CMOS Low Power Timer – LMC555

Rev 1.1

21/01/18

 

 

LIMITS

AC Electrical Characteristics3

PARAMETER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

SYMBOL

VDD

CONDITIONS

TYP

MAX

UNITS

MIN

RL = 10MΩ, CL = 10pF

35

TJ = 25°C

-

75

Rise/Fall output time

ns

(Figure 1)

tTHL, tTLH

5V

RL = 10MΩ, CL = 1pF

TJ = -55°C to +125°C

70

-

150

TJ = 25°C

500

-

-

Guaranteed OSC freq

Astable operation

fMIN

2-18V

TJ = -55°C to +125°C

200

-

-

kHz

Initial Accuracy Error

-

-

-

-

-

5

%

5V

-

-

0.02

10V

-

-

0.03

RL = 1-100kΩ

Drift with

Temperature

αf

15V

CL = 0.1µF

%/°C

TJ = -55°C to +125°C

-

-

0.06

TJ = 25°C

3

Drift with Supply

Voltage

Δf

5V

TJ = -55°C to +125°C

-

-

%/B

6

 

3. Not production tested in die form, characterized by chip design and tested in package LAT.

Application Notes

The LMC555 is in most instances a direct replacement for the NE555, SE555 and LM555. Produced using a CMOS

process this device offers the possibility to reduce the external passive component count and also delivers improved

electrical performance. All unused inputs must be tied to an appropriate logic level to prevent false triggering.

Supply decoupling capacitor

All legacy bipolar 555 devices produce large crowbar currents in the output driver necessitating power supply

decoupling via an external capacitor located close to the device. The LMC555 produces supply current spikes of only

2-3mA instead of 300-400mA, therefore supply decoupling is not normally necessary and optional.

Control Voltage decoupling capacitors

For most applications capacitors are not required and optional since the input impedance of the CMOS comparators is

very high versus the legacy bipolar 555.

Supply Current

The supply current consumed by LMC555 is very low versus legacy 555. However, total system supply will be high

unless the timing components are high impedance. Therefore, use high values for R and low values for C.

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 LMC555 will drive at least x2 standard TTL loads.

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