4a ultra low dropout positi ve adjustable regulator ap1184p this datasheet contains new product information. anachip corp. reserves the rights to modify the product specification without notice. no liability is assumed as a result of the use of this product. no rights under any patent accompany the sale of the product. rev.1.0 may 11, 2004 1/8 ? feature ? 0.7v maximum dropout voltage at 4a load current ? built-in thermal shutdown ? output current limiting ? adjustable output voltage ? fast transient response ? good noise rejection ? packages: sop-7l ? general description ap1184p is a 4a regulator with extremely low dropout voltage. this product is specifically designed to provide well regulated supply for applications requiring 2.8v or lower voltages from 3.3v atx power supplies where high efficiency of the switch can be achieved without the cost and complexity associated with switching regulator. one such application is the new graphic chipsets that requires anywhere from 2.4v to 2.7v supply. ? ordering information ap1184 x x x low dropout regulator package p7:sop-7l packing blank : tube a : taping lead free blank : normal l : lead free package ? typical application 470uf + 470uf + 5v 470uf + 3.3v 2.5v/4a adj vsense vctrl nc vin vout vout nc ap1184p 121 121
4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 2/8 ? block diagram thermal shutdown vout adj 1.25v + current limit vin + - + + - vsense vctrl ? pin configuration ( ap1184p7 ) adj vsense nc vctrl vin vout nc 7 6 5 8 2 3 4 1 ? pin descriptions pin numbers with boldface type are for sop-7l name i/o description adj a resistor divider from this pin to t he vout pin and ground se ts the output voltage. vsense i this pin is the positive side of the reference that allows remote load sensing to achieve excellent load regulation. a minimum of 10uf c apacitor must be connect ed from this pin to ground to insure stability. vin i the input of the regulator. typically a large st orage capacitor is connected from this pin to ground to insure that the input voltage does not sag below the minimum dropout voltage during the load transient respons e. this pin must always be higher than vout in order for the device to regulate. vctrl i this pin is the supply pin for the internal cont rol circuit as well as the base drive for the pass transistor. this pin must always by hig her than the vout pin in order the device to regulate. a minimum of 100uf capacitor mu st be connected from this pin to ground to insure stability. nc no connection vout o the output of the regulator. a minimum of 100u f capacitor must be connected from this pin to ground to insure stability.
4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 3/8 ? absolute maximum ratings symbol parameter rating unit v in input voltage 16 v v ctrl control input voltage 18 v p d power dissipation in ternally limited t st storage temperature range -65 to +150 o c t op operation junction temperature range 0 to +150 o c ? electrical characteristics unless otherwise specified, these specifications apply over, cin=1uf, cout=10uf, and tj=0 to 150 o c. typical value refer to tj=25 o c. vout=vsense. sym. parameter test condition min. typ. max. unit v ref reference voltage ap1184p-adj io=10ma, tj=25 o c, (vin-vout)=0.7v, v ctrl =v in +1v 1.225 1.250 1.275 v line regulation ap1184p-adj i o =10ma, v out +0.7v 4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 4/8 ? functional d escriptions introduction the ap1184p regulator is 5 terminal device designed specifically to provide extremely low dropout voltages comparable to the pnp type without the disadvantage of the extra power dissipation due to the base current associated with pnp regulators. this is done by bringing out the control pin of the regulator that provides the base current to the power npn and connecting it to a voltage that is greater than the voltage present at the vin pin. this flexibility makes the ap1184p ideal for applications where dual inputs are available such as a computer motherboard with an atx style power supply that provides 5v and 3.3v to the board. one such application is the new graphic chip sets that require anywhere from 2.4v to 2.7v supply. the ap1184p can easily be programmed with the addition of two external resistors to any voltages within the range of 1.25v to 15.5v. another major requirement of these graphic chips is the need to switch the load current from zero to several amps in tens of nanoseconds at the processor pins, which translates to an approximately 300 to 500ns of current step at the regulator. in addition, the output voltage tolerances are also extremely tight and they include the transient response as part of the specification. the ap1184p is specifically designed to meet the fast current transient needs as well as providing an accurate initial vo ltage, reducing the overall system cost with the need for fewer number of output capacitors. another feature of the device is its true remote sensing capability that allows accurate voltage setting at the load rather than at the device. output voltage setting the ap1184p-adj can be programmed to any voltages in the range of 1.25v to 15.5v with the addition of r1 and r2 external resistors according to the following formula: vout = vref (1+r2/r1) + iadj * r2 where : vref = 1.25v & iadj=50ua typically ap1184p-adj vin vctrl adj vout vsense r1+ r2+ vref iadj=50ua the ap1184p-adj keeps a constant 1.25v between the vsense pin and the adj pin. by placing a resistor r1 across these two pins and connecting the vsense and vout pin together, a constant current flows through r1, adding to the iadj current and into the r2 resistor producing a voltage equal to the (1.25/r1)*r2 + iadj*r2. this voltage is then added to the 1.25v to set the output voltage. this is summarized in the above equation. since the minimum load current requirement of the ap1184p-adj is 10ma, r1 is typically selected to be a 121 resistor so that it automatically satisfies this condition. notice that since the iadj is typically in the range of 50ua it only adds a small error to the output voltage and should be considered when very precise output voltage setting is required. load regulation since the ap1184p has separate pins for the output (vout) and the sense (vsense), it is ideal for providing true remote sensing of the output voltage at the load. this means that the voltage drops due to parasitic resistance such as pcb traces between the regulator and the load are compensated for using remote sensing. figure following shows a typical application of the ap1184p-adj with remote sensing.
