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參數(shù)資料
| 型號(hào)： | ICM7242CBAZ |
| 廠商： | INTERSIL CORP |
| 元件分類： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | Long Range Fixed Timer |
| 中文描述： | SQUARE, 13 MHz, TIMER, PDSO8 |
| 封裝： | ROHS COMPLIANT, PLASTIC, MS-012AA, SOIC-8 |
| 文件頁數(shù)： | 4/10頁 |
| 文件大?。?/td> | 266K |
| 代理商： | ICM7242CBAZ |
4
FN2866.4
February 9, 2007
Test Circuit
Application Information
Operating Considerations
Shorting the RC terminal or output terminals to V
DD
may
exceed dissipation ratings and/or maximum DC current limits
(especially at high supply voltages).
There is a limitation of 50pF maximum loading on the TB I/O
terminal if the timebase is being used to drive the counter
section. If higher value loading is used, the counter sections
may miscount.
For greatest accuracy, use timing component values shown
in Figure 8. For highest frequency operation it will be
desirable to use very low values for the capacitor; accuracy
will decrease for oscillator frequencies in excess of 200kHz.
The timing capacitor should be connected between the RC
pin and the positive supply rail, V
DD
, as shown in Figure 1.
When system power is turned off, any charge remaining on
the capacitor will be discharged to ground through a large
internal diode between the RC node and V
SS
. Do NOT
reference the timing capacitor to ground, since there is no
high current path in this direction to safely discharge the
capacitor when power is turned off. The discharge current
from such a configuration could potentially damage the
device.
When driving the counter section from an external clock, the
optimum drive waveform is a square wave with an amplitude
equal to the supply voltage. If the clock is a very slow ramp
triangular, sine wave, etc., it will be necessary to “square up”
the waveform; this can be done by using two CMOS
inverters in series, operating from the same supply voltage
as the ICM7242.
The ICM7242 is a non-programmable timer whose principal
applications will be very low frequency oscillators and long
range timers; it makes a much better low frequency
oscillator/timer than a 555 or ICM7555, because of the on-
chip 8-bit counter. Also, devices can be cascaded to produce
extremely low frequency signals.
Because outputs will not be ANDed, output inverters are
used instead of open drain N-Channel transistors, and the
external resistors used for the 2242 will not be required for
the ICM7242. The ICM7242 will, however, plug into a socket
for the 2242 having these resistors.
The timing diagram for the ICM7242 is shown in Figure 1.
Assuming that the device is in the RESET mode, which
occurs on power up or after a positive signal on the RESET
terminal (if TRIGGER is low), a positive edge on the trigger
input signal will initiate normal operation. The discharge
transistor turns on, discharging the timing capacitor C, and
all the flip-flops in the counter chain change states. Thus, the
outputs on terminals 2 and 3 change from high to low states.
After 128 negative timebase edges, the
÷
2
8
output returns to
the high state.
NOTE:
4.
÷
2
1
and
÷
2
8
outputs are inverters and have active pullups.
V
DD
÷2
1
(RC/2) OUTPUT
1
2
3
4
8
7
6
5
TIME BASE INPUT/OUTPUT
R
TRIGGER
RESET
C
V
DD
÷2
8
(RC/256) OUTPUT
TIME BASE PERIOD = 1.0RC;
1s = 1M
Ω
x 1μF
TRIGGER INPUT
(TERMINAL 6)
TIMEBASE INPUT
(TERMINAL 8)
÷2 OUTPUT
(TERMINAL 2)
÷128/256 OUTPUT
(TERMINAL 3) (ASTABLE
OR “FREE RUN” MODE)
÷128/256 OUTPUT
(TERMINAL 3)
(MONOSTABLE
OR “ONE SHOT” MODE)
128RC
128RC
128RC
FIGURE 1. TIMING DIAGRAMS OF OUTPUT WAVEFORMS
FOR THE ICM7242 (COMPARE WITH FIGURE 5)
OUTPUTS
1
2
3
4
8
7
6
5
>
3
/
4
(V+)
<
1
/
4
(V+)
V
DD
f
IN
V
DD
f
IN/2
f
IN/256
FIGURE 2. USING THE ICM7242 AS A RIPPLE COUNTER
(DIVIDER)
ICM7242
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ICM7242CBAZ-T | 功能描述:計(jì)數(shù)器 IC LONG RNG FIXED TIMR COM RoHS:否 制造商:NXP Semiconductors 計(jì)數(shù)器類型:Binary Counters 邏輯系列:74LV 位數(shù):10 計(jì)數(shù)法: 計(jì)數(shù)順序: 工作電源電壓:1 V to 5.5 V 工作溫度范圍:- 40 C to + 125 C 封裝 / 箱體:SOT-109 封裝:Reel |
| ICM7242D | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:TIMERS COUNTERS AND DISPLAY DRIVERS |
| ICM7242I/D | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog Timer Circuit |
| ICM7242IBAZ | 功能描述:計(jì)數(shù)器 IC LONG RNG FIXED TIMR IND RoHS:否 制造商:NXP Semiconductors 計(jì)數(shù)器類型:Binary Counters 邏輯系列:74LV 位數(shù):10 計(jì)數(shù)法: 計(jì)數(shù)順序: 工作電源電壓:1 V to 5.5 V 工作溫度范圍:- 40 C to + 125 C 封裝 / 箱體:SOT-109 封裝:Reel |
| ICM7242IBAZ-T | 功能描述:計(jì)數(shù)器 IC LONG RNG FIXED TIMR IND RoHS:否 制造商:NXP Semiconductors 計(jì)數(shù)器類型:Binary Counters 邏輯系列:74LV 位數(shù):10 計(jì)數(shù)法: 計(jì)數(shù)順序: 工作電源電壓:1 V to 5.5 V 工作溫度范圍:- 40 C to + 125 C 封裝 / 箱體:SOT-109 封裝:Reel |
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