,

 

The PWM control of that IC is not about blink rate. It is used to reduce the current to the LEDs.

Look at the section 3 of the datasheet on the CR Timer:

This IC determines the flasher cycle from the internal clock generated by CR timer. The CR timer period, ON Duty, can be
set by the external resistor RCRT1, RCRT2 and the capacitance CCRT.

This is where you set the blink rate. You can either ignore the PWM (in which case you get 100% duty cycle) or choose to use it to reduce current to the LEDs.

Considering what this IC does, it is very complicated. I think they should have simplified the application by abstracting some of this rather than making it so directly coupled to the architecture.

 

Hi,
Thank you very much.
May I know my led blinking frequency calculation is correct or not.

Led blinking frequency is[ (90+/-30)/60]Hz.

Regards

 

Given the relatively high unit price and complexity as well as having to use a surface mount device with so many pins I’d seriously consider using a 555 astable, even two separate circuits for left and right for simplicity and cost reasons.

 

It would be much simpler to just use a standard Automotive-Turn-Signal-Flasher, and cheaper too.
The type that You need has 3-Terminals, not 2-Terminals.
You can get one for less than ~$5.oo.
.
.
.

 

May I know by " Automotive-Turn-Signal-Flasher " you mean LED blink Flasher Relay.

 

The "3-Terminal-type" of Flasher will flash almost any Load attached to it.
.
.
.

 

Dear Team,

I need to design a LED turn indicator for two wheeler.
The standard requirement is given below.

View attachment 308792

I need to calculate the blinking frequency from the above spec.
Does that means my pwm frequency is[ (90+/-30)/60]Hz.

I will be using BD18327EFV-M for this application.

Regards
HARI

f=60/90=0.666667 Hz
p=1/f=1.5 sec

PWM is related to duty cycle.
50% duty is roughly p x 0.5=0.75 sec

What type of two wheeler?

 

Thank you very much.
This is an electric bike.
In the datasheet application example how they arrived the clock frequency 763Hz

 

The frequency was probably chosen to meet an automotive lighting standard.
You'll have to do some research to find out why 736Hz was chosen.

 

automotive standard is

 

automotive standard is

View attachment 308837

That's not an automotive standard. That is a design requirement.

 

Fine.
But from that design requirement we need to drive the clock I believe
The PWM duty cycle is determined by the clock