MAX17079
4-Level or 2-Level Logic to High-Voltage
Level Shifter for TFT LCD TV Display
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Sequential Operation
Connect CH to AGND and ST to VCC for four-level
sequential operation. If EN is LOW or VCC is less than its
UVLO or V
VLS
is less than its UVLO, the outputs are in
STANDBY and the outputs connect to VCOM. After EN is
HIGH, VCC exceeds its UVLO and VLS exceeds its
UVLO, the outputs are ready to respond to logic inputs at
Ax and Bx. In sequential operation, the logic inputs and
corresponding output states sequence only in a prede-
fined order. In four-level operation, it is only possible to
progress from STATE 1 to STATE 2 or to STANDBY. The
same applies to the other transitions, including from
STATE 4 to STATE 1. Table 2 shows the logic states of
the level shifter in a sequential mode of operation.
Figure 3 shows the sequence of operation. Outputs
OAx and OBx always change in the same sequence.
Two-Level Operation
The MAX17079 also has a two-level output voltage
operation. Connect CH to VCC for two-level operation.
In two-level operation, the device transitions between
two states and the outputs can be connected only to
VH2 or VL2 or VCOM in STANDBY. Other than the start-
up condition, there is no way to distinguish between
sequential operation and combinational operation. If EN
is LOW or VCC is less than its UVLO or VLS is less than
its UVLO, the outputs are in STANDBY and the outputs
connect to VCOM. After EN is HIGH, VCC is greater
than its UVLO and VLS is greater than its UVLO, the
outputs are ready to respond to logic inputs at Ax.
Connect Bx to AGND, as the outputs respond only to
the rising and falling edge of Ax. The outputs transition
from VCOM to the specific output only on the rising
edge of Ax in sequential mode. In combinational mode,
the outputs transition from VCOM to the specific output
on either rising or falling edge of Ax. The following truth
table (Table 3) shows the output states.
