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HA16117FPBJ 参数 Datasheet PDF下载

HA16117FPBJ图片预览
型号: HA16117FPBJ
PDF下载: 下载PDF文件 查看货源
内容描述: CMOS看门狗定时器 [CMOS Watchdog Timer]
分类和应用: 光电二极管
文件页数/大小: 31 页 / 250 K
品牌: HITACHI-METALS [ HITACHI METALS, LTD ]
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HA16117F Series  
Internal Operation and Usage Notes  
Figure 3 shows an equivalent circuit of the watchdog timer block with a VCC pin level of 5 V and ACC pin  
level of 0 V, and the following pages show internal operation timing charts for different P-RUN  
frequencies. (Descriptions apply to conditions CF = 0.01 µF, CR = 0.1 µF, R2/(R1 + R2) = 0.6.)  
Operation  
The power-on and auto-reset circuit is a multivibrator with timing controlled by CR charge current I1 and  
discharge current I2. As I1 : I2 3 : 1 (Typ design value), when the (WD) (watchdog filter circuit output)  
on-duty is 25% or above, the CR pin potential does not fall below 1.6 V. Therefore, (C) in the figure below  
is fixed low, and RES is not output. The (WD) on-duty varies according to the P-RUN frequency. If the  
frequency is lower or higher than the design value, the (WD) on-duty decreases, and at 25% or below, RES  
is output. Refer to the timing charts on the following pages for an explanation of the operation of the  
watchdog filter.  
Usage Notes  
When the P-RUN frequency reaches 20 kHz or above, tOFF is short (see the timing charts on the  
following pages). This must be borne in mind in the design stage.  
If the P-RUN frequency fluctuates, RES may also be output within the normal detection set frequency  
(see the timing charts on the following pages).  
Detection frequencies fH and fL described in the Data Book are Typ values, and a certain amount of  
dispersion can be expected. A margin of ±30% or more should be allowed for in the design.  
0.1 µ  
A
Low voltage detection block  
VCC (5 V)  
CR  
I1  
Iw  
0.8 µ  
typ  
8 µ typ  
RES  
C
3.6 V  
+
+
3.2 V  
1.6 V  
CF  
Q
0.9 V  
+
I 2  
0.01 µ  
B
10.7 µ  
WD  
D Q  
typ  
P-RUN  
φ
Q
Q
1/2  
frequency divider  
Watchdog filter circuit  
Power-on and auto-reset circuit  
Figure 3 Watchdog Timer Evaliation Circuit  
7
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