收藏本站
______________________________________________________ GENERAL OVERVIEW
for Rs in the range of 0.5k
to 3k . For Rs larger
Overcurrent Protection (OCP)
SP6127
Vin
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 .
Ov er-Current Comparator
Gate
LX
Rs
Q1
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
Vin - 0.3V
30uA
Ds
MOSFET on-time is less than 150ns, the OCP
circuit will not detect overcurrent.
Using the ON/OFF Function
Figure 3 Overcurrent protection circuit
The overcurrent protection (OCP) circuit
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:
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
Rs =
0 . 3 ? ( 1 . 15 × Iout × Rds ( on ) × Kt )
30 uA
...(5)
To program the output voltage, calculate R2
using the following equation:
? ?
? 1 ? ?
Where:
1.15 is used to calculate peak inductor current
which is nominally 15% higher than average
R 2 =
R 1
? Vout
? Vref
?
?
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.
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 .
Rs =
Rs=800
0 . 3 ? ( 1 . 15 × 2 A × 0 . 08 Ohm × 1 . 5 )
30 uA
Soft Start
Soft Start is preset internally to 5ms (nominal).
Internal Soft Start eliminates the need for the
Using the above equation there is good
agreement between calculated and test results
external capacitor CSS that is commonly used to
program this function.
Jan28-08 RevE
SP6127 TSOT-6 PFET Buck Controller
Page 6
? 2007 Exar Corporation
发布紧急采购，3分钟左右您将得到回复。

采购需求

(若只采购一条型号，填写一行即可)

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

发布成功！您可以继续发布采购。也可以进入我的后台，查看报价

*型号 *数量 厂商 批号 封装
添加更多采购

我的联系方式

*
*
*
相关PDF资料
R1S8-1524/P-R CONV DC/DC 1W 15VIN 24VOUT
R1S8-1515/P-R CONV DC/DC 1W 15VIN 15VOUT
A9CCG-0506F FLEX CABLE - AFG05G/AF05/AFG05G
ECM08DRTS CONN EDGECARD 16POS DIP .156 SLD
SP6126EB EVAL BOARD FOR SP6126
R1S8-1512/P-R CONV DC/DC 1W 15VIN 12VOUT
SP6125EB EVAL BOARD FOR SP6125
R1S8-1509/P-R CONV DC/DC 1W 15VIN 09VOUT
相关代理商/技术参数
SP6127EK1 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual
SP6127EK1L 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High-Voltage, Step-Down Controller in TSOT6
SP6127EK1-L 功能描述:DC/DC 开关控制器 RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK
SP6127EK1L/TR 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High-Voltage, Step-Down Controller in TSOT6
SP6127EK1-L/TR 功能描述:电压模式 PWM 控制器 High-Voltage Step Down Controller RoHS:否 制造商:Texas Instruments 输出端数量:1 拓扑结构:Buck 输出电压:34 V 输出电流: 开关频率: 工作电源电压:4.5 V to 5.5 V 电源电流:600 uA 最大工作温度:+ 125 C 最小工作温度:- 40 C 封装 / 箱体:WSON-8 封装:Reel
SP6128A 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Voltage, Synchronous Step Down PWM Controller Ideal for 2A to 10A, Small Footprint, DC-DC Power Converters
SP6128A_05 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Low Voltage, Synchronous Step Down PWM Controller Ideal for 2A to 10A, Small Footprint, DC-DC Power Converters
SP6128AB 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Non-Isolated DC-DC SIP Modules:3.0Vdc-5.5Vdc In, 0.9Vdc-3.3Vdc out, 10A