![]() |
Electronic Components Datasheet Search |
|
LMR23630AFDDA Datasheet(PDF) 15 Page - Texas Instruments |
|
|
|
LMR23630AFDDA Datasheet(HTML) 15 Page - Texas Instruments |
15 / 42 page ![]() OUT IN _ MIN SW OFF _ MIN V V 1 f T u OUT IN _ MAX SW ON _ MIN V V f T u 15 LMR23630 www.ti.com SNVSAH2C – DECEMBER 2015 – REVISED JUNE 2017 Product Folder Links: LMR23630 Submit Documentation Feedback Copyright © 2015–2017, Texas Instruments Incorporated Figure 18. Synchronizing in PWM Mode Figure 19. Synchronizing in PFM Mode 8.3.5 VCC, UVLO The LMR23630 integrates an internal LDO to generate VCC for control circuitry and MOSFET drivers. The nominal voltage for VCC is 4.1 V. The VCC pin is the output of an LDO and must be properly bypassed. Place a high-quality ceramic capacitor with a value of 2.2 µF to 10 µF, 16 V or higher rated voltage as close as possible to VCC and grounded to the exposed PAD and ground pins. The VCC output pin must not be loaded, or shorted to ground during operation. Shorting VCC to ground during operation may cause damage to the LMR23630. VCC undervoltage lockout (UVLO) prevents the LMR23630 from operating until the VCC voltage exceeds 3.3 V (typical). The VCC UVLO threshold has 400 mV (typical) of hysteresis to prevent undesired shutdown due to temporary VIN drops. 8.3.6 Minimum ON-time, Minimum OFF-time and Frequency Foldback at Dropout Conditions Minimum ON-time, TON_MIN, is the smallest duration of time that the HS switch can be on. TON_MIN is typically 60 ns in the LMR23630. Minimum OFF-time, TOFF_MIN, is the smallest duration that the HS switch can be off. TOFF_MIN is typically 100 ns in the LMR23630. In CCM operation, TON_MIN and TOFF_MIN limit the voltage conversion range given a selected switching frequency. The minimum duty cycle allowed is: DMIN = TON_MIN × fSW (3) And the maximum duty cycle allowed is: DMAX = 1 – TOFF_MIN × fSW (4) Given fixed TON_MIN and TOFF_MIN, the higher the switching frequency the narrower the range of the allowed duty cycle. In the LMR23630, a frequency foldback scheme is employed to extend the maximum duty cycle when TOFF_MIN is reached. The switching frequency decreases once longer duty cycle is needed under low VIN conditions. Wide range of frequency foldback allows the LMR23630 output voltage stay in regulation with a much lower supply voltage VIN. This leads to a lower effective dropout voltage. Given an output voltage, the choice of the switching frequency affects the allowed input voltage range, solution size and efficiency. The maximum operation supply voltage can be found by: (5) At lower supply voltage, the switching frequency decreases once TOFF_MIN is tripped. The minimum VIN without frequency foldback can be approximated by: (6) Taking considerations of power losses in the system with heavy load operation, VIN_MAX is higher than the result calculated in Equation 5. With frequency foldback, VIN_MIN is lowered by decreased fSW. |
Similar Part No. - LMR23630AFDDA |
|
Similar Description - LMR23630AFDDA |
|
|
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 |