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參數(shù)資料
| 型號： | S-8340B |
| 廠商： | Seiko Instruments Inc. |
| 英文描述： | PWM Control High-Frequency Step-Up Switching Regulator-Controllers(PWM控制，高頻步升開關穩(wěn)壓器-控制器) |
| 中文描述： | PWM控制高頻升壓型開關穩(wěn)壓器控制器（脈寬調制控制，高頻步升開關穩(wěn)壓器-控制器） |
| 文件頁數(shù)： | 17/38頁 |
| 文件大小： | 420K |
| 代理商： | S-8340B |
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PWM Control & PWM/PFM Control High-Frequency Step-Up Switching Regulator-Controllers
S-8340/8341 Series
Rev.1.00
Seiko Instruments Inc.
16
If the L-value is increased in an S-8340/41 Series product, the output voltage may turn unstable in some
cases, depending on the conditions of the input voltage, output voltage, and the load current. Perform
thorough evaluations under the conditions of actual service and decide on an optimum L-value. An L
value should be selected from 2.2 to 22 H for A & B Series
In many applications, selecting a value of A/B Series 10 H will allow a S-8340/41 Series product to yield
its best characteristics in a well balanced manner.
When choosing an inductor, pay attention to its allowable current, since a current applied in excess of
the allowable value will cause the inductor to produce magnetic saturation, leading to a marked decline
in efficiency.
Therefore, select an inductor in which the peak current Ipk will not surpass its allowable current at any
moment. The peak current Ipk is represented by the following equation in non-continuous operation
mode:
I
PK
=
2
I
V
V
V
fosc
OUT
OUT
F
IN
(
)
L
×
×
+
×
Where fosc is the oscillation frequency, L the inductance value of the inductor, and V
F
the forward
voltage of the diode (appropriate 0.4V).
For example, if a power supply with input voltage V
IN
=3 V, output voltage V
OUT
=5 V, and load current
I
OUT
=30 mA is used, fosc=600 kHz when S-8340A50AFT is used. When 10 H is selected for the L
value, I
PK
=155 mA from the above formula. Therefore, select an inductor with a permissible current of
155 mA or higher for the L value of 10 H.
3.
Diode
The diode to be externally coupled to the IC should be a type that meets the following conditions:
Its forward voltage is low (Schottky barrier diode recommended).
Its switching speed is high (50 ns max.).
Its reverse direction breakdown voltage is higher than V
OUT
+ V
F
.
Its current rating is higher than I
PK
.
4.
Capacitors (CIN, CL)
The capacitor inserted on the input side (C
IN
) serves to lower the power impedance and to average the
input current for better efficiency. Select the C
IN
-value according to the impedance of the power supplied.
As a rough rule of thumb, you should use a value of 47 to 100 F, although the actual value will depend
on the impedance of the power in use and the load current value.
If the input voltage is extremely high or load current is extremely large, the output voltage of the S-
8340/41 Series may become unstable. The unstable range can be narrowed, however, by selecting an
output side capacitor (CL) with a large capacitance. If a capacitor with high ESR (Equivalent Series
Resistance), such as an aluminum electrolytic capacitor, or with low ESR, such as a ceramic capacitor,
the unstable range widens. Thus, a tantalum electrolytic capacitor is recommended. We recommend
that you evaluate it by testing performance with the actual equipment.
The capacity should be 47 to 200 F and ESR should be 40 to 270 m as a recommended yardstick.
5.
External Switching Transistor
The S-8340/41 Series can be operated with an external switching transistor of the enhancement (Nch)
MOS FET type or bipolar (NPN) type.
5.1 Enhancement MOS FET type
The EXT pin of the S-8340/41 Series is capable of directly driving a Nch power MOS FET.
When a Nch power MOS FET is chosen, because it has a higher switching speed than a NPN type
bipolar transistor and because power losses due to the presence of a base current are avoided,
efficiency will be 2 to 3% higher than NPN type bipolar transistor.
相關PDF資料 |
PDF描述 |
|---|---|
| S-8341 | PWM/PFM Control High-Frequency Step-Up Switching Regulator-Controllers(PWM/PFM控制，高頻步升開關穩(wěn)壓器-控制器) |
| S-8341A | PWM/PFM Control High-Frequency Step-Up Switching Regulator-Controllers(PWM/PFM控制，高頻步升開關穩(wěn)壓器-控制器) |
| S-8341B | PWM/PFM Control High-Frequency Step-Up Switching Regulator-Controllers(PWM/PFM控制，高頻步升開關穩(wěn)壓器-控制器) |
| S-8420AF | BATTERY BACKUP IC FOR 1-CHIP CPU |
| S-8420BF | BATTERY BACKUP IC FOR 1-CHIP CPU |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| S-8340B00AFT-T2 | 功能描述:DC/DC 開關控制器 Adj Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| S-8340B00AFT-T2-G | 功能描述:DC/DC 開關控制器 Adj Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| S-8340B00AFT-T2-U | 功能描述:IC REG CTRLR BOOST 8TSSOP 制造商:ablic u.s.a. inc. 系列:- 包裝:剪切帶（CT） 零件狀態(tài):在售 輸出類型:晶體管驅動器 功能:升壓 輸出配置:正 拓撲:升壓 輸出數(shù):1 輸出階段:1 電壓 - 電源（Vcc/Vdd）:0.8 V ~ 6 V 頻率 - 開關:600kHz 占空比（最大）:0.89 同步整流器:無 時鐘同步:無 串行接口:- 控制特性:限流，使能，軟啟動 工作溫度:-40°C ~ 85°C（TA） 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應商器件封裝:8-TSSOP 標準包裝:1 |
| S-8340C25AFT-T2 | 功能描述:DC/DC 開關控制器 2.5V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
| S-8340C25AFT-T2-G | 功能描述:DC/DC 開關控制器 2.5V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 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 安裝風格: 封裝 / 箱體:CPAK |
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