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? semiconductor components industries, llc, 2006 february, 2006 ? rev. 2 1 publication order number: NCP1406/d NCP1406 25 v/25 ma pfm step?up dc?dc converter the NCP1406 is a monolithic pfm step?up dc?dc converter. this device is designed to boost single lithium or two cells aa/aaa battery voltage up to 25 v (with internal mosfet) output for handheld applications. a pullup chip enable feature is built?in with this device to extend battery?operating life. in addition to standard boost converter topologies, this device can be configured for voltage?inverting and step?down applications. this device is available in space?saving tsop?5 package. with its small footprint, the device is also ideal for generating a boosted voltage from a 3.3 v or 5.0 v power rail. features ? 85% efficiency at v out = 25 v, i out = 25 ma, v in = 5.0 v ? low operating current of 15 a (not switching) ? low shutdown current of 0.3 a ? low startup voltage of 1.8 v typical at 0 ma ? output voltage up to 25 v with built?in 26 v mosfet switch ? pfm switching frequency up to 1.0 mhz ? chip enable ? output voltage soft?start ? feedback pin open/short circuit protection ? input undervoltage lockout ? thermal shutdown ? low profile and minimum external parts ? micro miniature tsop?5 package ? pb?free package is available typical applications ? lcd bias ? white led driver ? oled driver ? personal digital assistants (pda) ? digital still camera ? cellular telephone ? hand?held games ? hand?held instrument tsop?5/sot23?5/sc59?5 sn suffix case 483 pin connections device package shipping ? ordering information NCP1406snt1 tsop?5 3000 tape & ree l 1 2 3 4 http://onsemi.com dam = device marking a = assembly location y = year w = work week = pb?free package (note: microdot may be in either location) marking diagram vdd 5 gnd 1 5 1 5 damayw fb ce lx (top view) ?for information on tape and reel specifications, including part orientation and tape sizes, please refer to our tape and reel packaging specification brochure, brd801 1/d. NCP1406snt1g tsop?5 (pb?free) 3000 tape & ree l
NCP1406 http://onsemi.com 2 v in 2.0 v to 5.5 v c 1 10 f 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 enable l1 8.2 h d1 mbr0530t1 v out 25 v c 3 82 pf c 2 3.3 f r 1 r 2 v out 1.19 r 1 r 2 1 figure 1. typical 25 v step?up application circuit 2.2 m 110 k v in 2.0 v to 5.5 v c 1 10 f 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 enable l1 8.2 h d1 mbr0520lt1 v out 15 v c 3 68 pf c 2 4.7 f r 1 r 2 v out 1.19 r 1 r 2 1 figure 2. typical 15 v step?up application circuit 1.3 m 110 k v in 2.0 v to 5.5 v c 1 10 f 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 enable l1 8.2 h d1 mbr0520lt1 v out 8 v c 3 12 pf c 2 4.7 f r 1 r 2 v out 1.19 r 1 r 2 1 figure 3. typical 8.0 v step?up application circuit 620 k 110 k
NCP1406 http://onsemi.com 3 figure 4. representative block diagram lx pfm on/off timing control driver + ? tsd fb fault protection vdd uvlo + ? vref soft?start pfm comparator ce gnd fb pin function description pin symbol description 1 ce chip enable pin (1) the chip is enabled if a voltage which is equal to or greater than 0.9 v is applied. (2) the chip is disabled if a voltage which is less than 0.3 v is applied. (3) the chip will be enabled if it is left floating. 2 fb pfm comparator inverting input, and is connected to off?chip resistor divider which sets output voltage. 3 vdd power supply pin for internal circuit. 4 gnd ground pin. 5 lx external inductor connection pin. maximum ratings rating symbol value unit power supply voltage (pin 3) vdd ?0.3 to 6.0 v input/output pin lx (pin 5) lx peak sink current fb (pin 2) v lx i lx v fb ?0.3 to 27 1.5 ?0.3 to 6.0 v a v ce (pin 1) input voltage range v ce ?0.3 to 6.0 v power dissipation and thermal characteristics maximum power dissipation @ t a = 25 c thermal resistance, junction?to?air p d r ja 500 250 mw c/w operating ambient temperature range t a ?40 to +85 c operating junction temperature range t j ?40 to +150 c storage temperature range t stg ?55 to +150 c maximum ratings are those values beyond which device damage can occur. maximum ratings applied to the device are individual stress limi t values (not normal operating conditions) and are not valid simultaneously. if these limits are exceeded, device functional operation is not implied, damage may occur and reliability may be af fected. 1. this device series contains esd protection and exceeds the following tests: human body model (hbm) 2.0 kv per jedec standard: jesd22?a114 for all pins. machine model (mm) 200 v per jedec standard: jesd22?a115 for all pins. 2. latchup current maximum rating: 150 ma per jedec standard: jesd78. 3. moisture sensitivity level (msl): 1 per ipc/jedec standard: j?std?020a.
