參數(shù)資料
型號： S-8340B00AFT-T2-U
元件分類： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 690 kHz SWITCHING FREQ-MAX, PDSO8
封裝： HALOGEN FREE AND LEAD FREE, TSSOP-8
文件頁數(shù)： 9/55頁
文件大?。?/td> 740K
代理商： S-8340B00AFT-T2-U
STEP-UP, 600 kHz, PWM CONTROL OR PWM/PFM SWITCHABLE SWITCHING REGULATOR CONTROLLER
Rev.4.0_00
S-8340/8341 Series
Seiko Instruments Inc.
17
Operation
1. Switching Control Method
1. 1
PWM Control (S-8340 Series)
The S-8340 Series is a DC-DC converter using a pulse width modulation method (PWM).
In conventional PFM DC-DC converters, pulses are skipped when the output load current is low, causing a
fluctuation in the ripple frequency of the output voltage, resulting in an increase in the ripple voltage.
The switching frequency does not change, although the pulse width changes from 0 to 82% corresponding to each
load current in the S-8340 Series.
The ripple voltage generated from switching can thus be eliminated easily
through a filter. When the pulse width is 0% (when no load is applied or the input voltage is high), pulses are
skipped and the current consumption is low.
1. 2
PWM/PFM Switching Control (S-8341 Series)
The S-8341 Series is a DC-DC converter that automatically switches between a pulse width modulation method
(PWM) and a pulse frequency modulation method (PFM) depending on the load current.
The S-8341 Series operates under PWM control with the pulse duty changing from 27 to 82% (A and B types) and
from 21 to 82% (C and D types) in a high output load current area.
The S-8341 Series operates under PFM control with the pulse duty fixed at 27% (A and B types) and at 21% (C and
D types) in a low load current area, and pulses are skipped according to the load current. The oscillation circuit
thus oscillates intermittently so that the resultant lower self current consumption prevents a reduction in the
efficiency at a low load current. The switching point from PWM control to PFM control depends on the external
devices (coil, diode, etc.), and input and output voltage values. The S-8341 Series is an especially highly efficient
DC-DC converter at an output load current around 1 mA.
2. Soft-Start Function
The S-8340/8341 Series has a built-in soft-start circuit.
This circuit enables the output voltage (VOUT) to rise gradually over the specified soft-start time (tSS) to suppress the
overshooting of the output voltage and the rush current from the power supply when the power is switched on or the
ON/OFF pin is changed to “H”.
Generally, a rush current flows to an output capacitor through an inductor and a diode in the step-up circuit
immediately after the power is turned on as shown in Figure 9. Note that the soft-start function of this IC, however,
does not limit this current.
t (2 m s /d iv )
O ut pu t voltag e
(1 V /d i v )
R u s h cu rrent
(0. 5 A /d iv )
3 V
0 V
1.5 A
0 A
S -83 40A 33A F T (V IN = 0 → 1.9 V , R L = 300 k Ω )
Figure 9 Waveforms of Output Voltage and Rush Current at Soft-Start
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
S-8340C25AFT-T2 功能描述:DC/DC 開關(guān)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(guān)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(fēng)格: 封裝 / 箱體:CPAK
S-8340C25AFT-T2-G 功能描述:DC/DC 開關(guān)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(guān)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(fēng)格: 封裝 / 箱體:CPAK
S-8340C30AFT-T2 功能描述:DC/DC 開關(guān)控制器 3.0V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK
S-8340C30AFT-T2-G 功能描述:DC/DC 開關(guān)控制器 3.0V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK
S-8340C33AFT-T2 功能描述:DC/DC 開關(guān)控制器 3.3V Step-Up 2.0% RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)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(fēng)格: 封裝 / 箱體:CPAK
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