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PDF ICM7226A Data sheet ( Hoja de datos )
| Número de pieza | ICM7226A | |
| Descripción | Frequency Counter/Timer | |
| Fabricantes | Intersil Corporation | |
| Logotipo |  |
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May 2001
POSSIOBBLSEOSLUEIBCTSMET7PI2TR1UO6TDEUPCRTODUCT
ICM7226A,
ICM7226B
8-Digit, Multi-Function,
Frequency Counter/Timer
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Features
Description
• CMOS Design for Very Low Power
• Output Drivers Directly Drive Both Digits and
Segments of Large 8-Digit LED Displays
• Measures Frequencies from DC to 10MHz; Periods
from 0.5µs to 10s
• Stable High Frequency Oscillator uses either 1MHz or
10MHz Crystal
• Both Common Anode and Common Cathode Available
• Control Signals Available for External Systems
Interfacing
• Multiplexed BCD Outputs
Applications
• Frequency Counter
• Period Counter
• Unit Counter
• Frequency Ratio Counter
• Time Interval Counter
Part Number Information
TEMP.
PART NUMBER RANGE (oC)
PACKAGE
ICM7226AlJL
-25× to 85 40 Ld CERDIP
ICM7226BlPL
-25× to 85 40 Ld PDIP
PKG.
NO.
F40.6
E40.6
The ICM7226 is a fully integrated Universal Counter and
LED display driver. It combines a high frequency oscillator, a
decade timebase counter, an 8-decade data counter and
latches, a 7-segment decoder, digit multiplexer and segment
and digit drivers which can directly drive large LED displays.
The counter inputs accept a maximum frequency of 10MHz
in frequency and unit counter modes and 2MHz in the other
modes. Both inputs are digital inputs. In many applications,
amplification and level shifting will be required to obtain
proper digital signals for these inputs.
The ICM7226 can function as a frequency counter, period
counter, frequency ratio (fA/fB) counter, time interval counter
or as a totalizing counter. The devices require either a
10MHz or 1MHz quartz crystal timebase, or if desired an
external timebase can also be used. For period and time
interval, the 10MHz timebase gives a 0.1µs resolution. In
period average and time interval average, the resolution can
be in the nanosecond range. In the frequency mode, the
user can select accumulation times of 0.01s, 0.1s, 1s and
10s. With a 10s accumulation time, the frequency can be
displayed to a resolution of 0.1Hz. There is 0.2s between
measurements in all ranges. Control signals are provided to
enable gating and storing of prescaler data.
Leading zero blanking has been incorporated with frequency
display in kHz and time in µs. The display is multiplexed at a
500Hz rate with a 12.2% duty cycle for each digit. The
ICM7226A is designed for common anode displays with typi-
cal peak segment currents of 25mA, and the ICM7226B is
designed for common cathode displays with typical segment
currents of 12mA. In the display off mode, both digit drivers
and segment drivers are turned off, allowing the display to
be used for other functions.
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CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil and Design is a trademark of Intersil Americas Inc. | Copyright © Intersil Americas Inc. 2001
1
File Number 3169.2
1 page  
ICM7226A, ICM7226B
Electrical Specifications VDD = 5.0V, TA = 25oC, Unless Otherwise Specified (Continued)
PARAMETER
TEST CONDITIONS
Multiplex Inputs: Pins 1, 4, 20, 21
Input Low Voltage, VIL
Input High Voltage, VIH
Input Resistance to VSS, RIN
VIN = +1.0V
Digit Driver: Pins 22-24, 26-30
Low Output Current, IOL
High Output Current, IOH
ICM7226B
VO = +1.0V
VO = VDD -2.0V
Segment Driver: Pins 22-24, 26-30
Leakage Current, IL
VO = VSS
High Output Current, IOH
VO = VDD -2.0V
Multiplex Inputs: Pins 1, 4, 20, 21
Input Low Voltage, VIL
Input High Voltage, VIH
Input Resistance to VSS, RIN
VIN = VDD -1.0V
Digit Driver: Pins 8-11, 13-16
Low Output Current, IOL
VO = +1.0V
High Output Current, IOH
VO = VDD -2.5V
NOTES:
1. Assumes all leads soldered or welded to PC board and free air flow.
2. Typical values are not tested.
MIN
-
2.0
50
-
150
-
10
-
VDD-0.8
100
50
-
TYP
-
-
100
-0.3
180
-
15
-
-
360
75
100
MAX UNITS
0.8 V
-V
- kΩ
- mA
- mA
10 µA
- mA
VDD-2.0
-
-
V
V
kΩ
- mA
- µA
Timing Waveform
STORE
30ms TO 40ms
RESET
MEASUREMENT
IN PROGRESS
40ms
60ms
40ms
UPDATE
190ms TO 200ms
FUNCTION:
TIME INTERVAL
PRIMING
MEASUREMENT INTERVAL
UPDATE
INPUT A
PRIMING EDGES
INPUT B
NOTE:
