2007 8 HM9.1/2HXOSS GELLI LM2735 520kHz/1.6MHz SEPIC DC-DC LM2735 SEPIC DC-DC 2.1 A DC/DC : 2.7V     5.5V : 3V     24V PCB 1.6MHz 520kHz : 2.1A 90% High 80nA 170m　NMOS 80nA ± 2% SOT23-5 LLP-6 eMSOP-8 2 520kHz (LM2735-Y) 1.6MHz (LM2735-X) SOT23-5　LLP-6　eMSOP-8 LCD OLED USB LED Efficiency vs Load Current Vo = 12V © National Semiconductor Corporation     DS202158-03-JP 1 00-00ンルシンLM2735
GELSN
LM2735 V IN SW FB EN ESD (Note 4) (Note 2) (Note 1) 0.5V 7V 26.5V 0.5V (Note 1) V IN 3.0V 0.5V Vsw 0.5V 7.0V V EN (Note 5) 2kV 150 150 65 ( ) SOT23-5 40 3V 0V 125 400mW (Typ) 25 T j T J 25
(15 ) 2.7V 5.5V 24V V IN 125 40 Conditions (T j ) 220 T j    25 40 125 (T j ) SELSM. (Typ)      T j 25 Conditions
Note 1: Note 2: Note 3:     2 (70μ m ) 4 3 (     75mm) Note 4: 100pF 1.5k V IN    0.3V Note 5: LM2735 ( ) GELSM EFFICIENCY ( LM2735 LM2735 2.1A PWM IC 520 kHz 1.60 MHz LM2735 LM2735 DC/DC LM2735 LM2735 (Figure 1) LM2735 NMOS Low SW NMOS (Vsw) (I L ) GND IL Vref
PWM High SW (D) D1 (VD) FIGURE 2.   Simplified Schematic (Figure 3) SELSM (Vo) (D1) LM2735 NMOS 2Δίι VIN DTs L LM2735 (EN) EN Low 80nA lμ A
0.3V Δί」＝ VIN xDTs 2L 10% 30% IC 160 150 / V IN L = x DTs 2 x Δίω LM2735 ( ) 1/Ts  Fsw (2.1A) (I LPK ) ILpk I IN L ILpk Iout/D' IL MLCC LM2735 MLCC Vout x D 2 x Fsw x R Load x C OUT 90° 1.75A 1.5A 1.75A 1 4.7μ F X5R 3A LM2735 (DCR) FB R1 FB R2   Vour V IN LM2735 ESL ESL (2 fL) ESL (MLCC) MLCC X7R X5R R1 FIGURE 5.   Setting Vout 10k R 2 = Vour 1 x R 1 Vref LM2735 LM2735 LM2735 (ESR) 5V 12V LM2735 2 SELSM 5kHz 10kHz FIGURE 6.   LM2735 Without External Compensation (22°) 0 B C3 45° 8kHz R2
R 1 R2 5kHz 10kHz 1 F ZERO-CF = = 5 kHz → 10 kHz 2π(R 2 xC r) / gm F P-ORIGIN 1 Fp-rc 2π(R LoadCout) CMC (VMC) 650Hz lkHz R2 FIGURE 8.   Setting External Pole-Zero 1 Fzero-cf 2π(R 2 ×C 3 ) F POLE-CF = 2x((R 1 ||R 2 ) x C 3 ) 20dB/ (RHPZ) 45°/ RHPZ RHPZ C3 dB LM2735 ( ) PCB (D') R Load RHP7FR0 2π x L LM2735 PCB C OUT  LM2735  PGND GND GND 2 2 ( ) FIGURE 9.   Boost PCB Layout Guidelines FB FB
IC IC  GND (LLP R2 Vour : s) V IN SW V OUT AC IC : AN-1229 4 LM2735 PCB LM2735 2      PCB PCB PCB LM2735دى8  LLP) (5      SOT23 eMSOP (DAP) SOT23 LLP PCB l LM2735 LM2735 ( ) : SELSM 32 (PCB Vout ) V IN : : : R ja- R JC: C JC: R ja : C CA: R JA   R JC: 2 2
W . . . . ( ) R  JC R  JC RDSon R ja FIGURE 10.   Simplified Thermal Impedance Model ( ) PCB LM2735 LM2735 LM7235 T A LM2735 DC/DC ( ) or
V D (P LOSS ) 2 P DIODE VD× IO LM2735 Ploss  Pcond  Psw Po 1 NMOS LM2735 Vout = 1
 Vin VIN
l P IND I IN 2R DCR P IND =
LM2735 P COND-NFET FIGURE 13.   LM2735 Switch Current lsw-rms = l ND VD x ～ I IND VD P IND = I IN ² x R IND-DCR ( P COND-NFET I IN 2× R DSON× D P COND-NFET = DCR GELSM
