PCA9922 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 2 — 6 April 2011 10 of 27
NXP Semiconductors
PCA9922
8-channel constant current LED driver with output error detection
7.2.6 Exit error detect mode
The ‘Exit error detect mode’ sequence is used to exit the error detect mode of operation
and resume normal mode. This is a 5-clock timing sequence using CLK, OE
and LE. This
sequence consists of LE being held inactive for all five clocks. OE
is active in the second
clock for one and only one clock. Figure 8
shows the timing for this sequence.
7.2.7 Error detection data
The PCA9922 will return a logical 1 for each output pin that has an error condition
detected as described in Table 4
and Table 5. An error condition may be either an
open circuit or short-circuit at the output pin. Once the Capture Fault sequence has
completed, the resultant fault/output error data may be shifted out of the device by issuing
8 clocks and reading the data at the SDO pin. If more than one device is connected in
series, then more than 8 clocks will be needed to shift all of the data from all of the devices
through to the last SDO pin in the chain.
Figure 9
shows a complete error detection sequence.
Fig 8. Timing for ‘Exit Error Detect Mode’ command
CLK
LE
OE
002aad20
