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參數(shù)資料
| 型號： | S-8520 |
| 廠商： | Seiko Instruments Inc. |
| 英文描述： | PWM Control Step-Down Switching Regulator-Controller(PWM 控制，步降開關(guān)穩(wěn)壓器-控制器) |
| 中文描述： | PWM控制降壓型開關(guān)穩(wěn)壓控制器（脈寬調(diào)制控制，步降開關(guān)穩(wěn)壓器-控制器） |
| 文件頁數(shù)： | 9/30頁 |
| 文件大?。?/td> | 650K |
| 代理商： | S-8520 |
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PWM Control & PWM/PFM Control Step-Down Switching Regulator-Controllers
S-8520/8521 Series
Rev.6.1
8
Seiko Instruments Inc.
S-8520A33MC (Vin:0
4.0V)
t(1msec/div)
Output voltage
(1V/div)
Rush current
(0.5A/div)
0A
1.5A
0V
3V
Power switched on
Figure 5. Waveforms of Output Voltage and Rush Current at Soft-Start
4. Overload Protection Circuit (A & C Series)
The S-8520/21A and S-8520/21C Series come with a built-in overload protection circuit.
If the output voltage falls because of an overload, the maximum duty state (100%) will continue. If this 100% duty state lasts longer
than the prescribed overload detection time (TPRO), the overload protection circuit will hold the EXT terminal at "H," thereby
protecting the switching transistor and inductor. When the overload protection circuit is functioning, the reference voltage circuit will
be activated by means of a soft-start in the IC, and the reference voltage will rise slowly from 0V. The reference voltage and the
feedback voltage obtained by dividing the output voltage are compared to each other. So long as the reference voltage is lower, the
EXT terminal will be held at "H" to keep the oscillation inactive. If the reference voltage keeps rising and exceeds the feedback
voltage, the oscillation will resume.
If the load is heavy when the oscillation is restarted, and the EXT terminal holds the "L" level longer than the specified overload
detection time (TPRO), the overload protection circuit will operate again, and the IC will enter intermittent operation mode, in which
it repeats the actions described above. Once the overload state is eliminated, the IC resumes normal operation.
Waveforms at
EXT pin
Protection circuit ON
(TSS x 0.3)
Overload detection time
(TPRO)
Figure 6. Waveforms Appearing at EXT Pin As the Overload Protection Circuit Operates
5. 100% Duty Cycle
The S-8520/21 Series operates with a maximum duty cycle of 100%. When a B Series or C Series product not provided with an
overload protection circuit is used, the switching transistor can be kept ON to supply current to the load continually, even in cases
where the input voltage falls below the preset output voltage value. The output voltage delivered under these circumstances is one
that results from subtracting, from the input voltage, the voltage drop caused by the DC resistance of the inductance and the on-
resistance of the switching transistor.
If an A Series or C Series product provided with an overload protection circuit is used, this protection circuit will function when
the 100% duty state has lasted longer than the preset overload detection time (TPRO), causing the IC to enter intermittent operation
mode. Under these conditions, the IC will not be able to supply current to the load continually, unlike the case described in the
preceding paragraph.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
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| S-8520A20MC-AVFT2G | 功能描述:DC/DC 開關(guān)控制器 Step Down SWR PWM 180kHz 60uA Iq 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-8520A21MC-AVG-T2 | 功能描述:DC/DC 開關(guān)控制器 2.1V Step-Down PWM 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-8520A21MC-AVGT2G | 功能描述:DC/DC 開關(guān)控制器 2.1V Step-Down PWM 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-8520A25MC-ARK-T2 | 制造商:SII 制造商全稱:Seiko Instruments Inc 功能描述:PWM CONTROL & PWM/PFM CONTROL STEP-DOWN SWITCHING REGULATOR-CONTROLLERS |
| S-8520A25MC-AVK-T2 | 功能描述:DC/DC 開關(guān)控制器 2.5V Step-Down PWM 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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