ICM7555IN PHILIPS [NXP Semiconductors], ICM7555IN Datasheet - Page 8

• Manufacturer Part Number: ICM7555IN
• Description: General purpose CMOS timer
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors Linear Products
TYPICAL PERFORMANCE CHARACTERISTICS (continued)
APPLICATION NOTES
General
The ICM7555 device is, in most instances, a direct replacement for
the NE/SE555 device. However, it is possible to effect economies in
the external component count using the ICM7555. Because the
August 31, 1994
General purpose CMOS timer
Compared With a Standard Bipolar 555
Figure 1. Supply Current Transient
500
400
300
200
100
0
0
During an Output Transition
T
A
= +25 C
0.0001
0.0001
200
100.0
0.001
100.0
0.001
10.0
0.01
10.0
0.01
1.0
0.1
0.0
1.0
0.1
0.0
100ns
0.1
TIME (ns)
400
NE/SE555
ICM7555
V
T
A
DD
1.0
1 s
= +25 C
= 5V
600
Free-Running Frequency as a Function of R
10 s
10
Monostable Time Delay vs R
800
R
A
100 s
100
FREQUENCY (Hz)
(R
TIME DELAY
A
+ 2R
1ms
1k
344
B
100k
1M
10M
10k
)
1k
bipolar 555 device produces large crowbar currents in the output
driver, it is necessary to decouple the power supply lines with a
good capacitor close to the device. The 7555 device produces no
such transients. See Figure 1.
The ICM7555 produces supply current spikes of only 2-3mA instead
of 300-400mA and supply decoupling is normally not necessary.
Secondly, in most instances, the CONTROL VOLTAGE decoupling
capacitors are not required since the input impedance of the CMOS
comparators on chip are very high. Thus, for many applications, 2
capacitors can be saved using an ICM7555.
Power Supply Considerations
Although the supply current consumed by the ICM7555 device is
very low, the total system supply can be high unless the timing
components are high impedance. Therefore, high values for R and
low values for C in Figures 2 and 3 are recommended.
Output Drive Capability
The output driver consists of a CMOS inverter capable of driving
most logic families including CMOS and TTL. As such, if driving
CMOS, the output swing at all supply voltages will equal the supply
voltage. At a supply voltage of 4.5V or more, the ICM7555 will drive
at least 2 standard TTL loads.
10M
10k
100k
10ms
1M
10k
1k
A
and C
100ms
100k
A
, R
B
V
T
, and C
A
DD
1M
= +25 C
1s
= 5V
10M
10s
Product specification
ICM7555