Electronic Components Datasheet Search |
|
NCV885300D1R2G Datasheet(PDF) 9 Page - ON Semiconductor |
|
NCV885300D1R2G Datasheet(HTML) 9 Page - ON Semiconductor |
9 / 12 page NCV8853 www.onsemi.com 9 Gate Drive To turn on the P−Channel MOSFET, the gate driver turns on a current source to ground. A clamp ensures that the gate drive voltage does not exceed 10 V. When the clamp starts conducting the current source starts to turn off. To turn off the external MOSFET, the gate driver turns on a current source to VIN. 100% Duty Cycle Operation Each cycle, the oscillator allows either a maximum duty cycle up to 93% or 100% duty cycle operation. The oscillator does not allow duty cycles between 93% and 100%. Every cycle, the oscillator determines whether an off−time is necessary. If so, the oscillator creates a duty cycle up to 93%. If an off−time is not required, it can be skipped and 100% duty cycle is allowed for the cycle. Below are a few examples of what this could look like on the switching node: Figure 14. Duty Cycle Timing A B D 1234 C ≤93% 93% 93% 100% 93% 100% 93% 100% 93% 100% 100% 100% 100% ≤93% ≤93% ≤93% A: Continuous operation. Each period has a duty cycle that is less than or equal to 93%. B: One off−time is skipped in period 3, while the minimum off−time is maintained in periods 1, 2, and 4. C: An off−time is skipped in period 1 and in period 3, while the minimum off−time is maintained in periods 2 and 4. D: Low input voltage causes the IC to regulate at continuous 100% duty cycle (dropout). EN/SYNC This pin has three modes. When a dc logic high (CMOS/TTL compatible) voltage is applied to this pin the NCV8853 operates at the default frequency. When a dc logic low voltage is applied to this pin the NCV8853 enters a low quiescent current sleep mode. When a square wave of at least 40% of the switching frequency is applied to this pin the switcher operates at the same frequency as the square wave. If the signal is slower than 40% of the switching frequency, it will be interpreted as enabling and disabling the part. The falling edge of the square wave corresponds to the start of the switching cycle. Power Good The power good pin is high when the reference voltage reaches 90% of its target of 800 mV. The pin should be pulled up with a 10 k W resistor to 5 V. The output voltage of the controller may be used in this case. Overvoltage Lockout To protect the IC, if the voltage on the VIN pin the exceeds Vovlo the NCV8853 will shutdown. When the voltage drops below this voltage the part will go through the normal soft−start procedure. Undervoltage Lockout Undervoltage lockout protection is engaged when the input voltage drops below the Vuvlo signal. The part will remain off until the input voltage rises above the Vuvlo value plus hysteresis. Depending on the desired output voltage, it is possible to engage the short-circuit hiccup mode before undervoltage lockout occurs. Soft−Start To ensure moderate inrush current and reduce output overshoot, the NCV8853 features a soft start which periodically adds charge to a capacitor until the final reference voltage is achieved. When using an external SYNC signal, charging is based on the switching frequency. If, for example, the NCV8853 is synchronized to twice the free running (not synced) frequency, the soft−start will be half as long. |
Similar Part No. - NCV885300D1R2G |
|
Similar Description - NCV885300D1R2G |
|
|
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 |