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參數(shù)資料
| 型號： | SP6138ER1-L |
| 廠商： | EXAR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2 A SWITCHING CONTROLLER, 2800 kHz SWITCHING FREQ-MAX, QCC16 |
| 封裝： | 3 X 3 MM, LEAD FREE, MO-220VEED-4, QFN-16 |
| 文件頁數(shù)： | 15/17頁 |
| 文件大?。?/td> | 958K |
| 代理商： | SP6138ER1-L |
7
Oct 24-06 Rev J
SP638 Synchronous Buck Controller
2006 Sipex Corporation
THEORY OF OPERATION
The common mode output of the error ampli-
fier (COMP) is 0.9V to 2.2V. Therefore, the
PWM voltage ramp has been set between
.0V and 2.0V to ensure proper 0% to 00%
duty cycle capability. The voltage loop also
includes two other very important features.
One is an non-synchronous start up mode.
Basically,theGLdrivercannotturnonunless
the GH driver has attempted to turn on or
the SS pin has exceeded .7V. This feature
preventsthecontrollerfrom“draggingdown”
the output voltage during startup or in fault
modes. The second feature is a 00% duty
cycle timeout that ensures synchronized
refreshing of the BST capacitor at very high
duty ratios. In the event that the GH driver is
on for 20 continuous clock cycles, a reset is
given to the PWM flip flop half way through
the 20th cycle. This forces GL to rise for the
remainder of the cycle, in turn refreshing the
BST capacitor.
Gate Drivers
The SP638 contains a pair of powerful 2.5
pull-up and .5 pull-down drivers. These
state-of-the-art drivers are designed to drive
an external NFET capable of handling up to
30A. Rise, fall, and non-overlap times have
all been minimized to achieve maximum
efficiency. All drive pins GH, GL, & SWN
are monitored continuously to ensure that
only one external NFET is ever on at any
given time.
Thermal & Short-Circuit Protection
Because the SP638 is designed to drive
large NFETs running at high current, there is
a chance that either the controller or power
converter will become too hot. Therefore, an
internal thermal shutdown (145°C) has been
included to prevent the IC from malfunction-
ing at extreme temperatures.
Over-Current Protection
Over-current is detected by monitoring a
differential voltage across the output induc-
tor as shown in figure 1. Inputs to an over-
current detection comparator, set to trigger
at 60 mV nominal, are connected to the in-
ductor as shown.
Since the average voltage sensed by the
comparator is equal to the product of in-
ductor current and inductor DC resistance
(DCR) then Imax = 60mV / DCR. Solving
this equation for the specific inductor in cir-
cuit , Imax = 4.6A. When Imax is reached,
a 220 ms time-out is initiated, during which
top and bottom drivers are turned off. Fol-
lowing the time-out, a restart is attempted.
If the fault condition persists, then the time-
out is repeated (referred to as hiccup).
Figure 1: Over-current detection circuit
ISN
SP613X
SWN
ISP
Vout
L = 2.7uH, DCR = 4.mOhm
RS
5.K
RS2
5.K
CS
0.uF
CSP
6.8nF
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| SP6138ER1-L/TR | 功能描述:開關變換器、穩(wěn)壓器與控制器 Synchronous Controller 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 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
| SP6139 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input, 1.3MHz Synchronous PWM Controller |
| SP6139EU | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input, 1.3MHz Synchronous PWM Controller |
| SP6139EU/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input, 1.3MHz Synchronous PWM Controller |
| SP6139EU-L | 功能描述:開關變換器、穩(wěn)壓器與控制器 Wide Input, 1.3MHz 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 開關頻率:1 MHz 工作溫度范圍: 安裝風格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel |
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