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參數(shù)資料
| 型號： | SP6659EK1-1.5/TR |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 1.3 A SWITCHING REGULATOR, 1800 kHz SWITCHING FREQ-MAX, PDSO5 |
| 封裝： | SOT-23, 5 PIN |
| 文件頁數(shù)： | 10/11頁 |
| 文件大小： | 204K |
| 代理商： | SP6659EK1-1.5/TR |
8
Date: 08/15/05
SP6659 1.5MHz, 600mA Synchronous Buck Regulator
Copyright 2005 Sipex Corporation
In the Idle Mode, the inductor current may
reach zero Amps or reverse on each pulse.
The PWM control loop will automatically
skip pulses to maintain output regulation.
The bottom MOSFET is turned off by the
current reversal comparator, IZERO, and the
switch voltage will ring. This is discontinu-
ous mode operation, and is normal behavior
for the switching regulator.
_______________________ DROPOUT
OPERATION
When the input voltage decreases toward
the value of the output voltage, the SP6659
allows the main switch to remain on for more
than one switching cycle and increases the
duty cycle until it reaches 100%.
The duty cycle D of a step-down converter is
defined as:
D = T
ON X OSC X 100%
≈ VOUT
X 100%
V
IN
where TON is the main switch on time, and
OSC is the oscillator frequency (1.5Mhz).
The output voltage then is the input voltage
minus the voltage drop across the main
switch and the inductor. At low input supply
voltage, the RDSON of the P-Channel
MOSFET increases, and the efficiency of
the converter decreases. Caution must be
exercised to ensure that the heat dissipated
does not exceed the maximum junction tem-
perature of the IC.
THEORY OF OPERATION
________________________ MAXIMUM
LOAD CURRENT
The SP6659 will operate with an input sup-
ply voltage as low as 2.5V, however, the
maximum load current decreases at lower
inputs due to a large IR drop on the main
switch and synchronous rectifier. The slope
compensation signal reduces the peak in-
ductor current as a function of the duty cycle
to prevent sub-harmonic oscillations at duty
cycles greater than 50%. Conversely, the
current limit increases as the duty cycle
decreases.
_______________________ INDUCTOR
SELECTION
For most designs, the SP6659 operates with
inductors of 1H to 4.7H. Low inductance
values are physically smaller but require
faster switching, which can result in some
efficiency loss. The inductor value can be
derived from the following equation:
L = VOUT X (VINMax - VOUT)
VINMax X IL X
OSC
Where IL is the inductor Ripple Current.
Large value inductors lower ripple current
and small value inductors result in higher
ripple current. Choose inductors at ripple
current of approximately 35% of the maxi-
mum load current 600mA, or ~ 210mA.
For output voltages above 2.0V, when light-
load efficiency is important, the minimum
recommended inductor is 2.2H. For opti-
mum voltage-positioning load transients,
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6659EK118 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:1.5MHz, 600mA Synchronous Buck Regulator |
| SP6659EK118/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:1.5MHz, 600mA Synchronous Buck Regulator |
| SP6659EK1-L | 制造商:Exar Corporation 功能描述:REG BUCK 1.5MHZ 0.6A TSOT23-5 |
| SP6659EK1-L/TR | 功能描述:DC/DC 開關(guān)控制器 1.5MHz, 600mA Synchronous 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 |
| SP6659EK1-L-1-5/TR | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 1.5MHz, 600mA Synchronous RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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