Relay Driver Help

08 Feb 2011

I have the following relay driver:


Here is the datasheet:

I am going to connect this to mbed to control pinball lamps using the SPI interface.

But before I attempt this I want to power the mbed through the relay driver's 5V OUT pin.

I've connected the relay driver to +10V and GND,

and mbed to the relay V OUT pin and GND.

But no luck.

Am I missing something?

Cheers Dave

08 Feb 2011


You don't mention connecting Brown Out (BO pin 20). It needs to be above 1.2V (1.3 typical on page 6) for the outputs to work. The block diagram does not show a connection from BO to the LDO output, however, it does show a 1.2V reference to the comparator which is later contradicted in the electrical characteristics.


08 Feb 2011

Which pin have you connected the 5V out to, It should be pin 2, not pin 39.

Also have you checked you actually have 5Volts, Out from relay chip.

Enjoy, Ceri

09 Feb 2011

I have tried connected brown out to 1.2 1.3 1.4 1.5 V etc... Also directly to 14V supply

I cannot get 5VDC on my multimeter, it reads 1.2V

Damn it all.

14 Apr 2011

Hi David,

Did your code work ?

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