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features applications general description n n n n n n n n n n n efficiency up to 95% only 40 a(typ.) quiescent current output current: up to 1a internal synchronous rectifier 3mhz switching frequency soft start under-voltage lockout short circuit protection thermal shutdown small tsot23-5, tdfn22-8 and tdfn22-6 packages smart phone mid portable electronics wireless devices cordless phone computer peripherals battery powered widgets electronic scales digital frame the PAM2304 is a step-down current-mode, dc- dc converter. at heavy load, the constant- frequency p wm cont rol per for ms exc ellent stability and transient response. to ensure the longest battery life in portable applications, the pa m 2 3 0 4 p r o v i d e s a p o w e r - s a v i n g p u l s e - skipping modulation (psm) mode to reduce quiescent current under light load operation to save power. the PAM2304 supports a range of input voltages from 2.5v to 5.5v, allowing the use of a single li+/li-polymer cell, multiple alkaline/nimh cell, usb, and other standard power sources. the output voltage is adjustable from 0.6v to the input voltage. all versions employ internal power switch and synchronous rectifierfor to minimize external part count and realize high efficiency. during shutdown, the input is disconnected from the output and the shutdown current is less than 1 a. other key features include under-voltage lockout to prevent deep battery discharge. the PAM2304 is available in tsot23-5, tdfn22- 8 and tdfn22-6 packages. rohs pass and green package n n n n n n n n n typical application 1 www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter 11/2011 rev1.1 , power analog microelectronics inc 1 0 . 6 1 2 o r v r ? ? = ? + ? ? ? ? vin sw gnd en l 1uh vo co 10f v c in in 10f r1 r2 fb cfw 100pf
block diagram 2 pin configuration & marking information top view tsot23-5 cj: product code of PAM2304 v: output voltage y: year w: week , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter 1 2 3 5 4 en gnd sw fb vin en fb + - iamp + - ircmp sw gnd synchronous rectifier nch ( ) main switch pch ( ) vin comp vin shutdown osc rs latch 0.6vref freq shift - + ea s q r q switching logic and blanking circuit slope comp 3.0m osc anti shoot thru - - 11/2011 rev1.1 top view tdfn22-8 1 2 3 4 8 7 6 5 fb agnd vin pgnd sw sw nc en dfn22-6 top view t gnd vin en 1 2 3 6 5 4 sw nc fb
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 6.0v 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................................2.5v 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 s y m b o l p a c k a g e m a x i m u m u n i t t s o t 2 3 - 5 n o t e 1 3 0 t d f n 2 2 - 8 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 c a s e ) j c t d f n 2 2 - 6 2 5 t s o t 2 3 - 5 2 5 0 t d f n 2 2 - 8 7 0 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 ) j a t d f n 2 2 - 6 6 8 c / w t s o t 2 3 - 5 4 0 0 t d f n 2 2 - 8 1 4 0 0 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 a = 2 5 c ) p d t d f n 2 2 - 6 9 8 0 m w , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter note: the maximun output current for tsot23-5 package is limited by internal power dissipation capacity a s described in application information hereinafter. 11/2011 rev1.1 t s o t 2 3 t d f n 2 2 - 8 t d f n 2 2 - 6 n a m e f u n c t i o n 1 8 4 e n e n a b l e c o n t r o l i n p u t . f o r c e t h i s p i n v o l t a g e a b o v e 1 . 5 v , e n a b l e s t h e c h i p , a n d b e l o w 0 . 3 v s h u t s d o w n t h e d e v i c e . 2 - 6 g n d g r o u n d 3 5 , 6 1 s w t h e d r a i n s o f t h e i n t e r n a l m a i n a n d s y n c h r o n o u s p o w e r m o s f e t . 4 3 5 v i n c h i p m a i n p o w e r s u p p l y p i n 5 1 3 f b 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 . - 2 - a g n d a n a l o g g r o u n d . - 4 - 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 . - 7 2 n c n o c o n n e c t e d pin description
