參數(shù)資料
型號(hào)： SC2440TETRT
廠商： Semtech Corporation
英文描述： 2.5 MHz Dual Switching Regulator with Integrated 2A Switches
中文描述： 2.5 MHz雙開(kāi)關(guān)穩(wěn)壓器集成甲開(kāi)關(guān)
文件頁(yè)數(shù)： 17/26頁(yè)
文件大?。?/td> 643K
代理商： SC2440TETRT
17
2005 Semtech Corp.
www.semtech.com
SC2440
POWER MANAGEMENT
Applications Information
Overload / Short-Circuit Protection
Each current limit comparator in the SC2440 limits the
peak inductor current to 2.6A. The regulator output
voltage will fall if the load is increased above the current
limit. If overload is detected (the output voltage falls
below 74% of the set voltage), then the regulator will be
shut off. An internal 0.8μA current sink starts to
discharge the soft-start capacitor. As the soft-start
capacitor is discharged below 1V, the discharge current
source turns off and the soft-start capacitor is recharged
with a 1.8μA current source. The regulator undergoes
soft-start. During soft-start (1V < V
< 2V), the overload
shutdown latch in Figure 3 cannot be set. When V
exceeds 2V, the set input of the overload latch is no
longer blanked. If V
FB
is still below 0.74V, then the
regulator will undergo shutdown and restart. The soft-
start process should allow the output voltage to reach
74% of its final value before C
is charged above 2V.
Figures 10(a) and 10(b) show the timing diagrams of
successful and failed start-up waveforms respectively.
The soft-start interval should also be made sufficiently
long so that the output voltage rises monotonically and
it does not overshoot its final voltage by more than 5%.
When starting into a shorted output, the SC2440 will
repeatedly start and shut off (“hiccup”). V
and V
will appear as asymmetrical triangular waves [Figure
10(b)].
Power Good Indicators
The PGOOD pins (Pins 11 and 14) are the open-collector
outputs of the power good comparators. These slow
comparators are incorporated with small amount of
hysteresis. The FB low-to-high trip voltage of the power
good comparators is 90% of the final regulation voltage.
A pull-up resistor from each PGOOD pin to the input supply
or the regulator output set the logic high level of the
comparator.
The power good comparator output becomes valid
provided that V
is above 0.9V. In shutdown the power
good output is actively pulled low. A power good pull-up
resistor tied to the input will therefore increase current
drain during shutdown. Tying the power good pull-up
resistor to the regulator output is preferred, as this will
minimize the shutdown supply current. In shutdown there
(b)
ON
OFF
SC2440
PGOOD1
SS1
SS2
CSS1
CSS2
PGOOD2
(a)
SC2440
PGOOD1
SS1
SS2
CSS1
PGOOD2
CSS2
CONTROL1
CONTROL2
ON
OFF
CONTROL1
ON
OFF
CONTROL2
T
D
Figure 11. Sequencing the Outputs by (a) Delaying Release of one Channel Relative to
the Other and (b) Using the PGOOD of one Channel to Control the Other.
相關(guān)PDF資料
PDF描述
SC2441A 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441AEVB 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441ATETRT 1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441 Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441EVB Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
SC2441 制造商:SEMTECH 制造商全稱(chēng):Semtech Corporation 功能描述:Very Low Input Voltage 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441A 制造商:SEMTECH 制造商全稱(chēng):Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441A_09 制造商:SEMTECH 制造商全稱(chēng):Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441AEVB 制造商:SEMTECH 制造商全稱(chēng):Semtech Corporation 功能描述:1.8V to 20V Input 2-Phase Synchronous Step-down Controllers with Step-up Converter
SC2441ATETRT 制造商:Semtech Corporation 功能描述:
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