Electronic Components Datasheet Search |
|
LM21215AMHX-1/NOPB Datasheet(PDF) 13 Page - Texas Instruments |
|
|
LM21215AMHX-1/NOPB Datasheet(HTML) 13 Page - Texas Instruments |
13 / 38 page Vss VFB VEN VPGOOD VSW OVP UVP PRE-BIASED STARTUP DISABLE Vovp Vuvp tPGDGL 0.6V t RESETSS t PGDGH VOVPHYS VUVPHYS LM21215A www.ti.com SNOSB87C – MARCH 2011 – REVISED JANUARY 2016 Feature Description (continued) As shown above, the soft-start capacitance is set by the nominal feedback voltage level 0.6 V, the soft-start charging current ISS, and the desired soft-start time. If a soft-start capacitor is not installed, the LM21215A defaults to a soft-start time of 500 µs. The LM21215A cannot startup faster than 500 µs. When Enable is cycled or the device enters UVLO, the soft-start capacitor is discharged to reset the startup process. This also occurs when the device enters short circuit mode following an overcurrent event. 7.3.4 PGOOD Indicator The PGOOD flag provides the user with a way to monitor the status of the LM21215A. In order to use the PGOOD function, the application must provide a pullup resistor to a desired DC voltage, for example VIN. PGOOD responds to a fault condition by pulling PGOOD low with the open-drain output. PGOOD pulls low on the following conditions: 1) VFB moves above or below the VOVP or VUVP, respectively; 2) The EN voltage is brought below the Enable turn-off threshold; 3) A pre-biased output condition exists (VFB > VSS/TRK). PGOOD has 12 μs and 15 μs of built-in deglitch time for rising and falling edges, respectively. Figure 24 shows the conditions that cause PGOOD to respond. Figure 24. PGOOD Indicator Operation 7.3.5 Frequency Synchronization The SYNC pin allows the LM21215A to be synchronized to an external clock frequency. When a clock signal within the allowable frequency range of 300 kHz to 1.5 MHz is present on SYNC, an internal PLL synchronizes the turn-on of the high-side MOSFET (SW voltage rising) to the negative edge of the clock signal, as seen in Figure 25. The clock signal can be present on the SYNC pin before the device is powered on without loading of the clock signal. Alternatively, if a clock signal is not present while the device is powered up, the default switching frequency is 500 kHz. Once the clock signal is available, the device synchronizes to the clock frequency. The time required to achieve synchronization depends on the clock frequency. Copyright © 2011–2016, Texas Instruments Incorporated Submit Documentation Feedback 13 Product Folder Links: LM21215A |
Similar Part No. - LM21215AMHX-1/NOPB |
|
Similar Description - LM21215AMHX-1/NOPB |
|
|
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 |