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参数资料
| 型号： | SP6126EB |
| 厂商： | Exar Corporation |
| 文件页数： | 7/14页 |
| 文件大小： | 0K |
| 描述： | EVAL BOARD FOR SP6126 |
| 标准包装： | 1 |
| 系列： | * |
GENERAL OVERVIEW
Power MOSFET Selection
Select the Power MOSFET for Voltage rating
BV DSS , On resistance R DS(ON) , and thermal
resistance Rthja. BV DSS should be about twice
as high as V IN in order to guard against
switching transients. Recommended MOSFET
voltage rating for V IN of 5V, 12V and 24V is
12V, 30V and 40V respectively. R DS(ON) has to
be selected such that when operating at peak
current and junction temperature the
Overcurrent threshold of the SP6126 is not
exceeded. Allowing 50% for temperature
coefficient of R DS(ON) and 15% for inductor
current ripple, the following expression can be
where:
Vf is diode forward voltage at I OUT
Schottky’s AC losses due to its switching
capacitance are negligible.
Inductor Selection
Select the Inductor for inductance L and
saturation current I SAT . Select an inductor with
I SAT higher than the programmed overcurrent.
Calculate inductance from:
RDS ( ON ) ≤ ?
L = ( Vin ? Vout ) × ?
? × ? ?
? ? × ? ?
? ?
used:
? 300 mV ?
?
? 1 . 5 × 1 . 15 × Iout ?
where:
? Vout ? ? 1 ? ? 1 ?
? Vin ? ? f ? ? Irip ?
Pcond = Iout × RDS ( ON ) × ?
? Vout ?
Within this constraint, selecting MOSFETs with
lower R DS(ON) will reduce conduction losses at
the expense of increased switching losses. As
a rule of thumb select the highest R DS(ON)
MOSFET that meets the above criteria.
Switching losses can be assumed to roughly
equal the conduction losses. A simplified
expression for conduction losses is given by:
?
? Vin ?
V IN is converter input voltage
V OUT is converter output voltage
f is switching frequency
I RIP is inductor peak-to-peak current ripple
(nominally set to 30% of I OUT )
Keep in mind that a higher I RIP results in a
smaller inductor which has the advantages of
small size, low DC equivalent resistance DCR,
high saturation current I SAT and allows the use
of a lower output capacitance to meet a given
MOSFET’s junction
temperature
can
be
step load transient. A higher
I RIP , however,
estimated from:
T = ( 2 × Pc × Rthja ) + Tambient
Schottky Rectifier selection
Select the Schottky for Voltage rating V R ,
Forward voltage V f , and thermal resistance
Rthja. Voltage rating should be selected using
the same guidelines outlined for MOSFET
voltage selection. For a low duty cycle
application such as the circuit shown on first
page, the Schottky is conducting most of the
time and its conduction losses are the largest
component of losses in the converter.
Conduction losses can be estimated from:
increases the output voltage ripple and
increases the current at which converter enters
Discontinuous Conduction Mode. The output
current at which converter enters DCM is ? of
I RIP . Note that a negative current step load that
drives the converter into DCM will result in a
large output voltage transient. Therefore the
lowest current for a step load should be larger
than ? of I RIP .
Output Capacitor Selection
Select the output capacitor for voltage rating,
capacitance and Equivalent Series Resistance
(ESR). Nominally the voltage rating is selected
to be twice as large as the output voltage.
Select the capacitance to satisfy the
Pc = Vf × Iout × ? 1 ?
Vout ?
corresponds to inductor stored energy of ? L I OUT .
?
?
?
Vin ?
specification for output voltage
overshoot/undershoot caused by current step
load. A steady-state output current I OUT
2
Nov07 -08 Rev G
SP6126: TSOT-6 PFET Buck Controller
7
? 200 8 Exar Corporation
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SP6126EK1 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:Evaluation Board Manual |
| SP6126EK1L | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High-Voltage, Step Down Controller in TSOT6 |
| SP6126EK1-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 |
| SP6126EK1L/TR | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:High-Voltage, Step Down Controller in TSOT6 |
| SP6126EK1-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 |
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