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參數(shù)資料
| 型號： | ISL6244 |
| 廠商： | Intersil Corporation |
| 英文描述： | Multi-Phase PWM Controller(多相PWM控制器) |
| 中文描述： | 多相PWM控制器（多相脈寬調(diào)制控制器） |
| 文件頁數(shù)： | 21/25頁 |
| 文件大?。?/td> | 845K |
| 代理商： | ISL6244 |
21
FN9106.3
December 28, 2004
Since the capacitors are supplying a decreasing portion of
the load current while the regulator recovers from the
transient, the capacitor voltage becomes slightly depleted.
The output inductors must be capable of assuming the entire
load current before the output voltage decreases more than
V
MAX
. This places an upper limits on inductance.
Equation 29 gives the upper limit on L for the cases when
the trailing edge of the current transient causes a greater
output-voltage deviation than the leading edge. Equation 28
addresses the leading edge. Normally, the trailing edge
dictates the selection of L because duty cycles are usually
less than 50%. Nevertheless, both inequalities should be
evaluated, and L should be selected based on the lower of
the two results. In each equation, L is the per-channel
inductance, C is the total output capacitance, and N is the
number of active channels.
Input Supply Voltage Selection
The VCC input of the ISL6244 can be connected to either a
+5V supply directly or through a current limiting resistor to a
+12V supply. An integrated 5.8V shunt regulator maintains
the voltage on the VCC pin when a +12V supply is used. A
300
resistor is suggested for limiting the current into the
VCC pin to approximately 20mA.
Switching Frequency
There are a number of variables to consider when choosing
the switching frequency, as there are considerable effects on
the upper-MOSFET loss calculation. These effects are
outlined in
MOSFETs
, and they establish the upper limit for
the switching frequency. The lower limit is established by the
requirement for fast transient response and small output-
voltage ripple as outlined in
Output Filter Design
. Choose the
lowest switching frequency that allows the regulator to meet
the transient-response requirements.
Switching frequency is determined by the selection of the
frequency-setting resistor, R
T
(see Figure 11). Figure 27 and
Equation 30 are provided to assist in the selecting the
correct value for R
T
.
Input Capacitor Selection
The input capacitors are responsible for sourcing the ac
component of the input current flowing into the upper
MOSFETs. Their RMS current capacity must be sufficient to
handle the ac component of the current drawn by the upper
MOSFETs which is related to duty cycle and the number of
active phases.
For a two phase design, use Figure 28 to determine the
input-capacitor RMS current requirement given the duty
cycle, maximum sustained output current (I
O
), and the ratio
of the combined peak-to-peak inductor current (I
C,PP
) to I
O
.
Select a bulk capacitor with a ripple current rating which will
minimize the total number of input capacitors required to
support the RMS current calculated. The voltage rating of
the capacitors should also be at least 1.25 times greater
than the maximum input voltage.
(EQ. 28)
L
O
I
(
)
2
2NCV
V
MAX
I ESR
)
–
≤
(EQ. 29)
L
N
V
C
------------------------------------------------------------------–
(
)
1.5
V
I
)
)
(
≤
FIGURE 27. R
T
vs SWITCHING FREQUENCY
100
1000
10000
10
SWITCHING FREQUENCY (kHz)
10
100
1000
R
T
)
R
T
10
11.09
1.13
f
S
(
)
log
–
[
]
=
(EQ. 30)
0.3
0.1
0
0.2
I
R
I
O
)
FIGURE 28. NORMALIZED INPUT-CAPACITOR RMS
CURRENT vs DUTY CYCLE FOR 2-PHASE
CONVERTER
0
0.4
1.0
0.2
0.6
0.8
DUTY CYCLE (V
IN/
V
O
)
I
C,PP
= 0
I
C,PP
= 0.5 I
O
I
C,PP
= 0.75 I
O
ISL6244
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6244CR | 功能描述:IC REG CTRLR BUCK PWM 32-QFN RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| ISL6244CR-T | 功能描述:IC REG CTRLR BUCK PWM 32-QFN RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標(biāo)準(zhǔn)包裝:4,000 系列:- PWM 型:電壓模式 輸出數(shù):1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| ISL6244CRZ | 功能描述:電流型 PWM 控制器 VER OF ISL6244CR RoHS:否 制造商:Texas Instruments 開關(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 |
| ISL6244CRZ-T | 功能描述:電流型 PWM 控制器 VER OF ISL6244CR-T RoHS:否 制造商:Texas Instruments 開關(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 |
| ISL6244EVAL1 | 功能描述:EVALUATION BOARD ISL6244 RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC（離線）SMPS 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:True Shutdown™ 主要目的:DC/DC，步升 輸出及類型:1，非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓?fù)浣Y(jié)構(gòu):升壓 頻率 - 開關(guān):3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
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