NCP1406 http://onsemi.com 4 dissipation ratings package power rating @t a 25 c derating factor @t a 25 c power rating @t a = 70 c power rating @t a = 85 c tsop?5 500 mw 4.0 mw/ c 320 mw 260 mw electrical characteristics (v out = 25 v, t a = ?40 c to +85 c for min/max values, typical values are at t a = 25 c, unless otherwise noted.) characteristic symbol min typ max unit on/off timing control minimum off time (v dd = 3.0 v, v fb = 0 v) t off 0.08 0.13 0.20 s maximum on time (current not asserted) t on 0.58 0.90 1.40 s maximum duty cycle d max 84 90 96 % minimum startup voltage (i out = 0 ma) v start ? 1.8 2.0 v minimum startup voltage t emperature coefficient (t a = ?40 to +85 c) v start ? 1.6 ? mv/ c minimum hold voltage (i out = 0 ma) v hold ? 1.7 1.9 v soft?start time t ss ? 3.0 8.0 ms lx (pin 5) internal switch voltage (note 4) (note 5) v lx ? ? 26 v lx pin on?state resistance (v lx = 0.4 v, v dd = 5.0 v) r sw(on) ? 0.7 ? current limit (when i lx reaches i lim , the lx switch is turned off by the lx switch protection circuit) (note 5) i lim ? 0.80 ? a off?state leakage current (v lx = 26 v) i lkg ? 0.1 1.0 a ce (pin 1) ce input voltage (v dd = 3.0 v, v fb = 0 v) high state, device enabled low state, device disabled v ce(high) v ce(low) 0.9 ? ? ? ? 0.3 v v ce input current high state, device enabled (v dd = v ce = 5.5 v) low state, device disabled (v dd = 5.5 v, v ce = v fb = 0 v) i ce(high) i ce(low) ? ?500 10 ?150 500 ? na na total device supply v oltage v dd 1.4 ? 5.5 v undervoltage lockout (v dd falling) v uvlo ? 1.0 1.3 v feedback v oltage t a = 25 c t a = ?40 to +85 c v fb 1.178 1.170 1.190 1.190 1.202 1.210 v feedback pin bias current (v fb = 1.19 v) i fb ? 15 45 na operating current 1 (v fb = 0 v, v dd = v ce = 3.0 v, maximum duty cycle) i dd1 ? 0.7 1.5 ma operating current 2 (v dd = v ce = v fb = 3.0 v, not switching) i dd2 ? 15 25 a off?state current (v dd = 5.0 v, v ce = 0 v) i off ? 0.3 1.3 a thermal shutdown (note 5) t sd ? 140 ? c thermal shutdown hysteresis (note 5) t sdhys ? 10 ? c 4. recommended maximum v out up to 25 v. 5. guaranteed by design, not tested.
NCP1406 http://onsemi.com 5 typical characteristics v in = 2.0 v 2.4 v 3.0 v 4.2 v 5.0 v i out , output current (ma) v out , output voltage (v) 3.7 v v in = 2.0 v 2.4 v 3.0 v i out , output current (ma) v out = 15 v l1 = 8.2 h, sumida cr43?8r2mc c1 = 10 f c2 = 4.7 f c3 = 68 pf t a = 25 c figure 2 02040608 0 efficiency (%) v in = 2.0 v 2.4 v 3.0 v 4.2 v 5.0 v i out , output current (ma) v out = 15 v l1 = 8.2 h, sumida cr43?8r2mc c1 = 10 f c2 = 4.7 f c3 = 68 pf t a = 25 c figure 2 14.0 14.5 15.0 15.5 16.0 020406080 v out , output voltage (v) v in = 2.4 v 3.0 v 3.7 v 4.2 v 5.0 v i out , output current (ma) v out = 25 v l1 = 8.2 h, sumida cr43?8r2mc c1 = 10 f c2 = 3.3 f c3 = 82 pf t a = 25 c figure 1 60 70 80 90 100 0 102030405 0 efficiency (%) 60 70 80 90 100 figure 5. output voltage versus output current (v out = 25 v, l = 8.2 h) figure 6. efficiency versus output current (v out = 25 v, l = 8.2 h) figure 7. output voltage versus output current (v out = 15 v, l = 8.2 h) figure 8. efficiency versus output current (v out = 15 v, l = 8.2 h) 7.0 7.5 8.0 8.5 9.0 0 25 50 75 100 125 150 figure 9. output voltage versus output current (v out = 8.0 v, l = 8.2 h) figure 10. efficiency versus output current (v out = 8.0 v, l = 8.2 h) v in = 2.4 v 3.0 v 3.7 v 4.2 v 5.0 v i out , output current (ma) v out = 25 v l1 = 8.2 h, sumida cr43?8r2mc c1 = 10 f c2 = 3.3 f c3 = 82 pf t a = 25 c figure 1 24.0 24.5 25.0 25.5 26.0 01020 v out , output voltage (v) 3.7 v 4.2 v 3.7 v 5.0 v v out = 8.0 v l1 = 8.2 h, sumida cr43?8r2mc c1 = 10 f c2 = 4.7 f c3 = 12 pf t a = 25 c figure 3 v in = 2.0 v 2.4 v 3.0 v 4.2 v 5.0 v efficiency (%) 3.7 v 60 70 80 90 100 0 25 50 75 100 125 1 50 i out , output current (ma) v out = 8.0 v l1 = 8.2 h, sumida cr43?8r2mc c1 = 10 f c2 = 4.7 f c3 = 12 pf t a = 25 c figure 3 30 40 50
NCP1406 http://onsemi.com 6 typical characteristics v in = 2.0 v 2.4 v 3.0 v 4.2 v 5.0 v i out , output current (ma) v out , output voltage (v) 3.7 v v in = 2.0 v 2.4 v 3.0 v 4.2 v 5.0 v i out , output current (ma) 14.0 14.5 15.0 15.5 16.0 0204060 v out , output voltage (v) v in = 2.0 v 3.0 v 3.7 v 4.2 v 5.0 v i out , output current (ma) v out = 25 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 3.3 f c3 = 150 pf t a = 25 c figure 1 60 70 80 90 100 0 5 10 15 20 25 efficiency (%) figure 11. output voltage versus output current (v out = 25 v, l = 10 h) figure 12. efficiency versus output current (v out = 25 v, l = 10 h) figure 13. output voltage versus output current (v out = 15 v, l = 10 h) figure 14. efficiency versus output current (v out = 15 v, l = 10 h) 7.0 7.5 8.0 8.5 9.0 0 25 50 75 100 figure 15. output voltage versus output current (v out = 8.0 v, l = 10 h) figure 16. efficiency versus output current (v out = 8.0 v, l = 10 h) v in = 2.0 v 3.0 v 3.7 v 4.2 v 5.0 v i out , output current (ma) 24.0 24.5 25.0 25.5 26.0 0 v out , output voltage (v) 3.7 v v out = 8.0 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 4.7 f c3 = 20 pf t a = 25 c figure 3 v in = 2.0 v 2.4 v 3.0 v 5.0 v efficiency (%) 3.7 v 60 70 80 90 100 025507510 0 i out , output current (ma) v out = 8.0 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 4.7 f c3 = 20 pf t a = 25 c figure 3 0 5 10 15 20 25 30 v v out = 25 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 3.3 f c3 = 150 pf t a = 25 c figure 1 2.4 v 3 0 2.4 v 10 30 50 v out = 15 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 4.7 f c3 = 120 pf t a = 25 c figure 2 v in = 2.0 v 3.0 v 3.7 v 4.2 v 5.0 v i out , output current (ma) 60 70 80 90 100 0 1020304050 efficiency (%) 6 0 2.4 v v out = 15 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 4.7 f c3 = 120 pf t a = 25 c figure 2 4.2 v
