THV6530 Datasheet, PDF (8/11 Pages) THine Electronics, Inc. – THV6530 is a controller IC power supply system with

THL6530_Rev.1.00_E
VLS
VGH_OUT
VGH
R6
VGH_FB
R5
Fig. 2 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 240mV. The output
voltage VGL is regulated as the following equation. The
output voltage VGL is regulated as the following
equation. VREF is 1.2V.
VGL  V_{VGL _ FB}  ^R8 (V_VREF  V_{VGL _ FB} )
R₇
VGL
VGL_OUT
R8
VGL_FB
R7
VREF
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 purpose of the VCOM buffer
is to hold the bias voltage steady while pixel voltage
changes dynamically. The buffer is designed to sustain
up to ±75mA of output current. In transients, it can
deliver up to 150mA at which point the over current
protection circuit limits the output current. Excessive
current draw over a period of time may cause the chip
temperature to rise and set off the over temperature
protection circuit.
Protection circuits
Under voltage lock out protection (UVLO)
The UVLO function is carried in order to prevent
malfunction in the state where input voltage is low. A
boost converter is suspended to the power supply voltage
which can carry out operational stability. UVLO is
released by more than 1.8V input voltage. And a boost
converter carries out, after starting soft start operation.
During normal operation (after completing the soft start
sequence) THV6530 constantly monitors feedback pins
FB, VGH_FB and VGL_FB. A fault condition occurs if
FB falls below 0.95V or VGH_FB falls below 0.95V or
VGL_FB rises above 0.45V. If any of the fault
conditions persist for longer than 100ms, the chip sets a
fault latch and shuts down. To turn the power supplies
back on requires cycling of VIN supply below the UVLO
level or toggling the EN pin low and high. This will clear
the fault latch and restore normal operation.
Fig. 3 VGL setup
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THine Electronics, Inc.