Cirrus Logic CS1631 - Manual (Page 30)

CS1630/31
30 DS954F3
6.5 Color Polynomial Coefficient (Q3, Q2, Q1, Q0) – Address 25 - 32
Coefficients of the color polynomial used to calculate the gain (GAIN
DR
) that controls the current in the white
LED channel based on the current dim level. The value is a two's complement number in the range of
-8.0
value<8.0, with the binary point to the right of bit 12. Coefficients Q3, Q2, Q1, and Q0 are distributed in
the gain polynomial:
where,
D = the normalized dim value and is 0GAIN
DR
= gain of the channel based on the dim value. The polynomial coefficients should be selected such
that the computed GAIN
DR
is always a positive number such that 0
DR
<4.
Color Polynomial Coefficients, Qxx, are 16-bits in length where Qxx-MSB is the most significant byte and
Qxx-LSB is the least significant byte.
6.6 Gate Drive Duration (GD_DUR) – Address 33
GD_DUR sets the maximum gate drive duration for the second stage (flyback, buck, or tapped buck). The reg-
ister value is an unsigned integer in the range of 0 value255. The maximum gate drive duration is determined
by:
The maximum gate drive duration can be configured from 350ns to 102.35 s.
MSB 14 13 12 11 10 9 8 7 6 5 4 3 2 1 LSB
-(2 3 ) 2 2 2 1 2 0 2 -1 2 -2 2 -3 2 -4 2 -5 2 -6 2 -7 2 -8 2 -9 2 -10 2 -11 2 -12
7 6 5 4 3 2 1 0
2 7 2 6 2 5 2 4 2 3 2 2 2 1 2 0
GAINDR Q  3 = D
3
  Q2 D
2
 Q1 D  Q0 + + +
GD_DUR 8    7 +   50  ns