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參數資料
| 型號： | FA3641N |
| 廠商： | FUJI ELECTRIC CO LTD |
| 元件分類： | 穩壓器 |
| 英文描述： | PWM control IC with light load power saving function For Switching Power Supply Control |
| 中文描述： | 1 A SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | SOP-8 |
| 文件頁數： | 18/21頁 |
| 文件大小： | 406K |
| 代理商： | FA3641N |
FA3641P(N), FA3647P(N)
75
17. Loss calculation
IC loss must be confirmed to use the IC within the ratings.
Since it is hard to directly measure IC loss, some examples of
calculating approximate IC loss are given below.
17.1 Calculation example 1
Suppose the supply voltage is Vcc, IC current consumption is
lccop, the total gate charge of the power MOSFET is Qg, and
the switching frequency is f
SW
. Total IC loss Pd can be
calculated by:
Pd = Vcc (Iccop + Qg fsw)
................................(14)
This expression calculates an approximate value of Pd, which is
normally a little larger than the actual loss. Since various
conditions such as temperature characteristics apply,
thoroughly verify the appropriateness of the calculation under
all applicable conditions.
Example:
When Vcc = 18V, lccop = 2.5mA (max.) is obtained from the
specifications. Suppose Qg = 80nC and fsw = 100kHz.
17.2 Calculation example 2
The IC loss consists of the loss caused by operation of the
control circuit and the loss caused at the output circuit to drive
the power MOSFET.
(1) Loss at the control circuit
The loss caused by operation of the IC control circuit is
calculated by the supply voltage and IC current consumption.
When the supply voltage is Vcc and IC current consumption is
lccop, loss Pop at the control circuit is:
Pop = Vcc Iccop
....................................................... (15)
Example:
When Vcc = 18, lccop = 1.9mA (typ) is obtained from the
specifications. The typical IC loss is given by:
Pop = 18V 1.9mA = 34.2mW
(2) Loss at the output circuit
The output circuit of the IC is a MOSFET push-pull circuit.
When the ON resistances of MOSFETs making up the output
circuit are Ron and Roff, the resistances can be determined as
shown below based on Vcc = 18V and Tj = 25
C obtained from
the output characteristics included in the specifications:
Ron = 15
(typ)
Roff = 7
(typ)
When the total gate charge of the power MOSFET is Qg, the
switching frequency is f
SW
, the supply voltage is Vcc, and
gate resistance is Rg, the loss caused at the IC output circuit
is given by:
....... (16)
Fig. 35 Output stage
Pd 18V (2.5mA + 80nC 100kHz)
= 189mW
Pdr = 1
Vcc
Qg
fsw
2
Ron
Roff
Rg
Ron
Rg
Roff
)
相關PDF資料 |
PDF描述 |
|---|---|
| FA3641P | PWM control IC with light load power saving function For Switching Power Supply Control |
| FA3647 | PWM control IC with light load power saving function For Switching Power Supply Control |
| FA3647N | PWM control IC with light load power saving function For Switching Power Supply Control |
| FA3647P | PWM control IC with light load power saving function For Switching Power Supply Control |
| FA365 | THIN SMD HIGH-FREQUENCY CRYSTAL UNIT |
相關代理商/技術參數 |
參數描述 |
|---|---|
| FA3641N-H1 | 制造商:Fuji Electric 功能描述: |
| FA3641P | 制造商:FUJI 制造商全稱:Fuji Electric 功能描述:PUJI Power Supply Controllc |
| FA3641P_00 | 制造商:FUJI 制造商全稱:Fuji Electric 功能描述:PUJI Power Supply Controllc |
| FA3641P-D1 | 制造商:Fuji Electric 功能描述: |
| FA3647 | 制造商:FUJI 制造商全稱:Fuji Electric 功能描述:PWM control IC with light load power saving function For Switching Power Supply Control |
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