PCA9626 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 5 — 19 June 2014 25 of 48
NXP Semiconductors
PCA9626
24-bit Fm+ I
2
C-bus 100 mA 40 V LED driver
b. Byte 2 = 5Ah: the PCA9626 acknowledges this value only. If byte 2 is not equal to
5Ah, then the PCA9626 does not acknowledge it.
If more than 2 bytes of data are sent, the PCA9626 does not acknowledge any more.
5. Once the right 2 bytes (SWRST data byte 1 and byte 2 only) have been sent and
correctly acknowledged, the master sends a STOP command to end the
SWRST Call: the PCA9626 then resets to the default value (power-up value) and is
ready to be addressed again within the specified bus free time (t
BUF
).
The I
2
C-bus master must interpret a non-acknowledge from the PCA9626 (at any time) as
a ‘SWRST Call Abort’. The PCA9626 does not initiate a reset of its registers. This
happens only when the format of the SWRST Call sequence is not correct.
7.7 Individual brightness control with group dimming/blinking
A 97 kHz fixed frequency signal with programmable duty cycle (8 bits, 256 steps) is used
to control individually the brightness for each LED.
On top of this signal, one of the following signals can be superimposed (this signal can be
applied to the 4 LED outputs):
• A lower 190 Hz fixed frequency signal with programmable duty cycle (8 bits,
256 steps) is used to provide a global brightness control.
• A programmable frequency signal from 24 Hz to
1
⁄
10.73
Hz (8 bits, 256 steps) with
programmable duty cycle (8 bits, 256 steps) is used to provide a global blinking
control.
Minimum pulse width for LEDn Brightness Control is 40 ns.
Minimum pulse width for Group Dimming is 20.48 s.
When M = 1 (GRPPWM register value), the resulting LEDn Brightness Control + Group Dimming signal has 2 pulses of the
LED Brightness Control signal (pulse width = N 40 ns, with ‘N’ defined in PWMx register).
This resulting Brightness + Group Dimming signal above shows a resulting Control signal with M = 4 (8 pulses).
Fig 6. Brightness + Group Dimming signals
123456789101112 507
508
509
510
511
512
1234567891011
Brightness Control signal (LEDn)
M × 256 × 2 × 40 ns
with M = (0 to 255)
(GRPPWM Register)
N × 40 ns
with N = (0 to 255)
(PWMx Register)
256 × 40 ns = 10.24 μs
(97.6 kHz)
1234567812345678
Group Dimming signal
resulting Brightness + Group Dimming signal
256 × 2 × 256 × 40 ns = 5.24 ms (190.7 Hz)
002aab417
