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參數(shù)資料
| 型號： | SP6127 |
| 英文描述： | High-Voltage, Step-Down Controller in TSOT6 |
| 中文描述： | 高電壓，降壓型控制器在TSOT6 |
| 文件頁數(shù)： | 6/12頁 |
| 文件大?。?/td> | 564K |
| 代理商： | SP6127 |
______________________________________________________
GENERAL OVERVIEW
June 26, 2007 SP6127 TSOT-6 PFET Buck Controller
2007 Sipex Corporation
Page 6
Overcurrent Protection (OCP)
Ds
Q1
Rs
SP6127
Gate
LX
30uA
+
-
Vin - 0.3V
Vin
Over-Current Comparator
Figure 3 Overcurrent protection circuit
The
overcurrent
functions by monitoring the voltage across the
high-side FET Q1. When this voltage exceeds
0.3V, the overcurrent comparator triggers and
the controller enters hiccup mode. For example
if Q1 has R
DS
(
ON
)=0.1
, then the overcurrent
will trigger at
I
= 0.3V/0.1
=3A. To program a
lower overcurrent use a resistor Rs as shown in
figure 1. Calculate Rs from:
(
Iout
Rs
30
Where:
1.15 is used to calculate peak inductor current
which is nominally 15% higher than average
output current
R
DS
(
ON
)
is MOSFET ON-resistance rating
Kt is a multiplier that accounts for increase in
R
DS
(
ON
)
due to temperature
Example: A switching MOSFET used with
SP6127 has R
DS
(
ON
)
of 0.08
and Kt is 1.5.
Program the over-current circuit so that
maximum output is 2A.
(
Rs
=
protection
(OCP)
circuit
)
uA
Kt
on
Rds
)
(
15
.
3
×
×
×
=
...(5)
)
uA
Ohm
A
30
5
×
08
.
2
15
.
3
×
×
Rs=800
Using the above equation there is good
agreement between calculated and test results
for Rs in the range of 0.5k
to 3k
. For Rs larger
than 3k
, test results are lower than those
predicted by (5), due to circuit parasitics.
Therefore the maximum value of Rs should be
limited to 3k
.
Note that in order to safeguard against false
overcurrent trigger due to transients, there is a
150ns delay between the turn on of the MOSFET
and when OCP circuit is activated. As a
consequence at very high Vo/V
IN
ratio, where
MOSFET on-time is less than 150ns, the OCP
circuit will not detect overcurrent.
Using the ON/OFF Function
The Feedback pin serves a dual role of ON/OFF
control. The MOSFET driver is disabled when a
voltage greater than 1V is applied at the FB pin.
Maximum voltage rating of this pin is 5.5V. The
controlling signal should be applied through a
small signal diode as shown on page 1.
Please note that an optional 10k
bleeding
resistor across the output helps keep the output
capacitor discharged under no load condition.
Programming the Output Voltage
To program the output voltage, calculate R2
using the following equation:
=
1
1
2
Vref
Vout
R
R
Where:
V
REF
=0.6 is the reference voltage of the SP6127
R1=200k
is a fixed-value resistor that, in
addition to being a voltage divider, it is part of the
compensation network. In order to simplify
compensation calculations, R1 is fixed at 200k
.
Soft Start
Soft Start is preset internally to 5ms (nominal).
Internal Soft Start eliminates the need for the
external capacitor CSS that is commonly used to
program this function.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SP6127_07 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP6127EB | 功能描述:電源管理IC開發(fā)工具 Eval Board for SP6127 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 |
| SP6127EK1 | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP6127EK1L | 制造商:SIPEX 制造商全稱:Sipex Corporation 功能描述:High-Voltage, Step-Down Controller in TSOT6 |
| SP6127EK1-L | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
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