NCP1406 http://onsemi.com 7 typical characteristics ?50 t a , ambient temperature ( c) 25 i dd2 , operating current 2 ( a) ?25 0 25 50 75 10 0 20 15 10 5 0 v dd = v ce = v fb = 3.0 v ?50 t a , ambient temperature ( c) 60 70 80 90 100 d max , maximum cycle (%) ?25 0 25 50 75 10 0 v dd = 3.0 v v fb = 0 v ?50 figure 17. feedback voltage versus ambient temperature figure 18. maximum duty cycle versus ambient temperature figure 19. maximum on time versus ambient temperature figure 20. minimum off time versus ambient temperature figure 21. operating current 1 versus ambient temperature figure 22. operating current 2 versus ambient temperature t a , ambient temperature ( c) 1.14 1.16 1.18 1.20 1.22 v fb , feedback voltage (v) ?25 0 25 50 75 100 v dd = 3.0 v ?50 t a , ambient temperature ( c) 0.18 t off , minimum off time ( s) ?25 0 25 50 75 10 0 ?50 t a , ambient temperature ( c) t on , maximum on time ( s) ?25 0 25 50 75 100 v dd = 3.0 v 0.6 0.7 0.8 0.9 1.0 1.1 1.2 0.16 0.14 0.12 0.10 0.08 v dd = 3.0 v ?50 t a , ambient temperature ( c) i dd1 , operating current 1 ( a) ?25 0 25 50 75 100 v dd = v ce = 3.0 v v fb = 0 v 1000 900 800 700 600 500
NCP1406 http://onsemi.com 8 typical characteristics ?50 t a , ambient temperature ( c) 6 t ss , soft?start time (ms) ?25 0 25 50 75 10 0 ?50 t a , ambient temperature ( c) 50 i ce(high) , ce ?high? input current (na) ?25 0 25 50 75 10 0 v dd = v ce = 5.5 v ?50 figure 23. off?state current versus ambient temperature figure 24. ce ?high? input current versus ambient temperature figure 25. ce ?low? input current versus ambient temperature figure 26. minimum startup voltage versus ambient temperature figure 27. undervoltage lockout voltage versus ambient temperature figure 28. soft?start time versus ambient temperature t a , ambient temperature ( c) i off , off?state current (na) ?25 0 25 50 75 100 v dd = 5.0 v v ce = 0 v ?50 t a , ambient temperature ( c) 2.4 v start , minimum startup voltage (v) ?25 0 25 50 75 10 0 ?50 t a , ambient temperature ( c) i ce(low) , ce ?low? input current (na) ?25 0 25 50 75 100 v dd = 5.5 v v ce = 0 v ?500 i out = 0 ma ?50 t a , ambient temperature ( c) v uvlo , undervoltage lockout voltage (v) ?25 0 25 50 75 100 1.3 0 200 400 600 800 1000 40 30 20 10 0 ?400 ?300 ?200 ?100 0 2.2 2.0 1.8 1.6 1.4 1.2 1.1 1.0 0.9 0.8 5 4 3 2 1 0
NCP1406 http://onsemi.com 9 typical characteristics 3.7 v 3.0 v 2.4 v 2.0 v 1.8 v v dd = 5.0 v ?50 t a , ambient temperature ( c) 1.1 i limit , current limit (a) ?25 0 25 50 75 10 0 1 figure 29. no load input current versus input voltage figure 30. current limit versus ambient temperature figure 31. switch?on resistance versus input voltage figure 32. switch?on resistance versus ambient temperature figure 33. lx pin off?state leakage current versus ambient temperature figure 34. feedback pin bias current versus ambient temperature v in , input voltage (v) i in , no load input current (ma) 23456 1 v in , input voltage (v) r sw(on) , switch?on resistance ( ) 234 5 6 t a = 85 c 1.4 ?50 t a , ambient temperature ( c) i lkg , lx pin off?state leakage current (na) ?25 0 25 50 75 100 1000 0.5 0.4 0.3 0.2 0.1 0 v out = 25 v l1 = 8.2 h d1 = mbr0530lt1 c1 = 10 f c2 = 3.3 f c3 = 82 pf r1 = 2.2 m r2 = 110 k t a = 25 c 1.0 0.9 0.8 0.7 0.6 1.2 1.0 0.8 0.6 0.4 t a = ?40 c t a = 25 c ?50 t a , ambient temperature ( c) r sw(on) , switch?on resistance ( ) ?25 0 25 50 75 1.4 1.2 1.0 0.8 0.6 0.4 10 0 800 600 400 200 0 v dd = 3.0 v v lx = 26 v v ce = 0 v ?50 t a , ambient temperature ( c) i fb , feedback pin bias current (na) ?25 0 25 50 75 10 0 50 40 30 20 10 0 v dd = 3.0 v v fb = 1.19 v
NCP1406 http://onsemi.com 10 typical characteristics figure 35. load transient response (v out = 25 v) l1 = 8.2 h, c1 = 10 f, c2 = 3.3 f, v in = 3.7 v 1. v out = 25 v (ac coupled), 100 mv/div 2. i out = 1.0 ma to 15 ma, 20 ma/div l1 = 8.2 h, c1 = 10 f, c2 = 4.7 f, v in = 3.7 v 1. v out = 15 v (ac coupled), 100 mv/div 2. i out = 1.0 ma to 20 ma, 20 ma/div figure 36. load transient response (v out = 15 v) figure 37. line transient response (v out = 25 v) l1 = 8.2 h, c1 = 10 f, c2 = 3.3 f, i out = 15 ma 1. v out = 25 v (ac coupled), 100 mv/div 2. v in = 3.0 v to 4.0 v, 2.0 v/div figure 38. line transient response (v out = 15 v) l1 = 8.2 h, c1 = 10 f, c2 = 4.7 f, i out = 15 ma 1. v out = 15 v (ac coupled), 100 mv/div 2. v in = 3.0 v to 4.0 v, 2.0 v/div figure 39. operating waveforms (light load) figure 40. operating waveforms (heavy load) l1 = 8.2 h, c1 = 10 f, c2 = 3.3 f, v in = 4.2 v, v out = 25 v, i out = 5.0 ma 1. v lx , 10 v/div 2. i l , 200 ma/div 3. v ripple , 50 mv/div l1 = 8.2 h, c1 = 10 f, c2 = 3.3 f, v in = 4.2 v, v out = 25 v, i out = 30 ma 1. v lx , 10 v/div 2. i l , 200 ma/div 3. v ripple , 50 mv/div
NCP1406 http://onsemi.com 11 typical characteristics 0 i out , output current (ma) 5.0 v start , startup voltage (v) 510152025 4.0 3.0 2.0 1.0 0 figure 41. startup/shutdown waveforms (v out = 25 v) l1 = 8.2 h, c1 = 10 f, c2 = 3.3 f, v in = 4.2 v, i out = 20 ma 1. v ce , 0 v to 1.0 v to 0 v, 1.0 v/div 2. i l , 500 ma/div 3. v out , 10 mv/div figure 42. startup/shutdown waveforms (v out = 15 v) l1 = 8.2 h, c1 = 10 f, c2 = 4.7 f, v in = 4.2 v, i out = 25 ma 1. v ce , 0 v to 1.0 v to 0 v, 1.0 v/div 2. i l , 500 ma/div 3. v out , 10 mv/div figure 43. startup voltage versus output current (v out = 25 v) 0 i out , output current (ma) 5.0 v start , startup voltage (v) 51015202 5 4.0 3.0 2.0 1.0 0 figure 44. startup voltage versus output curren t (v out = 15 v) 30 v out = 25 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 3.3 f d1 = mbr0530lt1 figure 1 t a = 25 c v out = 15 v l1 = 10 h, sumida cmd4d11?100mc c1 = 10 f c2 = 4.7 f d1 = mbr0520lt1 figure 2 t a = 25 c
