THV6531 Datasheet, PDF (8/11 Pages) THine Electronics, Inc. – THV6531 is a controller IC power supply system with

THL6531_Rev.1.01_E
Positive charge pump (VGH)
The positive charge pump is used to generate the TFT
LCD gate on voltage. The output voltage, VGH, can be
set by an external resistive divider.
Voltage V_{VGH_FB} is typically 1.25V. A single stage
charge pump can produce an output voltage less than
approximately twice the charge pump input voltage VLS.
The maximum voltage VGH should not exceed 36V if it
is used to supply the Gate slope circuit. The output
voltage VGH is regulated as the following equation.
VGH  V_{VGH _ FB}  ^{R5  R6}
R₅
VLS
VGL_OUT
VGL_FB
VREF
VGL
R8
R7
Fig. 4 VGL setup
VGH_OUT
VGH
R6
VGH_FB
R5
Fig. 3 VGH setup
Negative charge pump (VGL)
The negative charge pump is used to generate the TFT
LCD gate off voltage. The output voltage, VGL, is set
with an external resistive divider from its output to
VREF with the midpoint connected to VGL_FB. The
error amplifier compares the feedback signal from
VGL_FB with an internal reference 250mV. The output
voltage VGL is regulated as the following equation.
VGL  V_{VGL _ FB}  ^R8 (V_VREF  V_{VGL _ FB} )
R₇
Gate slope
The Gate slope is a flicker compensation circuit to
reduce the coupling effect of gate lines, and is controlled
by timing controller to modulate GOUT, the Gate-On
voltage. This block is not activated until the below 3
conditions are satisfied: 1) The input voltage exceeds its
UVLO, 2) No fault condition is detected, and 3)
GDELAY exceeds its turn-on threshold. Once Gate slope
activates and GIN is high, the internal switch between
V_VGH and GOUT turns on and the switch between
GOUT and GR turns off. If GIN is low, the internal
switch between V_VGH and GOUT turns off and the
switch between GOUT and GR turns on. At that time,
the falling time and delay time of the Gate-On voltage
are programmable by an external resistor connected
between GR and GND.
Operational amplifier
The operational amplifier is typically used for LCD
VCOM buffer. The VCOM buffer generates the bias
supply for the back plane of an LCD screen which is
capacitively coupled to the pixel drive voltage. The
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