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參數(shù)資料
| 型號： | L5980 |
| 廠商： | 意法半導體 |
| 英文描述： | 0.7A step-down switching regulator |
| 中文描述： | 0.7A的降壓開關穩(wěn)壓器 |
| 文件頁數(shù)： | 12/37頁 |
| 文件大小： | 959K |
| 代理商： | L5980 |
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Functional description
L5980
12/37
4.4
Over-current protection
The L5980 implements the over current protection sensing current flowing through the
power MOSFET. Due to the noise created by the switching activity of the power MOSFET,
the current sensing is disabled during the initial phase of the conduction time. This avoids
an erroneous detection of a fault condition. This interval is generally known as “masking
time” or “blanking time”. The masking time is about 200ns.
When the over current is detected, two different behaviors are possible depending on the
operation condition.
1.
Output voltage in regulation
. When the over current is sensed, the power MOSFET
is switched off and the internal reference (V
REF
), that biases the non-inverting input of
the error amplifier, is set to zero and kept in this condition for a soft start time (T
SS
,
2048 clock cycles). After this time, a new soft start phase takes place and the internal
reference begins ramping (see
Figure 8
.a).
2.
Soft start phase
. If the over current limit is reached the power MOSFET is turned off
implementing the pulse by pulse over current protection.
During the soft start phase,
u
nder over current condition, the device can skip pulses in order to keep the output
current constant and equal to the current limit. If at the end of the "masking time" the
current is higher than the over current threshold, the power MOSFET is turned off and it
will skip one pulse. If, at the next switching on at the end of the "masking time" the
current is still higher than the threshold, the device will skip two pulses. This
mechanism is repeated and the device can skip up to seven pulses. While, if at the end
of the "masking time" the current is lower than the over current threshold, the number of
skipped cycles is decreased of one unit. At the end of soft start phase the output
voltage is in regulation and if the over current persists the behavior explained above
take place. (see
Figure 8
.b)
So the over current protection can be summarized as an “hiccup” intervention when the
output is in regulation and a constant current during the soft start phase. If the output is
shorted to ground when the output voltage is on regulation, the over current is triggered and
the device starts cycling with a period of 2048 clock cycles between “hiccup” (power
MOSFET off and no current to the load) and “constant current” with very short on-time and
with reduced switching frequency (up to one eighth of normal switching frequency). See
Figure 30.
for short circuit behavior.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| L5980_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:0.7 A step-down switching regulator |
| L5980TR | 功能描述:直流/直流開關調(diào)節(jié)器 700mA Step-Down Switching Reg RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L5980TR-CUT TAPE | 制造商:ST 功能描述:L5980 Series 15 V 250 kHz 0.7 A Step Down Switching Regulator - VFQFPN-8 |
| L5981 | 功能描述:直流/直流開關調(diào)節(jié)器 1A STEP-DOWN SWITCH REG RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| L5981_08 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:1 A step-down switching regulator |
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