NCP1406 http://onsemi.com 12 detailed operating description operation the NCP1406 is a monolithic dc?dc switching converter optimized for single lithium or two cells aa/aaa size batteries powered portable products. the NCP1406 device consists of soft?start circuit, chip enable circuit, pfm comparator, voltage reference, pfm on/off timing control circuit, driver, current limit circuit, open?drain mosfet switch, input voltage uvlo, thermal shutdown, and feedback pin short?circuit/ open?circuit protection. the device operating current is typically 15 a, and can be further reduced to about 0.3 a when the chip is disabled (v ce < 0.3 v). the operation of NCP1406 can be best understood by referring to the block diagram and typical application circuit in figures 1 and 4. the pfm comparator monitors the output voltage via the external feedback resistor divider by comparing the feedback voltage with the reference voltage. when the feedback voltage is lower than the reference voltage, the pfm control and driver circuit turns on the n?channel mosfet switch and the current ramps up in the inductor. the switch will remain on for the maximum on?time, 0.90 s, or until the current limit is reached, whichever occurs first. the mosfet switch is then turned off and energy stored in the inductor will be discharged to the output capacitor and load through the schottky diode. the mosfet switch will be turned off for at least the minimum off?time, 0.13 s, and will remain off if the feedback voltage is higher than the reference voltage and output capacitor will be discharged to sustain the output current, until the feedback voltage is again lower than reference voltage. this switching cycle is then repeated to attain voltage regulation. soft?start there is a soft?start circuit in NCP1406. when power is applied to the device, the soft?start circuit limits the device to switch at a small duty cycle initially, the duty cycle is then increased gradually until the output voltage is in regulation. with the soft?start circuit, the output voltage over?shoot is minimized and the startup capability with heavy loads is also improved. on/off t iming control the maximum on?time is typically 0.90 s, whereas, the minimum off?time is typically 0.13 s. the switching frequency can be up to 1.0 mhz. voltage reference and output voltage the internal bandgap voltage reference is trimmed to 1.19 v at an accuracy of 1.0% at 25 c. the voltage reference is connected to the non?inverting input of the pfm comparator and the inverting input of the pfm comparator is connected to the fb pin. the output voltage can be set by connected an external resistor voltage divider from the v out to the fb pin. with the internal 26 v mosfet switch, the output voltage can be set between v in to 25 v. current limit the current limit circuit limits the maximum current flowing through the lx pin to typical 0.80 a during the mosfet switch turn?on period. when the current limit is exceeded, the switch will be turned off. with the current limit circuit, the peak inductor current is limited to the current limi t, saturation of inductor is prevented and output voltage over?shoot during startup can also be minimized. n?channel mosfet switch the NCP1406 is built?in with a 26 v open drain n?channel mosfet switch which allows high output voltage up to 25 v to be generated from simple step?up topology. input voltage undervoltage lockout there is an undervoltage lockout circuit continuously monitoring the voltage at the vdd pin. the device will be disabled if the vdd pin voltage drops below the uvlo threshold voltage. fb pin short?circuit/open?circuit protection with the fb protection circuit, the drain?to?source leakage current of the n?ch mosfet is sensed. when the fb pin connection is shorted or opened, the converter switches at maximum duty cycle, the peak of v lx and the v out will build up, and the leakage current will increase. when the leakage current increases to a certain level, the converter will stop switching with the protection circuit. therefore, the peak of v lx will stop increasing at a certain level before the n?ch mosfet is damaged immediately. however, the sensing of the leakage current is not very accurate and cannot be too close to the normal 26 v maximum operating condition. therefore, the v lx is around 30 v to 40 v during a fb pin protection fault. thermal shutdown when the chip junction temperature exceeds 140 c, the entire ic is shutdown. the ic will resume operation when the junction temperature drops below 130 c. enable/disable operation the NCP1406 offers ic shutdown mode by the chip enable pin (ce pin) to reduce current consumption. an internal 150 na pullup current source ties the ce pin to the vdd pin by default. therefore, the user can float the ce pin for permanent ?on?. when the voltage at the ce pin is equal to or greater than 0.9 v, the chip will be enabled, which means the device is in normal operation. when the voltage at the ce pin is less than 0.3 v, the chip is disabled, which means ic is shutdown. during shutdown, the ic supply current reduces to 0.3 a and the lx pin enters high impedance state. however, the input remains connected to the output through the inductor and the schottky diode, keeping the output voltage one diode forward voltage drop below the input voltage.
