THV6530 datasheet(6/11 Pages) THINE | THV6530 is a controller IC power supply system with

6 / 11 page

THine Electronics, Inc.

6/11

THL6530_Rev.1.00_E

Function

Boost converter

The LCD panel VLS supply is generated from a

high-efficiency PWM boost converter operating with

current mode control, and the switching frequency is

1.2MHz. During the on-period, TON, the synchronous

FET connects one end of the inductor to ground,

therefore increasing the inductor current. After the FET

turns off, the inductor switching node, LX, is charged to

a positive voltage by the inductor current. The

freewheeling diode turns on and the inductor current

flows to the output capacitor.

The converter operates in continuous conduction mode

when the load current IVLS is at least one-half of the

inductor ripple current ΔIrip.

VLS

OSC

rip











)

(

The output voltage (VLS) is determined by the duty

cycle(D) of the power FET on-time and the input

voltage, VIN.

VLS





The average load current, IVLS, can be calculated from

the power conservation law.

VLS









where η is the power conversion efficiency. For a lower

load current, the inductor current would decay to zero

during the free-wheeling period and the output node

would be disconnected

from the

inductor for the

remaining portion of the switching period. The converter

would operate in the discontinuous conduction mode .

Current mode control is well known for its robustness

and fast transient response. An inner current feedback

loop sets the on-time and the duty cycle such that the

current through the inductor equals to the current

computed by the compensator. This loop acts within one

switching cycle. A slope compensation ramp is added to

suppress sub-harmonic oscillations. An outer voltage

feedback loop subtracts the voltage on the FB pin from

the internal reference voltage and feeds the difference to

the compensator operational transconductance amplifier.

This amplifier is compensated by an external R-C

network to allow the user to optimize the transient

response and loop stability for the specific application

conditions.

The output voltage VLS can be set by external resistor

divider R1 and R2 connected to FB.



















VLS

Fig. 1 FB setup

[Compensator selection]

This current mode boost converter has a current sense

loop and a voltage feedback loop. The current sense

loop does not need any

compensation. The voltage

feedback loop is compensated by an external series

R-C network

RPC and CPC from PC pin to ground.

RCOMP is set to define the high frequency integrator gain

for loop bandwidth which relates to the transient

response. CPC is set to ensure the loop stability.

[Output capacitor selection]

The output voltage ripple due to converter switching is

VLS

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