Electronic Components Datasheet Search |
|
LT4180MPGN-PBF Datasheet(PDF) 10 Page - Linear Technology |
|
LT4180MPGN-PBF Datasheet(HTML) 10 Page - Linear Technology |
10 / 16 page LT4180 10 4180fp APPLICATIONS INFORMATION With an oscillator tolerance of ±15%, the minimum dither frequency is 414.8Hz, so the minimum decoupling capacitance is: C Hz µF LOAD == 22 57 2 2 414 8 46 36 . .• • . . Ω This is the minimum value. Select a nominal value to ac- count for all factors which could reduce the nominal, such as initial tolerance, voltage and temperature coefficients and aging. CHOLD Capacitor Selection and Compensation With dither frequency determined, use the following equa- tions to determine CHOLD values: C nF fkHz HOLD DITHER 1 11 9 = . () and CC nF fkHz HOLD HOLD DITHER 23 25 == . () So, with a dither frequency of 488Hz: C nF kHz nF HOLD1 11 9 0 488 24 4 == . . . and CC nF kHz nF HOLD HOLD 23 25 0 488 512 == = . .( ) . NPO ceramic or other capacitors with low leakage and dielectric absorption should be used for all hold capa- citors. Set CHOLD4 to 1μF. Start with a 47pF capacitor between the COMP and DRAIN pins of the LT4180. Add an RC network in parallel with the 47pF capacitor. 10k and 10nF are good starting values. Connect a DC load corresponding to full-scale load cur- rent and verify that VOUT produces a rounded squarewave without any noticeable overshoot or ringing (similar to the VOUT waveform in Figure 3). If overshoot or ringing is observed, decrease the value of the resistor until it just disappears. If overshoot or ringing is not observed, increase the value of the resistor until it is observed, then slightly decrease the value of the resistor so that overshoot and ringing disappear. Check for proper voltage drop cor- rection and converter behavior (start-up, regulation etc.), over the load range, and repeat the above procedure with a smaller value of the compensation capacitor, if necessary. Decrease CHOLD4 capacitance until VOUT exhibits slight low frequency instability, then increase CHOLD4 slightly from this value. Setting Output Voltage, Undervoltage and Overvoltage Thresholds The RUN pin has accurate rising and falling thresholds whichmaybeusedtodeterminewhenVirtualRemoteSense operation begins. Undervoltage threshold should never be set lower than the minimum operating voltage of the LT4180 (3.1V). The overvoltage threshold should be set slightly greater than the highest voltage which will be produced by the power supply or regulator: VOUT(MAX) = VLOAD(MAX) + VWIRE(MAX) VOUT(MAX) should never exceed 1.5 • VLOAD Since the RUN and OV pins connect to MOSFET input comparators, input bias currents are negligible and a com- mon voltage divider can be used to set both thresholds (Figure 7). Figure 7. Voltage Divider for Output Voltage, UVL and OVL R3 FB 4180 F07 RUN R2 LT4180 R4 OV R1 VIN |
Similar Part No. - LT4180MPGN-PBF |
|
Similar Description - LT4180MPGN-PBF |
|
|
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 |