CSS555 APPLICATION CIRCUITS
& SPICE SIMULATION MODELS
In our last Newsletter, we introduced the CSS555 family of timer ICs. As you may remember, the CSS555 is a micro-power version of the industry's popular 555 Timer IC. It is pin-for-pin compatible with the standard 555 timer and features an operating current under 5µA and minimum supply voltage is 1.2V, making it ideal for battery-operated applications. A six-decade programmable counter is included to allow generation of long timing delays. Also, a version with a built-in timing capacitor is available: the CSS555C.
The CSS555 in 8P DIP and SOIC
There has been a lot of interest in applications for the CSS555 family, so we have put together an Application Note which describes in detail 20 different applications of the CSS555 and CSS555C. There has also been interest in using the CSS555 in circuit simulations. For this purpose we have completed a model that may be used in the SPICE circuit simulator.
1. CSS555 Application Circuits
The CSS555 Application Note includes 20 example application circuits. These applications show the advantages of the CSS555C timer and how it can reduce power, decrease PCB area and eliminate the external timing capacitor. They demonstrate many of the basic 555 timer functions and illustrate how the CSS555 may improve your existing timer circuit's performance. They may also serve as a basis to develop new applications. An example application circuit is indicated below. The CSS 555 Application Note is available on our website.
One Shot with Delay
You will notice in the Application Note that Calculators are used to determine the setting for the CSS555. These Calculators (CSS555_Timer_Delay_Calculator) and (CSS555_Adj_Duty_Cycle_Calculators) are available for download on the same website page as the Application Note (see above).
CSS also has a Demo Kit that provides a quick and easy way configure the timer's operating modes or to trim the internal timing capacitor. This Kit includes a PC board, a USB interface to your PC, sample CSS555 devices and a software program to make this task simple and straightforward.
PC Card in CSS 555 Demo Kit
2. SPICE Simulation Model
CSS has just released SPICE simulation models for our CSS555 and CSS555C ICs. These models provide a simulation capability at the component level. The models are simplified to reduce simulation time but still provide a very good representation of the real IC.
SPICE Simulation of a CSS555 Application
The CSS555 Timer Model includes the following features:
1. Supply Current (over VDD)
2. Input Switch Levels
3. Propagation Delay Time
4. Output Drive (over temperature and VDD)
5. ESD Clamp Diodes and Pad Capacitance
