- 您现在的位置：买卖IC网 > PDF目录14872 > LT1616ES6#TRMPBF (Linear Technology)IC REG BUCK 3.3V/5V 0.6A SOT23-6 PDF资料下载
参数资料
| 型号： | LT1616ES6#TRMPBF |
| 厂商： | Linear Technology |
| 文件页数： | 7/16页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK 3.3V/5V 0.6A SOT23-6 |
| 标准包装： | 1 |
| 类型： | 降压（降压） |
| 输出类型： | 固定 |
| 输出数： | 1 |
| 输出电压： | 3.3V，5V |
| 输入电压： | 3.6 V ~ 25 V |
| PWM 型： | 电流模式 |
| 频率 - 开关： | 1.4MHz |
| 电流 - 输出： | 600mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SOT-23-6 |
| 包装： | 标准包装 |
| 供应商设备封装： | SOT-23-6 |
| 产品目录页面： | 1328 (CN2011-ZH PDF) |
| 其它名称： | LT1616ES6#TRMPBFDKR |
LT1616
APPLICATIO S I FOR ATIO
Inductor Selection and Maximum Output Current
The duty cycle of the internal switch is:
DC = (V OUT + V D )/(V IN – V SW + V D )
where V D is the forward voltage drop of the catch diode
(D1) and V SW is the voltage drop of the internal switch.
Usually one is interested in DC at full load current, so you
can use V D = V SW = 0.4V. Note that the LT1616 has a
maximum guaranteed duty cycle of 0.8. This will limit the
minimum input voltage for a particular output voltage.
When the switch is off, the inductor sees the output
voltage plus the catch diode drop. This gives the peak-to-
peak ripple current in the inductor:
? I L = (1 – DC)(V OUT + V D )/(L ? f)
where f is the switching frequency of the LT1616 and L is
the value of the inductor. The average inductor current is
equal to the output current, so the peak inductor current
will be the output current plus one half of the ripple
current:
I LPK = I OUT + ? I L /2.
To maintain output regulation, this peak current must be
less than the LT1616’s switch current limit I LIM . I LIM is at
least 630mA at low duty cycles, decreasing to 430mA at
80% duty cycle. The maximum output current is a function
of the chosen inductor value:
I OUT(MAX) = I LIM – ? I L /2.
If the inductor value is chosen so that the ripple current is
small, then the available output current will be near the
switch current limit. A good approach is to choose the
inductor so that the peak-to-peak inductor ripple is equal
to one third of the switch current limit. This leads to:
L = 3(1 – DC)(V OUT + V D )/(I LIM ? f)
and
I OUT(MAX) = (5/6)I LIM .
These expressions depend on duty cycle and therefore on
input voltage. Pick a nominal input voltage to calculate L,
then check the maximum available output current at the
minimum and maximum input voltages.
If your application calls for output current less than
400mA, you may be able to relax the value of the inductor
and operate with higher ripple current. This may allow you
to pick a physically smaller inductor or one with a lower DC
resistance. Be aware that these equations assume con-
tinuous inductor current. If the inductor value is low or the
load current is light, then the inductor current may become
discontinuous. This occurs when ? I L = 2I OUT . For details
of discontinuous mode operation, see Linear Technology
Application Note AN44. Also, high duty cycle operation
may require slightly higher inductor values to avoid sub-
harmonic oscillations. See AN19.
The maximum load current as a function of input voltage
is plotted in the Typical Performance Characteristics sec-
tion of this data sheet. Maximum load current for 3.3V and
5V outputs is shown for several values of L. At the highest
input voltages, the load current is limited by power dissi-
pation in the LT1616.
Choose an inductor that is intended for power applica-
tions. Table 1 lists several manufacturers and inductor
series. The saturation current of the inductor should be
above 0.5A. The RMS current rating should be equal to or
greater than output current. For indefinite operation into a
short circuit, the RMS current rating should be greater
than 0.7A. The DC resistance should be less than 0.5 ? in
order maintain circuit efficiency.
Capacitor Selection
A Buck regulator draws from its input a square wave of
current with peak-to-peak amplitude as high as the switch
current limit. The input capacitor (C1) must supply the AC
component of this current. An RMS current rating of
250mA is adequate for LT1616 circuits. The input capaci-
tor must bypass the LT1616 internal control circuitry and
any other circuitry that operates from the input source. A
1 μ F ceramic capacitor will satisfy both of these require-
ments. If the impedance of the input source is high (due to
long wires or filter components), additional bulk input
capacitance may be required. In high duty cycle applica-
tions (5V IN to 3.3V OUT , for example), increase the input
capacitor to 2.2 μ F. It may be possible to achieve lower cost
by using an electrolytic capacitor (tantalum or aluminum)
7
相关PDF资料 |
PDF描述 |
|---|---|
| VE-JVM-EY-F4 | CONVERTER MOD DC/DC 10V 50W |
| VE-JVM-EY-F2 | CONVERTER MOD DC/DC 10V 50W |
| MIC4721YMM | IC REG BUCK ADJ 1.5A 10MSOP |
| VE-JVM-EY-F1 | CONVERTER MOD DC/DC 10V 50W |
| VE-JVL-EY-F4 | CONVERTER MOD DC/DC 28V 50W |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LT1617 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Inverting Micropower DC/DC Converter with Schottky in ThinSOT Package |
| LT1617-1 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Inverting Micropower DC/DC Converter with Schottky in ThinSOT Package |
| LT1617ES5 | 制造商:LINER 制造商全称:Linear Technology 功能描述:Micropower Inverting DC/DC Converters in SOT-23 |
| LT1617ES5#PBF | 制造商:Linear Technology 功能描述: 制造商:Linear Technology 功能描述:SP-SWREG/Monolithic, CUT TAPE Micropower Inverting DC/DC Converters in SOT-23 制造商:Linear Technology 功能描述:IC, DC/DC CONVERTER, 5-SOT-23, Primary Input Voltage:12V, No. of Outputs:1, Output Voltage:34V, Output Current:350mA, No. of Pins:5, Operating Temperature Min:-40C, Operating Temperature Max:85C, MSL:MSL 1 - Unlimited , RoHS Compliant: Yes |
| LT1617ES5#PBF | 制造商:Linear Technology 功能描述:IC DC/DC CONVERTER 制造商:Linear Technology 功能描述:IC, DC/DC CONVERTER, 5-SOT-23 |
发布紧急采购，3分钟左右您将得到回复。