Electronic Components Datasheet Search |
|
ISL6554CB-T Datasheet(PDF) 9 Page - Intersil Corporation |
|
ISL6554CB-T Datasheet(HTML) 9 Page - Intersil Corporation |
9 / 16 page 9 FN9003.3 February 11, 2005 Note that Figure 5 shows the 12V gate driver voltage available before the 5V supply to the ISL6554 has reached its threshold level. If conditions were reversed and the 5V supply was to rise first, the start-up sequence would be different. In this case the ISL6554 will sense an overcurrent condition due to charging the output capacitors. The supply will then restart and go through the normal soft-start cycle. Fault Protection The ISL6554 protects the microprocessor and the entire power system from damaging stress levels. Within the ISL6554 both Overvoltage and Overcurrent circuits are incorporated to protect the load and regulator. Overvoltage The VSEN pin is connected to the microprocessor CORE voltage. A CORE overvoltage condition is detected when the VSEN pin goes more than 15% above the programmed VID level. The overvoltage condition is latched, disabling normal PWM operation, and causing PGOOD to go low. The latch can only be reset by lowering and returning VCC high to initiate a POR and soft-start sequence. During a latched overvoltage, the PWM outputs will be driven either low or three state, depending upon the VSEN input. PWM outputs are driven low when the VSEN pin detects that the CORE voltage is 15% above the programmed VID level. This condition drives the PWM outputs low, resulting in the lower or synchronous rectifier MOSFETs to conduct and shunt the CORE voltage to ground to protect the load. If after this event, the CORE voltage falls below the over- voltage limit (plus some hysteresis), the PWM outputs will three state. The HIP6601 family drivers pass the three-state information along, and shuts off both upper and lower MOSFETs. This prevents “dumping” of the output capacitors back through the lower MOSFETs, avoiding a possibly destructive ringing of the capacitors and output inductors. If the conditions that caused the overvoltage still persist, the PWM outputs will be cycled between three state and VCORE clamped to ground, as a hysteretic shunt regulator. Undervoltage The VSEN pin also detects when the CORE voltage falls more than 9% below the VID programmed level. This causes PGOOD to go low, but has no other effect on operation and is not latched. There is also hysteresis in this detection point. Overcurrent In the event of an overcurrent condition, the overcurrent protection circuit reduces the RMS current delivered to 41% of the current limit. When an overcurrent condition is detected, the controller forces all PWM outputs into a three state mode. This condition results in the gate driver removing drive to the output stages. The ISL6554 goes into a wait delay timing cycle that is equal to the soft-start ramp PWM 1 PGOOD VCORE 5V OUTPUT VCC VIN = 12V DELAY TIME FIGURE 3. START-UP OF 4 PHASE SYSTEM OPERATING AT 500kHz PGOOD VCORE 5V V COMP VCC VIN = 12V DELAY TIME FIGURE 4. START-UP OF 4 PHASE SYSTEM OPERATING AT 200kHz 12V ATX SUPPLY PGOOD 5 V ATX VCORE SUPPLY ATX SUPPLY ACTIVATED BY ATX “PS-ON PIN” VIN = 5V, CORE LOAD CURRENT = 31A FIGURE 5. SUPPLY POWERED BY ATX SUPPLY FREQUENCY 200kHz ISL6554 |
Similar Part No. - ISL6554CB-T |
|
Similar Description - ISL6554CB-T |
|
|
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 |