參數(shù)資料
型號： LM26480SQ-BF/NOPB
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 穩(wěn)壓器
英文描述： 2.4 A SWITCHING REGULATOR, 2400 kHz SWITCHING FREQ-MAX, QCC24
封裝： 4 X 4 MM, 0.80 MM HEIGHT, LLP-24
文件頁數(shù)： 8/30頁
文件大小： 2447K
代理商： LM26480SQ-BF/NOPB
30040405
SHUTDOWN MODE
During shutdown the PFET switch, reference, control and
bias circuitry of the converters are turned off. The NFET
switch will be on in shutdown to discharge the output. When
the converter is enabled, soft start is activated. It is recom-
mended to disable the converter during the system power up
and under voltage conditions when the supply is less than
2.8V.
SOFT START
The soft-start feature allows the power converter to gradually
reach the initial steady state operating point, thus reducing
startup stresses and surges. The two LM26480 buck con-
verters have a soft-start circuit that limits in-rush current dur-
ing startup. During startup the switch current limit is increased
in steps. Soft start is activated only if EN goes from logic low
to logic high after V
IN reaches 2.8V. Soft start is implemented
by increasing switch current limit in steps of 250 mA, 500 mA,
950 mA and 2A for both bucks (typ. switch current limit). The
startup time thereby depends on the output capacitor and load
current demanded at start-up.
LOW DROPOUT OPERATION
The LM26480 can operate at 100% duty cycle (no switching;
PMOS switch completely on) for low dropout support of the
output voltage. In this way the output voltage will be controlled
down to the lowest possible input voltage. When the device
operates near 100% duty cycle, output voltage ripple is ap-
proximately 25 mV. The minimum input voltage needed to
support the output voltage is
V
IN, MIN = ILOAD * (RDSON, PFET + RINDUCTOR) + VOUT
— ILOAD
Load current
— RDSON, PFET
Drain to source resistance of
PFET switch in the triode region
— RINDUCTOR
Inductor resistance
FLEXIBLE POWER-ON RESET (i.e., POWER GOOD WITH
DELAY)
The LM26480 is equipped with an internal Power-On-Reset
(“POR”) circuit which monitors the output voltage levels on
bucks 1 and 2. The nPOR is an open drain logic output which
is logic LOW when either of the buck outputs are below 91%
of the rising value , or when one or both outputs fall below
82% of the desired value. The time delay between output
voltage level and nPOR is enabled is (50 s, 50 ms, 100 ms,
200 ms), 50 ms by default. For any other delay option, other
than the default, please consult a National Sales Represen-
tative. The system designer can choose the external pull-up
resistor (i.e. 100 k
) for the nPOR pin.
www.national.com
16
LM26480
相關(guān)PDF資料
PDF描述
LM26480SQX-BF/NOPB 2.4 A SWITCHING REGULATOR, 2400 kHz SWITCHING FREQ-MAX, QCC24
LM2661M/NOPB SWITCHED CAPACITOR CONVERTER, 80 kHz SWITCHING FREQ-MAX, PDSO8
LM2660MMX/NOPB SWITCHED CAPACITOR CONVERTER, 40 kHz SWITCHING FREQ-MAX, PDSO8
LM2661MM/NOPB SWITCHED CAPACITOR CONVERTER, 80 kHz SWITCHING FREQ-MAX, PDSO8
LM2661MMX/NOPB SWITCHED CAPACITOR CONVERTER, 80 kHz SWITCHING FREQ-MAX, PDSO8
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM26480SQX-AA 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Externally Programmable Dual High-Current Step-Down DC/DC and Dual Linear Regulators
LM26480SQX-AA/NOPB 功能描述:PMIC 解決方案 RoHS:否 制造商:Texas Instruments 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-24 封裝:Reel
LM26480SQX-BF 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Externally Programmable Dual High-Current Step-Down DC/DC and Dual Linear Regulators
LM26480SQX-BF/NOPB 功能描述:直流/直流開關(guān)調(diào)節(jié)器 Externally Pgrm Dual Hi-Current SD DC/DC RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關(guān)頻率:1.5 MHz 輸出電壓:0.5 V to 0.86 V 輸出電流:4 A 輸出端數(shù)量: 最大工作溫度: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5
LM26484 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Power Management Unit
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