參數(shù)資料
型號(hào)： MAX1865UEEP
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： xDSL/Cable Modem Triple/Quintuple Output Power Supplies
中文描述： 0.5 A SWITCHING CONTROLLER, 120 kHz SWITCHING FREQ-MAX, PDSO20
封裝： 0.150 INCH, 0.025 INCH PITCH, QSOP-20
文件頁(yè)數(shù)： 15/25頁(yè)
文件大?。?/td> 384K
代理商： MAX1865UEEP
M
xDSL/Cable Modem Triple/Quintuple Output
Power Supplies
______________________________________________________________________________________
15
where f
SW
is 200kHz for MAX186_T and 100kHz for
MAX186_U. The exact inductor value is not critical and
can be adjusted to make trade-offs among size, cost,
and efficiency. Lower inductor values minimize size
and cost, but they also increase the output ripple and
reduce the efficiency due to higher peak currents. On
the other hand, higher inductor values increase effi-
ciency, but at some point resistive losses due to extra
turns of wire will exceed the benefit gained from lower
AC current levels.
Find a low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions. Ferrite
cores are often the best choice, though powdered iron
is inexpensive and can work well at 200kHz. The cho-
sen inductor
’
s saturation rating must exceed the peak
inductor current:
Setting the Current Limit
The minimum current-limit threshold must be high
enough to support the maximum load current at the
minimum tolerance level of the current-limit circuit. The
valley of the inductor current occurs at I
LOAD(MAX)
minus half of the ripple current:
where R
DS(ON)
is the on-resistance of the low-side
MOSFET (N
L
). For the MAX1864/MAX1865, the mini-
mum current-limit threshold is 190mV (for the typical
250mV default setting). Use the worst-case maximum
value for R
DS(ON
) from the MOSFET N
L
data sheet, and
add some margin for the rise in R
DS(ON)
over tempera-
ture. A good general rule is to allow 0.5% additional
resistance for each
°
C of the MOSFET junction temper-
ature rise.
Connect ILIM to VL for the default 250mV (typ) current-
limit threshold. For an adjustable threshold, connect a
resistive-divider from VL to ILIM to GND. The 500mV to
2.5V external adjustment range corresponds to a
106mV to 530mV current-limit threshold. When adjust-
ing the current limit, use 1% tolerance resistors and a
10μA divider current to prevent a significant increase in
the current-limit tolerance.
V
R
I
LIR
2
I
VALLEY LOW
DS ON
(
LOAD MAX
LOAD MAX
(
)
)
(
)
(
)
>
-
I
I
LIR
2
I
PEAK
LOAD MAX
LOAD MAX
=
+
(
)
(
)
BST
C1
D1
C2
R2
R1
N
H
N
L
C
BST
R
POK
R
COMP
C
COMP
C
OUT
C
IN
DH
LX
L
OUTPUT
1.25V TO 5V*
INPUT
4.5V TO 28V
DL
OUT
GND
FB
IN
VL
ILIM
POK
COMP
MAX1864
MAX1865
* FOR OUTPUT VOLTAGES > 5V, SEE "OUTPUT VOLTAGE SELECTION."
Figure 4. Adjustable Output Voltage
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1865UEEP-T 功能描述:電流和電力監(jiān)控器、調(diào)節(jié)器 RoHS:否 制造商:STMicroelectronics 產(chǎn)品:Current Regulators 電源電壓-最大:48 V 電源電壓-最小:5.5 V 工作溫度范圍:- 40 C to + 150 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:HPSO-8 封裝:Reel
MAX1868EGL 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1868ETL 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1869EGL 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
MAX1869ETL 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
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