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參數(shù)資料
| 型號(hào)： | 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(yè)數(shù)： | 14/17頁(yè) |
| 文件大?。?/td> | 958K |
| 代理商： | SP6138ER1-L |
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6
Oct 24-06 Rev J
SP638 Synchronous Buck Controller
2006 Sipex Corporation
THEORY OF OPERATION
The SP6138 contains two unique control
features that are very powerful in distributed
applications. First, non-synchronous driver
control is enabled during start up to prohibit
the low side NFETfrom pulling down the out-
put until the high side NFEThas attempted to
turn on. Second, a 00% duty cycle timeout
ensuresthatthelowsideNFETisperiodically
enhanced during extended periods at 00%
dutycycle.Thisguaranteesthesynchronized
refreshing of the BST capacitor during very
large duty ratios.
The SP638 also contains a number of valu-
able protection features. A programmable
input UVLO allows a user to set the exact
value at which the conversion voltage is at a
safe point to begin down conversion, and an
internalVCCUVLOensuresthatthecontroller
itselfhasenoughvoltagetoproperlyoperate.
Other protection features include thermal
shutdown and short-circuit detection. In the
event that either a
thermal, short-circuit, or UVLO fault is de-
tected,theSP638isforcedintoanidlestate
where the output drivers are held off for a
finite period before a re-start is attempted.
Soft Start
“Soft Start” is achieved when a power con-
verter ramps up the output voltage while
controlling the magnitude of the input sup-
ply source current. In a modern step down
converter,rampingupthenon-invertinginput
of the error amplifier controls soft start. As a
result, excess source current can be defined
as the current required to charge the output
capacitor
IVIN, X =
Cout Vout
TSoft-start
The SP638 provides the user with the op-
tion to program the soft start rate by tying
a capacitor from the SS pin to GND. The
selection of this capacitor is based on the
0A pull up current present at the SS pin
and the 0.8V reference voltage. Therefore,
the excess current source can be redefined as:
IVIN, X = COUT VOUT
0A
(CSS 0.8V)
Hiccup
Upon the detection of a power, thermal, or
short-circuit fault, the SP638 is forced into
an idle state for a minimum of 30ms. The SS
and COMP pins are immediately pulled low,
and the gate drivers are held off for the dura-
tionofthetimeoutperiod.Powerandthermal
faults have to be removed before a restart
may be attempted, whereas, a short-circuit
faultisinternallyclearedshortlyafterthefault
latch is set. Therefore, a restart attempt is
guaranteed every 30ms (typical) as long as
the short-circuit condition persists.
A short-circuit detection comparator has
also been included in the SP638 to protect
against the accidental short or severe build
up of current at the output of the power con-
verter. This comparator constantly monitors
the inputs to theerror amplifier, and if the
VFB pin ever falls more than 250mV (typical)
below the reference voltage, a short-circuit
fault is set. Because the SS pin overrides the
internal 0.8V reference during soft start, the
SP638 is capable of detecting short-circuit
faults throughout the duration of soft start as
well as in regular operation.
Error Amplifier & Voltage Loop
As stated before, the heart of the SP638
voltage error loop is a high performance,
wide bandwidth transconductance ampli-
fier. Because of the amplifier’s current
limited (+00A) transconductance, there
are many ways to compensate the voltage
loop or to control the COMP pin externally.
If a simple, single pole, single zero response
is required, then compensation can be as
simple as an RC circuit to ground. If a more
complex compensation is required, then the
amplifierhasenoughbandwidthtorunTypeIII
compensation schemes with adequate gain
andphasemarginsatcrossoverfrequencies
greater than 200 kHz.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6138ER1-L/TR | 功能描述:開關(guān)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(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 |
| 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(guān)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(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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