Electronic Components Datasheet Search |
|
LP3905SD-A3 Datasheet(PDF) 10 Page - National Semiconductor (TI) |
|
|
LP3905SD-A3 Datasheet(HTML) 10 Page - National Semiconductor (TI) |
10 / 15 page Functional Description (Continued) the cycle repeats to restore the output voltage (average voltage in pfm mode) to ∼1.15% above the nominal PWM output voltage. If the load current should increase during PFM mode caus- ing the output voltage to fall below the ‘low2’ PFM threshold, the part will automatically transition into fixed-frequency PWM mode. When V IN =2.8V the part transitions from PWM to PFM mode at ~35mA output current and from PFM to PWM mode at ~85mA , when V IN=3.6V, PWM to PFM tran- sition happens at ~50mA and PFM to PWM transition hap- pens at ~100mA, when V IN =4.5V, PWM to PFM transition happens at ~65mA and PFM to PWM transition happens at ~115mA. SOFT START The LP3905 Buck Converters have a soft-start circuit that limits in-rush current during start-up. Additionally, in case EN1 and EN2 are enabled at the same time, a typical 500µs delay between Buck1 and Buck2 Power Up prevents any further Inrush current from the battery. During start-up the switch current limit is increased in steps. Soft start is activated only if EN goes from logic low to logic high after Vin reaches 3V. Soft start is implemented by increasing switch current limit in steps of 70mA, 140mA, 280mA and 1000mA (typ. switch current limit). The start-up time thereby depends on the output capacitor and load current demanded at start-up. Typical start-up times with 22µF output capacitor and 300mA load current is 400µs and with 1mA load current its 275µs. 20152903 FIGURE 10. Operation in PFM Mode and Transfer to PWM Mode www.national.com 10 |
Similar Part No. - LP3905SD-A3 |
|
Similar Description - LP3905SD-A3 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.NET |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | 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 |