THV6531 Datasheet, PDF (9/11 Pages) THine Electronics, Inc. – THV6531 is a controller IC power supply system with

THL6531_Rev.1.01_E
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 ±200mA of output
short-circuit current. In transients, it can deliver up to
200mA 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 2.25V input voltage. And a boost
converter carries out, after starting soft start operation.
During steady-state operation, if the feedback voltage pin
FB is below 1V of the nominal value, the THV6531
activates an internal fault timer. If any condition
indicates a continuous fault for the fault timer duration
55ms, the IC sets the fault latch to shut down all its
outputs except the reference. Once the fault condition is
removed, cycle the VIN (below the UVLO falling
threshold) to clear the fault latch and reactivate the
device. The fault-detection circuit is disabled during the
soft-start ramp.
The positive and negative charge pump controller also
provide the under voltage protection function during
steady-state operation. If VGH_FB voltage is lower than
1V or VGL_FB voltage is higher than 0.45V, and the
fault duration is over 55ms, the IC sets the fault latch to
shut down all its outputs as well.
Soft start (SS)
The boost converter carries the soft start function in
order to prevent the rush current at a start-up. This
function is to raise output voltage slowly. It is because
overshooting and rush current occur when input voltage
is inputted.
The soft-start time of the boost controller is 14ms,
and the soft-start time of positive and negative
charge pump is 3.4ms.
Over current protection (OCP)
In order to restrict the over-current by the abnormalities
of load, etc., the over-current protection circuit is built in.
Over-current detection of pulse-by-pulse system is
adopted. An output transistor is turned off if the current
which flows into an output transistor reaches boost
converter limit current (Ilim). An over-current protection
circuit detects the peak current of an inductor.
Input-and-output voltage and ripple current is taken into
consideration.
Thermal shut down (TSD)
In order to prevent destruction by heat, the thermal
shutdown circuit is built in. If the junction temperature
Tj is 125^oC or more, the thermal shutdown circuit will
operate and it will stop switching operation. Moreover,
the hysteresis of a thermal shutdown circuit is 15 ^oC. If
Tj falls, output voltage will return.
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