features package option cs5253b-8 3a ldo 5-pin 2.5v fixed linear regulator for remote sense applications cs5253b-8 description applications diagram 1 5 lead d 2 pak 1 1. v sense 2. gnd 3. v out 4. v control 5. v power tab = v out rev. 12/22/99 cherry semiconductor corporation 2000 south county trail, east greenwich, ri 02818 tel: (401)885-3600 fax: (401)885-5786 email: info@cherry-semi.com web site: www.cherry-semi.com a company ? v out fixed @ 2.5v 1.5% v power dropout < 0.40v @ 3a v control dropout < 1.05v @ 3a 1.5% trimmed reference fast transient response remote voltage sensing thermal shutdown current limit short circuit protection drop-in replacement for ez1582 backwards compatible with 3-pin regulators very low dropout reduces total power consumption this new very low dropout linear regulator reduces total power dissi- pation in the application. to achieve very low dropout, the inter- nal pass transistor is powered sepa- rately from the control circuitry. furthermore, with the control and power inputs tied together, this device can be used in single supply configuration and still offer a better dropout voltage than conventional pnp-npn based ldo regulators. in this mode the dropout is deter- mined by the minimum control voltage. the cs5253b-8 is offered in a five- terminal d 2 pak package, which allows for the implementation of a remote-sense pin permitting very accurate regulation of output volt- age directly at the load, where it counts, rather than at the regulator. this remote sensing feature virtual- ly eliminates output voltage varia- tions due to load changes and resis- tive voltage drops. typical load regulation measured at the sense pin is less than 1mv for an output voltage of 2.5v with a load step of 10ma to 3a. the cs5253b-8 has a very fast tran- sient loop response. internal protection circuitry pro- vides for ?bust-proof? operation, similar to three-terminal regulators. this circuitry, which includes over- current, short circuit, and over-tem- perature protection will self protect the regulator under all fault condi- tions. the cs5253b-8 is ideal for generat- ing a 2.5v supply to power graph- ics controllers used on vga cards. its remote sense and low value capacitance requirements make this a low cost high performance solu- tion. the cs5253b-8 is optimized from the cs5253-1 to allow a lower value of output capacitor to be used at the expense of a slower transient response. cs5253b-8 v out v sense v control v power gnd 2.5v @3a 33 f 5v 100 f 5v 10 f 10v +3.3v +5v c load gnd gnd r dis r dis (optional)
electrical characteristics: 0c t a 70c; 0c t j 150c; v sense = v out and ground = 0v; unless otherwise specified. parameter test conditions min typ max unit cs5253b-8 2 absolute maximum ratings v power input voltage.................................................................................................................. .....................................................6v v control input voltage.................................................................................................................. ...............................................13v operating junction temperature range ........................................................................................... .....................0c t j 150c storage temperature range...................................................................................................... ...............................?65c to +150c lead temperature soldering reflow (smd styles only) ......................................................................................60 sec. max above 183c, 230c peak esd damage threshold........................................................................................................... .................................................2kv output voltage v control = 3.9v to 12v, 2.463 2.50 2.538 v v power = 3.13v to 5.5v, i out = 10ma to 3a (?1.5%) (+1.5%) line regulation v control = 3.9v to 12v, .02 .20 % v power = 3.13v to 5.5v, i out = 10ma load regulation v control = 3.9v, .04 .30 % v power = 3.13v, i out = 10ma to 3a, with remote sense minimum load current v control = 5v, v power = 3.3v, 0 0 ma (note 1) ? v out = +1% control pin current v control = 3.9v, v