參數(shù)資料
型號(hào)： MAX1887
廠商： Maxim Integrated Products, Inc.
英文描述： Quick-PWM Slave Controllers for Multiphase, Step-Down
中文描述： Quick-PWM從控制器，用于多相、降壓型電源
文件頁(yè)數(shù)： 22/33頁(yè)
文件大?。?/td> 1018K
代理商： MAX1887
M
Quick-PWM Slave Controllers for
Multiphase, Step-Down Supplies
22
______________________________________________________________________________________
When unadjusted, the on-resistance variation of the
low-side MOSFETs results in a maximum current-limit
variation (
I
LIMIT
) determined by the following equation:
where A
RDS
= R
DS(ON)(MAX)
/R
DS(ON)(MIN)
. Using the
MAX1887/MAX1897 to adjust the master
’
s current-limit
threshold results in a maximum current-limit variation
less than the peak-to-peak inductor current:
Adjusted
I
LIMIT
≤
I
INDUCTOR
As shown in Figure 6, the resulting current-limit varia-
tion of the master is dramatically reduced. For the
above example, this control scheme reduces the cur-
rent-limit variation from 21.7A (unadjusted) to less than
6.4A (adjusted).
Output Capacitor Selection
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.
In CPU V
CORE
converters and other applications where
the output is subject to large load transients, the output
capacitor selection 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:
R
V
I
ESR
STEP
LOAD MAX
≤
(
)
Unadjusted I
V
A
R
LIMIT
ITHM HIGH
(
RDS
(
DS ON MAX
=
)
)(
)
1
0
20
40
60
80
100
120
140
160
0
10
20
30
40
50
SLAVE CURRENT-LIMIT VOLTAGES
vs. AVERAGE INDUCTOR CURRENT
AVERAGE INDUCTOR CURRENT (A)
V
I
ADJ(MIN)
= I
PEAK
= V
ITHS
V
ITHM(HIGH)
R
CM
V
ITHM(LOW)
V
ITHS
I
ADJ
-
I
INDUCTOR
=
R
CM
I
LM(PEAK)
= R
CS
I
LS(PEAK)
R
CM
I
LM(VALLEY)
= R
CS
I
LS(VALLEY)
V
OUT
(V
IN
- V
OUT
)
V
IN
f
SW
L
[
]
0
20
40
60
80
100
120
140
160
0
10
20
30
40
50
MASTER CURRENT-LIMIT VOLTAGES
vs. AVERAGE INDUCTOR CURRENT
AVERAGE INDUCTOR CURRENT (A)
V
V
ITHM(HIGH)
V
ITHM(LOW)
R
DS(ON)(MIN)
= L
LM(VALLEY)
ADJUSTED
I
LIMIT
≤
I
INDUCTOR
UNADJUSTED
I
LIMIT
≤
I
LIMIT
= V
ITHM(HIGH)
R
DS(ON)(MIN)
= L
LM(VALLEY)
MASTER
CONTROLLER
SLAVE
CONTROLLER
A
RDS
- 1
R
DS(ON)(MAX)
(
)
Figure 6. Master/Slave Current-Limit Thresholds
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX1887EEE 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1887EEE+ 功能描述:電流型 PWM 控制器 CDMA Cellular/PCS System Power Supplies RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1887EEE+T 功能描述:電流型 PWM 控制器 CDMA Cellular/PCS System Power Supplies RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1887EEE-T 功能描述:電流型 PWM 控制器 RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
MAX1888EUA 功能描述:其他電源管理 RoHS:否 制造商:Texas Instruments 輸出電壓范圍: 輸出電流:4 mA 輸入電壓范圍:3 V to 3.6 V 輸入電流: 功率耗散: 工作溫度范圍:- 40 C to + 110 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-48 封裝:Reel
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