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参数资料
| 型号： | TC1303B-EF1EUNTR |
| 厂商： | Microchip Technology Inc. |
| 英文描述： | 500 mA Synchronous Buck Regulator, + 300 mA LDO with Power-Good Output |
| 中文描述： | 500毫安同步降压稳压器，300 mA的LDO具有电源就绪输出 |
| 文件页数： | 11/30页 |
| 文件大小： | 441K |
| 代理商： | TC1303B-EF1EUNTR |
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2005 Microchip Technology Inc.
DS21949A-page 19
TC1303B
5.5
Inductor Selection
For most applications, a 4.7 H inductor is recom-
mended to minimize noise. There are many different
magnetic core materials and package options to select
from. That decision is based on size, cost and accept-
able radiated energy levels. Toroid and shielded ferrite
pot cores will have low radiated energy but tend to be
larger and higher is cost. With a typical 2.0 MHz switch-
ing frequency, the inductor ripple current can be
calculated based on the following formulas.
EQUATION 5-2:
Duty cycle represents the percentage of switch-on
time.
EQUATION 5-3:
The inductor ac ripple current can be calculated using
the following relationship:
EQUATION 5-4:
Solving for
ΔIL = yields:
EQUATION 5-5:
When considering inductor ratings, the maximum DC
current rating of the inductor should be at least equal to
the maximum buck regulator load current (IOUT1), plus
one half of the peak-to-peak inductor ripple current
(1/2 *
ΔIL). The inductor DC resistance can add to the
buck converter I2R losses. A rating of less than 200 m
Ω
is recommended. Overall efficiency will be improved by
using lower DC resistance inductors.
TABLE 5-2:
TC1303B RECOMMENDED
INDUCTOR VALUES
5.6
Thermal Calculations
5.6.1
BUCK REGULATOR OUTPUT
(VOUT1)
The TC1303B is available in two different 10-pin
packages (MSOP and 3X3 DFN). By calculating the
power dissipation and applying the package thermal
resistance, (
θJA), the junction temperature is estimated.
The maximum continuous junction temperature rating
for the TC1303B is 125°C.
To quickly estimate the internal power dissipation for
the switching buck regulator, an empirical calculation
using measured efficiency can be used. Given the
measured efficiency (Section 2.0 “Typical Perfor-
mance Curves”), the internal power dissipation is
estimated below.
EQUATION 5-6:
The first term is equal to the input power (definition of
efficiency, POUT/PIN = Efficiency). The second term is
equal to the delivered power. The difference is internal
power dissipation. This is an estimate assuming that
most of the power lost is internal to the TC1303B.
There is some percentage of power lost in the buck
inductor, with very little loss in the input and output
capacitors.
DutyCycle
V
OUT
V
IN
-------------
=
T
ON
DutyCycle
1
F
SW
----------
×
=
Where:
FSW = Switching Frequency.
V
L
ΔI
L
Δt
--------
×
=
Where:
VL = voltage across the inductor (VIN – VOUT)
Δt = on-time of P-channel MOSFET
ΔI
L
V
L
------
Δt
×
=
Part
Number
Value
(H)
DCR
Ω
(MAX)
MAX
IDC (A)
Size
WxLxH (mm)
Coiltronics
SD10
2.2
0.091
1.35
5.2, 5.2, 1.0 max.
SD10
3.3
0.108
1.24
5.2, 5.2, 1.0 max.
SD10
4.7
0.154
1.04
5.2, 5.2, 1.0 max.
Coiltronics
SD12
2.2
0.075
1.80
5.2, 5.2, 1.2 max.
SD12
3.3
0.104
1.42
5.2, 5.2, 1.2 max.
SD12
4.7
0.118
1.29
5.2, 5.2, 1.2 max.
Sumida Corporation
CMD411
2.2
0.116
0.950 4.4, 5.8, 1.2 max.
CMD411
3.3
0.174
0.770 4.4, 5.8, 1.2 max.
CMD411
4.7
0.216
0.750 4.4, 5.8, 1.2 max.
Coilcraft
1008PS
4.7
0.35
1.0
3.8,3.8,2.74 max.
1812PS
4.7
0.11
1.15
5.9,5.0, 3.81 max
V
OUT1
I
OUT1
×
Efficiency
-------------------------------------
V
OUT1
I
OUT1
×
()
–
P
Diss ipation
=
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相关代理商/技术参数 |
参数描述 |
|---|---|
| TC1303B-IA0EMF | 功能描述:低压差稳压器 - LDO PWM/LDO combo w/PG RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| TC1303B-IA0EMFTR | 功能描述:低压差稳压器 - LDO PWM/LDO combo w/PG RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| TC1303B-IA0EUN | 功能描述:低压差稳压器 - LDO PWM/LDO combo w/PG RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| TC1303B-IA0EUNTR | 功能描述:低压差稳压器 - LDO PWM/LDO combo w/PG RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
| TC1303B-PA0EMF | 功能描述:低压差稳压器 - LDO PWM/LDO combo w/PG RoHS:否 制造商:Texas Instruments 最大输入电压:36 V 输出电压:1.4 V to 20.5 V 回动电压（最大值）:307 mV 输出电流:1 A 负载调节:0.3 % 输出端数量: 输出类型:Fixed 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-20 |
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