electrical characteristic t =25 , v =3.6v, v =1.8v, c =10f, c =10f, l=1h, unless otherwise noted. a in o in o c 4 , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter 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 . 5 5 . 5 v 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 0 . 5 8 8 0 . 6 0 . 6 1 2 v r e f e r e n c e v o l t a g e l i n e r e g u l a t i o n v f b 0 . 3 % / v r e g u l a t e d o u t p u t v o l t a g e a c c u a r y v o i o = 1 0 0 m a - 3 + 3 % p e a k i n d u c t o r c u r r e n t i p k v i n = 3 v , v f b = 0 . 5 v o r v o = 9 0 % 1 . 5 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 = 2 . 5 v t o 5 v , i o = 1 0 m a 0 . 2 0 . 5 % / 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 8 0 0 m a 0 . 5 1 . 5 % q u i e s c e n t c u r r e n t i q n o l o a d 4 0 7 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 v o = 1 0 0 % 3 m h z o s c i l l a t o r f r e q u e n c y f o s c v f b = 0 v o r v o = 0 v 1 m h z p m o s f e t 0 . 3 0 . 4 5 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 0 . 3 5 0 . 5 s w l e a k a g e c u r r e n t i l s w 0 . 0 1 1 a h i g h e f f i c i e n c y 9 5 % e n t h r e s h o l d h i g h v e h 1 . 5 v e n t h r e s h o l d l o w v e l 0 . 3 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 11/2011 rev1.1
5 , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter 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=2.8v) eifficiency vs output current (vo=3.3v) efficiency vs output current (vo=1.2v) typical performance characteristics c t =25 , c =10 f, c =10 f, l=1 h, unless otherwise noted. a in o 11/2011 rev1.1 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) 2 . 5 v 3 . 3 v 4 . 2 v 5 v 5 . 5 v 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) 2 . 5 v 3 . 3 v 4 . 2 v 5 v 5 . 5 v 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) 2 . 5 v 3 . 3 v 4 . 2 v 5 v 5 . 5 v 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) 3 . 3 v 4 . 2 v 5 v 5 . 5 v 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) 3 . 3 v 4 . 2 v 5 v 5 . 5 v 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 1 0 1 0 0 1 0 0 0 o u t p u t c u r r e n t ( m a ) 4 . 2 v 5 v 5 . 5 v
PAM2304 3mhz, 1a step-down dc-dc converter efficiency vs input voltage ( ) vo=1.5v efficiency vs input voltage ( ) vo=1.8v efficiency vs input voltage ( ) vo=2.8v efficiency vs input voltage ( ) vo=2.5v 6 , power analog microelectronics inc www.poweranalog.com eifficiency vs input voltage (vo=3.3v) efficiency input voltage ( ) vs vo=1.2v typical performance characteristics c t =25 , c =10 f, c =10 f, l=1 h, unless otherwise noted. a in o 11/2011 rev1.1 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 m a 1 0 m a 0 . 1 a 0 . 3 a 0 . 6 a 1 a 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 m a 1 0 m a 0 . 1 a 0 . 3 a 0 . 6 a 1 a 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 m a 1 0 m a 0 . 1 a 0 . 3 a 0 . 6 a 1 a 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 m a 1 0 m a 0 . 1 a 0 . 3 a 0 . 6 a 1 a 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 m a 1 0 m a 0 . 1 a 0 . 3 a 0 . 6 a 1 a 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 0 . 7 0 . 8 0 . 9 1 1 . 1 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 m a 1 0 m a 0 . 1 a 0 . 3 a 0 . 6 a 1 a
PAM2304 3mhz, 1a step-down dc-dc converter 7 , power analog microelectronics inc www.poweranalog.com typical performance characteristics t =25 c, c =10 f, c =10 f, l=1 h, unless otherwise noted. a in o o 0 . 1 0 . 1 5 0 . 2 0 . 2 5 0 . 3 0 . 3 5 0 . 4 2 3 4 5 6 i n p u t v o l t a g e 0 0 . 1 0 . 2 0 . 3 0 . 4 0 . 5 0 . 6 2 0 7 0 1 2 0 t e m p e r a t u r e ( ) v i n = 4 . 2 v v i n = 3 . 6 v v i n = 2 . 7 v r vs input voltage dson rdson vs temperature vin =3.6v quiescent current vs input voltage oscillator frequency vs input voltage 11/2011 rev1.1 3 5 3 7 3 9 4 1 4 3 4 5 4 7 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 . 2 v 1 . 5 v 1 . 8 v 2 . 5 v 2 . 8 v 1 . 2 1 . 4 1 . 6 1 . 8 2 2 . 2 2 . 4 2 . 6 2 . 8 3 3 . 2 2 . 5 3 3 . 5 4 4 . 5 5 5 . 5 i n p u t v o l t a g e ( v ) 1 . 2 v 1 . 5 v 1 . 8 v 2 . 5 v 2 . 8 v 3 . 3 v
8 , power analog microelectronics inc www.poweranalog.com application information the basic PAM2304 application circuit is shown in 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 1h. 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 1. a reasonable startin g point for setting ripple current is i = 400ma (40% of 1a). (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 1.4a rated inductor should be enough for most applications (1a + 400ma). for better efficiency, choose a low dc-resis tance inductor. in continuous mode, the source current of the top mosfet is a square wa ve 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 further dera te 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 output volt age, 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. these dielec trics 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 thermal consideration thermal protection limits power dissipation in the PAM2304. 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 f ull 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: q ( ) 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 - ? ? ? ? @ o u t l o u t 1 v i e s r + 8 f c ? ? @ ? ? ? ? v v PAM2304 3mhz, 1a step-down dc-dc converter ( ) ( ) ? ? 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 11/2011 rev1.1
