ISL97645AIRZ 데이터 시트보기 (PDF) - Renesas Electronics
부품명
상세내역
일치하는 목록
ISL97645AIRZ Datasheet PDF : 16 Pages
| |||
ISL97645A
VIN
x
>VLOR
x
>VLOR
x
VDPM
x
<1.215V
<1.215V
>1.215V
x
TABLE 6. VGH_M STATUS TABLE
RESET
VGH
x
<2.5V
x
High
High
>2.5V
>2.5V
>2.5V
Low
>2.5V
VGH_M
GROUND
GROUND
GROUND
Switching
controlled by
VFLK
VGH
COMMENT
Will be grounded if VIN is above
a logic threshold. Could occur at
power-up or power-down
Start-up only condition: If either
VIN> VLOR or reset is H, but
VDPM < 1.215V, GND VGHM
Power-down state. Could occur
at power-up if part starts with
VGH > 2.5V
Start-Up Sequence
When VIN exceeds VLOR and ENABLE reaches the VIH
threshold value, Boost converter starts up, and gate pulse
modulator circuit output holds until VDPM is charged to
1.215V. Note that there is a DC path in the boost converter
from the input to the output through the inductor and diode,
hence the input voltage will be seen at output with a forward
voltage drop of diode before the part is enabled. If this voltage
is not desired, the following circuit can be inserted between
input and inductor to disconnect the DC path when the part is
disabled.
.
TO INDUCTOR
INPUT
amplifier will top the reservoir capacitor back up once the pulse
has stopped. This will happen on the µs time scale in practical
systems and for pulses 2 or 3 times the current limit, the VCOM
voltage will have settled again before the next line is
processed.
Fault Protection
ISL97645A provides the overall fault protections including over
current protection and over-temperature protection.
An internal temperature sensor continuously monitors the die
temperature. In the event that die temperature exceeds the
thermal trip point, the device will shut down and disable itself.
The upper and lower trip points are typically set to +140°C and
+100°C respectively.
ENABLE
FIGURE 18. CIRCUIT TO DISCONNECT THE DC PATH OF
BOOST CONVERTER
VCOM Amplifier
The VCOM amplifier is designed to control the voltage on the
back plate of an LCD display. This plate is capacitively coupled
to the pixel drive voltage which alternately cycles positive and
negative at the line rate for the display. Thus the amplifier must
be capable of sourcing and sinking capacitive pulses of
current, which can occasionally be quite large (a few 100mA
for typical applications).
The ISL97645A VCOM amplifier's output current is limited to
400mA. This limit level, which is roughly the same for sourcing
and sinking, is included to maintain reliable operation of the
part. It does not necessarily prevent a large temperature rise if
the current is maintained. (In this case the whole chip may be
shut down by the thermal trip to protect functionality.) If the
display occasionally demands current pulses higher than this
limit, the reservoir capacitor will provide the excess and the
FN6353 Rev 1.00
October 21, 2010
Page 14 of 16
Share Link: 