參數(shù)資料
型號(hào): L6599AN
廠商: STMICROELECTRONICS
元件分類: 穩(wěn)壓器
英文描述: SWITCHING CONTROLLER, DIP16
封裝: ROHS COMPLIANT, DIP-16
文件頁(yè)數(shù): 17/36頁(yè)
文件大?。?/td> 1595K
代理商: L6599AN
Application information
L6599A
24/36
Doc ID 15308 Rev 5
Equation 5
where fstart is recommended to be at least 4 times fmin. The proposed criterion for CSS is
quite empirical and is a compromise between an effective soft-start action and an effective
OCP (see next section). Please refer to the timing diagram of Figure 27 to see some
significant signals during the soft-start phase.
7.4
Current sense, OCP and OLP
The resonant half-bridge is essentially voltage-mode controlled; hence a current sense input
will only serve as an overcurrent protection (OCP).
Unlike PWM-controlled converters, where energy flow is controlled by the duty cycle of the
primary switch (or switches), in a resonant half-bridge the duty cycle is fixed and energy flow
is controlled by its switching frequency. This impacts on the way current limitation can be
realized. While in PWM-controlled converters energy flow can be limited simply by
terminating switch conduction beforehand when the sensed current exceeds a preset
threshold (this is commonly now as cycle-by-cycle limitation), in a resonant half-bridge the
switching frequency, that is, its oscillator’s frequency must be increased and this cannot be
done as quickly as turning off a switch: it takes at least the next oscillator cycle to see the
frequency change. This implies that to have an effective increase, able to change the energy
flow significantly, the rate of change of the frequency must be slower than the frequency
itself. This, in turn, implies that cycle-by-cycle limitation is not feasible and that, therefore,
the information on the primary current fed to the current sensing input must be somehow
averaged. Of course, the averaging time must not be too long to prevent the primary current
from reaching too high values.
In Figure 28 a couple of current sensing methods are illustrated that will be described in the
following. The circuit of Figure 28a is simpler but the dissipation on the sense resistor Rs
might not be negligible, hurting efficiency; the circuit of Figure 28b is more complex but
virtually lossless and recommended when the efficiency target is very high.
SS
3
SS
min
start
min
SS
R
10
3
C
;
1
f
RF
R
=
=
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L6599ATDTR 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 IMPROVED High-Volt RESONANT CONTROLLER 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(kāi)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
L6599ATN 制造商:STMicroelectronics 功能描述:
L6599D 功能描述:軟開(kāi)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(kāi)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
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