LP3950 Datasheet, PDF (23/31 Pages) National Semiconductor (TI) – Color LED Driver with Audio Synchronizer

Audio Synchronization (Continued)
MODE CONTROL IN THE AMPLITUDE MODE
During the amplitude synchronization mode (SYNC_MODE
= 0) the user can select between three different amplitude
mappings by using MODE_CTRL[1:0] select. These three
mapping options give different light responses as shown in
Figure 20. Again, the user can select the desired mapping
speed by SPEED_CTRL[1:0]. Maximum duty cycle is
A100%. If MODE_CTRL[1:0] = 11 and SYNC_MODE = 0,
audio synchronization is inactive.
MODE_CTRL[1:0] = [00] = MODE0
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MODE_CTRL[1:0] = [10] = MODE2
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Note 18: This figure is for illustrating purpose only and does not necessarily
represent the accurate function of the circuit.
MODE_CTRL[1:0] = [01] = MODE1
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FIGURE 20. Amplitude Synchronization Mapping Options
MODE CONTROL IN THE DEFAULT MODE
One of the main benefits of LP3950 is the default mode,
which enables user to build applications without I²C or SPI
control. The LP3950 is set to the default mode when DME
pin is high. DME pin high –state forces registers NSTBY and
EN_SYNC to the high [1] state so that the start-up sequence
get started (see start-up sequence on Section Modes of
Operation ). Function of LP3950 in the default mode of
operation is controlled by AMODE pin. If AMODE is pulled
low the LP3950 is in the amplitude synchronization mode. If
the AMODE pin is pulled high the LP3950 is in the frequency
synchronization mode. In the default mode default control
register values are used, see Table LP3950 Control Register
Names and Default Values. Please refer to Figure 22 on
Typical Applications section at the end of this document for
wiring.
RGB OUTPUT SELECTOR
The usage of RGB outputs (RGB1 and RGB2) can be se-
lected with RGB_SEL[1:0] control bits. Audio synchroniza-
tion and RGB pattern generator output can be connected to
RGB ports as shown in the following table.
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