pca9901 NXP Semiconductors, pca9901 Datasheet - Page 10

• Manufacturer Part Number: pca9901
• Description: One Wire Single Led Driver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
PCA9901_1
Product data sheet
8.8.1 CTRL LOW too long after receiving a TRAINING START command
8.8.2 CTRL HIGH too long during the training sequence
8.8.3 CTRL LOW too long during the training sequence
8.8 Time-out
The time-out circuitry allows the PCA9901 to be safely set back to the Shutdown mode
when a communication problem occurs between the host controller and the PCA9901.
The PCA9901 is waiting for the first LED ON timing.
Remark: When the time-out occurs and the PCA9901 goes to Shutdown mode, the
registers are still programmed with zeroes.
The PCA9901 is counting the ON timing and reaches the counter maximum value (0xFF).
If CTRL does not go LOW when reaching the max value:
The PCA9901 is counting the OFF timing and reaches the counter maximum value
(0xFF). If CTRL does not go HIGH when reaching the maximum value:
1. Once the TRAINING START command has been decoded (end of the 1.5 ms
2. The time-out counter counts until it reaches the maximum allowed ON value. The
3. If the maximum time-out value is reached, the training sequence is automatically
1. The PCA9901 switches off the LEDOUT pin.
2. Maximum ON count is stored in the corresponding ON register.
3. A time-out counter starts counting until it reaches the maximum allowed OFF value.
4. When the maximum time-out counter value is reached, maximum OFF count is stored
5. If the maximum time-out value is reached, the training sequence is automatically
1. Maximum OFF count is stored in the corresponding OFF register.
2. A time-out counter starts counting until it reaches the maximum allowed OFF value.
3. When the maximum time-out counter value is reached, the training sequence is
window), a time-out counter starts counting as long as CTRL stays LOW.
maximum allowed ON time is greater than or equal to 255 ms.
Remark: If CTRL goes HIGH before reaching the maximum counter value, the
time-out counter is reset and the PCA9901 starts counting the LED ON timing or
decoding the command that has been issued.
terminated and the PCA9901 goes to Shutdown mode.
The maximum allowed OFF time is greater than or equal to 5.11 seconds.
in the corresponding OFF register.
Remark: If CTRL goes LOW before reaching the maximum counter value, the
time-out counter is reset and the PCA9901 starts counting the LED OFF timing.
terminated and the PCA9901 goes to Shutdown mode.
The maximum allowed OFF time is greater than or equal to 5.11 seconds.
automatically terminated and the PCA9901 goes to Shutdown mode.
Remark: If CTRL goes HIGH before reaching the maximum counter value, the
time-out counter is reset and the PCA9901 starts counting the LED ON timing or
decoding the command that has been issued.
Rev. 01 — 3 December 2009
One wire single LED driver
PCA9901
© NXP B.V. 2009. All rights reserved.
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