- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄97867 > DS21Q48N (DALLAS SEMICONDUCTOR) DATACOM, PCM TRANSCEIVER, PBGA144 PDF資料下載
參數(shù)資料
| 型號： | DS21Q48N |
| 廠商： | DALLAS SEMICONDUCTOR |
| 元件分類： | Digital Transmission Interface |
| 英文描述： | DATACOM, PCM TRANSCEIVER, PBGA144 |
| 封裝： | BGA-144 |
| 文件頁數(shù)： | 3/16頁 |
| 文件大小： | 296K |
| 代理商： | DS21Q48N |
MAX863
Dual, High-Efficiency, PFM, Step-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:
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 Switching Current
(Graphical Method)
The peak switching current set by RSENSE 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 Switching Current and
Inductance (Analytical 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,
ξMIN
(Figure 6):
where tOFF(MIN) = 2s and tON(MAX) = 17.5s.
Select a value for
ξ greater than ξMIN. If ξMIN is less
than 1, an acceptable choice is (
ξMIN + 1) / 2. If ξMIN is
greater than 1, values between
ξMIN and 2 x ξMIN are
acceptable (1.5 x
ξMIN, 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
ξMIN ≤ξ≤ 1, use:
For
ξ≥ 1%, use:
The suggested inductor value is:
Round L up to the next standard inductor value.
Choose RSENSE
The peak switching current is set by RSENSE (R1 and
R2 in Figure 2):
Verify that you’ve selected the correct RSENSE 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 RSENSE
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
IPEAK
L
V
- V
x t
Ix
OUT
IN MIN
OFF MIN
PEAK
()
ξ
I
= 2 x I
x
V
+ V
x
PEAK
IN,DC MAX
OUT
IN
()
()
ξ 1
VOUT
I
= I
x
2
2-
PEAK
IN,DC MAX
()
ξ
ξMIN
OFF MIN
ON MAX
OUT
IN MIN
t
x
VV
V
=
()
I
V
x I
0.8 x V
IN,DC MAX
OUT
IN MIN
()
INDUCTOR
CURRENT,
I
L
t
IL
ξMIN =
IL
IPEAK
Figure 6. Ratio of Inductor AC Ripple Current to Peak Current
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS21Q48 | DATACOM, PCM TRANSCEIVER, PBGA144 |
| DS21Q552 | DATACOM, PCM TRANSCEIVER, PBGA256 |
| DS2250-32-16 | 8-BIT, 16 MHz, MICROCONTROLLER, SMA40 |
| DS2250T-32-16 | 8-BIT, 16 MHz, MICROCONTROLLER, SMA40 |
| DS2250-8-16 | 8-BIT, 16 MHz, MICROCONTROLLER, DMA40 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS21Q48NB | 功能描述:網(wǎng)絡(luò)控制器與處理器 IC RoHS:否 制造商:Micrel 產(chǎn)品:Controller Area Network (CAN) 收發(fā)器數(shù)量: 數(shù)據(jù)速率: 電源電流（最大值）:595 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PBGA-400 封裝:Tray |
| DS21Q50 | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Quad E1 Transceiver |
| DS21Q50L | 功能描述:網(wǎng)絡(luò)控制器與處理器 IC Quad E1 Transceiver RoHS:否 制造商:Micrel 產(chǎn)品:Controller Area Network (CAN) 收發(fā)器數(shù)量: 數(shù)據(jù)速率: 電源電流（最大值）:595 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PBGA-400 封裝:Tray |
| DS21Q50L+ | 功能描述:網(wǎng)絡(luò)控制器與處理器 IC Quad E1 Transceiver RoHS:否 制造商:Micrel 產(chǎn)品:Controller Area Network (CAN) 收發(fā)器數(shù)量: 數(shù)據(jù)速率: 電源電流（最大值）:595 mA 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PBGA-400 封裝:Tray |
| DS21Q50L-C01 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。