Electronic Components Datasheet Search |
|
LTC4214-1CMS Datasheet(PDF) 11 Page - Linear Technology |
|
LTC4214-1CMS Datasheet(HTML) 11 Page - Linear Technology |
11 / 32 page LTC4214-1/LTC4214-2 11 421412f Hot Circuit Insertion When circuit boards are inserted into a live backplane, the supply bypass capacitors can draw huge transient cur- rents from the power bus as they charge. The flow of current damages the connector pins and glitches the power bus, causing other boards in the system to reset. The LTC4214 is designed to turn on a circuit board supply in a controlled manner, allowing insertion or removal without glitches or connector damage. Initial Start-Up The LTC4214 resides on a removable circuit board and controls the path between the connector and the load with an external MOSFET switch (see Figure 1). Both inrush control and short-circuit protection are provided by the MOSFET. A detailed schematic is shown in Figure 2. – 12V and GND receive power through the longest connector pins and are the first to connect when the board is inserted. The GATE pin holds the MOSFET off during this time. UV/OV determines whether or not the MOSFET should be turned on based upon internal high accuracy thresholds and an external divider. UV/OV does double duty by also monitor- ing whether or not the connector is seated. The top of the divider detects GND by way of a short connector pin that is the last to mate during the insertion sequence. Interlock Conditions A start-up sequence commences once these “interlock” conditions are met. 1. The input voltage VIN exceeds 5.1V (UVLO). 2. The voltage at UV > 2.25V. OPERATIO Figure 1. Basic LTC4214 Hot Swap Topology Figure 2. –12V, 2A Hot Swap Controller 3. The voltage at OV < 2.85V. 4. The (SENSE – VEE) voltage is < 50mV (VCB). 5. The voltage at SS is < 0.2V (20 • VOS). 6. ThevoltageontheTIMERcapacitor(CT)is<1.7V(VTMRL). 7. The voltage at GATE is < 0.5V (VGATEL). The first three conditions are continuously monitored and the latter four are checked prior to initial timing or GATE ramp-up. Upon exiting an OV condition, the TIMER pin voltage requirement is inhibited. Details are described in the Applications Information, Timing Waveforms section. TIMER begins the start-up sequence by sourcing 5 µA into CT. If VIN, UV or OV falls out of range, the start-up cycle stops and TIMER discharges CT to less than 1.7V, then waits until the aforementioned conditions are once again met. If CT successfully charges to 3V, TIMER pulls low and both SS and GATE pins are released. GATE sources 50 µA (IGATE), charging the MOSFET gate and associated capacitance. The SS voltage ramp limits VSENSE to control the inrush current. PWRGD pulls active low when GATE is within 2.8V of VIN and DRAIN is lower than VDRNL. Two modes of operation are possible during the time the MOSFET is first turning on, depending on the values of external components, MOSFET characteristics and nomi- nal design current. One possibility is that the MOSFET will 4214 F01 LTC4214 CLOAD PLUG-IN BOARD BACKPLANE GND –12V LONG LONG + LOAD 4214 F02 GND –12V GND VOUT EN UV OV PWRGD TIMER VEE VIN SENSE GATE SS DRAIN LTC4214-1 R1 121k 1% R2 32.4k 1% RD 475k CT 47nF Z1: SMAJ15A CSS 22nF CC 10nF RS 0.025 Ω Q1 IRF7413 RC 10Ω R4 10k C1 1nF CIN 0.1 µF 1 2 9 8 10 3 7 6 4 5 Z1 CX 100nF RX 10 Ω RIN 470 Ω R3 10k CLOAD 100 µF TYP LONG LONG SHORT + |
Similar Part No. - LTC4214-1CMS |
|
Similar Description - LTC4214-1CMS |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | 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 |