GENERAL DESCRIPTION

The ALD1502/ALD2502 timers are high performance single/dual monolithic

timing circuits built with advanced silicon gate CMOS technology.

They offer the benefits of high input impedance, thereby allowing

smaller timing capacitors and a longer timing cycle; high speed, with

typical cycle time of 400ns; low power dissipation for battery operated

environment; reduced supply current spikes, allowing smaller and

lower cost decoupling capacitors.

Each timer is capable of producing accurate time delays and oscillations

in both monostable and astable operation, and operates in the

one-shot (monostable) mode or 50 duty cycle free running oscillation

mode with a single resistor and one capacitor. The inputs and outputs

are fully compatible with CMOS, NMOS or TTL logic.

There are three matched internal resistors (approximately 200KΩ

each) that set the threshold and trigger levels at two-thirds and one-third

respectively of V+. These levels can be adjusted by using the control

terminal. When the trigger input is below the trigger level, the output is

in the high state and sourcing 2mA. When the threshold input is above

the threshold level at the same time the trigger input is above the trigger

level, the internal flip-flop is reset, the output goes to the low state and

sinks up to 10mA. The reset input overrides all other inputs and when

it is active (reset voltage less than 1V), the output is in the low state.

FEATURES

• High speed operation -- 2.5MHz typical oscillation at 5V

• High discharge sinking current of 80mA at 5V

• Guaranteed low operating supply voltage of 2V to 12V

• Functional equivalent to and same pin-out as NE555/NE556

with greatly expanded high and low frequency ranges

• High speed, low power, monolithic CMOS technology

• Low supply current: 50µA typical for ALD1502

and100µA typical for ALD2502

• Extremely low trigger, threshold and reset currents: 10pA typical

• Operates in both monostable and astable modes

• Fixed 50 duty cycle or adjustable duty cycle

• CMOS, NMOS and TTL compatible input/output

APPLICATIONS

• High speed one-shot (monostable)

pulse generation

• Precision timing

• Sequential timing

• Long delay timer

• Pulse width and pulse position

modulation

• Missing pulse detector

• Frequency divider

• Synchronized timer

• Low supply current spikes