8 0 k 1 5 0 k pam2316 2.5mhz,fast transient 2a step-down converter
9 , power analog microelectronics inc www.poweranalog.com pcb layout check list when laying out the printed circuit board, the following checklist should be used to ensure proper operation of the pam2316. check the following in your layout: 1. the input capacitor should be close to ic as close as possible. 2. must put a small decoupling capacitor between vin pin and agnd pin. 3. minimize the switching loop area to avoid excessive switching noise. 4. agnd and pgnd should connect at input capacitor gnd. 5. for the good thermal dissipation, pam2316 has a heat dissipate pad in the bott om side, it should be soldered to pcb surface. for the copper area can't be large in the component side, so we can use mu ltiple vias connect to other side of the pcb. 12/2011 rev1.1 pam2316 2.5mhz,fast transient 2a step-down converter
ordering information pam 2316 x x x xxx output voltage number of pins package type pin configuration 10 , power analog microelectronics inc www.poweranalog.com p i n c o n f i g u r a t i o n p a c k a g e t y p e n u m b e r o f p i n s o u t p u t v o l t a g e a t y p e g : t d f n 2 2 - 8 c : 8 a d j : a d j u s t a b l e ( 0 . 6 v ) 12/2011 rev1.1 p a r t n u m b e r m a r k i n g p a c k a g e t y p e s t a n d a r d p a c k a g e p a m 2 3 1 6 a g c a d j c h v y w t d f n 2 2 - 8 3 , 0 0 0 u n i t s / t a p e & r e e l pam2316 2.5mhz,fast transient 2a step-down converter
11 , power analog microelectronics inc www.poweranalog.com 12/2011 rev1.1 outline dimensions pam2316 2.5mhz,fast transient 2a step-down converter tdfn 2x2 plane seating 0 08 . c 8 b c ( / / ) d 2 xe 2 4 index area top view 9 side view bottom view pin 1 id # d e nxb d2 8 0 50 . 2x2 body size lead pitch e ( ) count lead summary table r0 20 . pin 1 id # symbol min nom max a1 0 00 . 0 02 . 0 05 . a 0 70 . 0 75 . 0 80 . common dimension unit: millimeters d b s c 2 . 0 0 e b s c 2 . 0 0 m i n 0 . 1 8 n o m 0 . 2 5 b m a x 0 . 3 0 m i n 1 . 5 5 n o m 1 . 6 0 d 2 m a x 1 . 6 5 m i n 0 . 8 5 n o m 0 . 9 0 e 2 m a x 0 . 9 5 m i n 0 . 2 0 n o m 0 . 3 0 l m a x 0 . 4 0 n 8

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