CS1630 Datasheet, PDF (17/56 Pages) Cirrus Logic – 2-Channel TRIAC Dimmable LED Driver IC

CS1630/31
The buck stage is controlled by measuring current in the buck
inductor and voltage on the auxiliary winding. Quasi-resonant
operation is achieved by detecting buck inductor
demagnetization using an auxiliary winding. The digital control
algorithm rejects line-frequency ripple created on the second
stage input by the front-end boost stage, resulting in the
highest possible LED efficiency and long LED life.
The tapped buck stage operates similar to a buck stage. The
tapped buck topology provides minimum turn-on time and
improves conversion efficiency when large input-to-output
voltage ratio is present. The tapped buck inductor behaves as
a transformer for voltage conversion and is controlled by
measuring current in the tapped inductor and voltage on the
auxiliary winding. Quasi-resonant operation is achieved by
detecting tapped inductor demagnetization using an auxiliary
winding.
VBST
CS1630 /31
GD ¹³
Q4
FBAUX ¹⁵
FBSENSE ¹¹
D8
R12
R15 D10
D9
VCC _
Q
D
GN D
C9 Z3
R16
C10
LED2 +
C11
LED 2-
D11
Q5
LED1+
C12
L3
LED1-
IGND
R13
GND
12
R11
R14
Figure 17. Tapped Buck Parallel Output Model
5.8.1 Series & Parallel Two-Channel Output
The CS1630/31 is designed to be programmed to support
series or parallel two-channel output configurations using one
set of power magnetics. Series or parallel configuration is set
by bit STRING and bit LED_ARG in the Config3 register (see
"Configuration 3 (Config3) – Address 35" on page 32). A
parallel connection for a flyback stage and buck stage are
connected differently: an NMOS switch is used in flyback
configuration, and a PMOS switch is used in buck/tapped
buck configuration (see Figures 15, 16, and 17).
VBST
T1
Z2
D7
R15 D10
C9 Z3
D9
LED 1+
C12
LED 1-
CS1630 /31
GD ¹³
Q4
FBAUX ¹⁵
FBSENSE ¹¹
R12
VCC _
Q
D
GND
D8
R16
C10
Q5
D11
LED 2+
IGND
C11
LED2 -
GND
12
R13
R11
R14
Figure 18. Flyback Series Output Model
Similarly, a series connection in a flyback stage and buck
stage use an NMOS switch and a PMOS switch, respectively,
as shown in Figures 18 and 19.
VBST
LED1+
R15 D10
C12
LED1-
C9 Z3
D8
D9
CS1630 /31
GD ¹³
FBAUX ¹⁵
FBSENSE ¹¹
R12
VCC _
Q
D
GND
R16
C10
L3
Q4
R13
Q5
D11
LED2+
C11
IGND
LED 2-
GND
12
R11
R14
Figure 19. Buck Series Output Model
DS954F2
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