1. If range is set to 1 event, first and last measured interval will coincide.
250ns MIN
MEASURED
INTERVAL
(FIRST)
MEASURED
INTERVAL
(LAST)
FIGURE 1. WAVEFORMS FOR TIME INTERVAL MEASUREMENT (OTHERS ARE SIMILAR, BUT WITHOUT PRIMING PHASE)
5
5 Page 
ICM7226A, ICM7226B
Overflow Indication
When overflow happens in any measurement it will be indicated
on the decimal point of the digit 8. A separate LED indicator can
be used. Figure 14 shows how to connect this indicator.
When timing repetitive signals, it is not necessary to “prime”
the lCM7226A and lCM7226B as the first alternating signal
states automatically prime the device. See Figure 1.
During any time interval measurement cycle, the ICM7226A
and lCM7226B requires 200ms following B going low to
update all internal logic. A new measurement cycle will not
take place until completion of this internal update time.
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DP
LED overflow indicator connections: Overflow will be
indicated on the decimal point output of digit 8.
DEVICE
ICM7226A
ICM7226B
CATHODE
Decimal Point
D8
ANODE
D8
Decimal Point
FIGURE 14. SEGMENT IDENTIFICATION AND DISPLAY FONT
Time Interval Measurement
When in the time interval mode and measuring a single
event, the lCM7226A and lCM7226B must first be “primed”
prior to measuring the event of interest. This is done by first
generating a negative going edge on Channel A followed by a
negative going edge on Channel B to start the “measurement
interval”. The inputs are then primed ready for the measure-
ment. Positive going edges on A and B, before or after the
priming, will be needed to restore the original condition.
Priming can be easily accomplished using the circuit in
Figure 15.
SIGNAL A
2 INPUT A
VDD
SIGNAL B
VDD
2 INPUT B
N.O.
PRIME
1
150K
1
100K
1N914
0.1µF
1 10K
1
10nF
Oscillator Considerations
The oscillator is a high gain complementary FET inverter. An
external resistor of 10MΩ or 22MΩ should be connected
between the oscillator input and output to provide biasing.
The oscillator is designed to work with a parallel resonant
10MHz quartz crystal with a static capacitance of 22pF and
a series resistance of less than 35Ω. Among suitable
crystals is the 10MHz CTS KNIGHTS ISI-002.
For a specific crystal and load capacitance, the required gM
can be calculated as follows:
gM
=
ω2
CIN
COUT
RS
1
+
-CC----O-L--
2
where CL
=
-C--C--I--N-I--N--+--C---C--O---O-U---U--T--T--
CO = Crystal Static Capacitance
RS = Crystal Series Resistance
CIN = Input Capacitance
COUT = Output Capacitance
ω = 2πf
The required gM should not exceed 50% of the gM specified
for the lCM7226 to insure reliable startup. The OSCillator
INPUT and OUTPUT pins each contribute about 4pF to CIN
and COUT. For maximum stability of frequency, CIN and
COUT should be approximately twice the specified crystal
static capacitance.
In cases where non decade prescalers are used, it may be
desirable to use a crystal which is neither 10MHz or 1MHz.
In that case both the multiplex rate and time between
measurements will be different. The multiplex rate is:
fMUX
1MHz
=m-2o--f--Od-×---e-S1---.0-C---T4- hfeorti1m0eMbHeztwmeoednemaenadsufMreUmX e=nt-2s--f--O-×i--s--S1---0-C-2-----3f---O-×----Sf1--o--C0-r--6-thine
the 10MHz mode and 2---f--O-×----S1----0C---5- in the 1MHz mode.
VSS
VSS
VSS
DEVICE
1
2
TYPE
CD4049B Inverting Buffer
CD4070B Exclusive - OR
FIGURE 15. PRIMING CIRCUIT, SIGNALS A AND B BOTH HIGH
OR LOW
Following the priming procedure (when in single event or 1
cycle range) the device is ready to measure one (only) event.
The buffered oscillator output should be used as an oscillator
test point or to drive additional logic; this output will drive one
low power Schottky TTL load. When the buffered oscillator
output is used to drive CMOS or the external oscillator input,
a 10kΩ resistor should be added from the buffered oscillator
output to VDD .
The crystal and oscillator components should be located as
close to the chip as practical to minimize pickup from other
signals. Coupling from the EXTERNAL OSClLLATOR INPUT
to the OSClLLATOR OUTPUT or INPUT can cause
undesirable shifts in oscillator frequency.
11
11 Page | ||
| Páginas | Total 19 Páginas | |
| PDF Descargar | [ Datasheet ICM7226A.PDF ] | |
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