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參數(shù)資料
| 型號： | LX13088CLD |
| 廠商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | DUAL SWITCHING CONTROLLER, PDSO10 |
| 封裝： | 3 X 3 MM, ROHS COMPLIANT, PLASTIC, DFN-10 |
| 文件頁數(shù)： | 2/12頁 |
| 文件大?。?/td> | 422K |
| 代理商： | LX13088CLD |
LX13088
PRODUCTION DATASHEET
Microsemi
Analog Mixed Signal Group
11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570
Page 10
Copyright
2010
Rev. 1.1, 2010-06-08
Dual 1A Step-Down Converters
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THEORY OF OPER ATION
DC-DC SWITCHING STEP DOWN CONVERTERS
The LX13088 dual DC-DC converters are current mode buck
converters with integrated high side switch, synchronous
rectifier and internal compensation. They are designed to be
stable with a3.3H inductor value and 10F to 22F output
capacitor. Both output voltages are resistor divider
programmable. The switching frequency of the converter is
fixed and the switches turn on at alternating 180° phase
intervals.
The converters operate in 3 possible modes: continuous mode
(CM), discontinuous mode (DM), and pulse skipping mode
(PSM). CM is the default mode under normal loading. DM
occurs under light loads, where switching still occurs at the
programmed frequency. In DM, a zero crossing detector shuts
off the synchronous rectifier to prevent reverse rectifier current;
this results in a portion of the switch period where neither
switch is on. Under very light loads, PSM mode occurs, where
switching cycles are skipped if the current demand is low in
order to provide better efficiency.
SOFTSTART
The DC-DC converters contain a soft start function that
brings the output voltages up via a slowly increasing ramp with
any resistive load from open circuit to 1A. The output voltage
waveform shall not vary by more than 50mV from a straight
line drawn from the initial voltage to the final steady state
voltage. During soft start, the peak inductor current shall not
exceed 750mA until the output voltage reaches 25% of its final
value. Current limit shall be active but not trip during soft start
into a rated resistive load. Overshoot voltage during soft start
is limited to 1%.
ENABLE AND POWER UP SEQUENCING
When power is applied at VIN and if the E/S input is asserted
(High) or is toggling, the DC-DC converters will enter RUN
mode after a short settling period. If the E/S pin is a static low,
the IC will enter a SLEEP state where it draws very little input
current, less than 10uA.
When in RUN mode, if there is no fault condition, the VO1
output of converter 1 will be the first output to begin soft start.
When the reference voltage for FB1 reaches approximately 90%
of the final value, the VO2 output of converter 2 will begin soft
start.
POR
Under-voltage comparators are provided to monitor the output
voltages and the voltage at VMON which could be the input
supply voltage. If any of these voltages falls below its POR
threshold, the POR open drain output will turn on which pulls
the POR pin low. Note that the fault to POR assert delay time is
approximately 20S. If the POR fault condition is cleared,
there is a delay of 20ms before the POR output transistor is
turned off; when off the POR pin is high Z and may be pulled
up high via a resistor.
The POR function has built in deglitching. Once the POR is
detected, the power supply outputs will be discharged prior to a
restart condition, where soft start and power up sequencing will
occur.
OUTPUT DISCHARGE
After the occurrence of a POR situation, and the POR fault
condition is immediately cleared, startup and soft start is
delayed until the outputs are discharge to <10%. During the
discharge phase, the soft start internal reference voltages
(REFx) are shorted to ground to quickly discharge it. The output
capacitors are discharged via an internal 30 pull down switch
on each of the SW1 and SW2 pins. When the FBx voltage and
the REFx voltage are fully discharged and if there is not an OT
condition, the outputs are then allowed to begin the normal soft
start power up sequence. During the discharge phase, the
control high side and synchronous rectifier MOSFETs are in the
high-Z off state.
OVER CURRENT AND SHORT CIRCUIT PROTECTION
The DC-DC converters have over current and short circuit
protection. During any mode of operation, any value of load
resistance (including 0 ohms) can be applied to the DC-DC
outputs instantaneously and held in place indefinitely without
the switch current exceeding the peak current limit and without
the IC suffering any permanent damage or loss of performance.
The output voltage is allowed to drop under over current or
short circuit conditions. Both converters will stop switching if
either one experiences an over current condition for various
cycles.
Recovery to output voltage regulation occurs within 10ms of
the instant the loading is reduced to maximum allowable rated
load; the output voltage shall not exceed the dynamic load
excursion limits (+/-5% excursion) upon recovery.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LX13088CLD-TR | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:Dual 1A Step-Down Converters |
| LX-1309 | 制造商:UNBRANDED 功能描述:LIGHT METER 400 000 LUX USB 制造商:UNBRANDED 功能描述:LIGHT METER, 400, 000 LUX, USB |
| LX13097 | 制造商:Microsemi Corporation 功能描述:SWITCHING REGULATOR - Bulk |
| LX13097CSE | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:1A SYNCHRONOUS BUCK SWITCHER WITH FET ON BOARD |
| LX133 | 制造商:LUMINIS 制造商全稱:LUMINIS 功能描述:Wall mount |
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