NCP1406 http://onsemi.com 13 applications circuit information external component selection inductor the NCP1406 is designed to work well with a range of inductance values; the actual inductance value depends on the specific application, output current, efficiency, and output ripple voltage. for step?up conversion, the device works well with inductance ranging from 1.0 h to 47 h. in general, an inductor with small dcr, usually less than 1.0 , should be used to minimize loss. it is necessary to choose an inductor with saturation current greater than the peak switching current in the application. NCP1406 is designed to operate in discontinuous conduction mode (dcm). stable operation in continuous conduction mode is not guaranteed. for each switching cycle, if the internal mosfet is switched on, it will be switched off only when either the maximum on?time, t on , of typical 0.9 s is reached or the inductor current limit of 0.8 a is met, whichever is earlier. therefore, the designer can choose to use either the maximum on?time or the current limit to turn off the mosfet switch. if the goal is targeted to minimize output ripple voltage, the maximum on?time of 0.9 s should be used to turn off the mosfet; however, the maximum output current will be reduced. if we target to maximize the output current, the current limit should be chosen to turn off the mosfet, but this method will result in a larger output ripple voltage. if the maximum on?time is used to turn of f the mosfet in order to achieve a smaller output ripple voltage, it is critical to ensure that the maximum on?time has been reached before the current limit is met. to ensure this condition is met, the inductance l should be selected according to the following inequality: l v in i lim t on(max) where v in is the input voltage, i lim is the current limit which is typically 0.8 a, and t on(max) is the maximum on?time which is typically 0.9 s. the maximum output current under this maximum on?time control can be calculated from the equation below: i out(max) v 2 in t on(max) 2l(v out v d ) where v in is the input voltage, t on(max) is the maximum on?time which is typically 0.9 s, l is the selected inductance, v out is the desired output voltage, v d is the schottky diode forward voltage, and is the conversion efficiency which can be assumed typically 80% for better margin for estimation. the above equation for calculating i out(max) is for dcm mode operation only. in fact, the operation can go beyond the critical conduction mode if the current loading further increases above the maximum output current in dcm mode. however, stable operation in continuous conduction mode is hard to achieve, and double pulsing or group pulsing will occur which will lead to much larger inductor current ripple and result in larger output ripple voltage. if the current limit is used to turn off the mosfet in order to maximize the output current, it is critical to make sure that the current limit has been reached before the maximum on?time is met. to ensure this condition is met, the inductance l should be selected according the following inequality: l v in i lim t on(max) since there is 100 ns internal propagation delay between the time the current limit is reached and the time the mosfet is switched off, the actual peak inductor current can be obtained from the equation below: i pk i lim v in l 100 ns where i lim is the current limit which is typically 0.8 a, v in is the input voltage, l is the selected inductance. then the maximum output current under the current limit control can be calculated by the equation below: i out(max) v in i pk 2(v out v d ) this method can achieve larger maximum output current in dcm mode. since the current limit is reached in each switching cycle, the inductor current ripple is larger resulting in larger output voltage ripple. two ceramic capacitors in parallel can be used at the output to keep the output ripple small. diode the diode is the main source of loss in dc ? dc converters. the key parameters which affect their efficiency are the forward voltage drop, v d , and the reverse recovery time, trr. the forward voltage drop creates a loss just by having a voltage across the device while a current flowing through it. the reverse recovery time generates a loss when the diode is reverse biased, and the current appears to actually flow backwards through the diode due to the minority carriers being swept from the p ? n junction. a schottky diode with the following characteristics is recommended: 1. small forward voltage, v d < 0.3 v. 2. small reverse leakage current. 3. fast reverse recovery time/switching speed. 4. rated current larger than peak inductor current, i rated > i pk . 5. reverse voltage larger than output voltage, v reverse > v out .
