- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄44549 > LM2651MTC-2.5/NOPB (NATIONAL SEMICONDUCTOR CORP) 2.6 A SWITCHING REGULATOR, 345 kHz SWITCHING FREQ-MAX, PDSO16 PDF資料下載
參數(shù)資料
| 型號： | LM2651MTC-2.5/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 2.6 A SWITCHING REGULATOR, 345 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | TSSOP-16 |
| 文件頁數(shù)： | 2/11頁 |
| 文件大小： | 631K |
| 代理商： | LM2651MTC-2.5/NOPB |
Design Procedure (Continued)
EXTERNAL SCHOTTKY DIODE
A Schottky diode D
1 is recommended to prevent the intrinsic
body diode of the low-side MOSFET from conducting during
the deadtime in PWM operation and hysteretic mode when
both MOSFETs are off. If the body diode turns on, there is
extra power dissipation in the body diode because of the
reverse-recovery current and higher forward voltage; the
high-side MOSFET also has more switching loss since the
negative diode reverse-recovery current appears as the
high-side MOSFET turn-on current in addition to the load
current. These losses degrade the efficiency by 1-2%. The
improved efficiency and noise immunity with the Schottky
diode become more obvious with increasing input voltage
and load current.
The breakdown voltage rating of D
1 is preferred to be 25%
higher than the maximum input voltage. Since D
1 is only on
for a short period of time, the average current rating for D
1
only requires being higher than 30% of the maximum output
current. It is important to place D
1 very close to the drain and
source of the low-side MOSFET, extra parasitic inductance
in the parallel loop will slow the turn-on of D
1 and direct the
current through the body diode of the low-side MOSFET.
When an undervoltage situation occurs, the output voltage
can be pulled below ground as the inductor current is re-
versed through the synchronous FET. For applications which
need to be protected from a negative voltage, a clamping
diode D2 is recommended. When used, D2 should be con-
nected cathode to V
OUT and anode to ground. A diode rated
for a minimum of 2A is recommended.
PCB Layout Considerations
Layout is critical to reduce noises and ensure specified
performance. The important guidelines are listed as follows:
1.
Minimize the parasitic inductance in the loop of input
capacitors and the internal MOSFETs by connecting the
input capacitors to V
IN and PGND pins with short and
wide traces. This is important because the rapidly
switching current, together with wiring inductance can
generate large voltage spikes that may result in noise
problems.
2.
Minimize the trace from the center of the output resistor
divider to the FB pin and keep it away from noise
sources to avoid noise pick up. For applications requir-
ing tight regulation at the output, a dedicated sense
trace (separated from the power trace) is recommended
to connect the top of the resistor divider to the output.
3.
If the Schottky diode D
1 is used, minimize the traces
connecting D
1 to SW and PGND pins.
10092523
Schematic for the Typical Board Layout
LM2651
www.national.com
10
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2651MTC-1.8/NOPB | 2.6 A SWITCHING REGULATOR, 345 kHz SWITCHING FREQ-MAX, PDSO16 |
| LM2670-5.0MDC | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, UUC |
| LM2670LDX-3.3 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO14 |
| LM2670LD-3.3 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO14 |
| LM2670LD-12 | 5.4 A SWITCHING REGULATOR, 280 kHz SWITCHING FREQ-MAX, PDSO14 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2651MTC-3.3 | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM2651MTC-3.3/NOPB | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 1.5A HIGH EFFICIENCY SWITCHING REG RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM2651MTC-3.3/NOPB | 制造商:Texas Instruments 功能描述:DC/DC Converter (DC-DC) / Switching Regu |
| LM2651MTC-ADJ | 功能描述:直流/直流開關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開關(guān)頻率:1.5 MHz 輸出電壓:4.6 V 輸出電流:250 mA 輸出端數(shù)量:2 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT |
| LM2651MTC-ADJ | 制造商:Texas Instruments 功能描述:SWITCHING REG 1.5A ADJ SMD 2651 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。