Electronic Components Datasheet Search |
|
LTC4210-4CS6 Datasheet(PDF) 8 Page - Linear Technology |
|
LTC4210-4CS6 Datasheet(HTML) 8 Page - Linear Technology |
8 / 16 page 8 LTC4210-3/LTC4210-4 421034fa Undervoltage Lockout An internal undervoltage lockout (UVLO) circuit resets the LTC4210 if the VCC supply is too low for normal operation. The UVLO has a low-to-high threshold of 2.5V, a 100mV hysteresis and a high-to-low glitch filter of 30 µs. Above 2.5V supply voltage, the LTC4210 will start if the ON pin conditions are met. A short supply dip below 2.4V for less than 30 µs is ignored to allow for bus supply transients. ON Function The ON pin is the input to a comparator which has a low- to-high threshold of 1.3V, an 80mV hysteresis and a high- to-low glitch filter of 30 µs. A low input on the ON pin resets the LTC4210 TIMER status and turns off the external MOSFET by pulling the GATE pin to ground. A low-to-high transition on the ON pin starts an initial cycle followed by a start-up cycle. A 10k pull-up resistor connecting the ON pin to the supply is recommended. The 10k resistor shunts any potential static charge on the backplane and reduces the overvoltage stress at the ON pin during live insertion. Alternatively, an external resistor divider at the ON pin can be used to program an undervoltage lockout value higher than the internal UVLO circuit. An RC filter can be added at the ON pin to increase the delay time at card insertion if the internal glitch filter delay is insufficient. GATE Function During hot insertion of the PCB, an abrupt application of supply voltage charges the external MOSFET drain/gate capacitance. This can cause an unwanted gate voltage spike. An internal proprietary circuit holds GATE low before the internal circuitry wakes up. This reduces the MOSFET current surges substantially at insertion. The GATE pin is held low in reset mode and during the initial timing cycle. In the start-up cycle the GATE pin is pulled up by a 10 µA current source. During an overcurrent fault condition, the error amplifier servoes the GATE pin to maintain a constant current to the load until the circuit breaker trips. When the circuit breaker trips, the GATE pin shuts down abruptly. Current Limit Circuit Breaker Function The LTC4210 features a current limiting circuit breaker instead of a traditional comparator circuit breaker. When there is a sudden load current surge, such as a low impedance fault, the bus supply voltage can drop signifi- cantly to a point where the power to an adjacent card is affected, causing system malfunctions. The LTC4210 fast response error amplifier (EA) instantly limits current by reducing the external MOSFET GATE pin voltage. This minimizes the bus supply voltage drop and permits power budgeting and fault isolation without affecting neighbor- ing cards. A compensation circuit should be connected to the GATE pin for current limit loop stability. Sense Resistor Consideration The nominal fault current limit is determined by a sense resistor connected between VCC and the SENSE pin as given by Equation 1. I V R mV R LIMIT NOM CB NOM SENSE NOM SENSE () () () ( == 50 N NOM) (1) The power rating of the sense resistor should be rated at the fault current level. For proper circuit breaker operation, Kelvin-sense PCB connections between the sense resistor and the LTC4210 VCC and SENSE pins are strongly recommended. The drawing in Figure 1 illustrates the connections between the LTC4210 and the sense resistor. PCB layout should be balanced and symmetrical to minimize wiring errors. In addition, the PCB layout for the sense resistor should include good thermal management techniques for optimal sense resistor power dissipation. APPLICATIO S I FOR ATIO SENSE RESISTOR CURRENT FLOW TO LOAD TRACK WIDTH W: 0.03" PER AMP ON 1 OZ COPPER W TO VCC TO SENSE 4210 F01 CURRENT FLOW TO LOAD Figure 1. Making PCB Connections to the Sense Resistor |
Similar Part No. - LTC4210-4CS6 |
|
Similar Description - LTC4210-4CS6 |
|
|
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 |