Rev 2.0 ©2010 Advanced Linear Devices, Inc. 415 Tasman Drive, Sunnyvale, CA 94089-1706 Tel: (408) 747-1155 Fax: (408) 747-1286

www.aldinc.com

SINGLE/DUAL CMOS ANALOG RC TIMER

GENERAL DESCRIPTION

The ALD7555/ALD7556 timers are high performance single/dual mono-

lithic analog RC timing circuits. They offer significantly upgraded perfor-

mance in speed, leakage currents, supply current, stability, temperature

voltage stability, and discharge output drive when compared to SE555/

NE555,ICL7555, TLC555, and ICM7555.

The ALD7555/ALD7556 offer the benefits of high input impedance, thereby

allowing smaller timing capacitors and a longer timing cycle; high speed;

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 R and one capacitor C. 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 respec-

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. The discarge output has been

signifcantly enhanced to eliminate the need for a separate external driver.

FEATURES

• Improved accuracy and temperature stability

• 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 10V

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

SE555, TLC555, ICM7555/ICM7556

• Greatly expanded high and low frequency ranges

• High speed, low power, monolithic CMOS technology

• Low supply current, typically: 50µA for ALD7555, 100µA for ALD7556

• 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

• Low supply current spikes

• Rail to rail output

• High speed one-shot (monostable)

• Precision sequential timing

• Long delay timer

• Pulse width and pulse position modulation

• Missing pulse detector

• Frequency divider

• Synchronized timer

ALD7555/ALD7556

BENEFITS

• Saves battery power

• Eliminates additional buffer

• Smaller, lower cost capacitor

• Extended range of time constants

APPLICATIONS

BLOCK DIAGRAM (EACH TIMER)

OUTPUT

(3)

DISCHARGE

(7)

RESET

(4)

R

S

R

R

R

TRIGGER

(2)

GND

(1)

CONTROL

(5)

THRESHOLD

(6)

V+

(8)

* Contact factory for leaded (non-RoHS) or high temperature versions.

Operating Temperature Range *

0°C to +70°C0°C to +70°C

-55°C to +125°C

8-Pin Small Outline

8-Pin Plastic

8-Pin CERDIP

Package (SOIC)

DIP Package

Package

ALD7555SAL

ALD7555PAL

ALD7555DA

14-Pin Small Outline

14-Pin Plastic

14-Pin CERDIP

Package (SOIC)

DIP Package

Package

ALD7556SBL

ALD7556PBL

ALD7556DB

ORDERING INFORMATION (“L” suffix denotes lead-free (RoHS))

PIN CONFIGURATION

SAL, PAL, DA PACKAGES

1

2

3

4

8

7

6

5

GND

TRIG

OUT

RST

DISC

THRES

CONT

ALD7555

SBL, PBL, DB PACKAGES

DSC1

THRES1

CONT1

RST1

OUT1

TRIG1

GND

TRIG2

OUT2

RST2

CONT2

THRES2

DSC2

V+

2

3

4

5

6

7

9

10

11

12

13

14

1

8

ALD7556