參數(shù)資料
型號： L6599ATDTR
廠商： STMICROELECTRONICS
元件分類： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, 500 kHz SWITCHING FREQ-MAX, PDSO16
封裝： SOP-16
文件頁數(shù)： 13/31頁
文件大?。?/td> 861K
代理商： L6599ATDTR
Application information
L6599AT
20/31
Doc ID 15534 Rev 3
Figure 11.
Current sensing techniques: a) with sense resistor, b) “l(fā)ossless”,
with capacitive shunt
The L6599AT is equipped with a current sensing input (pin 6, ISEN) and a sophisticated
overcurrent management system. The ISEN pin is internally connected to the input of a first
comparator, referenced to 0.8 V, and to that of a second comparator referenced to 1.5 V. If
the voltage externally applied to the pin by either circuit in Figure 11 exceeds 0.8 V, the first
comparator is tripped and this causes an internal switch to be turned on and the soft-start
capacitor CSS to be discharged (see Section 6.3: Soft-start). This quickly increases the
oscillator frequency and thereby limits energy transfer. The discharge continues until the
voltage on the ISEN pin has dropped by 50 mV; this, with an averaging time in the range of
10/fmin, ensures an effective frequency rise. Under output short-circuit, this operation results
in a nearly constant peak primary current.
It is normal that the voltage on the ISEN pin could overshoot the 0.8 V. However, if the
voltage on the ISEN pin reaches 1.5 V, the second comparator is triggered and the L6599AT
shuts down and latches off with both the gate-drive outputs and the PFC_STOP pin low,
hence turning off the entire unit. The supply voltage of the IC must be pulled below the
UVLO threshold and then again above the start-up level in order to restart. Such an event
may occur if the soft-start capacitor CSS is too large, preventing it from discharging fast
enough, in cases of saturation of the transformer’s magnetizing inductance or a shorted
secondary rectifier.
In the circuit shown in Figure 11a, where a sense resistor Rs in series with the source of the
low-side MOSFET is used, note the specific connection of the resonant capacitor. In this
way, the voltage across Rs is related to the current flowing through the high-side MOSFET
and is positive most of the switching period, except for the time needed for the resonant
current to reverse after the low-side MOSFET has been switched off. Assuming that the time
constant of the RC filter is at least ten times the minimum switching frequency fmin, the
approximate value of Rs can be found using the empirical equation:
Equation 6
where ICrpkx is the maximum desired peak current flowing through the resonant capacitor
and the primary winding of the transformer, which is related to the maximum load and the
minimum input voltage.
Crpkx
pkx
I
4
I
8
.
0
5
I
Vs
Rs
≈
≈
=
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PDF描述
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L6599ATN 制造商:STMicroelectronics 功能描述:
L6599D 功能描述:軟開關(guān) PWM 控制器 Hi Vltg resonant Controller RoHS:否 制造商:Fairchild Semiconductor 輸出端數(shù)量: 輸出電流: 開關(guān)頻率: 工作電源電壓:30 V 電源電流: 最大工作溫度:+ 105 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel
L6599DTR 功能描述:軟開關(guān) PWM 控制器 Hi Vltg resonant Controller RoHS:否 制造商:Fairchild Semiconductor 輸出端數(shù)量: 輸出電流: 開關(guān)頻率: 工作電源電壓:30 V 電源電流: 最大工作溫度:+ 105 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel
L6599N 功能描述:軟開關(guān) PWM 控制器 Hi Vltg resonant Controller RoHS:否 制造商:Fairchild Semiconductor 輸出端數(shù)量: 輸出電流: 開關(guān)頻率: 工作電源電壓:30 V 電源電流: 最大工作溫度:+ 105 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-8 封裝:Reel
L6599NR 功能描述:電壓模式 PWM 控制器 HV resonant CNTRL RoHS:否 制造商:Texas Instruments 輸出端數(shù)量:1 拓?fù)浣Y(jié)構(gòu):Buck 輸出電壓:34 V 輸出電流: 開關(guān)頻率: 工作電源電壓:4.5 V to 5.5 V 電源電流:600 uA 最大工作溫度:+ 125 C 最小工作溫度:- 40 C 封裝 / 箱體:WSON-8 封裝:Reel
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