參數(shù)資料
型號(hào)： L6591TR
廠商： STMICROELECTRONICS
元件分類： 穩(wěn)壓器
英文描述： SWITCHING CONTROLLER, PDSO16
封裝： ROHS COMPLIANT, SOP-16
文件頁(yè)數(shù)： 14/32頁(yè)
文件大?。?/td> 560K
代理商： L6591TR
L6591
Application information
Doc ID 14821 Rev 4
21/32
Figure 13.
Oscillator waveforms and their relationship with gate-driving signals
5.7
Adaptive UVLO
A major problem when optimizing a converter for minimum no-load consumption is that the
voltage generated by the self-supply system under these conditions falls considerably as
compared even to a few mA load. This very often causes the IC's supply voltage Vcc to drop
and go below the UVLO threshold of the controller so that the operation becomes
intermittent, which is undesired. A low UVLO threshold would be helpful but it could be an
issue to drive the MOSFETS with a sufficient gate-drive voltage at heavy load during power
off.
To help the designer overcome this problem, the L6591, besides reducing its own
consumption during burst-mode operation, also features a proprietary adaptive UVLO
function. It consists of shifting the UVLO threshold downwards at light load, namely when
the voltage at pin COMP falls below a threshold VCOMPL internally fixed, so as to provide
more headroom. To prevent any malfunctioning during transients from minimum to
maximum load the normal (higher) UVLO threshold is re-established when the voltage at pin
COMP exceeds VCOMPL (with some mV hysteresis) and Vcc has exceeded the normal
UVLO threshold (see Figure 16). The normal UVLO threshold ensures that under heavy
load conditions the MOSFETS will be driven with an appropriate gate voltage.
Figure 14.
Adaptive UVLO block
OSC
HVG
t
LVG
t
Clock
t
Tsw
Td
T on
Td
+
-
UVLO
Vcc
L6591
COMP
R
S
Q
+
-
+
-
SW
9
7
VCOMPL
PFC_ ST OP
logic
PFC_STOP
8
VCOMP
Vcc
Q
t
(*) VCC OFF2 < VCC OFF1 is selected when Q is high
VCC OFF1
VCC OFF2 (*)
VCOMPO
VCOMPL
VCC OFF1
(*) VCC OFF2
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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L6598D013TR 功能描述:PMIC 解決方案 High Volt Reson Cont RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel
L6598D016TR 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:High voltage resonant controller
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