Editing 555 timer IC (section)

=== Internal schematic ===
The internal [[block diagram]] and [[schematic]] of the 555 timer are highlighted with the same color across all three drawings to clarify how the chip is implemented:<ref name="Signetics_1985_Linear_Databook"/>
* {{font color||#D5FFD5|Voltage divider}}: Between the positive [[Voltage source|supply voltage]] V<sub>CC</sub> and the [[Ground (electricity)|ground]] GND is a [[voltage divider]] consisting of three identical [[resistor]]s (5{{nbsp}}[[ohm|kΩ]] for bipolar timers, 100{{nbsp}}kΩ or higher for CMOS) to create reference voltages for the [[analog comparator]]s. CONTROL is connected between the upper two resistors, allowing an external voltage to control the reference voltages:
** When CONTROL is not driven, this divider creates an upper reference voltage of {{frac|2|3}} V<sub>CC</sub> and a lower reference voltage of {{frac|1|3}} V<sub>CC</sub>.
** When CONTROL is driven, the upper reference voltage will instead be V<sub>CONTROL</sub> and the lower reference voltage will be {{frac|1|2}} V<sub>CONTROL</sub>.
* {{font color||#FFEEAA|Threshold comparator}}: The [[comparator]]'s negative input is connected to voltage divider's upper reference voltage, and the comparator's positive input is connected to THRESHOLD.
* {{font color||#FFAAAA|Trigger comparator}}: The [[comparator]]'s positive input is connected to voltage divider's lower reference, and the comparator's negative input is connected to TRIGGER.
* {{font color||#AAAAFF|Latch}}: A [[Set-Reset latch|set-reset latch]] stores the [[State (computer science)|state]] of the timer and is controlled by the two comparators. RESET overrides the other two inputs, thus the latch (and therefore the entire timer) can be reset at any time.
* {{font color||#FFAAEE|Output}}: The output of the latch is followed by an output stage with [[Push–pull output|push{{ndash}}pull]] output drivers that can supply up to 200{{nbsp}}mA for bipolar timers, lower for CMOS timers.
* {{font color||#AAEEFF|Discharge}}: Also, the output of the latch controls a [[transistor]] acting as an [[electronic switch]] that connects DISCHARGE to ground.

<gallery mode="packed" widths="200px" heights="200px">
File:NE555 Bloc Diagram.svg|555 internal block diagram<ref name="TI_NE555_Datasheet"/>
File:NE555 Internal Circuit.svg|555 internal schematic of bipolar version
File:C555 Internal Circuit.svg|555 internal schematic of CMOS version
</gallery>