NCP1406 http://onsemi.com 14 input capacitor the input capacitor stabilizes the input voltage and minimizes peak current ripple from the power source. the capacitor should be connected directly to the inductor pin where the input voltage is applied in order to effectively smooth the input current ripple and voltage due to the inductor current ripple. the input capacitor is also used to decouple the high frequency noise from the vdd supply to the internal control circuit; therefore, the capacitor should be placed close to the vdd pin. for some particular applications, separate decoupling capacitors should be provided and connected directly to the vdd pin for better decoupling effect. a larger input capacitor can better reduce ripple current at the input. by reducing the ripple current at the input, the converter efficiency can be improved. in general, a 4.7 f to 22 f ceramic input capacitor is sufficient for most applications. x5r and x7r type ceramic capacitors are recommended due to their good capacitance tolerance and stable temperature behavior. output capacitor the output capacitor is used for sustaining the output voltage when no current is delivering from the input, and smoothing the ripple voltage. ceramic capacitors should be used for the output capacitor due to their low esr at high switching frequency and low profile in physical size. in general, a 3.3 f to 22 f ceramic capacitor should be appropriate for most applications. x5r and x7r type ceramic capacitors are recommended due to their good capacitance tolerance and temperature coefficient, while y5v type ceramic capacitors are not recommended since both their capacitance tolerance and temperature coefficient are too large. the output voltage ripple and switching frequency at nominal load current can be calculated by the following equations: v ripple i out c out 1 f sw(load)
i pk l v out v d ?v in
(i pk ?i out ) esr f sw(load) 2i out (v out v d ?v in ) i 2 pk l where i out is the nominal load current, c out is the selected output capacitance, i pk is the peak inductor current, l is the selected inductance, v out is the output voltage, v d is the schottky diode forward voltage, v in is the input voltage, esr is the esr of the output capacitor. feedback resistors to achieve better efficiency at light load, a high impedance feedback resistor divider should be used. choose the lower resistor r2 value from the range of 10 k to 200 k . the value of the upper resistor r1 can then be calculated from the equation below: r 1 r 2 v out 1.19
1 1% tolerance resistors should be used for both r 1 and r 2 for better v out accuracy. feedforward capacitor a feedforward capacitor is required to add across the upper feedback resistor to avoid double pulsing or group pulsing at the switching node which will cause larger inductor ripple current and higher output voltage ripple. with adequate feedforward capacitance, evenly distributed single pulses at the switching node can be achieved. the range of the capacitor value is from 5.0 pf to 200 pf for most applications. for NCP1406, the lower the switching frequency, the larger the feedforward capacitance is needed; besides, the higher the output voltage, the larger the feedforward capacitance is required. for the initial trial value of the feedforward capacitor, the following equation can be used; however, the actual value needs fine tuning: c ff 1 2 f sw(load) 20 r1 output voltage higher than 25 v the NCP1406 can be used to generate output voltage higher than 25 v by adding an external high voltage n?ch mosfet in series with the internal mosfet switch as shown in figure 51. the drain?to?source breakdown voltage of the external mosfet must be at least 1.0 v higher than the output voltage. the diode d2 connected across the gate and the source of the external mosfet helps the external mosfet to turn off and ensures that most of the voltage drops across the external mosfet during the switch?off period. since the high voltage external mosfet is in series with the internal mosfet, higher break down voltage is achieved but the current capability is not increased. there is an alternative application circuit shown in figure 53 which can output voltage up to 30 v. for this circuit, a diode?capacitor charge?pump voltage doubler constructed by d2, d3 and c1 is added. during the internal mosfet switch?on time, the lx pin is shorted to ground and d2 will charge up c1 to the stepped up voltage at the cathode of d1. during the mosfet switch?off time, the voltage at v out will be almost equal to the double of the voltage at the cathode of d1. the v out is monitored by the fb pin via the resistor divider and can be set by the resistor values. since the maximum voltage at the cathode of d1 is 15 v, the maximum v out is 30 v. the value of c1 can be in the range of 0.47 f to 2.2 f. negative voltage generation the NCP1406 can be used to produce a negative voltage output by adding a diode?capacitor charge?pump circuit (d2, d3, and c1) to the lx pin as shown in figure 50. the feedback voltage resistor divider is still connected to the positive output to monitor the positive output voltage and a small value capacitor is used at c2. when the internal mosfet switches off, the voltage at the lx pin charges up the capacitor through diode d2. when the mosfet
NCP1406 http://onsemi.com 15 switches on, the capacitor c1 is effectively connected like a reversed battery and c1 discharges the stored charge through the r ds(on) of the internal mosfet and d3 to charge up c out and builds up a negative voltage at v out . since the negative voltage output is not directly monitored by the NCP1406, the output load regulation of the negative output is not as good as the standard positive output circuit. the resistance values of the resistors of the voltage divider can be one?tenth of those used in the positive output circuit in order to improve the regulation at light load. the application circuit in figure 54, is actually the combination of the application circuits in figures 50 and 51. step?down converter NCP1406 can be configured as a simple step?down converter by using the open?drain lx pin to drive an external p?ch mosfet as shown in figure 52. the resistor r gs is used to switch off the p?ch mosfet during the switch?off period. t oo small a resistance value should not be used for r gs , otherwise, the efficiency will be reduced. r gs should be in the range of 510 to 5.1 k . white led driver the NCP1406 can be used as a constant current led driver which can drive up to 6 white leds in series as shown in figure 57. the led current can be set by the resistance value of r s . the desired led current can be calculated by the equation below: i led 1.19 r s moreover, the brightness of the leds can be adjusted by a dc voltage or a pwm signal with an additional circuit illustrated below: dc/ pwm signal r2 r1 100 k c2 680 pf gnd c1 0.1 f d2 to fb pin to led figure 45. rs with this additional circuit, the maximum led current is set by the above equation. the value of r2 can be obtained by the following equation: r2 v max d ctl(max)
v d
1.19 (i led(max)
i led(min) ) r s r1 v max is the maximum voltage of the control signal, d ctl(max) is the maximum duty cycle of the control signal, v d is the diode forward voltage, i led(max) is the maximum led current and i led(min) is the minimum led current. if a pwm control signal is used, the signal frequency can be in the range of 5.0 khz to 30 khz. it is recommended to keep the input pwm frequency about 15 khz to avoid generating audio noise.
