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參數(shù)資料
| 型號(hào)： | L6590A |
| 英文描述： | FULLY INTEGRATED POWER SUPPLY |
| 中文描述： | 完全集成的電源供應(yīng)器 |
| 文件頁數(shù)： | 15/19頁 |
| 文件大?。?/td> | 236K |
| 代理商： | L6590A |
15/19
L6590A
Another problem is the spurious restarts that are likely to occur during converter power down if the input voltage
decays slowly (e.g. with a large input bulk capacitor) and that cause the output voltage not to decay to zero
monothonically.
Convertershutdown can beaccomplished withtheL6590Abymeansofaninternalcomparatorthatcanbeused
to sense the voltage across the input bulk capacitor. This comparator is internally referenced to 2.5V and dis-
ables the PWMif the voltageapplied atits non-inverting input, externallyavailable, isbelowthe reference. PWM
operation is re-enabled as the voltage at the pin is more than 2.5V.
The brownout comparator is provided with current hysteresis instead of a more usual voltage hysteresis: an in-
ternal 50 μA current generator is ON as long as the voltage applied at the non-inverting input exceeds 2.5V and
is OFF if the voltage is below 2.5V. This approach provides an additional degree of freedom: it is possible to set
the ON threshold and the OFF threshold separately by properly choosing the resistors of the external divider,
which is not possible with voltage hysteresis.
Overvoltage Protection
The IC incorporates an Overvoltage Protection (OVP) thatcan be particularlyuseful toprotect the converter and
the load against voltage feedback loop failures. This kind of failure causes the output voltage to rise with no
control and easily leads to the destruction of the load and of the converter itself if not properly handled.
If such an event occurs, the voltage generated by the auxiliary winding that supplies the IC will fly up tracking
the output voltage. This will activate an internal clamp circuit and, as the current sunk by this clamp exceeds
about 10 mA, the operation of the IC will be stopped. This condition is latched and maintained until the Vcc volt-
age falls below the UVLO threshold. The converter will then operate intermittently.
Figure 30. OVP internal schematic
Overcurrent Protection
The device usespulse-by-pulse current limiting for Overcurrent Protection (OCP), in order to prevent overstress
of the internal MOSFET: its current during the ON-time is monitored and, if it exceeds a determined value, the
conductionisterminated immediately. TheMOSFETwillbeturnedon again inthe subsequentswitchingcycle.
As previously mentioned, the internal powerMOSFET has a SenseFET structure: the source of a few cells are
connectedtogetherand kept separate fromtheothersourceconnectionssoasto realizea1:100 current divider.
The "sense" portion is connected to a ground referenced, sense resistor having a low thermal coefficient. The
OCP comparator senses the voltage drop across the sense resistor and resets the PWM latch if the drop ex-
ceeds a threshold, thus turning off the MOSFET. In this way the overcurrent threshold is set at about 0.65 A
(typical value).
Vcc
DRAIN
+
OVP
-
to OVP
latch
GND
to
MOSFET
L6590A
CLAMP
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| L6590AN | Analog IC |
| L6590D | FULLY INTEGRATED POWER SUPPLY FIPS |
| L6590N | FULLY INTEGRATED POWER SUPPLY FIPS |
| L66-121 | Logic IC |
| L66-122 | Logic IC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| L6590AN | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 700 Volt Monolithic 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 |
| L6590D | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 700 Volt Monolithic 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 |
| L6590D013TR | 功能描述:開關(guān)變換器、穩(wěn)壓器與控制器 700 Volt Monolithic 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 |
| L6590ED | 功能描述:功率因數(shù)校正 IC STEP DOWN SWITCH REG RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
| L6590ED013TR | 功能描述:功率因數(shù)校正 IC STEP DOWN SWITCH REG RoHS:否 制造商:Fairchild Semiconductor 開關(guān)頻率:300 KHz 最大功率耗散: 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel |
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