CS1630 Datasheet, PDF (30/56 Pages) Cirrus Logic – 2-Channel TRIAC Dimmable LED Driver IC

CS1630/31
6.5 Color Polynomial Coefficient (Q3, Q2, Q1, Q0) – Address 25 - 32
MSB 14 13 12 11 10
9
8
7
6
5
4
3
2
1 LSB
-(2³) 2²
2¹
2⁰
2^-1
2^-2
2^-3
2^-4
2^-5
2^-6
2^-7
2^-8
2^-9
2^-10
2^-11 2^-12
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:
GAINDR = Q3  D³  + Q2  D² + Q1  D + Q0
where,
D = the normalized dim value and is 0<D<1.0
GAIN_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<GAIN_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
7
6
5
4
3
2
1
0
2⁷
2⁶
2⁵
2⁴
2³
2²
2¹
2⁰
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:
GD_DUR  8 + 7  50ns
The maximum gate drive duration can be configured from 350ns to 102.35s.
30
DS954F2