- 您現(xiàn)在的位置：買賣IC網(wǎng) > PDF目錄385480 > LM3224MMX-ADJ (NATIONAL SEMICONDUCTOR CORP) 615kHz/1.25MHz Step-up PWM DC/DC Converter PDF資料下載
參數(shù)資料
| 型號： | LM3224MMX-ADJ |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | 615kHz/1.25MHz Step-up PWM DC/DC Converter |
| 中文描述： | 2.8 A SWITCHING REGULATOR, 1500 kHz SWITCHING FREQ-MAX, PDSO8 |
| 封裝： | PLASTIC, MSOP-8 |
| 文件頁數(shù)： | 15/18頁 |
| 文件大小： | 920K |
| 代理商： | LM3224MMX-ADJ |
Application Information
(Continued)
The LM3224 can be configured to drive high current white
LEDs for the flash and torch functions of a digital camera,
camera phone, or any other similar light source. The flash/
torch can be set up with the circuit in
Figure 4
by using the
resistor R
SET
to determine the amount of current that will
flow through the LED using the equation:
I
LED
= V
FB
/R
SET
If the flash and torch modes will both be used the resistor
R
can be chosen for the higher current flash value. To
flash the circuit pull the SHDN high for the time duration
needed for the flash. To enable a lower current torch mode a
PWM signal can be applied to the SHDN pin. The torch
current would then be approximately the percent ON time of
the PWM signal multiplied by the flash (or maximum) cur-
rent. The optional disconnect FET can be used to eliminate
leakage current through the LEDs when the part is off and
also to disconnect the LED when the input voltage exceeds
the forward voltage drop of the LED. The maximum output
current the LM3224 can supply in this configuration is shown
in
Table 1
.
Figure 5
is another method of driving a high current white
LED. This circuit has a higher component count but allows
the switcher to remain on continuously for torch mode reduc-
ing stress on the supply. The two FETs also double for a
disconnect function as described above. In this circuit the
device and the torch enable FET are turned on setting a
lower current through the LED. When flash is needed the
flash enable FET is turned on to increase the current for the
amount of time desired. The minimum guaranteed maximum
output current for this circuit is the same as for
Figure 4
.
TABLE 1. Maximum LED Drive current
(F
SW
=1.25MHz, L=4.7μH, LED V
FMAX
=4V (V
OUT
=5.26V)
V
IN
4.2
4.1
4.0
3.9
3.8
3.7
3.6
3.5
3.4
3.3
3.2
3.1
3.0
2.9
2.8
2.7
LED Drive Current (mA)
1077
1047
1017
987
958
929
900
871
842
814
785
757
729
701
673
646
20097661
FIGURE 6. 1.25MHz, 5V Output
L
www.national.com
15
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LM3310 | Step-up PWM DC/DC Converter with Integrated Op-Amp and Gate Pulse Modulation Switch |
| LM3310SQ | Step-up PWM DC/DC Converter with Integrated Op-Amp and Gate Pulse Modulation Switch |
| LM3310SQX | Step-up PWM DC/DC Converter with Integrated Op-Amp and Gate Pulse Modulation Switch |
| LM3351 | Switched Capacitor Voltage Converter |
| LM3351MM | Switched Capacitor Voltage Converter |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM3224MMX-ADJ/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 |
| LM322H | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Precision Timers |
| LM322N | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Precision Timers |
| LM322N/B+ | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog Timer Circuit |
| LM323 | 制造商:STMICROELECTRONICS 制造商全稱:STMicroelectronics 功能描述:Three-terminal 3 A adjustable voltage regulators |
發(fā)布緊急采購，3分鐘左右您將得到回復(fù)。