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參數資料
| 型號： | ISL6431CB |
| 廠商： | INTERSIL CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Triple 3-Input Positive-NAND Gates 14-TSSOP -40 to 85 |
| 中文描述： | SWITCHING CONTROLLER, 300 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | PLASTIC, MS-012AA, SOIC-8 |
| 文件頁數： | 5/10頁 |
| 文件大?。?/td> | 187K |
| 代理商： | ISL6431CB |
5
completion of the OCP sampling and hold operation, the POR
function initiates the Soft Start operation.
Over Current Protection
The overcurrent function protects the converter from a shorted
output by using the upper MOSFET’s on-resistance, r
DS(ON)
,
to monitor the current. This method enhances the converter’s
efficiency and reduces cost by eliminating a current sensing
resistor.
The overcurrent function cycles the soft-start function in a
hiccup mode to provide fault protection. A resistor
(R
OCSET
) programs the overcurrent trip level (see Typical
Application diagram).
Immediately following POR, the ISL6431 initiates the
Overcurrent Protection sampling and hold operation. First,
the internal error amplifier is disabled. This allows an internal
20
μ
A current sink to develop a voltage across R
OCSET
. The
ISL6431 then samples this voltage at the COMP pin. This
sampled voltage, which is referenced to the VCC pin, is held
internally as the Overcurrent Set Point.
When the voltage across the upper MOSFET, which is also
referenced to the VCC pin, exceeds the Overcurrent Set
Point, the overcurrent function initiates a soft-start sequence.
Figure 1 shows this operation with an overload condition. This
current is repeated with a 21ms period. Note that the inductor
current increases to over 14A during the Soft Start interval and
causes an overcurrent trip. The converter dissipates very little
power with this method. The measured input power for the
conditions of Figure 1 is only 0.25W.
The overcurrent function will trip at a peak inductor current
(I
PEAK)
determined by:
where I
OCSET
is the internal OCSET current source (20
μ
A
typical). The OC trip point varies mainly due to the
MOSFET’s r
DS(ON)
variations. To avoid overcurrent tripping
in the normal operating load range, find the R
OCSET
resistor
from the equation above with:
1. The maximumr
DS(ON)
atthe highestjunctiontemperature.
2. The minimum I
OCSET
from the specification table.
3. Determine I
PEAK
for
where
I is the output inductor ripple current.
For an equation for the ripple current see the section under
component guidelines titled ‘Output Inductor Selection’.
,
Soft Start
The POR function initiates the soft start sequence after the
overcurrent set point has been sampled. Soft start clamps the
error amplifier output (COMP pin) and reference input (non-
inverting terminal of the error amp) to the internally generated
Soft Start voltage. Figure 2 shows a typical soft start interval.
Initially the clamp on the error amplifier (COMP/OCSET pin)
controls the converter’s output voltage. The oscillator’s
triangular waveform is compared to the ramping error amplifier
voltage. This generates PHASE pulses of increasing width that
charge the output capacitor(s). With sufficient output voltage,
the clamp on the reference input controls the output voltage.
When the internally generated Soft Start voltage exceeds the
feedback (FB pin) voltage, the output voltage is in regulation.
This method provides a rapid and controlled output voltage rise.
Application Guidelines
Layout Considerations
As in any high frequency switching converter, layout is very
important. Switching current from one power device to another
can generate voltage transients across the impedances of the
interconnecting bond wires and circuit traces. These
interconnecting impedances should be minimized by using
wide, short printed circuit traces. The critical components
should be located as close together as possible, using ground
plane construction or single point grounding.
O
FIGURE 1. OVERCURRENT OPERATION
0A
4A
2A
6A
8A
10A
12A
14A
TIME (50
μ
s/DIV.)
I
PEAK
I
x R
r
DS ON
)
----------------------------------------------------
=
I
PEAK
I
OUT MAX
)
I
2
(
----------
)
+
>
0V
TIME (1ms/DIV.)
FIGURE 2. SOFT START INTERVAL
V
OUT
500mV/DIV.
ISL6431
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相關代理商/技術參數 |
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| ISL6431CB-T | 功能描述:IC REG CTRLR BUCK PWM VM 8-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 標準包裝:4,000 系列:- PWM 型:電壓模式 輸出數:1 頻率 - 最大:1.5MHz 占空比:66.7% 電源電壓:4.75 V ~ 5.25 V 降壓:是 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:無 工作溫度:-40°C ~ 85°C 封裝/外殼:40-VFQFN 裸露焊盤 包裝:帶卷 (TR) |
| ISL6431IB | 制造商:Intersil Corporation 功能描述: |
| ISL6432CB | 制造商:Intersil Corporation 功能描述: |
| ISL6432CB-T | 功能描述:IC REG QD BCK/LINEAR 16-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 線性 + 切換式 系列:- 標準包裝:2,500 系列:- 拓撲:降壓（降壓）同步（3），線性（LDO）（2） 功能:任何功能 輸出數:5 頻率 - 開關:300kHz 電壓/電流 - 輸出 1:控制器 電壓/電流 - 輸出 2:控制器 電壓/電流 - 輸出 3:控制器 帶 LED 驅動器:無 帶監(jiān)控器:無 帶序列發(fā)生器:是 電源電壓:5.6 V ~ 24 V 工作溫度:-40°C ~ 85°C 安裝類型:* 封裝/外殼:* 供應商設備封裝:* 包裝:* |
| ISL6433BCB | 制造商:Intersil Corporation 功能描述: |
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