NCP1406 http://onsemi.com 16 pcb layout guidelines pcb layout is very important for switching converter performance. all the converter?s external components should be placed closed to the ic. the schematic, pcb trace layout, and component placement of the step?up dc?dc converter demonstration board are shown in figure 46 to figure 49 for pcb layout design reference. the following guidelines should be observed: 1. grounding single?point grounding should be used for the output power return ground, the input power return ground, and the device switch ground to reduce noise. the input ground and output ground traces must be thick and short enough for current to flow through. a ground plane should be used to reduce ground bounce. 2. power traces low resistance conducting paths (short and thick traces) should be used for the power carrying traces to reduce power loss so as to improve efficiency (short and thick traces for connecting the inductor l can also reduce stray inductance). the path between c1, l1, d1, and c2 should be kept short. the trace from l to lx pin of the ic should also be kept short. 3. external feedback components feedback resistors r1 and r2, and feedforward capacitor c3 should be located as close to the fb pin as possible to minimize noise picked up by the fb pin. the ground connection of the feedback resistor divider should be connected directly to the gnd pin. 4. input capacitor the input capacitor should be located close to both the input to the inductor and the vdd pin of the ic. 5. output capacitor the output capacitor should be placed close to the output terminals to obtain better smoothing effect on output ripple voltage. v in 1.8 v to 5.0 v c 1 10 f 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 l1 8.2 h d1 mbr0530t1 c 2 3.3 f figure 46. step?up converter demonstration board schematic tp1 c3 r1 enable r2 v out 25 v tp3 tp2 gnd tp4 gnd
NCP1406 http://onsemi.com 17 figure 47. step?up converter demonstration board top layer component silkscreen figure 48. step?up converter demonstration board top layer copper figure 49. step?up converter demonstration board bottom layer copper
NCP1406 http://onsemi.com 18 components supplier output voltage parts supplier part number description website 15 v c1 panasonic ecj2fb0j106m ceramic capacitor 0805 10 f/6.3 v www.panasonic.com c2 panasonic ecj3yb1e475m ceramic capacitor 1206 4.7 f/25 v www.panasonic.com c3 panasonic ecj1vc1h560k ceramic capacitor 0603 56 pf/50 v www.panasonic.com d1 on semiconductor mbr0520lt1 schottky power rectifier 20 v/500 ma www.onsemi.com l1 sumida electric co. ltd cmd4d11?100mc inductor 10 h 1.2 mm low profile www.sumida.com r1 panasonic erj3geyj135v resistor 0603 1.3 m www.panasonic.com r2 panasonic erj3geyj114v resistor 0603 110 k www.panasonic.com u1 on semiconductor NCP1406snt1 25 v step?up dc?dc converter www.onsemi.com 25 v c1 panasonic ecj2fb0j106m ceramic capacitor 0805 10 f/6.3 v www.panasonic.com c2 panasonic ecj5yb1h335m ceramic capacitor 1812 3.3 f/50 v www.panasonic.com c3 panasonic ecj1vc1h151k ceramic capacitor 0603 150 pf/50 v www.panasonic.com d1 on semiconductor mbr0530lt1 schottky power rectifier 30 v/500 ma www.onsemi.com l1 sumida electric co. ltd cmd4d11?100mc inductor 10 h 1.2 mm low profile www.sumida.com r1 panasonic erj3geyj225v resistor 0603 2.2 m www.panasonic.com r2 panasonic erj3geyj114v resistor 0603 110 k www.panasonic.com u1 on semiconductor NCP1406snt1 25 v step?up dc?dc converter www.onsemi.com other application circuits v in 2.0 v to 5.5 v c in 10 f 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 l 8.2 h d1 v out ?15 v c3 1000 pf c2 2.2 f r 1 r 2 v out
1.19 r 1 r 2 1 1 c1 2.2 f d3 d2 c out 4.7 f 25 v 6.0 ma at v in = 2.0 v 40 ma at v in = 5.5 v l: cr43?8r2mc, sumida c in : ecj2fb0j106m, panasonic c out : ecj3yb1e475m, panasonic c1: ecj2fb1c225k, panasonic c2: ecj2fb1c225k, panasonic c3: ecj1vc1h102j, panasonic d1, d2: mbr0520lt1, on semiconductor d3: mbr0520lt1 x 2, on semiconductor figure 50. positive?to?negative output converter for negative lcd bias
NCP1406 http://onsemi.com 19 v in 3.0 v to 5.5 v c in 10 f 10 v 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 l 8.2 h v out up to 30 v d2 r 1 r 2 v out 1.19 r 1 r 2 1 c out 3.3 f 50 v 6.0 ma at v in = 3.0 v 35 ma at v in = 5.5 v figure 51. step?up dc?dc converter with 30 v output voltage q1 c1 5 pf to 1000 pf d1 l: cr43?8r2mc, sumida c in : ecj2fb0j106m, panasonic c out : ecj5yb1h335m, panasonic q1: mgsf1n03t1, on semiconductor / nths5402t1, on semiconductor d1: mbr0530t1, on semiconductor d2: mmsd914t1, on semiconductor v in 3.0 v to 5.5 v c in 10 f 6.3 v 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 l 10 h v out 1.6 v 200 ma r 1 39 k r 1 110 k v out 1.19 r 1 r 2 1 c out 22 f 6.3 v figure 52. step?down dc?dc converter with 1.6 v output voltage for dsp circuit q1 c1 1000 pf r gs 1 k d1 l: cr43?100mc, sumida c in : ecj2fb0j106m, panasonic c out : ecjhvb0j226m, panasonic q1: mgsf1p02lt1, on semiconductor d1: mbr0530t1, on semiconductor
NCP1406 http://onsemi.com 20 v in 2.0 v to 5.5 v c in 10 f 6.3 v 3 vdd 2 fb 1 ce 5 lx 4 gnd NCP1406 l 6.8 h v out 30 v d1 r 1 2.2 m r 2 91 k v out 1.19 r 1 r 2 1 c out1 2.0 ma at v in = 2.0 v 35 ma at v in = 5.5 v figure 53. step?up dc?dc converter with 30 v output voltage c2 7.0 pf d2 d3 10 f 16 v 1.0 f c1 c out2 10 f 16 v l: cr43?6r8mc, sumida c in : ecj2fb0j106m, panasonic c out1, c out2 : ecj3yb1c106m, panasonic c1: ecj2fb1c225k, panasonic d1, d2, d3: mbr0540t1, on semiconductor v in 3.3 v to 5.0 v c in 10 f 6.3 v 3 vdd 2 fb 1 ce 5 lx 4 gnd u1 NCP1406 l 8.2 h v out ?28 v d1 r 1 r 2 v out
