© 2016 Littelfuse Protection Relays & Controls

Rev: 1-A-062016

Flashers and Tower Lighting Controls

Flashers

www.littelfuse.com/fs491

FS491

Description

The FS491 is a low leakage AC flasher designed to control LED,

or resistive loads. This product offers a solid-state output and

may be ordered with an input voltage of 24V to 240VAC, in two

ranges. It offers a factory fixed flash rate of 75 FPM or may be

ordered with a fixed, custom flash rate ranging from 45 to 150

FPM. The FS491 is the perfect solution for LED lamp flashing.

Operation

Upon application of input voltage, the output energizes and

the ON time begins. At the end of the ON time, the output

de-energizes and the OFF time begins. At the end of the OFF

time, the output energizes and the cycle repeats as long as

input voltage is applied.

Reset: Removing input voltage resets the output and the

flash sequence.

Features & Benefits

FEATURES

BENEFITS

Totally solid state

No moving parts to arc and wear out, up to 100

million operations under typical conditions

Fully encapsulated

Protects circuitry from shock, vibration and humidity

Extremely low

leakage current

Ideal for use in LED lighting applications

Specifications

Technical Data

Operation

ON/OFF solid-state flasher (continuous duty)

Flash Rate

Fixed at 75 FPM ±20%

Custom Flash Rates

45 - 150 FPM ±20%

ON/OFF Ratio

≅ 50%

Input

Voltage

24, or 120 - 240VAC

Tolerance

± 15%

AC Line Frequency

50/60Hz

Output

Load Type

LED or resistive

Output

Bridge Rectifier & FET

Maximum Load Rating

120VAC to 240VAC

0.5A steady state; 5A inrush

Max. Load Leakage Current

250µA

Voltage Drop

2V typical

Mechanical

Mounting

Surface mount with one #8 (M4 x 0.7) screw

Dimensions

Dia. 23.9 mm (0.94”); D 38.1 mm (1.5”)

Protection

Surge

IEEE C62.41 - 1991 Level A

Circuitry

Encapsulated

Environmental

Operating/Storage

Temperature

-20° to 60°C / -40° to 85°C

Humidity

95% relative, non-condensing

Weight

≅ 1.1 oz (31 g)

L1

N/L2

V = Voltage

L = Load

R = Red Wire

B = Black Wire

W = White Wire

Wiring Diagram

Function Diagram

FLASHER (ON FIRST)

ON time plus OFF time equals one

complete flash.

V = Voltage

R = Reset

L = Load

T1 = ONTime

T2 = OFFTime

T1 ≅ T2