lm5072mhx-80 National Semiconductor Corporation, lm5072mhx-80 Datasheet
lm5072mhx-80
Available stocks
Related parts for lm5072mhx-80
lm5072mhx-80 Summary of contents
Page 1
... Versatile Auxiliary Power Options ■ 9V Minimum Auxiliary Power Operating Range ■ 100V Maximum Input Voltage Rating Simplified Application Diagram © 2007 National Semiconductor Corporation ■ Programmable DC Current Limit Up To 800mA ■ 100V, 0.7Ω Hot Swap MOSFET ■ Integrated PD Signature Resistor ■ ...
Page 2
... Connection Diagram Ordering Information Order Number LM5072MH-50 50% Duty Cycle Limit LM5072MHX-50 50% Duty Cycle Limit LM5072MH-80 80% Duty Cycle Limit LM5072MHX-80 80% Duty Cycle Limit www.national.com 16 Lead TSSOP-EP Description NSC Package Type / Drawing TSSOP-16EP/MXA16A TSSOP-16EP/MXA16A TSSOP-16EP/MXA16A TSSOP-16EP/MXA16A 2 20184602 Supplied As 92 units per rail 2500 units on tape and reel ...
Page 3
Pin Descriptions Pin Number Name 1 RT PWM controller oscillator frequency programming pin Soft-start programming pin. 3 VIN Positive supply pin for the PD interface and the internal PWM controller start-up regulator. 4 RCLASS PD classification programming pin. ...
Page 4
Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN , RTN to VEE (Note 7) RAUX to ARTN ICL_FAUX to VEE DCCL, RCLASS to VEE nPGOOD to ...
Page 5
Symbol Parameter Auxiliary Power Option ICL_FAUX Threshold ICL_FAUX Pull Down Current RAUX Lower Threshold ( µA) RAUX Lower Threshold Hysteresis RAUX Upper Threshold (I = 250 µA) RAUX Lower Threshold Current RAUX Upper Threshold Current VCC Regulator VccReg ...
Page 6
Symbol Parameter Thermal Shutdown Temp. Thermal Shutdown Hysteresis Thermal Resistance θ Junction to Ambient JA Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device ...
Page 7
Typical Performance Characteristics UVLO Threshold vs Temperature Inrush Current Limit vs ICL_FAUX Resistor Programmed DC Current Limit vs Temperature Default Current Limit vs Temperature 20184603 DC Current Limit vs. DCCL Resistor 20184605 Oscillator Frequency vs Temperature 20184607 7 20184604 20184606 ...
Page 8
Oscillator Frequency vs RT Resistance Maximum Duty Cycle vs Temperature www.national.com Error Amplifier Reference Voltage vs Temperature 20184609 Input Current vs Input Voltage 20184611 Soft-start Current vs Temperature 20184613 8 20184610 20184612 20184614 ...
Page 9
Specialized Block Diagrams FIGURE 1. Top Level Block Diagram 9 20184615 www.national.com ...
Page 10
Description of Operation and Applications Information The LM5072 integrates a fully IEEE 802.3af compliant PD in- terface and PWM controller in a single integrated circuit, providing a complete and low cost power solution for devices that connect to PoE systems. ...
Page 11
Modes of Operation Per the IEEE 802.3af specification, when connected to a PoE system it transitions through several operating modes in sequence including detection, classification (op- tional), turn on, normal operation, and power removal. Each operating mode ...
Page 12
Detection Signature During detection mode must present a signature resis- tance between 23.75 kΩ and 26.25 kΩ to the PoE power sourcing equipment. This signature impedance distinguishes the PD from non-PoE capable equipment to protect the latter from ...
Page 13
IEEE802.3af limit of 75 ms. When the classification option is not required, simply leave the RCLASS pin open to set the PD to the default Class 0 state. ...
Page 14
DC-DC converter. To prevent excessive inrush current, the LM5072 will turn on the hot swap MOSFET in a constant current mode. The de- fault, pre-programmed inrush current of 150 mA can be ...
Page 15
FIGURE 9. "Powered-from-PoE" Indictor and Power Good Delay Timer The nPGOOD pin can be configured to perform multiple func- tions. As shown in Figure 9, it can be used to implement a “Powered from PoE” indicator using an LED with ...
Page 16
OR’d” with the PoE potential re- ceived from the Ethernet connector. The second configura- tion, shown in Figure 11, is the rear auxiliary (RAUX) option in ...
Page 17
TABLE 3. Comparison Between FAUX and RAUX Operation Tradeoff Hot Swap Protection / Current Limit Protection Minimum Auxiliary Voltage (at the IC pins) Auxiliary Dominance Over PoE Use of nPGOOD Pin as “Powered from PoE” Indicator Transient Protection The term ...
Page 18
DC current. This is commonly known as DC Maintain Power Sig- nature (DC MPS), a common feature in many PSE systems. The high voltage startup regulator of the PWM ...
Page 19
FIGURE 13. Internal Error Amplifier – Used for Non- isolated Output Applications For isolated applications, the error amplifier function is locat the isolated secondary side. The LM5072’s error am- plifier can be disabled by connecting the FB pin ...
Page 20
MOSFET DC current limit. Gate Driver and Maximum Duty Cycle Limit The LM5072’s gate drive (OUT) pin can source and sink a peak current of 800 ...
Page 21
This re-configuration should make use of the spare pins of the transformer. 5. R24 should be deleted from the schematic completely, being replaced by a short connection for an isolated application open for a non-isolated application. 6. ...
Page 22
Application Example #1 Figure 18 shows an application example of a single isolated output solution for the PD. Both front auxiliary (FAUX) and rear auxiliary (RAUX) power options are given, although only one option may be needed in practice. Note ...
Page 23
Application Example #3: Figure 20 shows an application example of the non-isolated version of Figure 18 . This non-isolated version saves many parts used in the isolated feedback example shown in Figure 18. Similar simplification also applies to the non-isolated ...
Page 24
Physical Dimensions www.national.com inches (millimeters) unless otherwise noted Package Number MXA16A 24 ...
Page 25
Notes 25 www.national.com ...
Page 26
... National Semiconductor and the National Semiconductor logo are registered trademarks of National Semiconductor Corporation. All other brand or product names may be trademarks or registered trademarks of their respective holders. ...