- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄358827 > LM2696 (National Semiconductor Corporation) 3A, Constant On Time Buck Regulator PDF資料下載
參數(shù)資料
| 型號(hào)： | LM2696 |
| 廠商： | National Semiconductor Corporation |
| 英文描述： | 3A, Constant On Time Buck Regulator |
| 中文描述： | 第3A，恒定時(shí)間降壓穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 16/19頁(yè) |
| 文件大?。?/td> | 833K |
| 代理商： | LM2696 |
第1頁(yè)第2頁(yè)第3頁(yè)第4頁(yè)第5頁(yè)第6頁(yè)第7頁(yè)第8頁(yè)第9頁(yè)第10頁(yè)第11頁(yè)第12頁(yè)第13頁(yè)第14頁(yè)第15頁(yè)當(dāng)前第16頁(yè)第17頁(yè)第18頁(yè)第19頁(yè)
Application Information
(Continued)
PRE-BIAS LOAD STARTUP
Should the LM2696 start into a pre-biased load the output
will not be pulled low. This is because the part is asynchro-
nous and cannot sink current. The part will respond to a
pre-biased load by simply enabling PWM high or extending
the off-time until regulation is achieved. This is to say that if
the output voltage is greater than the regulation voltage the
off-time will extend until the voltage discharges through the
feedback resistors. If the load voltage is greater than the
regulation voltage, a series of pulses will charge the output
capacitor to its regulation voltage.
THERMAL CONSIDERATIONS
The thermal characteristics of the LM2696 are specified
using the parameter
θ
, which relates the junction tempera-
ture to the ambient temperature. While the value of
θ
is
specific to a given set of test parameters (including board
thickness, number of layers, orientation, etc), it provides the
user with a common point of reference.
To obtain an estimate of a devices junction temperature, one
may use the following relationship:
T
J
= P
IN
(1-Efficiency) x
θ
JA
+ T
A
Where:
T
J
is the junction temperature in
o
C
P
IN
is the input power in Watts (P
IN
= V
IN
·I
IN
)
θ
JA
is the thermal coefficient of the LM2696
T
A
is the ambient temperature in
o
C
LAYOUT CONSIDERATIONS
The LM2696 regulation and under-voltage comparators are
very fast and will respond to short duration noise pulses.
Layout considerations are therefore critical for optimum per-
formance. The components at pins 5, 6, 7, 12 and 13 should
be as physically close as possible to the IC, thereby mini-
mizing noise pickup in the PC traces. If the internal dissipa-
tion of the LM2696 produces excessive junction tempera-
tures during normal operation, good use of the PC board’s
ground plane can help considerably to dissipate heat. The
exposed pad on the bottom of the TSSOP-16 package can
be soldered to a ground plane on the PC board, and that
plane should extend out from beneath the IC to help dissi-
pate the heat. Use of several vias beneath the part is also an
effective method of conducting heat. Additionally, the use of
wide PC board traces, where possible, can also help con-
duct heat away from the IC. Judicious positioning of the PC
board within the end product, along with use of any available
air flow (forced or natural convection) can help reduce the
junction temperatures. Traces in the power plane
(Figure 9)
should be short and wide to minimize the trace impedance;
they should also occupy the smallest area that is reasonable
to minimize EMI. Sizing the power plane traces is a tradeoff
between current capacity, inductance, and thermal dissipa-
tion. For more information on layout considerations, please
refer to National Semiconductor Application Note AN-1229.
20153450
FIGURE 9. Bold Traces Are In The Power Plane
L
www.national.com
16
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM26CIM5-PHA | Accurate, Factory Preset Thermostat |
| LM26CIM5-SHA | Accurate, Factory Preset Thermostat |
| LM26CIM5X-ZHA | Accurate, Factory Preset Thermostat |
| LM26CIM5-KLA | Accurate, Factory Preset Thermostat |
| LM26CIM5-NPA | Accurate, Factory Preset Thermostat |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2696EVAL | 功能描述:電源管理IC開(kāi)發(fā)工具 LM2696 EVAL BOARD RoHS:否 制造商:Maxim Integrated 產(chǎn)品:Evaluation Kits 類型:Battery Management 工具用于評(píng)估:MAX17710GB 輸入電壓: 輸出電壓:1.8 V |
| LM2696MXA | 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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 |
| LM2696MXA/NOPB | 功能描述:直流/直流開(kāi)關(guān)調(diào)節(jié)器 3A,CONSTANT ON TIME BUCK REG RoHS:否 制造商:International Rectifier 最大輸入電壓:21 V 開(kāi)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 |
| LM2696MXAX | 制造商:Texas Instruments 功能描述:Conv DC-DC Single Step Down 4.5V to 24V 16-Pin TSSOP EP T/R |
| LM2696MXAX/NOPB | 功能描述:直流/直流開(kāi)關(guān)轉(zhuǎn)換器 RoHS:否 制造商:STMicroelectronics 最大輸入電壓:4.5 V 開(kāi)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 |
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。