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參數(shù)資料
| 型號： | LM4510 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | Synchronous Step-Up DC/DC Converter with True Shutdown Isolation |
| 中文描述： | 同步升壓型DC / DC轉(zhuǎn)換器，具有真關(guān)斷隔離 |
| 文件頁數(shù)： | 11/18頁 |
| 文件大?。?/td> | 2362K |
| 代理商： | LM4510 |
Synchronous boost converter is shown in Figure 3. At the start
of each cycle, the oscillator sets the driver logic and turns on
the NMOS power device and turns off the PMOS power de-
vice.
Cycle 1 Description
Refer to Figure 4. NMOS switch turn-on
→
Inductor current
increases and flows to GND.
PMOS switch turn-off
→
Isolate VOUT from SW
→
Output ca-
pacitor supplies load current.
30031015
FIGURE 4. Equivalent Circuit During Cycle 1
During operation, EAMP output voltage (V
) increases for
larger loads and decreases for smaller loads. When the sum
of the ramp compensation and the sensed NMOS current
reaches a level determined by the EAMP output voltage, the
PWM COMP resets the logic, turning off the NMOS power
device and turning on the PMOS power device.
Cycle 2 Description
Refer to Figure 5. NMOS Switch turn-off
→
PMOS Switch turn-
on
→
Inductor current decreases and flows through PMOS
→
Inductor current recharges output capacitor and supplies
load current.
30031016
FIGURE 5. Equivalent Circuit During Cycle 2
After the switching period the oscillator then sets the driver
logic again repeating the process.
ON/OFF CONTROL
The LM4510 shuts down when the EN pin is low. In this mode
the feedback resistors and the load are disconnected from the
input in order to avoid leakage current flow and to allow the
output voltage to drop to 0V.
The LM4510 turns on when EN is high. There is an internal
pull-down resistor on the EN pin so the device is in a normally
off state.
SHORT CIRCUIT PROTECTION
When V
goes down to V
–0.7V (typ.), the device stops
switching due to the short-circuit protection circuitry and the
short-circuit output current is limited to I
INIT_CHARGE
.
FEEDBACK FAULT PROTECTION
The LM4510 features unique Feedback Fault Protection to
maximize safety when the feedback resistor is not properly
connected to a circuit or the feedback node is shorted directly
to ground.
Feedback fault triggers V
OUT
monitoring. During monitoring,
if V
reaches a protection level, the device shuts down.
When the feedback network is reconnected and V
is lower
than the OFF threshold level of Feedback Fault Protection,
V
monitoring stops. V
OUT
is then regulated by the control
loop.
INPUT UNDER-VOLTAGE LOCK-OUT
The LM4510 has dedicated circuitry to protect the IC and the
external components when the battery voltage is lower than
the preset threshold. This under-voltage lock-out with hys-
teresis prevents malfunctions during startup or abnormal
power off.
THERMAL SHUTDOWN
If the die temperature exceeds 150°C (typ.), the thermal pro-
tection circuitry shuts down the device. The switches remain
off until the die temperature is reduced to approximately
140°C (typ.).
Application Information
ADJUSTING OUTPUT VOLTAGE
The output voltage is set using the feedback pin and a resistor
voltage divider (R
F1
, R
F2
) connected to the output as shown
in the Typical Application Circuit.
The ratio of the feedback resistors sets the output voltage.
R
F2
Selection
First of all choose a value for R
F2
generally between 10 k
and 25 k
.
R
F1
Selection
Calculate R
F1
using the following equation:
Table 1 gives suggested component values for several typical
output voltages.
11
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|---|---|
| LM4510SD | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Up 2.7V to 5.5V 10-Pin LLP EP T/R |
| LM4510SD/NOPB | 功能描述:DC/DC 開關(guān)控制器 RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關(guān)頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風(fēng)格: 封裝 / 箱體:CPAK |
| LM4510SDEV | 功能描述:電源管理IC開發(fā)工具 LM4510S 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 |
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| LM4510SDX | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Synchronous Step-Up DC/DC Converter with True Shutdown Isolation |
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