power = 3.13v, i out = 100ma 6 10 ma (note 2) v control = 3.9v, v power = 3.13v, i out = 3a 35 120 ma ground pin current v control = 3.9v, v power = 3.13v, i out = 10ma 7 10 ma current limit v control = 3.9v, v power = 3.13v, 3.1 4.0 a ? v out = ?4% short circuit current v control = 3.9v, v power = 3.13v, v out = 0v 2.0 3.5 a ripple rejection v control = v power = 3.9v, 60 80 db (note 3) v ripple = 1v p-p @120hz, i out = 3a thermal regulation 30ms pulse, t a = 25c 0.002 %/w v control dropout voltage v power = 3.13v, i out = 100ma 0.90 1.15 v (minimum v control -v out )v power = 3.13v, i out = 1a 1.00 1.15 v (note 4) v power = 3.13v, i out = 3a 1.05 1.30 v v power dropout voltage v control = 3.9v, i out = 100ma .05 .15 v (minimum v power -v out )v control = 3.9v, i out = 1a .15 .25 v (note 4) v control = 3.9v, i out = 3a .40 .60 v rms output noise freq = 10hz to 10khz, t a = 25c 0.003 %v out temperature stability 0.5 % thermal shutdown (note 5) 150 180 210 c thermal shutdown hysteresis 25 c v control supply only v control = 13v, v power not connected, 50 ma output current gnd = v out = v sense = 0v v power supply only v power = 6v, v control not connected, 0.1 1.0 ma output current gnd = v out = v sense = 0v note 1: the minimum load current is the minimum current required to maintain regulation. note 2: the v control pin current is the drive current required for the output transistor. this current will track output current with roughly a 1:10 0 ratio. the minimum value is equal to the quiescent current of the device. note 3: this parameter is guaranteed by design and is not 100% production tested. note 4: dropout is defined as either the minimum control voltage, (v control) or minimum power voltage (v power ) to output voltage differential required to maintain 1.5% regulation at a particular load current. note 5: this parameter is guaranteed by design, but not parametrically tested in production. however, a 100% thermal shutdown fu nctional test is performed on each part.
cs5253b-8 package pin description package pin # pin symbol function 3 block diagram ? + + ? v power v control bias and tsd v ref ea ia v out v sense gnd 5lead d 2 pak 1v sense this kelvin sense pin allows for remote sensing of the output voltage at the load for improved regulation. it is internally connected to the positive input of the voltage sensing error amplifier. 2 gnd this pin is connected to system ground. 3v out this pin is connected to the emitter of the power pass transistor and provides a regulated voltage capable of sourcing 3a of current. 4v control this is the supply voltage for the regulator control circuitry. for the device to regulate, this voltage should be between 0.9v and 1.3v (depending on the output current) greater than the output voltage. the control pin current will be about 1% of the output current. 5v power this is the power input voltage. the pin is physically connected to the collector of the power pass transistor. for the device to regulate, this voltage should be between 0.1v and 0.6v greater than the output voltage, depending on output current. the out- put load current of 3a is supplied through this pin.
cs5253b-8 4 typical performance characteristics 0.5 1.0 1.5 2.0 2.5 output current (a) t j = 120 c t j = 20 c 0 3.0 0.08 0.10 0.12 0 0.02 0.04 0.06 load regulation (%) t j = 0 c load regulation vs output current 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 01 23456 v power - v out (v) output current (a) measured at ? vout = ?1.5% output current vs v power -v out transient response comparison between cs5253-1 and cs5253b-1 v out cs5253b-1 c out = 33 f 15a/ s 80a/ s i load 10ma to 3a v out cs5253-1 c out = 330 f v control = 5v v power =3.3v v out = 2.5v c control = 10 f c adj = 0.1 f transient response short circuit output current limit (a) 3.3 3.4 3.5 3.6 3.7 3.8 3.9 0 20 40 60 80 100 120 140 junction temperature (c) v power = 3.3v v control = 5v short circuit output current vs junction temperature 0 2 4 6 8 10 12 0 20 40 60 80 100 120 140 junction temperature (c) iout (ma) v control = 13v, v out = 0v, vpower not connected v control only output current vs junction temperature 0 20 40 60 80 100 120 reference voltage (v) junction temperature (c) 2.494 2.496 2.497 2.498 2.499 2.500 2.501 2.495 output voltage vs junction temperature
