 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
LTC4267-3 Datasheet(PDF) 10 Page - Linear Technology |
|
||||||||||||||||||||||||||||||
LTC4267-3 Datasheet(HTML) 10 Page - Linear Technology |
|
|
10 / 34 page  LTC4267-3 10 42673fb For more information www.linear.com/LTC4267-3 applicaTions inForMaTion avoid corrupting the 25k signature resistor while also sav- ing board space and cost. In addition, the inrush current limit requirement of the IEEE 802.3af standard can cause largetransientpowerdissipationinthePD.TheLTC4267-3 is designed to allow multiple turn-on sequences without overheating the miniature 16-lead package. In the event of excessive power cycling, the LTC4267-3 provides thermal overload protection to keep the onboard power MOSFET within its safe operating area. OPERATION The LTC4267-3 PD interface has several modes of opera- tion depending on the applied input voltage as shown in Figure 1 and summarized in Table 1. These modes satisfy therequirementsdefinedintheIEEE802.3afspecification. The input voltage is applied to the VPORTN pin and must be negative relative to the VPORTP pin. Voltages in the data sheet for the PD interface portion of the LTC4267-3 are with respect to VPORTP while the voltages for the switch- ing regulator are referenced to PGND. It is assumed that PGND is tied to POUT. Note the use of different ground symbols throughout the data sheet. Table 1. LTC4267-3 Operational Mode as a Function of Input Voltage INPUT VOLTAGE (VPORTN with RESPECT to VPORTP) LTC4267-3 MODE OF OPERATION 0V to –1.4V Inactive –1.5V to –9.5V** 25k Signature Resistor Detection –9.8V to –12.4V Classification Load Current Ramps up from 0% to 100% –12.5V to UVLO* Classification Load Current Active UVLO* to –57V Power Applied to Switching Regulator *VPORTN UVLO includes hysteresis. Rising input threshold ≅ –36.0V Falling input threshold ≅ –30.5V **Measured at LTC4267-3 pin. The LTC4267-3 meets the IEEE 802.3af 10V minimum when operating with the required diode bridges. Figure 1. Output Voltage, PWRGD and PD Current as a Function of Input Voltage DETECTION V1 CLASSIFICATION UVLO TURN-ON UVLO OFF POWER BAD UVLO OFF UVLO ON UVLO TURN-OFF τ = RLOAD C1 PWRGD TRACKS VPORTN DETECTION V2 –10 TIME –20 –30 –40 –50 –10 TIME –20 –30 –40 –50 –10 TIME –20 –30 –40 –50 ICLASS ILIM_LO dV dt ILIM_LO C1 = POWER BAD POWER GOOD DETECTION I1 CLASSIFICATION ICLASS DETECTION I2 LOAD, ILOAD (UP TO ILIM_HI) CURRENT LIMIT, ILIM_LO 42673 F01 ICLASS DEPENDENT ON RCLASS SELECTION ILIM_LO = 140mA (NOMINAL), ILIM_HI = 375mA (NOMINAL) I1 = V1 – 2 DIODE DROPS 25k ILOAD = (UP TO ILIM_HI) VOUT RLOAD I2 = V2 – 2 DIODE DROPS 25k VPORTP PSE IIN LTC4267-3 R9 RCLASS RLOAD VOUT C1 RCLASS PWRGD POUT PGND VPORTN VIN TIME VOLTAGES WITH RESPECT TO VPORTP |
Similar Part No. - LTC4267-3_15 |
|
Similar Description - LTC4267-3_15 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.NET |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
