- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄98000 > LM2633MTDX/NOPB (NATIONAL SEMICONDUCTOR CORP) SWITCHING CONTROLLER, 275 kHz SWITCHING FREQ-MAX, PDSO48 PDF資料下載
參數(shù)資料
| 型號： | LM2633MTDX/NOPB |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | SWITCHING CONTROLLER, 275 kHz SWITCHING FREQ-MAX, PDSO48 |
| 封裝： | TSSOP-48 |
| 文件頁數(shù)： | 30/40頁 |
| 文件大小： | 1350K |
| 代理商： | LM2633MTDX/NOPB |
第1頁第2頁第3頁第4頁第5頁第6頁第7頁第8頁第9頁第10頁第11頁第12頁第13頁第14頁第15頁第16頁第17頁第18頁第19頁第20頁第21頁第22頁第23頁第24頁第25頁第26頁第27頁第28頁第29頁當(dāng)前第30頁第31頁第32頁第33頁第34頁第35頁第36頁第37頁第38頁第39頁第40頁
Control Loop Design (Continued)
amplifier, and I
fb2 is the current drawn by the FB2 pin. The
V
fb2 and Ifb2 have a typical value of 1.24V and 18 nA
respectively.
Example: V
out2 = 1.5V, R1 =10 k.
(51)
To calculate the total system tolerance, use the following
equation:
(52)
where
φ is the tolerance of the Channel 2 reference voltage,
and
σ is the tolerance of the resistors.
Example: V
out2
= 3.3V, feedback resistors have a ±1%
tolerance.
(53)
That means the 3.3V output voltage will have a ±2.96%
tolerance over the (LM2633 die) temperature range of 0C to
125C.
Channel 2 output voltage should not go above 6V in
pulse-skip mode. That is because the SENSE2 pin cannot
take a voltage higher than 6V. However, if force-PWM op-
eration is the chosen operating mode, then the SENSE2 pin
can be grounded and there will be no limitation to Channel 2
output voltage.
If the desired Channel 1 voltage is higher than 2V, an
op-amp and a voltage divider can be used to expand the
voltage range, as shown in
It is recommended that the VIDx pins be all tied to ground so
that the DAC is set at 2.00V. That will reduce the total
tolerance. The equations used to calculate Channel 2’s feed-
back resistors and total tolerance still hold, except that the
reference voltage V
fb1 is 2.00V instead of 1.24V. Channel 1
can operate only in force-PWM mode when it is configured
as
Since an op-amp is an active device, pay close attention to
its start up and shut down behavior. Make sure that it does
not create a problem during those times.
Designing a Power Supply without a Load Transient
Specification
Many times the load transient response of a buck regulator is
not a critical issue. In that case, the selection of the power
stage components can start from the inductor ripple current.
Choosing the peak-to-peak ripple current to be 30% of the
maximum load current is often a good starting point. Then
the inductance value can be determined by ripple, switching
frequency and input and output voltages. By rearranging
Equation (13), the inductance value can be calculated as
follows:
(54)
Example: V
in_max = 21V, Vn = 1.6V, Iload_max = 10A.
The output capacitors can be chosen based on the output
voltage ripple requirement. If there is no specific require-
ment, then a ±1% ripple level may be a good starting point.
The equation for determining the impedance of the output
capacitors is:
(55)
If the ESR zero frequency of the capacitor is lower than the
switching frequency, such as the case of aluminum, tantalum
and OSCON capacitors, then the output capacitors are cho-
sen by the ESR value. Otherwise, such as in the case of
ceramic capacitors, the output capacitors are chosen by the
capacitance. The equation is:
(56)
Basically make sure that the product of the impedance of the
capacitors and the ripple current does not exceed the ripple
voltage requirement.
Example: V
n = 1.6V, Irip = 3A.
(57)
If ceramic capacitors are preferred, then the minimum ca-
pacitance is:
(58)
200008B6
FIGURE 18. How to Make V
OUT1 Higher Than 2V
LM2633
www.national.com
36
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM2635MX/NOPB | SWITCHING CONTROLLER, 350 kHz SWITCHING FREQ-MAX, PDSO20 |
| LM26480QSQX-CF/NOPB | 2.4 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, QCC24 |
| LM26480QSQ-CF/NOPB | 2.4 A SWITCHING REGULATOR, 2500 kHz SWITCHING FREQ-MAX, QCC24 |
| LM26480SQ-BF/NOPB | 2.4 A SWITCHING REGULATOR, 2400 kHz SWITCHING FREQ-MAX, QCC24 |
| LM26480SQX-BF/NOPB | 2.4 A SWITCHING REGULATOR, 2400 kHz SWITCHING FREQ-MAX, QCC24 |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM2635 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:5-Bit Programmable Synchronous Buck Regulator Controller |
| LM2635A WAF | 制造商:Texas Instruments 功能描述: |
| LM2635M | 制造商:Rochester Electronics LLC 功能描述: 制造商:Texas Instruments 功能描述: |
| LM2635M/NOPB | 功能描述:IC REG SYNCH BUCK 5-BIT 20-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 應(yīng)用說明:Ultrasound Imaging Systems Application Note 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:37 系列:- 應(yīng)用:醫(yī)療用超聲波成像，聲納 電流 - 電源:- 電源電壓:2.37 V ~ 6 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:56-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:56-TQFN-EP（8x8） 包裝:管件 |
| LM2635MX | 功能描述:IC REG SYNCH BUCK 5-BIT 20-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電源管理 - 專用 系列:- 應(yīng)用說明:Ultrasound Imaging Systems Application Note 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:37 系列:- 應(yīng)用:醫(yī)療用超聲波成像，聲納 電流 - 電源:- 電源電壓:2.37 V ~ 6 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:56-WFQFN 裸露焊盤 供應(yīng)商設(shè)備封裝:56-TQFN-EP（8x8） 包裝:管件 |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。