Literature Number: JAJA397
POWER designer Expert tips, tricks, and techniques for powerful designs No.104... 1-7 Power-over-Ethernet (PoE) PD... 2 Power-over-Ethernet L.H. Mweene RJ-45 Ethenet... 4 TX+ (1 ) 1A DC/DC... 6... 8 TX- (2) RX+ (3 ) PHY PHY RX- (6) (4) (5) (7) (8) Figure 1. CAT-5 Power-over-Ethernet (PoE) VoIP (Powered Device PD) AC Ethernet Ethernet PD
Power-over-Ethernet (PoE) PD LM5070 PoE PD /PWM LM5070 RJ-45 V OUT TX+ (1 ) TX- (2) RX+ (3 ) PHY PHY IEEE 802.3af LM5070 RX- (6) (4) (5) DC-DC PWM (7) (8) National Semiconductor Corporation, 2004. National Semiconductor,, and LLP are registered trademarks of National Semiconductor Corporation. All rights reserved. LM5070 PoE (Power over Ethernet) (PD) (PWM) LM5070 DC/DC IEEE 802.3af 80V/400mA (SMPS) IC 80 ( 80) 50 ( 50) 2 IEEE 802.3af 80V1 400mA MOSFET 80% ( 80 ) 50% ( 50 ) 800mA 2
POWER designer Power-over-Ethernet Ethernet Ethernet IEEE PD Ethernet (power sourcing equipment PSE) Ethernet IEEE 802.3af Power-over-Ethernet IEEE 802.3af IEEE 802.3af PSE 44V 57V CAT-5 CAT-6 () () PD Ethernet Figure 1 IEEE 802.3af PSE 4W7W 15.4W PSE PD PSE PD PSE PD Ethernet PD PSE 25k 0.1 F PD PD PSE PD PD PSE PD PD 450mA PD 36V PoE PoE (PD ) IEEE 802.3af (PDI) PoE IC PDI PWM PDI 2 IC PSE 0 15.4W 1 4.0W 2 7.0W 3 15.4W Figure 2. PoE power.national.com/jpn 3
LM5642 2 180 150kHz 200kHz 4.5V 36V 50 A 1.3V Vin 90% 0.04% () / (Figure 2 ) TSSOP V IN 4.5V to 36V UV_Delay SS/ON1 SS/ON2 SYNC LM5642 LM5642 V OUT1 1.3V - 0.9V IN V OUT2 1.3V - 0.9V IN LP3884x LM38842-Adj LP38841 75mV (typ) @0.8A LP38842 115mV (typ) @1.5A LP38843 210mV (typ) @3.0A (Vout+Vdo) 5.5V V IN 10 µf * Ceramic IN OUT LP38842-Adj R1 C FF V OUT Vbias=4.5V 5.5V ADJ 1.5% (@25 ) 0.8V1.2V1.5VADJ (0.56V 1.5V) BIAS 5V ± 10% 0.1 µf BIAS S/D GND R2 S/D 22 µf * Ceramic GND GND * LP38841 0.8A 0.8V1.2V1.5VADJ(0.56V 1.5V) TO220TO263PSOP-8(ADJ ) LP38842 1.5A 0.8V1.2V1.5VADJ(0.56V 1.5V) TO220TO263PSOP-8(ADJ ) LP38843 3.0A 0.8V1.2V1.5V TO220TO263 4
POWER designer Power-over-Ethernet PDI PWM IC 3 3 Figure 3 PDI PWM IC PoE PoE PD PSE PD (DCM) FET RMS (a) PDIPWM IC (CCM) DCM PDI IC PWM IC 2 PD CCM PoE PSE PD CCM (b) PDI ICPWM IC ƒ Z = V IN D 2πIIN L V IN DI IN L FET PSE PDI+PWM IC PD CCM L 100 H V IN 36V I IN 360mA D 0.4 ƒ Z 64 khz PoE (c) PDIPWM IC Figure 3. PoE power.national.com/jpn 5
1A DC/DC LM2734/36 3MHz DC/DC (3V 20V) (0.8V 18V) LM2734Y AC (16V19V ) 12V5V3.3V 0.8V (LM2734) LSI (SOT-23 3mm ) & ( 1mm) 4.4mm 5mm (TSSOP-16) 5V V IN OFF C1 10 F ON VIN BOOST SW LM2734Y EN FB GND D1 C2 0.01 F D2 L1 10 H R1 31.6 k R2 10 k V OUT 3.3V/1A C3 10 F 2.9mm 2.8mm (SOT-23) 63% () PWM 550kHz1.6MHz3MHz 3 LC PCB // ON/OFF (EN) (%) 100 90 80 70 60 50 40 30 20 LM2734 vs 10 0 10 100 1000 (ma) LM2734 LM2736 3.0V 20V 3.0V 18V 1A 750 ma 0.8V 18V 1.25V 16V 0.8V, 2% 1.25V, 2% 550 khz / 1.6 MHz / 3 MHz 6
POWER designer Power-over-Ethernet CCM + PDI & PWM IC + PD - PSE - Figure 4. PoE PoE 57V PoE PoE CCM PoE CCM PDI PWM IC LC PoE PoE 13W CCM 48V 3.3V 84 () () ( 3.3V 90%) PoE IEEE 802.3af IEEE 802.3af PWM IC power.national.com/jpn 7
WEBENCH 1. 2. 3. 4. webench.national.com/jpn "Power over Ethernet" www.national.com/jpn/onlineseminar/ power.national.com/jpn JPN.feedback@nsc.com 0120-666-116 135-00422-17-16 TEL 03-5639-7300www.national.com/jpn/ 2005, National Semiconductor Corporation. National Semiconductor,,, LLP, and WEBENCH are registered trademarks of National Semiconductor. All other brand or product names are trademarks or registered trademarks of their respective holders. 550263-004-JP
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