參數(shù)資料
型號： MAX1680ESA
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： 125mA, Frequency-Selectable, Switched-Capacitor Voltage Converters
中文描述： SWITCHED CAPACITOR CONVERTER, 348 kHz SWITCHING FREQ-MAX, PDSO8
封裝： 0.150 INCH, MS-012A, SOIC-8
文件頁數(shù)： 7/12頁
文件大?。?/td> 103K
代理商： MAX1680ESA
Operating Frequenc y T rade-Offs
It is important to recognize the trade-offs between
switching frequency, power consumption, noise, cost,
and performance. Higher frequency switching reduces
capacitor size while maintaining the same output
impedance, thus saving capacitor cost and board
space. Lower frequency designs use less supply cur-
rent. Table 2 summarizes the relative trade-offs.
Table 2. Switching-Frequency Trade-Offs
Capac itor S elec tion
The MAX1680/MAX1681 are tested with capacitor val-
ues of 10μF and 2.2μF, respectively. Capacitor size
and switching speed determine output resistance.
Larger C1 values decrease the output resistance until
the internal switch resistance (3.5
typ) becomes the
dominant term. Low-ESR capacitors minimize output
resistance and ripple voltage. The entire circuit’s output
resistance can be approximated by the following equa-
tion:
R
OUT
R
O
+ 4 x ESR
C1
+ ESR
C2
+ [1 / (f
OSC
x C1)] +
[1 / (f
OSC
x C2)]
where R
O
is the device’s internal effective switch resis-
tance and f
OSC
is the switching frequency. Output
resistance is a critical circuit component, as it deter-
mines the voltage drop that will occur at the output from
the ideal value of -V
INPUT
(or 2V
INPUT
when doubling).
To optimize performance, minimize overall resistance in
the system. In particular, equivalent series resistance
(ESR) in the capacitors produces significant losses as
large currents flow through them. Therefore, choose a
low-ESR capacitor for highest efficiency. Table 3 lists
recommended capacitors and their suppliers.
Calculate the output ripple voltage as follows:
V
RIPPLE
= [(I
OUT
) / (2 x f
OSC
x C2)] + 2 x (I
OUT
x ESR
C2
)
where I
OUT
is the load current, f
S
is the charge pump’s
operating frequency, C2 is the output capacitor, and
ESR
C2
is the output capacitor’s ESR.
Table 4 lists the minimum recommended capacitances
that allow for the maximum output current. The output
capacitor, C2, is normally equal to or greater than the
charge-pump capacitor, C1. Capacitor values can be
scaled directly proportional to the input voltage, fre-
quency, and load current. For example, for V
INPUT
=
5V, I
LOAD
= 125mA at f
OSC
= 125kHz, a 6.4μF mini-
mum capacitor is recommended. For an output of only
62.5mA, a 3.2μF capacitor is recommended. C1’s value
can be estimated as follows:
C1 = 6.4μF x (V
INPUT
/ 5.0V) x (125kHz / f
OSC
) x
(I
LOAD
/ 125mA)
where f
OSC
is the switching frequency (kHz) and I
LOAD
is the output current (mA) required.
M
125mA, Frequenc y-S elec table,
S witc hed-Capac itor Voltage Converters
_______________________________________________________________________________________
7
ATTRIBUTE
C1, C2 Values
Supply Current
Larger
Smaller
LOWER
FREQUENCY
Output Ripple
Larger
Smaller
Larger
Smaller
SUPPLIER
Marcon/United Chemi-Con
Matsuo
(847) 696-2000
(714) 969-2491
USA: (847) 843-7500
J apan: 81-7-5231-8461
PHONE
AVX
(803) 946-0690
(800) 282-4975
(847) 696-9278
(714) 960-6492
USA: (847) 843-2798
J apan: 81-7-5256-4158
(803) 626-3123
HIGHER
FREQUENCY
FAX
DEVICE TYPE
Ceramic capacitors
Surface mount, 267 series
Surface mount, TPS series
Nichicon
Sanyo
USA: (619) 661-6835
J apan: 81-7-2070-6306
(603) 224-1961
(847) 390-4373
(714) 255-9500
(203) 268-6261
USA: (619) 661-1055
J apan: 81-7-2070-1174
(603) 224-1430
(847) 390-4428
(714) 255-9400
(203) 452-5670
Through-hole, OS-CON series
Through-hole, PL series
Sprague
TDK
United Chemi-Con
Vishay/Vitramon
Ceramic capacitors
Through-hole, LXF series
Surface mount, 595D series
SMT ceramic chip capacitors
Table 3. Low-ESR Capacitor Suppliers
相關(guān)PDF資料
PDF描述
MAX1681ESA 125mA, Frequency-Selectable, Switched-Capacitor Voltage Converters
MAX1682EUK-T Switched-Capacitor Voltage Doublers
MAX1682-MAX1683 Switched-Capacitor Voltage Doublers
MAX1683EUK-T Switched-Capacitor Voltage Doublers
MAX1682 Switched-Capacitor Voltage Doublers
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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MAX1680ESA+T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 125mA f-Selct Swtchd Cap Volt Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX1680ESA-T 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 125mA f-Selct Swtchd Cap Volt Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT
MAX16810ATU+ 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N
MAX16810ATU+T 功能描述:LED照明驅(qū)動器 RoHS:否 制造商:STMicroelectronics 輸入電壓:11.5 V to 23 V 工作頻率: 最大電源電流:1.7 mA 輸出電流: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SO-16N
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