參數(shù)資料
型號(hào)： MAX1816ETM
廠(chǎng)商： MAXIM INTEGRATED PRODUCTS INC
元件分類(lèi)： 穩(wěn)壓器
英文描述： Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP
中文描述： DUAL SWITCHING CONTROLLER, 1000 kHz SWITCHING FREQ-MAX, CQCC48
封裝： 7 X 7 MM, 0.80 MM HEIGHT, THIN, QFN-48
文件頁(yè)數(shù)： 39/49頁(yè)
文件大?。?/td> 983K
代理商： MAX1816ETM
M
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
______________________________________________________________________________________
39
The minimum current-limit threshold must be great
enough to support the maximum load current when the
current limit is at the minimum tolerance value. The val-
ley of the inductor current occurs at I
LOAD(MAX)
minus
half of the ripple current; therefore:
where I
LIMIT(MIN)
equals the minimum current-limit
threshold voltage divided by the current-sense resistor.
The sense resistor (R2 in Figure 1) determines the achiev-
able current-limit accuracy. There is a trade-off between
current-limit accuracy and sense-resistor power dissipa-
tion. Most applications employ a current-sense voltage of
50mV to 100mV. Choose a sense resistor so that:
where 0.8 is a factor for worst-case low current-limit
threshold.
Extremely cost-sensitive applications that do not require
high-accuracy current sensing can use the on-resis-
tance of the low-side MOSFET switch in place of the
sense resistor by connecting CS2 to LX2. Use the worst-
case maximum value for R
DS(ON)
from the MOSFET
data sheet taking into account the rise in R
DS(ON)
with
temperature. A good general rule is to allow 0.5% addi-
tional resistance for each
°
C temperature rise.
Assume the current-sense resistor in the application cir-
cuit in Figure 1 is removed and CS2 is directly tied to
LX2. The Q4 maximum R
DS(ON)
= 3.8m
at T
J
= +25
°
C
and 5.7m
at T
J
= +125
°
C.
The minimum current-limit threshold is:
mV
LIMIT MIN
(
)
=
and the required valley current limit is:
I
LIMIT(MIN)
> 7A
(1 - 0.30/2) = 5.95A
since 7A is greater than the required 5.95A, the circuit
can deliver the 7A full-load current.
Output Capacitor Selection
(BUCK1 and BUCK2)
The output filter capacitor must have low enough effec-
tive series resistance (ESR) to meet output ripple and
load-transient requirements, yet have high enough ESR
to satisfy stability requirements. Also, the capacitance
value must be high enough to absorb the inductor ener-
gy going from a full-load to no-load condition without
tripping the OVP circuit.
In CPU core voltage regulators and other applications
where the output is subject to violent load transients,
the output capacitor
’
s size typically depends on how
much ESR is needed to prevent the output from dipping
too low under a load transient. Ignoring the sag due to
finite capacitance:
In non-CPU applications, the output capacitor
’
s size
often depends on how much ESR is needed to maintain
an acceptable level of output-voltage ripple:
The actual microfarad capacitance value required often
relates to the physical size needed to achieve low ESR,
as well as to the chemistry of the capacitor technology.
Thus, the capacitor is usually selected by ESR and volt-
age rating rather than by capacitance value (this is true
of tantalums, OSCONs, and other electrolytics).
When using low-capacity filter capacitors such as
ceramic or polymer types, capacitor size is usually deter-
mined by the capacity needed to prevent V
SAG
and
V
SOAR
from causing problems during load transients.
Generally, once enough capacitance is added to meet
the overshoot requirement, undershoot at the rising load
edge is no longer a problem.
The amount of overshoot due to stored inductor energy
can be calculated as:
where I
PEAK
is the peak inductor current.
V
L I
C
OUT
V
SOAR
PEAK
OUT
=
×
×
2
2
R
V
LIR I
ESR
P P
LOAD MAX
≤
(
)
R
V
I
ESR
DIP
LOAD MAX
≤
(
)
I
m
A
.
.
.
×
=
500
0 1 0 8
5 7
7
R
mV
I
V
Fixed Mode
(
R
I
Adjustable Mode
(
SENSE
LIMIT MIN
SENSE
ILIM
LIMIT MIN
=
×
=
×
50
0 8
.
0 1 0 8
.
2
)
.
)
(
)
(
)
I
I
LIR
2
LIMIT MIN
LOAD MAX
(
)
(
)
>
×
1
相關(guān)PDF資料
PDF描述
MAX199AEWI Fixed-Point Digital Signal Processor 532-FCBGA
MAX199AMYI Circular Connector; No. of Contacts:18; Series:MS27505; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:15; Circular Contact Gender:Socket; Circular Shell Style:Box Mount Receptacle RoHS Compliant: No
MAX199ACAI Multi-Range (【4V, 【2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface
MAX199AENI Multi-Range (【4V, 【2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface
MAX199BEAI Multi-Range (【4V, 【2V, +4V, +2V), +5V Supply, 12-Bit DAS with 8+4 Bus Interface
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1816ETM+ 功能描述:DC/DC 開(kāi)關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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
MAX1816ETM+T 功能描述:DC/DC 開(kāi)關(guān)控制器 NULL RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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
MAX1816ETM-T 功能描述:DC/DC 開(kāi)關(guān)控制器 NULL RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開(kāi)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
MAX1816XR31+ 制造商:Maxim Integrated Products 功能描述:
MAX1817EUB 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 Dual-Output Step-Up DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠(chǎng)商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*