advanced power electronics corp. features description ultra low dropout voltage 250mv at 1.5a output current low esr output capacitor (mlcc) applicable 0.8v reference voltage fast transient response current limit and thermal shutdown protection adjustable output voltage by external resistors power-on-reset monitoring on both vcntl and vin pins under voltage protection power ok output with a delay time internal soft-start sop-8 with exposed pad package rohs compliant & halogen free data and specifications subject to change without notice 20100107d APE8951 typical application ordering information 1 1.5a ultra low dropout linear regulator the APE8951 is a 1.5a ultra low dropout linear regulator. the product is specifically designed to provide well supply voltage for front side bus termination on motherboard and nb applications. the ic needs two supply voltages, a voltage for the circuitry and a main supply voltage for power conversion, to reduce power dissipation and provide extremely low dropout. the APE8951 integrates many functions. a power-on-reset(por) circuit monitors both supply voltage to prevent wrong operations. a thermal shutdown and current limit functions protect the device against thermal and current over-load. a pok indicates the output status with time delay which is set internally. it can control other converter for power sequence. the APE8951 can be enabled by other power system. pulling and holding the en pin below 0.4v shuts off the output. the APE8951 is available in esop-8 package which features small size as so-8 and exposed pad to reduce the j unction-to-case resistance, being applicable in 2~3w applications. figure 1. output capacitor with esr > 20m figure 2. output capacitor is mlcc vcntl 6 pok 7 8 en 1 gnd vin vout vout fb 5 4 3 2 APE8951 r3 1k c1 1uf vcntl=5v r1 1k r2 2k c6 12~48nf c4 220uf c5 0.1uf c3 0.1uf vin=1.5v vout=1.2v/1.5a c4 220uf vcntl 6 pok 7 8 en 1 gnd vin vout vout fb 5 4 3 2 APE8951 r3 1k c1 1uf vcntl=5v r1 39k r2 78k c4 56pf c3 22uf vin=1.5v vout=1.2v/1.5a vout=vfb x (1+r1/r2) vfb=0.8v c2 22uf package type APE8951x - hf halogen free mp : esop-8
advanced power electronics corp. APE8951 absolute maximum ratings vcntl supply voltage(v cntl ) -------------------------- - -0.3 to 7 v vin supply voltage(v in ) ---------------------------------- - -0.3 to 3.3 v en and fb pin voltage ----------------------------------- - -0.3 to vcntl + 0.3v power good voltage(v pok ) ------------------------------ - -0.3 to 7 v power dissipation(p d ) ------------------------------------- - 3 w storage temperature range(t st ) --------------------- - -65c to 150c junction temperature range(t j ) ---------------------- - -25c to 150c operating temperature range(t op ) ------------------ - -20c to + 85c thermal resistance from junction to case(rth jc ) - 15c/w 40c/w note. rth ja is measured with the pcb copper area(need connect to exposed pad) of approx. 1.5 in 2 (multi-layers) recommended operating conditions vcntl supply voltage(v cntl ) -------------------------- - +3.1 to 6 v vin supply voltage(v in ) ---------------------------------- - +1.1 to 3.3 v output voltage(v out )v cntl =3.3v +0.8 to 1.2 v v cntl =5v +0.8 to v in -0.2 v output current(i out ) --------------------------------------- - +0 to 1.5 a junction temperature range(t j ) ---------------------- - -25c to 125c package information electrical specifications ( v cntl =5v, v in =1.5v, v out =1.2v, t a =25 o c, unless otherwise specified) parameter sym test condition min typ max units vcntl por threshold v cntl(porth) 2.7 2.9 3.1 v vcntl por hysteresis v cntl(hys) - 0.4 - v vin por threshold v in(porth) 0.8 0.9 1.0 v vin por hysteresis v in(hys) - 0.5 - v vcntl nominal supply current i cntl en=v cntl 0.4 1 2 ma vcntl shutdown current i sd en=0v - 18 30 ua feedback voltage v fb v cntl =3.3 ~ 5v 0.784 0.8 0.816 v load regulation i out = 0a ~ 1.5a - 0.06 0.25 % i out = 1.5a, v cntl =5v, t j =25 o c - 0.23 0.3 v i out = 1.5a, v cntl =5v, t j =25~125 o c - - 0.3 v 2 thermal resistance from junction to ambient(rth ja ) dropout voltage v drop
advanced power electronics corp. APE8951 electrical specifications(cont.) soft start time t ss -2- ms en pin logic high threshold voltage en hysteresis -30-mv en pin pull-up current i en en=gnd - 10 - ua current limit i lim v cntl =3.3 ~ 5v, t j =25 o c234a v cntl =3.3 ~ 5v, t j =-25~125 o c2--a under voltage threshold vfb falling - 0.4 - v pok threshold voltage for powe r ok v pok vfb rising 89% 92% 95% vfb pok threshold voltage for powe r not ok v pnok vfb falling 78% 81% 84% vfb pok low voltage pok sinks 5ma - 0.25 0.4 v pok delay time t delay 0.8 2 10 ms thermal thutdown temp t sd - 150 - oc thermal thutdown hysteresis - 50 - oc pin descriptions pin symbol pin description gnd gnd pin fb feedback pin vout ic power supply pin en h : normal operation ; l : shutdown pok power ok output pin vcntl cntl pin input voltage vin input voltage 3 v enh enable 0.4 0.8 1.2 v block diagram - + vin vout gnd error amp en vcntl soft-start and control logic power -on reset current limit enable thermal shutdown bandgap fb -+ pok delay pok -+ uv 0.4v 90% vref n-mosfet
