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ADP1111AN

更新时间: 2024-02-13 01:08:02
品牌 Logo 应用领域
亚德诺 - ADI 稳压器开关式稳压器或控制器电源电路开关式控制器光电二极管
页数 文件大小 规格书
16页 409K
描述
Micropower, Step-Up/Step-Down SW Regulator; Adjustable and Fixed 3.3 V, 5 V, 12 V

ADP1111AN 技术参数

是否无铅: 含铅是否Rohs认证: 符合
生命周期:Active零件包装代码:SOIC
包装说明:SOIC-8针数:8
Reach Compliance Code:compliantECCN代码:EAR99
HTS代码:8542.39.00.01风险等级:5.14
Is Samacsys:N模拟集成电路 - 其他类型:SWITCHING REGULATOR
控制模式:VOLTAGE-MODE控制技术:PULSE FREQUENCY MODULATION
最大输入电压:30 V最小输入电压:2 V
标称输入电压:3 VJESD-30 代码:R-PDSO-G8
JESD-609代码:e3长度:4.9 mm
湿度敏感等级:1功能数量:1
端子数量:8最高工作温度:70 °C
最低工作温度:最大输出电流:1.5 A
标称输出电压:1.25 V封装主体材料:PLASTIC/EPOXY
封装代码:SOP封装等效代码:SOP8,.25
封装形状:RECTANGULAR封装形式:SMALL OUTLINE
峰值回流温度(摄氏度):260认证状态:Not Qualified
座面最大高度:1.75 mm子类别:Switching Regulator or Controllers
最大供电电流 (Isup):0.4 mA表面贴装:YES
切换器配置:BUCK-BOOST最大切换频率:88 kHz
技术:BIPOLAR温度等级:COMMERCIAL
端子面层:Matte Tin (Sn)端子形式:GULL WING
端子节距:1.27 mm端子位置:DUAL
处于峰值回流温度下的最长时间:30宽度:3.9 mm
Base Number Matches:1

ADP1111AN 数据手册

 浏览型号ADP1111AN的Datasheet PDF文件第4页浏览型号ADP1111AN的Datasheet PDF文件第5页浏览型号ADP1111AN的Datasheet PDF文件第6页浏览型号ADP1111AN的Datasheet PDF文件第8页浏览型号ADP1111AN的Datasheet PDF文件第9页浏览型号ADP1111AN的Datasheet PDF文件第10页 
ADP1111  
INDUCTOR SELECTION–STEP-UP CONVERTER  
In a step-up or boost converter (Figure 18), the inductor must  
store enough power to make up the difference between the input  
voltage and the output voltage. The power that must be stored  
is calculated from the equation:  
Substituting a standard inductor value of 68 µH with 0.2 dc  
resistance will produce a peak switch current of:  
1.0 7µs  
68 µH  
6V  
1.0 Ω  
IPEAK  
=
1 e  
= 587 mA  
PL = V  
+VD VIN(MIN) I  
(Equation 1)  
(
)
(
)
OUT  
OUT  
Once the peak current is known, the inductor energy can be  
calculated from Equation 5:  
where VD is the diode forward voltage (0.5 V for a 1N5818  
Schottky). Because energy is only stored in the inductor while  
the ADP1111 switch is ON, the energy stored in the inductor  
on each switching cycle must be equal to or greater than:  
1
EL  
=
68 µH 587 mA 2 =11.7µJ  
) (  
(
)
2
PL  
(Equation 2)  
Since the inductor energy of 11.7 µJ is greater than the PL/fOSC  
requirement of 3.6 µJ, the 68 µH inductor will work in this  
application. By substituting other inductor values into the same  
equations, the optimum inductor value can be selected.  
fOSC  
in order for the ADP1111 to regulate the output voltage.  
When the internal power switch turns ON, current flow in the  
inductor increases at the rate of:  
When selecting an inductor, the peak current must not exceed  
the maximum switch current of 1.5 A. If the equations shown  
above result in peak currents > 1.5 A, the ADP1110 should be  
considered. Since this device has a 70% duty cycle, more energy  
is stored in the inductor on each cycle. This results is greater  
output power.  
R't  
L
VIN  
R'  
IL t =  
( )  
1e  
(Equation 3)  
where L is in Henrys and R' is the sum of the switch equivalent  
resistance (typically 0.8 at +25°C) and the dc resistance of  
the inductor. In most applications, the voltage drop across the  
switch is small compared to VIN so a simpler equation can be  
used:  
The peak current must be evaluated for both minimum and  
maximum values of input voltage. If the switch current is high  
when VIN is at its minimum, the 1.5 A limit may be exceeded at  
the maximum value of VIN. In this case, the ADP1111’s current  
limit feature can be used to limit switch current. Simply select a  
resistor (using Figure 6) that will limit the maximum switch  
current to the IPEAK value calculated for the minimum value of  
VIN. This will improve efficiency by producing a constant IPEAK  
as VIN increases. See the “Limiting the Switch Current” section  
of this data sheet for more information.  
V
L
IL t = IN t  
(Equation 4)  
( )  
Replacing ‘t’ in the above equation with the ON time of the  
ADP1111 (7 µs, typical) will define the peak current for a given  
inductor value and input voltage. At this point, the inductor  
energy can be calculated as follows:  
Note that the switch current limit feature does not protect the  
circuit if the output is shorted to ground. In this case, current is  
only limited by the dc resistance of the inductor and the forward  
voltage of the diode.  
1
2
EL  
=
L I2 PEAK  
(Equation 5)  
As previously mentioned, EL must be greater than PL/fOSC so  
that the ADP1111 can deliver the necessary power to the load.  
For best efficiency, peak current should be limited to 1 A or  
less. Higher switch currents will reduce efficiency because of  
increased saturation voltage in the switch. High peak current  
also increases output ripple. As a general rule, keep peak current  
as low as possible to minimize losses in the switch, inductor and  
diode.  
INDUCTOR SELECTION–STEP-DOWN CONVERTER  
The step-down mode of operation is shown in Figure 19.  
Unlike the step-up mode, the ADP1111’s power switch does not  
saturate when operating in the step-down mode; therefore,  
switch current should be limited to 650 mA in this mode. If the  
input voltage will vary over a wide range, the ILIM pin can be  
used to limit the maximum switch current. Higher switch  
current is possible by adding an external switching transistor as  
shown in Figure 21.  
In practice, the inductor value is easily selected using the  
equations above. For example, consider a supply that will  
generate 12 V at 40 mA from a 9 V battery, assuming a 6 V  
end-of-life voltage. The inductor power required is, from  
Equation 1:  
The first step in selecting the step-down inductor is to calculate  
the peak switch current as follows:  
PL = 12V +0.5V 6V 40 mA = 260 mW  
(
) (  
)
2 IOUT  
DC  
VOUT + VD  
IN VSW +VD  
IPEAK  
=
(Equation 6)  
On each switching cycle, the inductor must supply:  
V
PL 260 mW  
fOSC 72 kHz  
=
= 3.6 µJ  
where DC = duty cycle (0.5 for the ADP1111)  
VSW = voltage drop across the switch  
VD = diode drop (0.5 V for a 1N5818)  
IOUT = output current  
Since the required inductor power is fairly low in this example,  
the peak current can also be low. Assuming a peak current of  
500 mA as a starting point, Equation 4 can be rearranged to  
recommend an inductor value:  
VOUT = the output voltage  
VIN  
6V  
VIN = the minimum input voltage  
L =  
t =  
7µs = 84 µH  
IL(MAX) 500 mA  
REV. 0  
–7–  

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