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參數資料
| 型號： | ISL6439AEVAL1 |
| 廠商： | Intersil Corporation |
| 英文描述： | Single Sync Buck PWM Controller for Broadband Gateway Applications |
| 中文描述： | 單同步降壓PWM控制器，寬帶網關應用 |
| 文件頁數： | 8/15頁 |
| 文件大?。?/td> | 379K |
| 代理商： | ISL6439AEVAL1 |
8
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
diagrams on pages 2 and 3). An internal 20
μ
A (typical)
current sink develops a voltage across R
OCSET
that is
referenced to V
IN
. When the voltage across the upper
MOSFET (also referenced to V
IN
) exceeds the voltage across
R
OCSET
, the overcurrent function initiates a soft-start
sequence.
Figure 3 illustrates the protection feature responding to an
overcurrent event. At time t0, an overcurrent condition is
sensed across the upper MOSFET. As a result, the regulator
is quickly shutdown and the internal soft-start function
begins producing soft-start ramps. The delay interval seen
by the output is equivalent to three soft-start cycles. The
fourth internal soft-start cycle initiates a normal soft-start
ramp of the output, at time t1. The output is brought back
into regulation by time t2, as long as the overcurrent event
has cleared.
Had the cause of the over current still been present after the
delay interval, the over current condition would be sensed
and the regulator would be shut down again for another
delay interval of three soft-start cycles. The resulting hiccup
mode style of protection would continue to repeat
indefinitely.
The overcurrent function will trip at a peak inductor current
(I
PEAK)
determined by:
I
x R
DS ON
)
where I
OCSET
is the internal OCSET current source (20
μ
A
typical). The OC trip point varies mainly due to the MOSFET
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 maximum r
DS(ON)
at the highest junction
temperature.
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’.
A small ceramic capacitor should be placed in parallel with
R
OCSET
to smooth the voltage across
R
OCSET
in the
presence of switching noise on the input voltage.
Current Sinking
The ISL6439 incorporates a MOSFET shoot-through
protection method which allows a converter to sink current
as well as source current. Care should be exercised when
designing a converter with the ISL6439 when it is known that
the converter may sink current.
When the converter is sinking current, it is behaving as a
boost converter that is regulating its input voltage. This
means that the converter is boosting current into the input
rail of the regulator. If there is nowhere for this current to go,
such as to other distributed loads on the rail or through a
voltage limiting protection device, the capacitance on this rail
will absorb the current. This situation will allow the voltage
level of the input rail to increase. If the voltage level of the rail
is boosted to a level that exceeds the maximum voltage
rating of any components attached to the input rail, then
FIGURE 2. OUTPUT VOLTAGE SELECTION
+
R1
C3
C
OUT
+3.3V
V
OUT
R4
L
OUT
ISL6439
C4
Q1
FB
UGATE
VCC
BOOT
COMP
D1
R2
C2
C1
R3
PHASE
LGATE
Q2
CPVOUT
VIN
I
PEAK
----------------------------------------------------
=
FIGURE 3. OVER CURRENT PROTECTION RESPONSE
0V
TIME
V
OUT
(2.5V)
T1
T0
T2
Internal Soft-Start Function
Delay Interval
I
PEAK
I
OUT MAX
(
)
I
2
(
----------
)
+
>
ISL6439
相關PDF資料 |
PDF描述 |
|---|---|
| ISL6439AEVAL2 | Single Sync Buck PWM Controller for Broadband Gateway Applications |
| ISL6439AIB-T | Circular Connector; No. of Contacts:3; Series:MS27473; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:12; Circular Contact Gender:Pin; Circular Shell Style:Straight Plug; Insert Arrangement:12-3 RoHS Compliant: No |
| ISL6439IB | Single Sync Buck PWM Controller for Broadband Gateway Applications |
| ISL6439IB-T | Single Sync Buck PWM Controller for Broadband Gateway Applications |
| ISL6439IBZ | Single Sync Buck PWM Controller for Broadband Gateway Applications |
相關代理商/技術參數 |
參數描述 |
|---|---|
| ISL6439AIB | 功能描述:IC REG CTRLR BUCK PWM VM 14-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) |
| ISL6439AIB-T | 功能描述:IC REG CTRLR BUCK PWM VM 14-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) |
| ISL6439AIBZ | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6439AIBZ-T | 功能描述:IC REG CTRLR BUCK PWM VM 14-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - DC DC 切換控制器 系列:- 產品培訓模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標準包裝:2,500 系列:- PWM 型:電流模式 輸出數:1 頻率 - 最大:275kHz 占空比:50% 電源電壓:18 V ~ 110 V 降壓:無 升壓:無 回掃:無 反相:無 倍增器:無 除法器:無 Cuk:無 隔離:是 工作溫度:-40°C ~ 85°C 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 包裝:帶卷 (TR) |
| ISL6439AIR | 功能描述:IC REG CTRLR BUCK PWM VM 16-QFN 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) |
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