cs5253b-8 5 typical performance characteristics 10.0 10 1 frequency (hz) ripple rejection (db) 20.0 30.0 40.00 60.0 70.0 80.0 90.0 10 2 10 3 10 4 10 6 10 5 50.0 v in ? v out = 2v i out = 3a v ripple = 1v p-p c out = 22 f c adj = 0.1 f ripple rejection vs frequency vcontrol dropout voltage (mv) 0.0 output current (a) 800 900 1000 1100 0.5 1.0 3.0 2.5 2.0 1.5 t j = 120 c t j = 20 c t j = 0 c v power = 2.05v v control dropout voltage vs output current vpower dropout voltage (v) 0 0.0 output current (a) 50 150 200 250 300 350 400 450 500 0.5 1.0 3.0 2.5 2.0 1.5 t j = 120 c t j = 20 c t j = 0 c v power dropout voltage vs output current i out (ua) 0 5 10 15 20 25 30 0 20 40 60 80 100 120 140 junction temperature (c) v power = 6v v out = 0v v control not connected i control (ma) 40 0 20 40 60 80 100 120 140 junction temperature (c) 35 30 25 20 15 10 5 0 i out = 3a i out = 1a i out = 100ma v control = 3.9v v power = 3.13v 5.0 4.5 4.0 3.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 current limit (a) v out (v) v power = 3.3v v control = 5.0v v out = 2.5v t a = 25 c v power only output current vs junction temperature v control supply current vs junction temperature current limit vs v out
cs5253b-8 6 typical performance characteristics: continued the cs5253b-8 linear regulator is fixed at 2.5v at currents up to 3a. the regulator is protected against short circuits, and includes a thermal shutdown circuit with hysteresis. the output, which is current limited, consists of a pnp- npn transistor pair and requires an output capacitor for stability. v power function the cs5253b-8 utilizes a two supply approach to maximize efficiency. the collector of the power device is brought out to the v power pin to minimize internal power dissipation under high current loads. v control provides for the con- trol circuitry and the drive for the output npn transistor. v control should be at least 1v greater than the output voltage. special care has been taken to ensure that there are no supply sequencing problems. the output voltage will not turn on until both supplies are operating. if the control voltage comes up first, the output current will be limited to about three milliamperes until the power input voltage comes up. if the power input voltage comes up first, the output will not turn on at all until the control voltage comes up. the output can never come up unregulated. the cs5253b-8 can also be used as a single supply device with the control and power inputs tied together. in this mode, the dropout will be determined by the minimum control voltage. output voltage sensing the cs5253b-8 five terminal linear regulator includes a dedicated v sense function. this allows for true kelvin sensing of the output voltage. this feature can virtually eliminate errors in the output voltage due to load regula- tion. regulation will be optimized at the point where the sense pin is tied to the output. remote sense remote sense operation can be easily obtained with the cs5253b-8 but some care must be paid to the layout and positioning of the filter capacitors around the part. the ground side of the input capacitors on the +5v and +3.3v lines and the local v out -to-ground output capacitor on the ic must be tied close to the ground pin of the regulator. this will establish the stability of the part. the ic ground may then be connected to ground remotely at the load, giv- ing the ground portion remote sense operation. the v sense line can then be tied remotely at the positive load connection, giving the feedback remote sense opera- tion. the remote sense lines should be kelvin connected so as to eliminate the effect of load current voltage drop. an optional bypass capacitor may be used at the load to reduce the effect of load variations and spikes. remote sense current limit the internal current limit circuit limits the output current under excessive load conditions. + + + + v control v power v sense v out gnd cs5253b-8 local connections 100 f 10 f 33 f optional +load ?load r dis r dis +5v +3.3v gnd remote connections design guidelines theory of operation application notes stability vs esr 6 5 4 3 2 1 0 0 102030405060708090100 esr (ohms) capacitance ( f) unstable stable region v power = 3.3v v control = 5.0v i load = 0 to 3a v out = 2.5v v out shorted to v sense t j = 0 to 150 c
