LP6288 datasheet(16/24 Pages) POWER

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Preliminary Datasheet

LP6288

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LP6288

Version 0.1 JAN.-2018

Application Information(Continued)

Positive Charge Pump (VGH)

The gate-high regulator is to provide the TFT-LCD

gate on voltage. The charge pump can provide a

programmable output voltage by register (R[08h] and

R[09h]. A temperature compensation for VGH is

implemented. The charge pump has an internal soft

start 3ms(Typ.).

VGH Temperature Compensation

When temperature compensation function is enabled,

the VGH voltage is dependent on VTC, and adjustable

from 20V to 40V. The VTC value can calculation as

below equation:

VTC=VL

× (R4//R7)

//R

)+R6

VGH

=�VGH_L

, V

≤1V

VGH_L

GH_H

×(V

−1), 1V<V

<2V

VGH_L

GH_H

, V

≥2V

Figure

exhibited

the

VGH

temperature

compensation curve. When VTC under 1V, the VGH

voltage will be equal VGH_L register (R[08h]) setting

voltage, and VTC large than 2V, the VGH voltage will

be equal VGH_L register add VGH_H register

(R[09h]) setting voltage.

VTC=2V

Temp.

VGH_L

VGH

Volt.

VTC=1V

Setting by R[08],R[09]

Setting by R[08]

Slope control

by R6, R7, RNTC

Figure 7. VGH Temperature Compensation

Over Temperature Protection

The

LP6288

device

enters

over

temperature

protection(OTP) if its junction temperature exceeds

150°C (Typ.). During over temperature protection

none of the device's functions are available. To

resume normal operation the junction temperature

need cool down, and the outputs will restart.

Negative Charge Pump (VGL)

The gate-low regulator is to provide the TFT-LCD gate

on voltage. Operation of the negative linear regulator

is similar to the positive linear regulator. The charge

pump can provide a programmable output voltage by

internal register (R[0Bh]). The charge pump has an

internal soft start 3ms(Typ.).

Gate Pulse Modulator (GPM)

The GPM is controlled by the frame signals from

timing controller to modulate the Gate-On voltage,

VGHM, which acts a flicker compensation circuit to

reduce the coupling effect between gate lines and

pixels. It also can delay the Gate-On voltage while

power-on for achieving a correct power-on sequence

for gate driver ICs. Both of the power on delay time

and the falling time of the Gate-On voltage are

programmable by external capacitor and resistor.

The startup delay of high voltage switch control block

is controlled by VGH power ready signal. The

discharge slop is control by the VGHM pin gate

capacitance, and the DRN pin external resistor.

LP6288 can programmed gate pulse modulation stop

level by register. When the stop level voltage is

reached

the DRN function will stop, and VGHM

output is high impedance until GVOFF goes high

again.

GVOFF

VGHM

VIN

TDLY

Delay time is control

by VGH power ready

The falling time can

control by RDRN

The GPM stop level

can control by R[0A]

Figure 8. GPM Function

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