7
Application Information
General
The ISL24010 is an Octal voltage level shifter. The part was
designed to level shifts a digital input signal to +22V and -5V
for TFT-LCD displays. The device is capable of level shifting
a CMOS logic signal between +40V and -20V.
Power Supply Decoupling
The ISL24010 requires a 0.1F decoupling capacitor as
close to the V
ON1
, V
ON2
and V
OFF
power supply pins for a
large load equal to 5k in parallel with 100pF (Figure 16).
This will deduce any dv/dt between the different supplies and
prevent the internal ESD clamp from turning on and
damaging the part.
Power Supply Sequence
The ISL24010 requires that V
ON2
be greater than or equal to
V
ON1
at all times. Therefore, if V
ON1
and Von 2 are different
supplies, then V
ON2
needs to be turned on before V
ON1
.
The reason for this requirement is shown in Circuit 4 in the
Pin Description Table. The ESD protection diode between
V
ON2
and Von 1 will forward bias if V
ON1
becomes a diode
drop greater than V
ON2
. Recommended power supply
sequence: V
ON2
, V
ON1
, V
OFF
then input logic signals.
The ESD protection scheme is based on diodes from the
pins to the V
ON2
supply and a dV/dt- triggered clamp. This
dV/dt triggered clamp imposes a maximum supply turn-on
slew rate of 10V/µs. This clamp will trigger if the supply
powers up too fast, causing amps of current to flow. Ground
and V
ON1
are treated as I/O pins with this protection
scheme. In applications where the dV/dt supply ramp could
exceed 10V/µs, such as hot plugging, additional methods
should be employed to ensure the rate of rise is not
exceeded.
Latch-up Proof
The ISL24010 is manufactured in a high voltage DI process
that isolates every transistor in it’s own tub making the part
latch-up proof.
Input Pin Connections
Unused inputs must be tied to ground. Failure to tie unused
input pins to ground will result in a rail to rail oscillations on
the respective output pins and higher unwanted power
dissipation in the part. Under these conditions, the
temperature of the part could get very hot.
Limiting the Output Current
No output short circuit current limit exists on this part. All
applications need to limit the output current to less than
80mA. Adequate thermal heat sinking of the parts is also
required.
Application Diagram (TV)
FIGURE 13. TRANSIENT RESPONSE vs LOAD CAPACITANCE
Typical Performance Curves T
A
= 25°C, Output load parallel RC (RL = 5k, CL = 100pF) unless otherwise specified. (Continued)
0
0
2µs/DIV
V
ON1
&
2
= 22V
V
OFF
= -5V
50kHz 50% Duty Cycle
100pF
1500pF
Pulse Input
2V/DIV
5V/DIV
ISL24010
FIGURE 14. TYPICAL TV APPLICATION CIRCUIT
1.0F
1.0F
DC/DC
CONVERTER
TIMING
CON-
LEVEL
LCD PANEL
1.0F
V
ON1
V
ON2
V
OFF
SHIFTER
TROLLER
ISL24010
