參數(shù)資料
型號: LM2736
廠商: National Semiconductor Corporation
英文描述: Thin SOT23 750mA Load Step-Down DC-DC Regulator
中文描述: 薄型SOT23負載電流降壓型DC - DC穩(wěn)壓器
文件頁數(shù): 7/22頁
文件大?。?/td> 444K
代理商: LM2736
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
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7
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LM2736X 制造商:TI 制造商全稱:Texas Instruments 功能描述:LM2736 Thin SOT 750mA Load Step-Down DC-DC Regulator
LM2736X EVAL 功能描述:BOARD EVALUATION LM2736X RoHS:否 類別:編程器,開發(fā)系統(tǒng) >> 評估板 - DC/DC 與 AC/DC(離線)SMPS 系列:- 產(chǎn)品培訓模塊:Obsolescence Mitigation Program 標準包裝:1 系列:True Shutdown™ 主要目的:DC/DC,步升 輸出及類型:1,非隔離 功率 - 輸出:- 輸出電壓:- 電流 - 輸出:1A 輸入電壓:2.5 V ~ 5.5 V 穩(wěn)壓器拓撲結(jié)構(gòu):升壓 頻率 - 開關(guān):3MHz 板類型:完全填充 已供物品:板 已用 IC / 零件:MAX8969
LM2736X EVAL/NOPB 功能描述:電源管理IC開發(fā)工具 RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
LM2736XEVAL 功能描述:電源管理IC開發(fā)工具 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V
LM2736XEVAL/NOPB 功能描述:電源管理IC開發(fā)工具 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V