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參數(shù)資料
| 型號： | LM2734YMK |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | Thin SOT23 1A Load Step-Down DC-DC Regulator |
| 中文描述： | 2.5 A SWITCHING REGULATOR, 660 kHz SWITCHING FREQ-MAX, PDSO6 |
| 封裝： | TSOT-23, 6 PIN |
| 文件頁數(shù)： | 7/22頁 |
| 文件大?。?/td> | 459K |
| 代理商： | LM2734YMK |
Application Information
THEORY OF OPERATION
The LM2734 is a constant frequency PWM buck regulator IC
that delivers a 1A load current. The regulator has a preset
switching frequency of either 550kHz (LM2734Y) or 1.6MHz
(LM2734X). These high frequencies allow the LM2734 to
operate with small surface mount capacitors and inductors,
resulting in DC/DC converters that require a minimum
amount of board space. The LM2734 is internally compen-
sated, so it is simple to use, and requires few external
components. The LM2734 uses current-mode control to
regulate the output voltage.
The following operating description of the LM2734 will refer
to the Simplified Block Diagram (
Figure 1
) and to the wave-
forms in
Figure 2
. The LM2734 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
LM2734 will operate with this minimum voltage, it may not
have sufficient gate drive to supply large values of output
Block Diagram
20102306
FIGURE 1.
20102307
FIGURE 2. LM2734 Waveforms of SW Pin Voltage and
Inductor Current
L
www.national.com
7
相關PDF資料 |
PDF描述 |
|---|---|
| LM2734XMKX | Thin SOT23 1A Load Step-Down DC-DC Regulator |
| LM2734XMK | Thin SOT23 1A Load Step-Down DC-DC Regulator |
| LM2734 | Thin SOT23 1A Load Step-Down DC-DC Regulator |
| LM2736 | Thin SOT23 750mA Load Step-Down DC-DC Regulator |
| LM2736XMK | Thin SOT23 750mA Load Step-Down DC-DC Regulator |
相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LM2734YMK/NOPB | 功能描述:直流/直流開關調(diào)節(jié)器 1A LOAD STEP-DOWN DC-DC REG RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率: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: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM2734YMKX | 功能描述:直流/直流開關調(diào)節(jié)器 RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率: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: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM2734YMKX/NOPB | 功能描述:直流/直流開關調(diào)節(jié)器 RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率: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: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
| LM2734YQMK | 制造商:Texas Instruments 功能描述:DC DC REG, BUCK, 1A, 550KHZ, 6TSOT 制造商:Texas Instruments 功能描述:DC DC REG, BUCK, 1A, 550KHZ, 6TSOT; Primary Input Voltage:20V; No. of Outputs:1; Output Voltage:18V; Output Current:1A; Voltage Regulator Case Style:SOT-23; No. of Pins:6; Operating Temperature Min:-40C; Operating Temperature ;RoHS Compliant: Yes |
| LM2734YQMK/NOPB | 功能描述:直流/直流開關調(diào)節(jié)器 RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開關頻率: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: 安裝風格:SMD/SMT 封裝 / 箱體:PQFN 4 x 5 |
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