advanced power electronics corp. APE8951 function pin description fb vout = 0.8 x (1 + r1/r2) vin and exposed pad vcntl pok en vout function description power-on-reset internal soft-start current limit 4 connecting this pin to an external resistor divider receives the feedback voltage of the regulator. the output voltage set by the resistor divider is determined by: where r1 is connected from vout to fb with kelvin sensing and r2 is connected from fb to gnd. a bypass capacitor may be connected with r1 in parallel to improve load transient response. the recommended r2 and r1 are in the range of 1k~100kohm. main supply input pins for power conversions. the exposed pad provides a very low impedance input path for the main supply voltage. please tie the exposed pad and vin pin (pin 5) together to reduce the dropout voltage. the voltage at this pin is monitored for power-on reset purpose. power input pin of the control circuitry. connecting this pin to a +5v(recommended) supply voltage provides the bias for the control circuitry. the voltage at this pin is monitored for power-on reset purpose. power-ok signal output pin. this pin is an open-drain output used to indicate status of output voltage by sensing fb voltage. this pin is pulled low when the rising fb voltage is not above the vpok threshold or the falling fb voltage is below the vpnok threshold, indicating the output is not ok. enable control pin. pulling and holding this pin below 0.4v shuts down the output. when re-enabled, the ic undergoes a new soft-start cycle. left this pin open, an internal current source 10ua pulls this pin up to vcntl voltage, enabling the regulator. output of the regulator. please connect pin 3 and 4 together using wide tracks. it's necessary to connect an output capacitor with this pin for closed-loop compensation and im p rovin g transient res p onses. power-on-reset (por) circuit monitors both input voltages at vcntl and vin pins to prevent wrong logic controls. the por function initiates a soft-start process after the two supply voltages exceed their rising por threshold voltages during powering on. the por function also pulls low the pok pin regardless the output voltage when the vcntl volta g e falls below it?s fallin g por threshold. an internal soft-start function controls rise rate of the output voltage to limit the current surge at start-up. the typical soft-start interval is about 2ms. the APE8951 monitors the current via the output nmos and limits the maximum current to prevent load and APE8951 from damage during overload or short circuit
advanced power electronics corp. APE8951 function description(cont.) output voltage regulation under voltage protection (uvp) thermal shutdown 5 an error amplifier working with a temperature compensated 0.8v reference and an output nmos regulates output to the preset voltage. the error amplifier designed with high bandwidth and dc gain provides very fast transient response and less load regulation. it compares the reference with the feedback voltage and amplifies the difference to drive the out p ut nmos which p rovides load current from vin to vout. the APE8951 monitors the voltage on fb pin after soft-start process is finished. therefore the uvp is disabling during soft-start. when the voltage on fb pin falls below the under-voltage threshold, the uvp circuit shuts off the output immediately. after a while, the APE8951 starts a new soft-start to regulate output. a thermal shutdown circuit limits the junction temperature of APE8951. when the junction temperature exceeds +150c, a thermal sensor turns off the output nmos, allowing the device to cool down. the regulator regulates the output again through initiation of a new soft-start cycle after the junction temperature cools by 50c, resulting in a pulsed out put durin g continuous thermal overload conditions.
advanced power electronics corp. APE8951 typical performance characteristics ch1 : v out , 500mv/div time : 2ms/div ch1 : v in , 1v/div time : 1ms/div ch2 : i out , 1a/div ch2 : v cntl , 5v/div ch3 : v pok , 1v/div ch4 : v out , 1v/div 6 current limit en pin floating test reference voltage vs. temperature 0.784 0.789 0.794 0.799 0.804 0.809 0.814 -40-25 0 255075100125 temperature( v in v cntl v pok v out
advanced power electronics corp. APE8951 typical performance characteristics ch1 : v in , 1v/div time : 10ms/div ch1 : v in , 1v/div time : 10ms/div ch2 : v out , 1v/div ch2 : v out , 1v/div ch3 : v pok , 1v/div ch3 : v pok , 1v/div ch4 : v cntl , 2v/div ch4 : v cntl , 2v/div ch1 : v en , 5v/div time : 1ms/div ch1 : v en , 5v/div time : 1ms/div ch2 : v out , 1v/div ch2 : v out , 1v/div ch3 : i out , 1a/div ch3 : i out , 1a/div ch4 : v pok , 1v/div ch4 : v pok , 1v/div ch1 : v in , 1v/div time : 500us/div ch1 : v out , 10mv/div time : 100us/div ch2 : v cntl , 5v/div ch2 : i out , 1a/div ch3 : v pok , 1v/div ch4 : v out , 1v/div 7 power on sequence power off sequence enable sequence shutdown sequence pok delay load transient response v en v out i out v pok v en v out i out v pok v out v pok v cntl v in pok delay v out v in v pok v cntl v in v out v pok v cntl i out v out
package outline : esop-8 millimeters symbols min nom max a 5.80 6.00 6.20 b 4.80 4.90 5.00 c 3.80 3.90 4.00 d 048 e 0.40 0.65 0.90 f 0.19 0.22 0.25 m 0.00 0.08 0.15 0.35 0.42 0.49 l 1.35 1.55 1.75 j k g p 3.15 3.25 3.35 q 2.25 2.35 2.45 1.all dimension are in millimeters. 2.dimension does not include mold protrusions. part marking information & packing : esop-8 1.27 typ. h advanced power electronics corp. 0.375 ref. 45 j l 8951mp ywwsss package code part numbe r date code (ywwsss) y last digit of the year ww week sss sequence b a2 i p q 8
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