micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 1 features description the sc1517-5 is pin compatible with ltc1517-5. this versatile charge pump produces a regulated 5v output from an input voltage ranging from 2.7v to 5v. the extremely low operating current (typically 10a with no load) prolongs battery usage time. the small device footprint and the low external parts count (one 0.1f flying capacitor and two small bypass capacitors at v in and v out ) make the part ideally suited for compact circuit design. the sc1517-5 charge pump can be used for applications that require up to 20ma (3v < v in < 5v) of output current, while providing a regulated 5v output voltage. during short circuit a current limit circuitry provides protection, while the thermal shutdown capability cycles v out to prevent device failure. the sc1517-5 is available in a 5 lead sot-23 package. applications ? = ultra low power: i cc = 10a typ ? = soft start / short circuit current limit ? = thermal protected ? = 5v+ 4% regulated output ? = v in range: 2.7v to 5v ? = output current: 10ma (v in > 2.7v) 20ma (v in > 3v) ? = no inductors ? = ultra small application circuit ? = 800khz switching frequency ? = surface mount packaging (5 pin sot-23) ? = all specifications rated over full temperature range (-40c to 85c) ? = cellular telephones ? = battery-operated equipment ? = local power supplies ? = handheld instruments ? = pcmcia supplies tel:805-498-2111 fax:805-498-3804 web:http:// www.semtech.com device (1) package temp. range (t a ) sc1517isk-5.tr sot-23-5 -40 to 85c ordering information notes: (1) only available in tape and reel packaging. a reel contains 3000 devices cin = = cout c1 = typical application schematic note : ceramic capacitors used for improved performance, low esr tantalum with esr < 0.5 ohms could also be used.
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 2 absolute maximum ratings parameter symbol maximum units input supply voltage v in -0.3 to 6 v output supply voltage v out -0.3 to 6 v power dissipation p d 391 mw thermal resistance ja 256 c/w operating ambient temperature range t a -40 to +85 c operating junction temperature range t j -40 to +125 c storage temperature range t stg -65 to +150 c lead temperature (soldering) 10 sec t lead +300 c esd rating (human body model) esd 2 kv electrical characteristics unless specified: t a = -40c to 85c, v in = 2.7v to 5v, c1 = 0.1f, c in = 3.3f, c out = 6.8f. parameter symbol conditions min typ max units operating input voltage v in 2.7 5 v output voltage v out 2.7v < v in < 5v, i out < 10ma 4.8 5.0 5.2 v 3v < v in < 5v, i out < 20ma 4.8 5.0 5.2 v input supply current i cc 2.7v < v in < 5v, i out = 0 10 15 a v out ripple (pk-pk) (1)(2) v r v in = 3v, i out = 20ma, c out = 6.8f 75 mv p-p oscillator frequency (1)(2) f osc 800 khz v out turn-on time (1)(2) t on v in = 3v, i out = 0ma 1 ms soft start / short circuit current limit (1)(2)(3) i limit short circuit applied at vout to gnd 35 65 ma notes: (1) all electrical characteristics are for the application circuit on page 1. (2) guaranteed by design. (3) indefinite duration.
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 3 pin description pin # pin name description 1 vin charge pump input voltage. may be between 2.7v and 5v. v in should be bypassed with a > 3.3f low esr capacitor as close as possible to the pin for best performance. 2 gnd ground pin. 3 vout regulated output voltage. v out should be bypassed with a > 3.3f low esr capacitor as close as possible to the pin for best performance. 4 c1+ charge pump flying capacitor positive terminal. 5 c1- charge pump flying capacitor negative terminal. pin configuration block diagram top view sot-23-5l
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 4 typical eff. vs iout (ta = 25 deg. c.) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 10.0e-6 100.0e-6 1.0e-3 10.0e-3 100.0e-3 iout (a) efficiency (%) vin = 2.75 v vin = 3.85 v vin = 5.00 v typical eff. vs vin (ta = 25 deg. c.) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 2.50 3.00 3.50 4.00 4.50 5.00 5.50 vin (v) efficiency (%) iout = 20ma iout = 10ma iout = 5ma iout = 200ua iout = 10ua typical iin vs iout (ta = 25 deg. c.) 000.0e+0 5.0e-3 10.0e-3 15.0e-3 20.0e-3 25.0e-3 30.0e-3 35.0e-3 40.0e-3 45.0e-3 50.0e-3 000.0e+ 0 5.0e-3 10.0e-3 15.0e-3 20.0e-3 25.0e-3 iout (a) iin (a) vin = 2.75 v vin = 3.85 v vin = 5.00 v typical output ripple vs vin ( ta = 25 deg. c.) 30.0e-3 50.0e-3 70.0e-3 90.0e-3 110.0e-3 130.0e-3 150.0e-3 2.50 3.00 3.50 4.00 4.50 5.00 5.50 vin (v) vout (v) cout = 3.3uf cout = 6.8uf cout = 10uf cout = 22uf iout = 10ma
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 5 typical iin vs ta (iout = 0 a) 8.0e-6 9.0e-6 10.0e-6 11.0e-6 12.0e-6 13.0e-6 14.0e-6 0 10203040506070 ta (deg. c.) iin (a) vin = 5.00 v vin = 3.85 v vin = 2.75 v typical eff. vs ta (iout = 10 ua) 0% 10% 20% 30% 40% 50% 60% 70% 0 10203040506070 ta (deg. c.) efficiency (%) vin = 2.75 v vin = 3.85 v vin = 5.00 v typical eff. vs ta (iout = 200 ua) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 0 10203040506070 ta (deg. c.) efficiency (%) vin = 2.75 v vin = 3.85 v vin = 5.00 v typical eff. vs ta (iout = 5 ma) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 10203040506070 ta (deg. c.) efficiency (%) vin = 2.75 v vin = 3.85 v vin = 5.00 v typical eff. vs ta (iout = 10 ma) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 10203040506070 ta (deg. c.) efficiency (%) vin = 2.75 v vin = 3.85 v vin = 5.00 v typical eff. vs ta (iout = 20 ma) 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 0 10203040506070 ta (deg. c.) efficiency (%) vin = 2.75 v vin = 3.85 v vin = 5.00 v
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 6 typical vout vs vin (iout = 10ma) 4.80 4.85 4.90 4.95 5.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 vin (v) vout (v) ta = 70 deg. c. ta = 25 deg. c. ta = 0 deg. c.
