參數(shù)資料
型號(hào)： S-8341B
廠商： Seiko Instruments Inc.
英文描述： PWM/PFM Control High-Frequency Step-Up Switching Regulator-Controllers(PWM/PFM控制，高頻步升開關(guān)穩(wěn)壓器-控制器)
中文描述： PWM / PFM切換控制高頻升壓型開關(guān)穩(wěn)壓器控制器（PWM / PFM切換控制，高頻步升開關(guān)穩(wěn)壓器-控制器）
文件頁(yè)數(shù)： 11/38頁(yè)
文件大?。?/td> 420K
代理商： S-8341B
PWM Control & PWM/PFM Control High-Frequency Step-Up Switching Regulator-Controllers
S-8340/8341 Series
Rev.1.00
Seiko Instruments Inc.
10
Operation
1.
Switching control method
1.1 PWM Control (S-8340 Series)
The S-8340 Series consists of DC/DC converters that employ a pulse-width modulation (PWM) system.
In conventional PFM system DC/DC converters, pulses are skipped when they are operated with a low
output load current, causing variations in the ripple frequency of the output voltage and an increase in
the ripple voltage. Both of these effects constitute inherent drawbacks to those converters.
In converters of the S-8340 Series, the pulse width varies in a range from 0% to 82%, according to the
load current, and yet ripple voltage produced by the switching can easily be removed through a filter
because the switching frequency remains constant. Therefore, these converters provide a low-ripple
power over broad ranges of input voltage and load current.
1.2 PWM/PFM-Switched Control (S-8341 Series)
The S-8341 Series consists of DC/DC converters capable of automatically switching the pulse-wide
modulation system (PWM) over to the pulse-frequency modulation system (PFM), and vice versa,
according to the load current.
In a region of high output load currents, the S-8341 Series converters function with PWM control, where
the pulse-width duty varies from 27% to 82%. This function realizes low ripple power.
For certain low output load currents, the converters are switched over to PFM control, whereby pulses
having their pulse-width duty fixed at 27% are skipped depending on the quantity of the load current, and
are output to a switching transistor. This causes the oscillation circuit to produce intermittent oscillation.
As a result, current consumption is reduced and efficiency losses are prevented under low loads.
Especially for output load currents in the region of 1 mA, these DC/DC converters can operate at
extremely high efficiency.
2.
Power-Off Pin (ON/OFF Pin)
This pin deactivates or activates the step-up operation. When the power-off pin is set to "L", the VSS
voltage appears through the EXT pin, prodding the switching transistor to go off. All the internal circuits
stop working, and substantial savings in current consumption are thus achieved.
The power-off pin is configured as shown in Figure 5. Since pull-up or pull-down is not performed
internally, please avoid operating the pin in a floating state. Also, try to refrain from applying a voltage of
0.3V to 0.8V to the pin, less such voltage makes the power on/off state indefinite. When this power-off
pin is not used, leave it coupled to the VDD pin.
The power-off pin does not have hysterisis.
Power-Off Pin
CR Oscillation
Circuit
Output Voltage
“H”
Activated
Set value
V
IN
*
“L”
Deactivated
*
Voltage obtained by extracting the voltage drop due to
DC resistance of the inductor and the diode forward
voltage from V
IN
.
ON/OFF
VDD
V
SS
Figure 5
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
S-8341B00AFT-T2 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Adj Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
S-8341B00AFT-T2-G 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 Adj Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
S-8341B00AFT-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(qū)動(dòng)器 功能:升壓 輸出配置:正 拓?fù)?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(guān):600kHz 占空比（最大）:0.89 同步整流器:無(wú) 時(shí)鐘同步:無(wú) 串行接口:- 控制特性:限流，使能，軟啟動(dòng) 工作溫度:-40°C ~ 85°C（TA） 封裝/外殼:8-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商器件封裝:8-TSSOP 標(biāo)準(zhǔn)包裝:1
S-8341C25AFT-T2 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 2.5V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
S-8341C25AFT-T2-G 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 2.5V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸出電壓:1.2 V to 10 V 輸出電流:300 mA 輸出功率: 輸入電壓:3 V to 17 V 開關(guān)頻率:1 MHz 工作溫度范圍: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:WSON-8 封裝:Reel
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