Motore di ricerca datesheet componenti elettronici |
|
LM2734ZSDX Scheda tecnica(PDF) 10 Page - Texas Instruments |
|
LM2734ZSDX Scheda tecnica(HTML) 10 Page - Texas Instruments |
10 / 36 page LM2734 VIN BOOST SW GND L D1 D2 D3 R3 C4 VBOOST CBOOST VZ V IN C IN V OUT C OUT LM2734Z, LM2734Z-Q1 SNVS334F – JANUARY 2005 – REVISED JANUARY 2016 www.ti.com Feature Description (continued) Resistor R3 must be chosen to provide enough RMS current to the Zener diode (D3) and to the BOOST pin. A recommended choice for the Zener current (IZENER) is 1 mA. The current IBOOST into the BOOST pin supplies the gate current of the NMOS control switch and varies typically according to Equation 8. IBOOST = (D + 0.5) × (VZENER – VD2) mA where • D is the duty cycle • VZENER and VD2 are in volts • IBOOST is in milliamps • VZENER is the voltage applied to the anode of the boost diode (D2) • VD2 is the average forward voltage across D2 (8) NOTE Equation 8 for IBOOST gives typical current. For the worst case IBOOST, increase the current by 25%. In that case, the worse-case boost current is: IBOOST-MAX = 1.25 × IBOOST (9) R3 is then given by Equation 10. R3 = (VIN - VZENER) / (1.25 × IBOOST + IZENER) (10) For example, let VIN = 10 V, VZENER = 5 V, VD2 = 0.7 V, IZENER = 1 mA, and duty cycle D = 50%. Then: IBOOST = (0.5 + 0.5) × (5 - 0.7) mA = 4.3 mA (11) R3 = (10 V - 5 V) / (1.25 × 4.3 mA + 1 mA) = 787 Ω (12) Figure 10. Boost Voltage Supplied from the Shunt Zener on VIN 7.3.3 Soft-Start This function forces VOUT to increase at a controlled rate during start-up. During soft-start, the reference voltage of the error amplifier ramps from 0 V to its nominal value of 0.8 V in approximately 200 µs. This forces the regulator output to ramp up in a more linear and controlled fashion, which helps reduce inrush current. 7.3.4 Output Overvoltage Protection The overvoltage comparator compares the FB pin voltage to a voltage that is 10% higher than the internal reference Vref. Once the FB pin voltage goes 10% above the internal reference, the internal NMOS control switch is turned off, which allows the output voltage to decrease toward regulation. 10 Submit Documentation Feedback Copyright © 2005–2016, Texas Instruments Incorporated Product Folder Links: LM2734Z LM2734Z-Q1 |
Codice articolo simile - LM2734ZSDX |
|
Descrizione simile - LM2734ZSDX |
|
|
Link URL |
Privacy Policy |
ALLDATASHEETIT.COM |
Lei ha avuto il aiuto da alldatasheet? [ DONATE ] |
Di alldatasheet | Richest di pubblicita | contatti | Privacy Policy | scambio Link | Ricerca produttore 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 |