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 7 turn on regulation time(ta = 25 deg. c.) load transient response(ta = 25 deg. c.) vin = 3v 2v/div. iout step 0 -10 ma vout 50mv/div. vout 2v/div. vin = 3.0v
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 8 application notes theory of operation the sc1517-5 utilizes a switched capacitor charge pump, to generate an output voltage regulated to 5v+/- 4%. an internal oscillator generates two out of phase clock signals which turn on and off internal mosfet switches. during phase1 of clock, the flying charge pump capacitor is charged to vin through switches s1, and s2. during phase2 the flying charge pump capacitor is connected in series with the input voltage via s3, and s4, producing an output voltage. an integrated comparator senses the output voltage vout vin gnd gnd cin cout c_charge s1 s4 s3 s2 s1,s2 s3,s4 on on off off charge transfer from cin to c_charge charge transfer from (cin,and c_charge) to cout current limit & soft start and disable the charge pump once an upper threshold is reached. as the output voltage drops below the lower threshold, the comparator enables the charge pump and hence regulation is achieved. short circuit / soft start an internal current limit and soft start circuit provides protection against output short circuit and limits large current spikes generated during the initial start up to charge output capacitor. as the over current condition is applied at the output, a comparator senses the output voltage and compares it to a signal approximating v in - 500mv. if v out < v in - 500mv, the comparator enables a 65ma typical limited current source and the charge pump is disabled. once the over current is removed and v out > v in - 500mv, the current source is disconnected from output and the charge pump circuitry is enabled again. thermal shutdown the thermal shutdown circuit provides added protection to the sc1517-5. during a v out short circuit condition or if the load is excessive (i out > = 20ma), the thermal shut down circuit is active and if the junction temperature exceeds approximately 160c, the charge pump is disabled. the charge pump is enabled only if the junction temperature drops to approximately 145c. the sc1517-5 will cycle in and out of thermal shut down until the short circuit or the excessive load condition on v out is removed, thereby improving device reliability. v out ripple & capacitor selection the peak to peak output ripple voltage is dependent on the following factors: 1- oscillator frequency 2- hysteresis window of the comparator 3- esr of c charge , and c out 4- capacitance value of c out , and c charge item 1, and 2 are fixed and depend on the charge pump device used. item 3, and 4 can be optimized for best performance and reduction of the output ripple. c1+ c1-
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 9 capacitor manufacturers layout consideration standard power board layout should followed to ensure proper operation. any stray inductance should be minimized, this can be achieved by using large power planes or traces, and reducing the distances between input, output and the load. all components should be placed as close as possible to the sc1517-5. the following formula could be used for an approximation for v out_ripple . figure below shows the effect of output capacitance value on the ripple voltage. capacitors used were multilayer ceramic with low esr < 0.1 ohms . following table shows typical capacitor characteristics : out out out osc out out_ripple c esr_ x i c x f x 2 i v + = typical output ripple vs vin (iout = 10ma) 30.0e-3 50.0e-3 70.0e-3 90.0e-3 110.0e-3 130.0e-3 150.0e-3 2.50 3.00 3.50 4.00 4.50 5.00 5.50 vin (v) vout (v) cout = 3.3uf cout = 6.8uf cout = 10uf cout = 22uf component esr (ohms) esl (nh) 0.1 uf ceramic 0603 package 0.100 1.60 1.0 uf ceramic 1206 package 0.120 0.47 10 uf ceramic 1206 package 0.075 0.5 47 uf, 16v tantalum d case 0.100 0.60 330 uf, 6.3v ?oscon? 0.025 2.5 330 uf, 16v al electrolytic 0.143 2.37 820 uf, 4.0v ?oscon? 0.012 2.5 1000 uf, 10v al electrolytic 0.053 5 manufacturer phone avx corp. (803)-448-9411 vishay (207)-324-4140 nichicon corp. (708)-843-7500 murata (800)-831-9172 tokin (408)-432-8020 taiyo yuden (800)-348-2496 sanyo (619)-661-6835
micropower, regulated 5v charge pump ? 2000 semtech corp. 652 mitchell road newbury park ca 91320 sc1517-5 october 3, 2000 10 device outline sot23-5l land pattern sot23-5l ecn00-1360
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