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參數(shù)資料
| 型號(hào)： | MAX863EEE |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Dual, High-Efficiency, PFM, Step-Up DC-DC Controller |
| 中文描述： | DUAL SWITCHING CONTROLLER, PDSO16 |
| 封裝： | 0.150 INCH, 0.025 INCH PITCH, QSOP-16 |
| 文件頁數(shù)： | 11/16頁 |
| 文件大?。?/td> | 194K |
| 代理商： | MAX863EEE |
M
Dual, High-Effic ienc y, PFM, S tep-Up
DC-DC Controller
______________________________________________________________________________________
11
minimum input voltages. Estimate the maximum input
currents for each output based on the minimum input
voltage and desired output power:
V
IN,DC MAX
where 0.8 is chosen as a working value for the nominal
efficiency. The power source must be capable of deliv-
ering the sum of the maximum input currents of both
DC-DC converters.
Determine the Peak S witc hing Current
(Graphic al Method)
The peak switching current set by R
SENSE
determines
the amount of energy transferred from the input on
each cycle. For 3.3V, 5V, 12V, and 24V output circuits,
the peak current can be selected using the output cur-
rent curves shown in Figures 5a–5d.
Determine the Peak S witc hing Current and
Induc tanc e (Analytic al Method)
The following boost-circuit equations are useful when
the desired output voltage differs from those listed in
Figure 5. They allow trading off peak current and induc-
tor value in consideration of component availability,
size, and cost.
Begin by calculating the minimum allowable ratio of
inductor AC ripple current to peak current,
ξ
MIN
(Figure 6):
t
x
=
where t
OFF(MIN)
= 2μs and t
ON(MAX)
= 17.5μs.
Select a value for
ξ
greater than
ξ
MIN
. If
ξ
MIN
is less
than 1, an acceptable choice is (
ξ
MIN
+ 1) / 2. If
ξ
MIN
is
greater than 1, values between
ξ
MIN
and 2 x
ξ
MIN
are
acceptable (1.5 x
ξ
MIN
, for example). Values greater
than 1 represent designs with full-load operation in dis-
continuous-conduction mode.
Now calculate the peak switching current and induc-
tance. If
ξ
MIN
≤
ξ
≤
1, use:
For
ξ
≥
1%, use:
The suggested inductor value is:
Round L up to the next standard inductor value.
Choose R
SENSE
The peak switching current is set by R
SENSE
(R1 and
R2 in Figure 2):
Verify that you’ve selected the correct R
SENSE
by test-
ing the prototype using the minimum input voltage
while supplying the maximum output current. If the out-
put voltage droops, then decrease the value of the cur-
rent-sense resistor and adjust the other components as
necessary.
The current-sense resistor must be a small, low-induc-
tance type such as a surface-mount metal-strip resistor.
Do not use wire-wound resistors, since their high induc-
tance will corrupt the current feedback signal. In order
to allow use of standard resistor values, round R
SENSE
to the next lowest value.
The current-sense resistor’s power rating should be
higher than:
R
V
R
POWER RATING
2
CS MAX
SENSE
=
)
R
V
I
SENSE
CS MIN
PEAK
≤
=
)
85mV
I
PEAK
L
V
- V
x t
I
x
OUT
IN MIN
OFF MIN
PEAK
)
)
ξ
I
= 2 x I
x V
+ V x
V
OUT
PEAK
IN,DC MAX
OUT
)
(
)
ξ
1
I
= I
x
2
2-
PEAK
IN,DC MAX
)
ξ
ξ
MIN
OFF MIN
t
ON MAX
OUT
V
IN MIN
V
)
IN MIN
V
)
)
)
I
x I
0.8 x V
OUT
OUT
IN MIN
)
)
I
L
t
I
L
I
L
=
PEAK
I
PEAK
Figure 6. Ratio of Inductor AC Ripple Current to Peak Current
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相關(guān)代理商/技術(shù)參數(shù) |
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|---|---|
| MAX863EEE+ | 功能描述:DC/DC 開關(guān)控制器 Dual PFM Step-Up DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX863EEE+T | 功能描述:DC/DC 開關(guān)控制器 Dual PFM Step-Up DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX863EEE-T | 功能描述:DC/DC 開關(guān)控制器 Dual PFM Step-Up DC/DC Controller RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX863EVKIT | 功能描述:DC/DC 開關(guān)控制器 Evaluation Kit for the MAX863 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| MAX8640EVKIT | 制造商:Maxim Integrated Products 功能描述:500MA 4MHZ/2MHZ SYNCHRONOUS STEP-D - Rail/Tube |
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