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參數(shù)資料
| 型號(hào)： | MAX749ESA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類(lèi)： | 穩(wěn)壓器 |
| 英文描述： | Digitally Adjustable LCD Bias Supply |
| 中文描述： | SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | 0.150 INCH, SOP-8 |
| 文件頁(yè)數(shù)： | 11/12頁(yè) |
| 文件大?。?/td> | 105K |
| 代理商： | MAX749ESA |
Capac itors
Output Filter Capacitor
A 22μF, 30V surface-mount (SMT) tantalum output filter
capacitor typically maintains 100mVp-p output ripple
when generating -24V at 40mA from a 5V input. Smaller
capacitors, down to 10μF, may be used for light loads
in applications that can tolerate higher output ripple.
Surface-mount capacitors are generally preferred
because they lack the inductance and resistance of the
leads of their through-hole equivalents.
Input Bypass Capacitor
A 22μF tantalum capacitor in parallel with a 0.1μF
ceramic normally provides sufficient bypassing.
Mount
the 0.1μF capacitor very close to the IC.
Larger
capacitors may be needed if the incoming supply has
high impedance. Less bypass capacitance is accept-
able if the circuit is run off a low-impedance supply.
Begin prototyping with a large bypass capacitor; when
the circuit is working, reduce the bypass to the smallest
value that gives good results. Although bench power
supplies have low impedance at DC, they often have
high impedance at the frequencies used by switching
DC-DC converters.
The effective series resistance (ESR) of both the
bypass and filter capacitors affects efficiency. Best per-
formance is obtained by doubling up on the filter
capacitors or using low-ESR types.
The smallest low-ESR SMT capacitors currently avail-
able are Sprague 595D series, which are about half the
size of competing products. Sanyo OS-CON organic
semiconductor through-hole capacitors also exhibit low
ESR, and are especially useful when operation below
0°C is required. Table 2 lists the phone numbers of
these and other manufacturers.
Compensation Capacitor
The high value of the feedback resistor makes the feed-
back loop susceptible to phase lag if parasitic capaci-
tance is present at the FB pin. To compensate for this, it
may be necessary to connect a capacitor, C
, in
parallel with R
. Although C
is normally not
required, the value of C
depends upon the value
of R
and on the individual circuit layout—typical val-
ues range from 0pF to 220pF.
PC Layout and Grounding
Due to high current levels and fast switching wave-
forms, proper PC board layout is essential. In particular,
keep all leads short, especially the lead connected to
the FB pin and those connecting Q1, L1, and D1
together.
Mount the R
FB
resistor very close to the IC.
Use a star ground configuration: Connect the ground
lead of the input bypass capacitor, the output capaci-
tor, and the inductor at a common point next to the
GND pin of the MAX749. Additionally, connect the posi-
tive lead of the input bypass capacitor as close as pos-
sible to the V+ pin of the IC.
M
Digitally Adjustable LCD Bias S upply
______________________________________________________________________________________
11
___________________Chip Topography
TRANSISTOR COUNT: 521;
SUBSTRATE CONNECTED TO GND.
ADJ
CTRL
0.070"
(0.1178mm)
0.808"
(0.2032mm)
DLOW
FB
GND
V+
V+
CS
DHI
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX749ESA+ | 功能描述:其他電源管理 Digitally Adjustable LCD Bias Supply RoHS:否 制造商:Texas Instruments 輸出電壓范圍: 輸出電流:4 mA 輸入電壓范圍:3 V to 3.6 V 輸入電流: 功率耗散: 工作溫度范圍:- 40 C to + 110 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-48 封裝:Reel |
| MAX749ESA+ | 制造商:Maxim Integrated Products 功能描述:IC LCD BIAS SUPPLY 8-SOIC 制造商:Maxim Integrated Products 功能描述:IC, LCD BIAS SUPPLY, 8-SOIC |
| MAX749ESA+T | 功能描述:顯示驅(qū)動(dòng)器和控制器 Digitally Adjustable LCD Bias Supply RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel |
| MAX749ESA-T | 功能描述:顯示驅(qū)動(dòng)器和控制器 Digitally Adjustable LCD Bias Supply RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel |
| MAX749ESA-TG074 | 制造商:Maxim Integrated Products 功能描述:DIGITALLY ADJUSTABLE LCD BIAS SUPPLY - Rail/Tube |
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