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AS1310-BTDT-27 参数 Datasheet PDF下载

AS1310-BTDT-27图片预览
型号: AS1310-BTDT-27
PDF下载: 下载PDF文件 查看货源
内容描述: 超低静态电流,滞回DC-DC升压转换器 [Ultra Low Quiescent Current, Hysteretic DC-DC Step-Up Converter]
分类和应用: 转换器升压转换器
文件页数/大小: 20 页 / 1271 K
品牌: AMSCO [ AMS(艾迈斯) ]
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AS1310  
Datasheet - Detailed Description  
Energy stored during the on time is given by:  
2
E = 0.5L(IPK  
)
Joules (Region A in Figure 13)  
(EQ 6)  
(EQ 7)  
If the overall time period (TON + TOFF) is T, the power taken from the input is:  
2
0.5L(IPK  
)
--------------------------  
Watts  
PIN  
=
T
Assume output power is 0.8 PIN to establish an initial value of operating period T.  
WAIT is determined by the time taken for the output voltage to fall to 0.99xVOUT. The longer the wait time, the lower will be the supply current f  
T
the converter. Longer wait times require increased output capacitance. Choose TWAIT = 10% T as a minimum starting point for maximum energy  
transfer. For very low power load applications, choose TWAIT 50% T.  
8.1.3 Output Loop Timing  
The output loop consists of the main inductor, P-channel synchronous switch (or diode if fitted), output capacitor and load. When the inpuop is  
interrupted, the voltage on the LX pin rises (Lenz’s Law). At the same time a comparator enables the synchronous switch, ad energy stored in  
the inductor is transferred to the output capacitor and load. Inductor peak current supports the load and replenishes the harge ost from the  
output capacitor. The magnitude of the current from the inductor is monitored, and as it approaches zero, the synchronous witch is turned off.  
No switching action continues until the output voltage falls below the output reference point (0.99 x VOUT).  
Output power is composed of the dc component (Region C in Figure 13):  
IPKTOFF  
I------------  
PREGION_C = V  
(EQ 8)  
(EQ 9)  
Output power is also composed of the inductor component (Region B in Fure 13), neglecting efficienclss:  
2
0.5L(IPK  
)
--------------------------  
=
PREGION_B  
T
Total power delivered to the load is the sum of (EQ 8) nd (EQ 9):  
2
IPKTOFF 0.5LIPK  
)
------- ------------ --------------------------  
PTAL = VIN  
+
(EQ 10)  
(EQ 11)  
2
T
T
From (EQ 3) (using nominal values) peak current is given by:  
TONVIN  
-----------------  
L
IP
=
Substituting (EQ 11) into (EQ 10) and re-arranging:  
V2INT  
ON  
---------------------  
TOTAL  
=
(0.9T)  
(EQ 12)  
2TL  
0.9T incorporates a wait time TWAIT = 10%
Output power in terms of regulaed utput voltage and load resistance is:  
V2  
RLOAD  
OUT  
----------------  
POUT  
=
(EQ 13)  
(EQ 14)  
Combining (EQ 2) and (EQ 13):  
V2INT  
V2  
OUT  
ON  
----------------  
---------------------  
(0.9T)η  
=
RLOAD  
2TL  
Symboη reflects total energy loss between input and output and is approximately 0.8 for these calculations. Use (EQ 14) to plot duty cycle  
(TON/T) changes for various output loadings and changes to VIN.  
www.austriamicrosystems.com/DC-DC_Step-Up/AS1310  
Revision 1.8  
10 - 19