1.19 r 1 r 2 1 1 c1 9.0 ma at v in = 3.3 v 20 ma at v in = 5.0 v figure 54. voltage inverting dc?dc converter with ?28 v output voltage c4 750 pf to 2000 pf 1 f 50 v 2.2 f/50 v c3 q1 d2 d3 d4 c2 3.3 f 50 v l: cr43?8r2mc, sumida c in : ecj2fb0j106m, panasonic c1: ecjgvb1c105m, panasonic c2: ecj5yb1h335m, panasonic c3: ecj4yb1h105m, panasonic q1: mgsf1n03t1, on semiconductor / nths5402t1, on semiconductor d1, d2: mmsd914t1, on semiconductor d3: mbr0530t1, on semiconductor d4: mbr0530t1 x 2, on semiconductor
NCP1406 http://onsemi.com 21 v in 2.0 v to 5.5 v c 1 10 f 6.3 v 3 vdd 2 fb 1 ce 5 lx 4 gnd u1 NCP1406 l1 10 h figure 55. +15 v, ?15 v outputs converter for lcd bias supply c3 r1 r2 on jp1 off c2 4.7 f 25 v 2.2 f c4 d2 d3 d1 v out1 15 v v out2 ?15 v c5 4.7 f 25 v 2.0 ma at v in = 2.0 v 5.0 ma at v in = 2.4 v 10 ma at v in = 3.0 v 2.0 ma at v in = 2.0 v 5.0 ma at v in = 2.4 v 10 ma at v in = 3.0 v v out1 1.19 r 1 r 2 1 v out2 ?v out1 0.3 l: cr43?100mc, sumida c1: ecj2fb0j106m, panasonic c2, c5: ecj3yb1e475m, panasonic c3: ecj1vc1h102j, panasonic c4: ecj2fb1c225k, panasonic d1: mbr0520lt1, on semiconductor d2, d3: mbr0520lt1 x 2, on semiconductor r1: 1.3 m r2: 110 k 5 pf to 1000 pf v in 3.0 v to 5.5 v c 1 10 f 6.3 v 3 vdd 2 fb 1 ce 5 lx 4 gnd u1 NCP1406 l1 10 h figure 56. +15 v, ?7.5 v outputs converter for ccd supply circuit c3 r1 r2 on jp1 off c6 10 f 16 v 2.2 f c5 d4 d5 v out1 15 v v out2 ?7.5 v c7 10 f 16 v 10 ma at v in = 3.0 v 10 ma at v in = 3.0 v v out1 1.19 r 1 r 2 1 v out2 ? v out1 2 820 pf c9 c4 2.2 f d2 d3 d1 c2 2.2 f 16 v l: cr43?100mc, sumida c1: ecj2fb0j106m, panasonic c6, c7: ecj3yb1c106m, panasonic c3: ecj1vc1h821j, panasonic c2, c4, c5: ecj2fb1c225k, panasonic d1, d2, d3, d4, d5: mbr0520lt1, on semiconductor r1: 1.3 m r2: 110 k
NCP1406 http://onsemi.com 22 tp1 v in 3.0 v to 5.5 v 3 vdd 2 fb 1 ce 5 lx 4 gnd u1 NCP1406 l1 4.7 h figure 57. white leds driver circuit on jp1 off i led(dc) 1.19 v r1 c2 10 f 16 v tp2 gnd ce c1 22 f 6.3 v control signal r2 100 k d1 r1 12 i led 100 ma tp4 gnd white led x 3 u1: NCP1406, on semiconductor d1: mbr0520lt1, on semiconductor l1: cr43?4r7mc, sumida c1: ecjhvb0j226m, panasonic c2: ecj3yb1c106m, panasonic led1, led2, led3: lwh1033 (luxpia) r1: 12 r2: 100 k tp3 v out
NCP1406 http://onsemi.com 23 package dimensions tsop?5 sn suffix case 483?02 issue e 0.7 0.028 1.0 0.039 mm inches scale 10:1 0.95 0.037 2.4 0.094 1.9 0.074 *for additional information on our pb?free strategy and soldering details, please download the on semiconductor soldering and mounting t echniques reference manual, solderrm/d. soldering footprint* notes: 1. dimensioning and tolerancing per ansi y14.5m, 1982. 2. controlling dimension: millimeter. 3. maximum lead thickness includes lead finish thickness. minimum lead thickness is the minimum thickness of base material. 4. a and b dimensions do not include mold flash, protrusions, or gate burrs. dim min max min max inches millimeters a 2.90 3.10 0.1142 0.1220 b 1.30 1.70 0.0512 0.0669 c 0.90 1.10 0.0354 0.0433 d 0.25 0.50 0.0098 0.0197 g 0.85 1.05 0.0335 0.0413 h 0.013 0.100 0.0005 0.0040 j 0.10 0.26 0.0040 0.0102 k 0.20 0.60 0.0079 0.0236 l 1.25 1.55 0.0493 0.0610 m 0 10 0 10 s 2.50 3.00 0.0985 0.1181 0.05 (0.002) 123 54 s a g l b d h c k m j on semiconductor and are registered trademarks of semiconductor components industries, llc (scillc). scillc reserves the right to mak e changes without further notice to any products herein. scillc makes no warranty, representation or guarantee regarding the suitability of its products for an y particular purpose, nor does scillc assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, in cluding without limitation special, consequential or incidental damages. ?typical? parameters which may be provided in scillc data sheets and/or specifications can and do vary in different a pplications and actual performance may vary over time. all operating parameters, including ?typicals? must be validated for each customer application by customer?s technical e xperts. scillc does not convey any license under its patent rights nor the rights of others. scillc products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the scillc prod uct could create a situation where personal injury or death may occur. should buyer purchase or use scillc products for any such unintended or unauthorized application, buyer shall indem nify and hold scillc and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney f ees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that scillc was neglig ent regarding the design or manufacture of the part. scillc is an equal opportunity/affirmative action employer. this literature is subject to all applicable copyright laws and is not for resale in any manner. publication ordering information n. american technical support : 800?282?9855 toll free usa/canada japan : on semiconductor, japan customer focus center 2?9?1 kamimeguro, meguro?ku, tokyo, japan 153?0051 phone : 81?3?5773?3850 NCP1406/d literature fulfillment : literature distribution center for on semiconductor p.o. box 61312, phoenix, arizona 85082?1312 usa phone : 480?829?7710 or 800?344?3860 toll free usa/canada fax : 480?829?7709 or 800?344?3867 toll free usa/canada email : orderlit@onsemi.com on semiconductor website : http://onsemi.com order literature : http://www.onsemi.com/litorder for additional information, please contact your local sales representative.

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