參數(shù)資料
型號(hào)： MAX1994ETM
廠商： MAXIM INTEGRATED PRODUCTS INC
元件分類： 穩(wěn)壓器
英文描述： Dual Step-Down Controllers Plus Linear- Regulator Controller for Notebook Computers
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
文件頁數(shù)： 38/49頁
文件大?。?/td> 983K
代理商： MAX1994ETM
M
Dual Step-Down Controllers Plus Linear-
Regulator Controller for Notebook Computers
38
______________________________________________________________________________________
5)
Inductor Ripple Current.
The inductor ripple cur-
rent also impacts transient response performance,
especially at low V
IN
- V
OUT
differentials. Low induc-
tor values allow the inductor current to slew faster,
replenishing charge removed from the output filter
capacitors by a sudden load step. The amount of
output sag is also a function of the maximum duty
factor, which can be calculated from the on-time
and minimum off-time:
where t
OFF(MIN)
is the minimum off-time (see the
Electrical Characteristics
table) and K is from Table 3.
Inductor Selection
The switching frequency and operating point (% ripple
current or LIR) determine the inductor value as follows:
Example: I
LOAD(MAX)
= 19A, V
IN
= 7V, V
OUT
= 1.25V,
f
SW
= 300kHz, 30% ripple current or LIR = 0.30:
Find a low-loss inductor having the lowest possible DC
resistance that fits in the allotted dimensions. Ferrite
cores are often the best choice, although powdered iron
is inexpensive and can work well at 200kHz. The core
must be large enough not to saturate at the peak induc-
tor current (I
PEAK
):
Setting the Current Limit for BUCK1
Connect ILIM1 to V
CC
for a default 50mV (CS1+ to CS1-)
current-limit threshold. For an adjustable threshold, con-
nect a resistive voltage-divider from REF to GND, with
ILIM1 connected to the center tap. The current-limit
threshold is precisely 1/10th of the voltage at ILIM1. When
adjusting the current limit, use 1% tolerance resistors for
the divider and a 10μA divider current to prevent a signifi-
cant increase of errors in the current-limit threshold.
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:
The current-sense resistor value (R1 in Figure 1) is cal-
culated according to the worst-case (minimum) current-
limit threshold voltage (see the
Electrical Characteristics
table) and the valley current-limit threshold I
LIMIT(MIN)
described above:
where 0.8 is a factor for the worst-case low current-limit
threshold.
To protect against component damage during short-cir-
cuit conditions, use the calculated value of R
SENSE
to
size the MOSFET switches and specify inductor satura-
tion-current ratings according to the worst-case high
current-limit threshold:
where 1.2 is a factor for worst-case high current-limit
threshold.
Low-inductance resistors, such as surface-mount metal
film, are recommended.
Setting the Current Limit for BUCK2
Connect ILIM2 to V
CC
for a default 50mV CS2 to GND
current-limit threshold. For an adjustable threshold,
connect a resistive voltage-divider from REF to GND,
with ILIM2 connected to the center tap. The current-
limit threshold is precisely 1/10th of the voltage at
ILIM2. When adjusting the current limit, use 1% toler-
ance resistors for the divider and a 10μA divider cur-
rent to prevent a significant increase of errors in the
current-limit threshold.
I
mV
R
SENSE
LIR
Fixed Mode
(
I
V
R
)
LIR
Adjustable Mode
(
PEAK MAX
PEAK MAX
ILIM
SENSE
(
)
(
)
.
(
)
)
.
.
(
)
=
×
×
+
=
×
×
+
50
1 2
1
0 1 1 2
1
1
R
mV
I
V
Fixed Mode
(
R
I
Adjustable Mode
(
SENSE
LIMIT MIN
SENSE
ILIM
LIMIT MIN
=
×
=
×
50
0 8
.
0 1 0 8
.
1
)
.
)
(
)
(
)
I
I
LIR
2
LIMIT MIN
LOAD MAX
(
)
(
)
>
×
1
I
I
LIR
2
PEAK
LOAD MAX
=
×
+
(
)
1
L
V
V
×
V
V
kHz
A
H
=
×
×
=
μ
0 30 19
.
1 25
300
7
1 25
.
7
0 60
.
.
(
)
L
V
×
V
V
V
f
LIR I
OUT
SW
IN
OUT
LOAD MAX
IN
=
×
×
(
)
(
)
V
I
I
L
KV
V
t
C
V
KV
V
V
t
SAG
LOAD
LOAD
OUT
IN
OFF MIN
(
OUT
OUT
IN
OUT
IN
OFF MIN
(
=
× ×
+
×
×
×
(
)
)
)
1
2
2
2
相關(guān)PDF資料
PDF描述
MAX1816 Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP
MAX1816ETM Replaced by TMS320VC5506 : Digital Signal Processors 144-LQFP
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
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1994ETM+ 功能描述:DC/DC 開關(guān)控制器 Integrated Circuits (ICs) 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
MAX1994ETM+T 功能描述:DC/DC 開關(guān)控制器 Integrated Circuits (ICs) 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
MAX1994ETM-T 功能描述:DC/DC 開關(guān)控制器 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
MAX1994EVKIT 功能描述:DC/DC 開關(guān)控制器 Evaluation Kit for the MAX1816 MAX1980 MAX1994 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
MAX1995EGI 功能描述:顯示驅(qū)動(dòng)器和控制器 RoHS:否 制造商:Panasonic Electronic Components 工作電源電壓:2.7 V to 5.5 V 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-44 封裝:Reel
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。

采購需求

(若只采購一條型號(hào)，填寫一行即可)

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

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購

我的聯(lián)系方式

*
*
*