9 , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter since r , quiescent current, and switching 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 tempera ture and is the thermal resistance from the junction to the ambient. based on the standard jedec for a two layers thermal test board, the thermal resistance of tsot23-5 package is 250c/w. the maximum power dissipation at t = 25c can be calculated by following formula: p =(125c-25c)/250c/w=0.4w 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 as the input vo ltage 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 PAM2304 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. the soft-start acts as a digital circuit to increase the switch current in several steps to the p-channel current limit (1500ma). the switch peak current is limited cycle-by-cycle to a typical value of 1500ma. in the event of an output voltage short circuit, the device operates with a frequency of 1mhz and minimum duty cycle, therefore the average input current is typically 200ma. when the d ie temperature exceeds 150c, a reset occurs and the reset remains until the temperature decrease to 120c, at which time the circuit can be restarted. ds(on) a ja ja a d out in load dson l dson l o a d l setting the output voltage table 1: 100% duty cycle operation uvlo and soft-start short circuit protection thermal shutdown ? ? ? ? ? ? o r 1 v = 0 . 6 1 + r 2 2 d o d s o n h q i n p = i r + i v j ( m a x ) a d j a t - t p = 11/2011 rev1.1 v o r 1 r 2 1 . 2 v 1 0 0 k 1 0 0 k 1 . 5 v 1 5 0 k 1 0 0 k 1 . 8 v 2 0 0 k 1 0 0 k 2 . 5 v 3 8 0 k 1 2 0 k 3 . 3 v 5 4 0 k 1 2 0 k
10 , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter pcb layout check list when laying out the printed circuit board, the following checklist should be used to ensure proper operation of the PAM2304. these items are also illustrated graphically in figure 1. check the following in your layout: 1. the power traces, consisting of the gnd trace, the sw trace and the vin trace should be kept shor t, direct and wide. 2. does the v pin connect directly to the feedback resistors? the resistive divider r1/r2 must be co n nected between the (+) plate of c and ground. 3. does the (+) plat e of cin connect to vin as closely as possible? this capacitor provides the ac current to the internal power mosfets. 4. keep the switching node, sw, away from the sensitive vfb node. 5. keep the (?) plates of c and c as close as possible. fb out in out 11/2011 rev1.1
ordering information pam 2304 x x x xxx output voltage number of pins package type pin configuration 11 , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter 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 5 p i n s b t y p e 6 p i n s c t y p e 8 p i n s a : t s o t - 2 3 k : t d f n 2 2 - 6 g : t d f n 2 2 - 8 b : 5 f : 6 c : 8 a d j : a d j u s t a b l e 11/2011 rev1.1 p a r t n u m b e r o u t p u t v o l t a g e 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 0 4 a a b a d j a d j t s o t - 2 3 - 5 3 , 0 0 0 u n i t s / t a p e & r e e l p a m 2 3 0 4 b k f a d j a d j t d f n 2 2 - 6 3 , 0 0 0 u n i t s / t a p e & r e e l p a m 2 3 0 4 c g c a d j a d j t d f n 2 2 - 8 3 , 0 0 0 u n i t s / t a p e & r e e l
outline dimensions 12 , power analog microelectronics inc www.poweranalog.com PAM2304 3mhz, 1a step-down dc-dc converter l ref. l1 (ref.) tsot23-5 m i l l i m e t e r r e f . m i n m a x a 1 . 1 0 m a x a 1 0 0 . 1 0 a 2 0 . 7 0 1 c 0 . 1 2 r e f . d 2 . 7 0 3 . 1 0 e 2 . 6 0 3 . 0 0 e 1 1 . 4 0 1 . 8 0 l 0 . 4 5 r e f . l 1 0 . 6 0 r e f . 0 o 1 0 o b 0 . 3 0 0 . 5 0 e 0 . 9 5 r e f . e 1 1 . 9 0 r e f . d e1 b e 11/2011 rev1.1
PAM2304 3mhz, 1a step-down dc-dc converter 13 , power analog microelectronics inc www.poweranalog.com 11/2011 rev1.1 outline dimensions tdfn2x2-8 plane seating 0 08 . c 8 b c 4 index area ( / / ) d 2 xe 2 ( / / ) 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 n 8 0 40 . 0 30 . 0 20 . nom l max min e bsc min nom max b 0 30 . 0 25 . 0 18 . 2 00 . 2 00 . d bsc 1 30 . max nom d2 1 20 . 1 05 . min max nom e2 min 0 60 . 0 70 . 0 45 . unit: millimeters
PAM2304 3mhz, 1a step-down dc-dc converter 14 , power analog microelectronics inc www.poweranalog.com 11/2011 rev1.1 outline dimensions tdfn2x2-6

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