The ISL97522 represents a 4-channel supply control IC for
use in large panel TFT-LCD displays. Supporting inputs from
4.5V to 13V, the ISL97522 includes a boost controller to
achieve the required AVDD output voltage. Both VON and
VOFF are generated using off-chip charge-pumps which are
then post regulated using on-board LDO controllers.
The logic supply is generated using an internal nonsynchronous
buck controller. This controller runs at 180° out
of phase with the AVDD supply to minimize input noise.
The AVDD, VOFF, and VON outputs are automatically
sequenced as AVDD, VOFF, and VON. By using an optional
external series transistor with AVDD (Q1), the start-up
sequence can be adjusted to VOFF, AVDD and then VON. A
VON slicing circuit is also included to reduce LCD flicker.
The ISL97522 also incorporates a fault protection circuit that
can disable the IC and turn off all outputs when an output
short is detected. (Note that to protect AVDD a single
external transistor is required).