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參數(shù)資料
| 型號(hào)： | ISL6271ACR |
| 廠商： | INTERSIL CORP |
| 元件分類(lèi)： | 穩(wěn)壓器 |
| 英文描述： | Integrated XScale Regulator |
| 中文描述： | 0.8 A SWITCHING REGULATOR, PQCC20 |
| 封裝： | 4 X 4 MM, PLASTIC, MO-220-VGGD, QFN-20 |
| 文件頁(yè)數(shù)： | 12/16頁(yè) |
| 文件大小： | 588K |
| 代理商： | ISL6271ACR |
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12
FN9171.1
Loop stability calculations are simplified when using the
ISL6271A and are limited to the selection of a single
feedback resistor, Rcomp. The Rcomp resistor will affect the
closed loop gain of the internal compensation network as in
Equation 2. Empirical and theoretical testing suggests that a
value of 50K will provide the most ideal transient response to
the expected XScale load and voltage transitions when used
with the recommended 4.7μH output inductor and 10μF
output capacitor. Using the ISL6271A evaluation board, a
50K feedback resistor resulted in a minimum of 60 degrees
of phase margin under worst case line and load transitions.
When placing the Rcomp feedback resistor, be sure to avoid
routing it parallel to switching circuits, especially the phase
node, that could otherwise induce noise into the FB pin.
Overcurrent Protection and Ripple Current
The OCL trip level inside the ISL6271A is a function of the
upper PMOS output transistor’s on-resistance and over-
current comparator threshold voltage. The device was
designed to accommodate a maximum RMS current of
800mA, and to accommodate this DC current level plus the
associated ripple current, the OC limit of the ISL6271A will
not trip below 950mA. Ripple current inside the ISL6271A is
defined by the expression,
where
“fs”
is the switching frequency of the converter. The
architecture of the ISL6271A is such that the switching
frequency will increase with higher input voltage. This
behavior attempts to keep the ripple current constant for a
given output inductor, input voltage and output voltage. To
minimize ripple current and preserve transient response,
Intersil recommends an output inductor between 3.3μH and
4.7μH. Higher values of inductance will minimize the risk of
tripling the over-current minimum threshold of 950mA.
SSR Theoretical Operation
The ISL6271A is a PWM controller that uses a novel
architecture developed by Intersil called
Synthetic Ripple
Regulation
. The architecture operates similar to a hysteretic
converter without the deficiencies of noise sensitivities.
Reduced to its simplest form, the Synthetic Ripple Regulator
inside the ISL6271A is made up of three elements as
illustrated in Figure 20: A transconductance amplifier
(Rippler Amplifier), a window comparator with hysteresis and
an Error Amplifier. While operating in continuous conduction
mode, the converter has a natural switching frequency of
1.2MHz delivering an ultra low output voltage ripple and
exceptional transient response as illustrated in Figures 23
and 24.
Figure 20 illustrates the two control loops inherent to the
SRR architecture. The inner loop consists of the ripple
amplifier, the window comparator, gate drive circuitry and the
power stage. The outer loop controls the inner loop and is
made up a high bandwidth error amplifier with internal and
external compensation.
CCM Operation - Heavy Current
Figure 21 illustrates the SSR in CCM. When the upper
P-MOSFET is turned on, the phase voltage equals the input
voltage and the ripple transconductance amplifier outputs a
current proportional to the difference of the input and output
voltage. This current will ramp the voltage on the ripple
capacitor Cr in Figure 20. As this voltage reaches the upper
threshold of the hysteretic comparator, the comparator
output will switch low. After a propagation delay, the upper
P-MOSFET is turned off and the lower N-MOSFET is turned
on, forcing synchronous rectification. At this point, the ripple
amplifier now has inputs of 0V and VOUT and will sink
current to discharge the ripple capacitor. When the voltage
across the ripple capacitor reaches the lower threshold of
the hysteresis window, the window comparator outputs a
high signal. After a propagation delay, the upper P-MOSFET
turns on repeating the previous switching cycle.
Gcomp
Rcomp
----------------------------------+
)
Cc
s
=
(EQ. 2)
Iripple
------------–
(
)
L
-------------
=
(EQ. 3)
FIGURE 20. SIMPLIFIED SRR DIAGRAM
Lo
+
off
,
ERROR AMP
Rcomp
Vref(DAC)
INPUT VOLTAGE
SYNTHETIC RIPPLE REGULATION
SIMPLIFIED DIAGRAM
+
-
WINDOW COMPARATOR
on
),
Vout
-
Vin
(
Gm
Vout
Gm
Iout =
{
Rc
Cc
ton
+
-
toff
Cr
SINK/SOURCE
CONTROL
Gm AMP
RIPPLE CAPACITOR
VOLTAGE
OUTPUT
VOLTAGE
VOUT
PHASE
VOLTAGE
VRP
HYSTERESIS
WINDOW
FIGURE 21. SYNTHETIC RIPPLE REGULATION IN CCM
ISL6271A
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ISL6271ACR-T | 功能描述:IC PMIC XSCALE PROCESSOR 20-QFN RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 電源管理 - 專(zhuān)用 系列:- 應(yīng)用說(shuō)明:Ultrasound Imaging Systems Application Note 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:37 系列:- 應(yīng)用:醫(yī)療用超聲波成像，聲納 電流 - 電源:- 電源電壓:2.37 V ~ 6 V 工作溫度:0°C ~ 70°C 安裝類(lèi)型:表面貼裝 封裝/外殼:56-WFQFN 裸露焊盤(pán) 供應(yīng)商設(shè)備封裝:56-TQFN-EP（8x8） 包裝:管件 |
| ISL6271ACRZ | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 LD PLL & SRAMG FOR I NTEL PROCESSORS IBM RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| ISL6271ACRZ-T | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 LD PLL & SRAMG FOR I NTEL PROCESSORS IBM RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| ISL6271AEVAL1 | 功能描述:EVALUATION BOARD FOR ISL6271A RoHS:否 類(lèi)別:編程器，開(kāi)發(fā)系統(tǒng) >> 評(píng)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(lèi)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(kāi)關(guān):3MHz 板類(lèi)型:完全填充 已供物品:板 已用 IC / 零件:MAX8969 |
| ISL6271CR | 制造商:Rochester Electronics LLC 功能描述:PLL & SRAM REGULATOR FOR INTEL PROCESSORS - Bulk 制造商:Intersil Corporation 功能描述: |
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