參數(shù)資料
型號(hào)： L6566A
廠商： 意法半導(dǎo)體
元件分類(lèi)： 基準(zhǔn)電壓源/電流源
英文描述： Multi-mode controller for SMPS with PFC front-end
中文描述： 多模式開(kāi)關(guān)電源控制器，PFC前端
文件頁(yè)數(shù)： 22/51頁(yè)
文件大?。?/td> 410K
代理商： L6566A
Application information
L6566A
22/51
Note:
When the system operates in valley skipping-mode, uneven switching cycles may be
observed under some line/load conditions, due to the fact that the OFF-time of the MOSFET
is allowed to change with discrete steps of one ringing cycle, while the OFF-time needed for
cycle-by-cycle energy balance may fall in between. Thus one or more longer switching
cycles will be compensated by one or more shorter cycles and vice versa. However, this
mechanism is absolutely normal and there is no appreciable effect on the performance of
the converter or on its output voltage.
If the MOSFET is enabled to turn on but the amplitude of the signal on the ZCD pin is
smaller than the arming threshold for some reason (e.g. a heavy damping of drain
oscillations, like in some single-stage PFC topologies, or when a turn-off snubber is used),
MOSFET’s turn-on cannot be triggered. This case is identical to what happens at start-up:
at the end of the next oscillator cycle the MOSFET will be turned on, and a new switching
cycle will take place after skipping no more than one oscillator cycle.
The operation described so far does not consider the blanking time T
BLANK
after MOSFET’s
turn off, and actually T
BLANK
does not come into play as long as the following condition is
met:
Equation 3
where D is the MOSFET duty cycle. If this condition is not met, things do not change
substantially: the time during which MOSFET’s turn-on is inhibited is extended beyond T
osc
by a fraction of T
BLANK
. As a consequence, the maximum switching frequency will be a little
lower than the programmed value f
osc
and valley-skipping mode may take place slightly
earlier than expected. However this is quite unusual: setting f
osc
= 150 kHz, the
phenomenon can be observed at duty cycles higher than 60%. See
Section 5.11: OVP block
on page 35
for further implications of T
BLANK
.
If the voltage on the COMP pin (9) saturates high, which reveals an open control loop, an
internal pull-up keeps the ZCD pin close to 2V during MOSFET's OFF-time to prevent noise
from false triggering the detection block. When this pull-up is active, the ZCD pin might not
be able to go below the triggering threshold, which would stop the converter. To allow auto-
restart operation, however ensuring minimum operating frequency in these conditions, the
oscillator frequency that retriggers MOSFET's turn-on is that of the external oscillator
divided by 128. Additionally, to prevent malfunction at converter's start-up, the pull-up is
disabled during the initial soft-start (see the relevant section). However, to ensure a correct
start-up, at the end of the soft-start phase the output voltage of the converter must meet the
condition:
Equation 4
where Ns is the turn number of the secondary winding, Naux the turn number of the
auxiliary winding and I
ZCD
the maximum pull-up current (130
μ
A).
osc
BLANK
T
T
1
D
≤
ZCD
1
Z
I
R
Naux
Ns
Vout
>
相關(guān)PDF資料
PDF描述
L6566ATR Multi-mode controller for SMPS with PFC front-end
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
L6566A_08 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Multi-mode controller for SMPS with PFC front-end
L6566ATR 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 Multi Mode PWM 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
L6566B 功能描述:開(kāi)關(guān)變換器、穩(wěn)壓器與控制器 Multi Mode PWM 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
L6566B_08 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Multi-mode controller for SMPS
L6566BH 功能描述:電流型 PWM 控制器 Multimode Controller SMPS 800V <3mA RoHS:否 制造商:Texas Instruments 開(kāi)關(guān)頻率:27 KHz 上升時(shí)間: 下降時(shí)間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14
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