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參數(shù)資料
| 型號： | DS14285 |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | Timer or RTC |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
| 封裝： | 0.600 INCH, DIP-24 |
| 文件頁數(shù)： | 6/16頁 |
| 文件大?。?/td> | 312K |
| 代理商： | DS14285 |
Capacitors
Choose the output capacitor (C4 of Figures 2, 3, and 4)
to be consistent with size, ripple, and output voltage
requirements. Place capacitors in parallel if the size
desired is unobtainable. This will not only increase the
capacitance, but also decrease the capacitor’s ESR (a
major contributor of ripple). A 330F tantalum output filter
capacitor with 0.07
ESR typically maintains 120mVP-P
output ripple when generating -5V at 1A from a 5V
input. Smaller capacitors are acceptable for lighter
loads or in applications that can tolerate higher output
ripple.
The value of C4 is chosen such that it acquires as
small a charge as possible during the switch on-time.
The amount of ripple as a function of capacitance is
give by:
VOUT x IOUT x ESR
IOUT x tOFF(min)
VP-P = _____________________ + _________________
VIN
C
When evaluating this equation, be sure to use the
capacitance value at the switching frequency. At
200kHz, the 330F tantalum capacitor of Figures 2, 3,
or 4 may degrade by a factor of ten, which will signifi-
cantly alter the ripple voltage calculation.
The ESR of both the bypass and filter capacitors also
affects efficiency. Best performance is obtained by
doubling up on the filter capacitors or using low-ESR
capacitors. Capacitors must have a ripple current rat-
ing equal to the peak current.
The smallest low-ESR SMT capacitors currently avail-
able are the Sprague 595D series. Sanyo OS-CON
organic semiconductor through-hole capacitors also
exhibit low ESR and are especially effective at low tem-
peratures. Table 1 lists the phone numbers of these
and other manufacturers.
PC Layout and Grounding
Due to high current levels and fast switching wave-
forms, proper PC board layout is essential. Use a star
ground configuration; connect the ground lead of the
input bypass capacitor, the output capacitor, the induc-
tor, and the GND pin of the MAX774/MAX775/MAX776
at a common point very close to the device. Addi-
tionally, input capacitor C2 (Figures 3 and 4) should be
placed extremely close to the device.
If an external resistor divider is used (Figures 3 and 4),
the trace from FB to the resistors must be extremely short.
MAX774/MAX775/MAX776
-5V/-12V/-15V or Adjustable, High-Efficiency,
Low IQ Inverting DC-to-DC Controllers
14
______________________________________________________________________________________
Table 1. Component Suppliers
SUPPLIER
PHONE
FAX
Coiltronics
(407) 241-7876
(407) 241-9339
Gowanda
(716) 532-2234
(716) 532-2702
Sumida Japan
81-3-3607-5111
81-3-3607-5144
Sumida USA
(708) 956-0666
(708) 956-0702
Kemet
(803) 963-6300
(803) 963-6322
Matsuo
(714) 969-2491
(714) 960-6492
Nichicon
(708) 843-7500
(708) 843-2798
Sanyo Japan
81-7-2070-6306
81-7-2070-1174
Sanyo USA
(619) 661-6835
(619) 661-1055
Sprague
(603) 224-1961
(603) 224-1430
United Chemi-Con
(714) 255-9500
(714) 255-9400
Motorola
(800) 521-6274
(602) 952-4190
Nihon USA
81-3-3494-7411
81-3-3494-7414
Nihon Japan
(805) 867-2555
(805) 867-2556
Harris
(407) 724-3729
(407) 724-3937
International Rectifier
(310) 322-3331
(310) 322-3332
Siliconix
(408) 988-8000
(408) 970-3950
IRC
(704) 264-8861
(704) 264-8866
INDUCTORS
CAPACITORS
DIODES
POWER MOSFETS
CURRENT-SENSE RESISTORS
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS1670S | 0 TIMER(S), REAL TIME CLOCK, PDSO20 |
| DS14287 | 1 TIMER(S), REAL TIME CLOCK, PDIP24 |
| DS1670E | 0 TIMER(S), REAL TIME CLOCK, PDSO20 |
| DS2282 | DATACOM, FRAMER, SMA30 |
| DS1486-120 | 1 TIMER(S), REAL TIME CLOCK, DIP32 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS14285_05 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:Real-Time Clock with NV RAM |
| DS14285+ | 功能描述:實時時鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS14285-DS14287 | 制造商:DALLAS 制造商全稱:Dallas Semiconductor 功能描述:Real Time Clock with NV RAM Control |
| DS14285N | 功能描述:實時時鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| DS14285N+ | 功能描述:實時時鐘 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
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