Ricoh gets into no

Jul 23, 2023

Ricoh has introduced its first LED lighting chip – apart from the camera/phone LED controller it makes.

R1580 is a dc-fed constant-current LED driver controller that needs on mosfet and a handful of passives to make a driver.

The novel bit is that it is either a fixed output device, programmable by a resistor, or it can be driven by a PWM signal to produce a fraction of that fixed output.

There is no flicker, because the PWM signal never reaches the leds as it is converted to a dc voltage in the chip before it gets there.

However, there is no option to dim using variable dc – it’s PWM or nothing.

Power can be 3.6 to 34V, but can control higher voltage strings up to what ever its external mosfet is rated at. The chi draws well under 1mA

It has the usual protection – thermal shutdown, under-voltage lock-out and a few othersto do with mosfet mis-connection.

The last one has slightly different PWM input hardware and a much lower quiescent current.

BTW, I found if hard to find the data sheet, or Ricoh’s component website.

They are both at this rather unusual address

www.e-devices.ricoh.co.jp