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參數(shù)資料
| 型號： | SP7655 |
| 英文描述： | Wide Input Voltage Range 8A, 300kHz, Buck Regulator |
| 中文描述： | 寬輸入電壓范圍8A條，300kHz的降壓穩(wěn)壓器 |
| 文件頁數(shù)： | 6/12頁 |
| 文件大小： | 121K |
| 代理商： | SP7655 |
6
Date: 08/17/04
SP7655 Wide Input Voltage Range 8A, 300kHz, Buck Regulator Copyright 2004 Sipex Corporation
THEORY OF OPERATION
zero response is desired, then compensation can
be as simple as an RC to ground. If a more
complex compensation is required, then the
amplifier has enough bandwidth (45
°
at 4 MHz)
and enough gain (60dB) to run Type III compen-
sation schemes with adequate gain and phase
margins at cross over frequencies greater than
50kHz.
The common mode output of the error amplifier
is 0.9V to 2.2V. Therefore, the PWM voltage
ramp has been set between 1.1V and 2.2V to
ensure proper 0% to 100% duty cycle capability.
The voltage loop also includes two other very
important features. One is an asynchronous start
up mode. Basically, the synchronous rectifier
can not turn on unless the high side switch has
attempted to turn on or the SS pin has exceeded
1.7V. This feature prevents the controller from
“dragging down” the output voltage during
startup or in fault modes. The second feature is
a 100% duty cycle timeout that ensures synchro-
nized refreshing of the BST capacitor at very
high duty ratios. In the event that the high side
NFET is on for 20 continuous clock cycles, a
reset is given to the PWM flip flop half way
through the 21st cycle. This forces GL to rise for
the cycle, in turn refreshing the BST capacitor.
The boost capacitor is used to generate a high
voltage drive supply for the high side switch,
which is 5V above V
IN
.
Power MOSFETs
The SP7655 contains a pair of integrated low
resistance N-channel switches designed to drive
up to 10A of output current. Care should be
taken to de-rate the output current based on the
thermal conditions in the system such as ambi-
ent temperature, airflow and heat sinking. Maxi-
mum output current could be limited by thermal
limitations of a particular application by taking
advantage of the integrated over temperature
protective scheme employed in the SP7655.
The SP7655 incorporates a built-in over-tem-
perature protection to prevent internal overheat-
ing.
GH
Voltage
GL
Voltage
V(VIN)
0V
-0V
-V(Diode) V
V(VIN)+V(VCC)
BST
Voltage
V(VCC)
TIME
SWN
Voltage
VBST
VSWN
V(VCC)
The SP7655 can be set to different output
voltages. The relationship in the following
formula is based on a voltage divider from the
output to the feedback pin VFB, which is set
to an internal reference voltage of 0.80V.
Standard 1% metal film resistors of surface
mount size 0603 are recommended.
Vout = 0.80V ( R1 / R2 + 1 ) => R2 = R1 / [ (
Vout / 0.80V ) – 1 ]
Where R1 = 68.1K
and for Vout = 0.80V
setting, simply remove R2 from the board.
Furthermore, one could select the value of R1
and R2 combination to meet the exact output
voltage setting by restricting R1 resistance
range such that 50K
< R1 < 100K
for
overall system loop stability.
Setting Output Voltages
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP7655_05 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7655_07 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
| SP7655EB | 功能描述:電源管理IC開發(fā)工具 Eval Board for SP7655 Series RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| SP7655ER | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP7655ER/TR | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Wide Input Voltage Range, 8Amp 300kHz, Buck Regulator |
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