參數(shù)資料
型號(hào)： TL3577-ADJIKTTR
廠商： TEXAS INSTRUMENTS INC
元件分類： 穩(wěn)壓器
英文描述： 6 A SWITCHING REGULATOR, 120 kHz SWITCHING FREQ-MAX, PSSO5
封裝： PLASTIC, D2PAK, TO-263, 5 PIN
文件頁(yè)數(shù)： 8/21頁(yè)
文件大小： 431K
代理商： TL3577-ADJIKTTR
www.ti.com
4. Input Capacitor Selection (CIN)
100-kHz CURRENT-MODE SIMPLE STEP-UP/FLYBACK SWITCHING REGULATOR
SLVS633 – OCTOBER 2006
C. Calculate the minimum value of CC.
CC ≥ (58.5 × VOUT
2
× C
OUT) / (RC
2
× V
IN(min))
The compensation capacitor also is used in the soft-start function of the regulator. When the input voltage is
applied to the part, the switch duty cycle is increased slowly at a rate defined by the compensation capacitor and
the soft-start current, thus eliminating high input currents. Without the soft-start circuitry, the switch duty cycle
would instantly rise to about 90% and draw large currents from the input supply. For proper soft starting, the
value for CC should be equal to or greater than 0.22 F.
Table 3 lists several types of aluminum electrolytic capacitors that could be used for the output filter. Use the
following parameters to select the capacitor:
Working Voltage (WVDC): Choose a capacitor with a working voltage at least 20% higher than the regulator
output voltage.
Ripple Current: This is the maximum RMS value of current that charges the capacitor during each switching
cycle. For step-up and flyback regulators, the formula for ripple current is:
IRIPPLE(rms) = (ILOAD(max) × Dmax)/(1 – Dmax)
Choose a capacitor that is rated at least 50% higher than this value at 100 kHz.
Equivalent Series Resistance (ESR): This is the primary cause of output ripple voltage, and it also affects the
values of RC and CC needed to stabilize the regulator. As a result, the preceding calculations for CC and RC are
only valid if the ESR does not exceed the maximum value specified by the following equations.
ESR
≤ (0.01 × 15 V)/I
RIPPLE(P-P) and ≤ (8.7 × 10
-3
× V
IN)/ILOAD(max) where
IRIPPLE(P-P) = (1.15 × ILOAD(max))/(1 – Dmax)
Select a capacitor with an ESR, at 100 kHz, that is less than or equal to the lower value calculated. Most
electrolytic capacitors specify ESR at 120 kHz, which is 15% to 30% higher than at 100 kHz. Also, note that
ESR increases by a factor of 2 when operating at –20
°C.
In general, low values of ESR are achieved by using large-value capacitors (C
≥ 470 F) and capacitors with
high WVDC, or by paralleling smaller-value capacitors.
To reduce noise on the supply voltage caused by the switching action of a step-up regulator (ripple current
noise), VIN should be bypassed to ground. A good quality 0.1-F capacitor with low ESR should provide
sufficient decoupling. If the TL3577 is located far from the supply-source filter capacitors, an additional
electrolytic (47
F, for example) is required.
Table 3. Aluminum Electrolytic Capacitors Recommended for Switching Regulators
Nichicon – Types PF, PX, or PZ
United Chemi-CON – Types LX, SXF, or SXJ
927 East State Parkway, Schaumburg, IL 60173
9801West Higgens, Rosemont, IL 60018
(708) 843-7500
(708) 696-2000
16
相關(guān)PDF資料
PDF描述
TL431ILP/1H 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.5 V, PBCY3
TL431AIX/11H-E3 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.5 V, PSSO3
TL431AIU2/48H 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.5 V, PDSO3
TL431AIU1/48H 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.5 V, PDSO3
TL431MFK 1-OUTPUT TWO TERM VOLTAGE REFERENCE, CQCC20
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
TL3577-ADJIKTTRG3 制造商:Texas Instruments 功能描述:CONV DC-DC SGL-OUT STEP UP 6PIN TO-263 - Tape and Reel
TL35A 功能描述:測(cè)試引線 TEST LEAD WITH ALL RoHS:否 制造商:Pomona Electronics 設(shè)備類型:Patch Cords 連接器類型:Banana plug (stackable) on both ends 長(zhǎng)度:60 in 顏色:Black
TL35B 功能描述:測(cè)試引線 TEST LEAD W/ALLIGATOR CLIPS-CE RoHS:否 制造商:Pomona Electronics 設(shè)備類型:Patch Cords 連接器類型:Banana plug (stackable) on both ends 長(zhǎng)度:60 in 顏色:Black
TL36 功能描述:測(cè)試引線 TEST LEADS W/CLIPS RoHS:否 制造商:Pomona Electronics 設(shè)備類型:Patch Cords 連接器類型:Banana plug (stackable) on both ends 長(zhǎng)度:60 in 顏色:Black
TL-36 制造商:B&K Precision Corporation 功能描述:
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