4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 5/8 ? functional descri ptions(continued) ap1184p-adj vin vctrl vin vctrl vout vsense adj r1 r2 r l stability the ap1184p-adj requires the use of an output capacitor as part of the frequency compensation in order to make the regulator stable. typical designs for the microprocessor applications use standard electrolytic capacitors with typical esr in the range of 50 to 100m and an output capacitance of 100uf to 1000uf. fortunately as the capacitance increases, the esr decreases resulting in a fixed rc time constant. the ap1184p-adj takes advantage of the phenomena in making the overall regulator loop stable. fo r most applications a minimum of 100uf aluminum electrolytic capacitor insures both stability and good transient response. thermal design the ap1184p-adj incorporates an internal thermal shutdown that protects the device when the junction temperature exceeds the allowable maximum junction temperature. although this device can operate with junction temperatures in the range of 150 o c, it is recommended that the selected heat sink be chosen such that during maximum continuous load operation, the junction temperature is kept below this number. the example below shows the steps in selecting the proper surface mount package. assuming, the following conditions: vout=2.5v vin=3.3v vctrl=5v iout=2a dc avg. calculate the maximum power dissipation using the following equation: pd=iout*(vin-vout)+(iout/60)*(vctrl-vout) pd=2*(3.3-2.5)+(2/60)*(5-2.5)=1.68w using table below select the proper package and the amount of copper board needed. package copper area ja ( o c/w) max pd (ta=25 o c) max pd (ta=45 o c) sop7 1.0? x 1.0? 65 1.7w 1.4w note: above table is based on the maximum junction temperature of 135 o c. as shown in the above table, the sop7 package meets the requirement.
4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 6/8 ? performance characteristic output current (a) v control dropout voltage vs output current vcontrol dropout voltage (mv) 800 900 1000 1100 1200 vpower = 2.05 v tj = 20 o c tj = 120 o c 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 output current (a) v power dropout voltage vs output current 0 vpower dropout voltage (mv) 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 vcontrol = 2.75 v tj = 120 o c tj = 20 o c junction temperature ( o c) reference voltage vs junction temperature 1. 247 1. 248 1. 249 1. 250 reference voltage (v) 1. 251 1. 252 1. 253 0 20 40 60 80 100 120 output current (a) load regulation vs output current load regulation (%) 0 0. 02 0. 04 0. 06 0. 08 0. 10 0. 12 0. 14 0. 15 tj = 20 o c tj = 120 o c 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 7/8 ? performance characteristic (continued ) transient response ? marking information p: internal code blank: normal l: lead free package ac 1184 yy ww p x logo part number (ap1184-adj) ( top view) yy : year : "01"=2001 "02"=2002 ww : nth week : 01~52 ~ ( sop-7l ) v control = 5.0v v power = 3.3v v out = 2.5v c contrrol =10uf c power = 100uf c adj = 0.1uf c out = 470uf i load 10ma to 4a
4a ultra low dropout positi ve adjustable regulator ap1184p anachip corp. www.anachip.com.tw rev.1.0 may 11, 2004 8/8 ? package outline (1). package type: sop-7l a c c2 b1 d e e b2 f c3 c1 dimensions in millimeters dimensions in inches symbol min. nom. max. min. nom. max. a 5.79 5.99 6.19 0.228 0.236 0.244 b1 3.83 3.91 3.99 0.151 0.154 0.157 b2 3.78 3.86 3.94 0.149 0.152 0.155 c 4.80 4.87 4.94 0.189 0.192 0.194 c1 1.57 1.67 1.77 0.062 0.066 0.070 c2 0.32 0.4 0.48 0.013 0.016 0.019 c3 1.17 1.27 1.37 0.046 0.050 0.054 d 0.19 0.22 0.25 0.007 0.009 0.010 e 1.04ref 0.041ref e 0.48 0.68 0.88 0.019 0.027 0.035 f 1.35 1.45 1.55 0.053 0.057 0.061 7o 7o
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