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參數(shù)資料
| 型號(hào)： | LM2736YMK |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Thin SOT23 750mA Load Step-Down DC-DC Regulator |
| 中文描述： | 2.3 A SWITCHING REGULATOR, 660 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | SOT-23, 6 PIN |
| 文件頁數(shù)： | 7/22頁 |
| 文件大小： | 444K |
| 代理商： | LM2736YMK |
Application Information
THEORY OF OPERATION
The LM2736 is a constant frequency PWM buck regulator IC
that delivers a 750mA load current. The regulator has a
preset switching frequency of either 550kHz (LM2736Y) or
1.6MHz (LM2736X). These high frequencies allow the
LM2736 to operate with small surface mount capacitors and
inductors, resulting in DC/DC converters that require a mini-
mum amount of board space. The LM2736 is internally
compensated, so it is simple to use, and requires few exter-
nal components. The LM2736 uses current-mode control to
regulate the output voltage.
The following operating description of the LM2736 will refer
to the Simplified Block Diagram (
Figure 1
) and to the wave-
forms in
Figure 2
. The LM2736 supplies a regulated output
voltage by switching the internal NMOS control switch at
constant frequency and variable duty cycle. A switching
cycle begins at the falling edge of the reset pulse generated
by the internal oscillator. When this pulse goes low, the
output control logic turns on the internal NMOS control
switch. During this on-time, the SW pin voltage (V
) swings
up to approximately V
, and the inductor current (I
) in-
creases with a linear slope. I
is measured by the current-
sense amplifier, which generates an output proportional to
the switch current. The sense signal is summed with the
regulator’s corrective ramp and compared to the error am-
plifier’s output, which is proportional to the difference be-
tween the feedback voltage and V
REF
. When the PWM
comparator output goes high, the output switch turns off until
the next switching cycle begins. During the switch off-time,
inductor current discharges through Schottky diode D1,
which forces the SW pin to swing below ground by the
forward voltage (V
) of the catch diode. The regulator loop
adjusts the duty cycle (D) to maintain a constant output
voltage.
BOOST FUNCTION
Capacitor C
BOOST
and diode D2 in
Figure 3
are used to
generate a voltage V
BOOST
. V
BOOST
- V
SW
is the gate drive
voltage to the internal NMOS control switch. To properly
drive the internal NMOS switch during its on-time, V
BOOST
needs to be at least 1.6V greater than V
SW
. Although the
LM2736 will operate with this minimum voltage, it may not
have sufficient gate drive to supply large values of output
Block Diagram
20124206
FIGURE 1.
20124207
FIGURE 2. LM2736 Waveforms of SW Pin Voltage and
Inductor Current
L
www.national.com
7
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2736YMK/NOPB | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 750MA LOAD STEP-DOWN DC-DC REG 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 |
| LM2736YMKNOPB | 制造商:National Semiconductor 功能描述:Conv DC-DC Single Step Down 3V to 18V 6-Pin TSOT T/R 制造商:National Semiconductor 功能描述:Conv DC-DC Single Step Down 3V to 18V 6-Pin SOT T/R |
| LM2736YMKX | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 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 |
| LM2736YMKX/NOPB | 功能描述:直流/直流開關(guān)調(diào)節(jié)器 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 |
| LM2737 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:N-Channel FET Synchronous Buck Regulator Controller for Low Output Voltages |
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