PCA9901_1

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 01 — 3 December 2009

12 of 27

NXP Semiconductors

PCA9901

One wire single LED driver

If the fault condition goes away during normal mode operation, the reference current

circuitry and the LED output stage are again enabled, allowing the PCA9901 to resume

control of the LED output stage (LEDOUT).

A short-circuit condition is detected when the PCA9901's current consumption becomes

higher than 50 mA.

An overtemperature condition is detected when the temperature goes above 125

°C. It

goes away when the temperature goes 15

°C below the overtemperature condition.

8.11 Shutdown mode

Shutdown mode is the low power mode where the internal oscillator, band gap, current

generator and LED driver are turned off to save power, and is the default mode at

power-up.

Shutdown mode is automatically entered after:

When in Shutdown mode, setting CTRL HIGH immediately exits the Shutdown mode: the

oscillator and the band gap are turned on and it takes up to 1.5 ms for the device to be up

and running and decode the command issued by the host controller.

8.12 Reset

Reset mode is achieved by sending a RESET command and causes all the registers to be

reset to zeroes and the device to go to Shutdown mode.