Datasheet

8-173
Schematic Diagram
Application Information
General
The ICM7555/6 devices are, in most instances, direct
replacements for the NE/SE 555/6 devices. However, it is
possible to effect economies in the external component
count using the ICM7555/6. Because the bipolar 555/6
devices produce 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 7555/6 devices pro-
duce no such transients. See Figure 1.
The ICM7555/6 produces supply current spikes of only
2mA - 3mA instead of 300mA - 400mA and supply decou-
pling is normally not necessary. Also, in most instances, the
CONTROL VOLTAGE decoupling capacitors are not
required since the input impedance of the CMOS compara-
tors on chip are very high. Thus, for many applications 2
capacitors can be saved using an ICM7555, and 3 capaci-
tors with an ICM7556.
RESET DISCHARGE
TRIGGER
THRESHOLD
GND
OUTPUT
CONTROL
VOLTAGE
R
NN
NPN
P
R
R
V
DD
NNNNN
PP
NN
PP P
R = 100kΩ±20% (TYP)
TIME (ns)
400 8006002000
0
100
200
300
400
500
SUPPLY CURRENT (mA)
SE/NE555
T
A
= 25
o
C
ICM7555/56
FIGURE 1. SUPPLY CURRENT TRANSIENT COMPARED WITH
A STANDARD BIPOLAR 555 DURING AN OUTPUT
TRANSITION
ICM7555, ICM7556