x R DSON X D Vout   = VIN Vout η = D' 2% VIN Vout = 1
 Vin = D' LM2735 ( 125 V IN 5V R DSON 250m ) NMOS (10% 90%) Pswr 1/2(VOUT× IIN× FSW× TRISE) Pswf 1/2(VOUT× I IN × FSW× T FALL ) Psw Pswr Pswf
4mA Po Io× V in TABLE 1.  Operating Conditions
P COND Psw P DIODE P IND PQ PLOSS IQ× V IN  20mW Po 80mW 6ns) Pswr 1/2(VOUT× I IN × F SW× T RISE 5ns) 70mW Pswf 1/2(VOUT× IIN× FSW× TFALL 150mW Pswf Psw Pswr NFET R DSON 250m 305mW I IN 2× D× R DSON P CONDUCTION VD 0.45V V D× I IN (1  D)  236mW P DIODE 75m R DCR 145mW I IN 2 × R DCR P IND TABLE 2.  Power Loss Tabulation
P INTERNAL    P COND     P SW 475mW R jc
R JC
T J - T A Roja = P Dissipation and T」 - T CASE RyJC= P Dissipation R ja R jc LM2735 150 160 R ja R  JC R jc R ja R  JC LM2735 4 R DSON ( ) Io 125 125دی) ( 125 R JC R jc (        ) SELSM. FIGURE 14.   R  JA vs Internal Dissipation for the LLP-6 and eMSOP-8 Package R oja = T J - T A T J - TCase-Top - R ¥JC = P Dissipation P Dissipation R JA LLP /W 55 R   JC LLP     21 /W LLP 50    /W /W eMOSP 65 /W /W 28 4 PCB DAP R jc 0.5 R ja 18 LM2735 SEPIC SEPIC 2 4 6 s SOT23 110 /W 65  /W R ja 80 50 R   JC
 /W 2 LM2735 SEPIC 4.5V 3V LM2735 4 PCB 4 2 GND SEPIC : SEPIC : LM2735 750mW 400mW 6 LLP 8 eMSOP Vo D = D' V IN Note: R ja Vo D = Vo + Vin : SEPIC DC DC l SEPIC (CUK ) Ta 139 155 Tc Pdiss 475mW : LM2735 ( /W 75 ) SEPIC ( ) C1 l L2 = x l L1 Vc1 = D'(Vo) D and DC l Ll Vin L2 C6 l L1 =
Vc1 V IN I L2 I L 1 D'(Vo) D V IN =タ| ઠ lL2 " L2 D (2.1A) IL1 I L2 LM2735 GELSM.
Efficiencies for Typical SEPIC Application SEPIC PCB LM2735 PCB SEPIC SEPIC FIGURE 17.   SEPIC PCB Layout LLP LLP 6 LM2735: FIGURE 18.   Internal LLP Connection PCB (Figure 19 R ja FIGURE 19.   PCB Dog Bone Layout and l L1 (D) D 2 Vo D x η 1 - D VIN D = Vo (V IN X η) +V o LM2735
1 LM2735X SOT23-5

GELSM
2 LM2735Y SOT23-5

LM2735 3 LM2735X LLP-6
GELSW
4 LM2735Y LLP-6

LM2735 5 LM2735Y eMSOP-8
GELSW
6 LM2735X SOT23-5

7 LM2735Y SOT23-5

LM2735 GELSW
8 LM2735X SOT23-5

9 LM2735Y SOT23-5
LM2735
GELSW
10 LM2735X LLP-6

11 LM2735Y LLP-6
LM2735
GELSW
12 LM2735X LLP-6 SEPIC

13 LM2735Y eMSOP-8 SEPIC
LM2735 GELSW
14 LM2735X SOT23-5 LED

15 LM2735Y LLP-6 LM2735
SELSMT NS Package Number SDE06A millimeters 5-Lead SOT23-5 Package NS Package Number MF05A CONTROLLING DIMENSION IS INCH
 VALUES IN [  ] ARE MILLIMETERS MUYOBA (Rev A) 8-Lead eMSOP Package NS Package Number MUY08A ( ) (CEO) (GENERAL COUNSEL) (a) (b) National Semiconductor Copyright © 2007 National Semiconductor Corporation www.national.com
SEPIC DC-DC M2735 520kHz/1.6MH