cs5253b-8 7 application notes: continued short circuit protection the device includes short circuit protection circuitry that clamps the output current at approximately 500ma less than its current limit value. this provides for a current fold- back function, which reduces power dissipation under a direct shorted load. thermal shutdown the thermal shutdown circuitry is guaranteed by design to activate above a die junction temperature of approximately 150c and to shut down the regulator output. this circuitry has 25c of typical hysteresis, thereby allowing the regula- tor to recover from a thermal fault automatically. calculating power dissipation and heat sink requirements high power regulators such as the cs5253b-8 usually oper- ate at high junction temperatures. therefore, it is important to calculate the power dissipation and junction temperatures accurately to ensure that an adequate heat sink is used. since the package tab is connected to v out on the cs5253b- 8, electrical isolation may be required for some applications. also, as with all high power packages, thermal compound in necessary to ensure proper heat flow. for added safety, this high current ldo includes an internal thermal shut- down circuit the thermal characteristics of an ic depend on the following four factors: junction temperature, ambient temperature, die power dissipation, and the thermal resistance from the die junction to ambient air. the maximum junction temperature can be determined by: t j(max) = t a(max) + pd (max) r ja the maximum ambient temperature and the power dissipa- tion are determined by the design while the maximum junc- tion temperature and the thermal resistance depend on the manufacturer and the package type. the maximum power dissipation for a regulator is: pd (max) = (v in(max) -v out(min) )i out(max) + v in(max) i in(max) a heat sink effectively increases the surface area of the pack- age to improve the flow of heat away from the ic and into the surrounding air. each material in the heat flow path between the ic and the outside environment has a thermal resistance which is measured in degrees per watt. like series electrical resistances, these thermal resistances are summed to determine the total thermal resistance between the die junction and the surrounding air, r ja . this total thermal resistance is comprised of three components. these resistive terms are measured from junction to case (r jc ), case to heat sink (r cs ), and heat sink to ambient air (r sa ). the equation is: r ja = r jc + r cs + r sa the value for r jc is 2.5c/watt for the cs5253b-8 in the d 2 pak package. for a high current regulator such as the cs5253b-8 the majority of heat is generated in the power transistor section. the value for r sa depends on the heat sink type, while the r cs depends on factors such as pack- age type, heat sink interface (is an insulator and thermal grease used?), and the contact area between the heat sink and the package. once these calculations are complete, the maximum permissible value of r ja can be calculated and the proper heat sink selected. for further discussion on heat sink selection, see our cherry application note ?thermal management for linear regulators.?
8 ordering information thermal data 5lead d 2 pak r jc typ 2.5 c/w r ja typ 10-50* c/w *depending on thermal properties of substrate. r ja = r jc + r ca package specification package dimensions in mm (inches) package thermal data part number description CS5253B-8GDP5 5 lead d 2 pak cs5253b-8gdpr5 5 lead d 2 pak (tape & reel) rev. 12/22/99 ? 1999 cherry semiconductor corporation cs5253b-8 5 lead d 2 pak (dp) 1.70 (.067) ref 0.10 (.004) 0.00 (.000) 10.31 (.406) 10.05 (.396) 0.91 (.036) 0.66 (.026) 1.40 (.055) 1.14 (.045) 4.57 (.180) 4.31 (.170) 1.68 (.066) 1.40 (.055) 2.74(.108) 2.49(.098) .254 (.010) ref 2.79 (.110) 2.29 (.090) 15.75 (.620) 14.73 (.580) 8.53 (.336) 8.28 (.326) cherry semiconductor corporation reserves the right to make changes to the specifications without notice. please contact cherry semiconductor corporation for the latest available information.
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