Rainbow Electronics MAX17127 - Manual (Page 14)

14 _____________________________________________________________________________________
MAX17127
Six-String WLED Driver with Integrated
Step-Up Converter
Shutdown
The MAX17127 can be placed into shutdown by pulling
the EN pin low. When a critical failure is detected, the
IC also enters shutdown mode. In shutdown mode, all
functions of the IC are turned off, including the 5V lin-
ear regulator. Only a crude linear regulator remains on,
providing a 3.3V (typ) output voltage to V
DDIO with 1FA
current-sourcing capability.
Frequency Selection
The boost converter switching frequency can be adjust-
ed by the external resistor on the FSLCT pin. The
switching frequency adjustable range is 250kHz to
1MHz. High-frequency (1MHz) operation optimizes the
regulator for the smallest component size at the expense
of efficiency due to increased switching losses. Low-
frequency (250kHz) operation offers the best overall effi-
ciency, but requires larger components and PCB area.
Figure 3. Startup Sequence
MIN FB_ CONTROL
(1ms)
V DDIO
V OUT
V EN
CHECK LED
V IN
0V
0V
0V
0V
I LED
STEP-UP REGULATOR
SOFT-START