IntersilISL97684 Quad TFT-LCD Display LED Backlight Driving Solution

IntersilISL97684 Quad TFT-LCD Display LED Backlight Driving Solution

Intersil’s ISL97684 is a quad LED driver for mid-size TFT-LCD backlighting with input voltages as low as 4V and output voltages as high as 45V. 8-bit PWM dimming is also available, with linearity as low as 0.009% at time, or 30kHz When it is 1.35%, it is mainly used in tablet PC and notebook computer Display LED backlight, PMP LED backlight. This article introduces the main characteristics of ISL97684, block diagram, and single power supply, dual power supply application circuit and PWM dimming application circuit.

The ISL97682, ISL97683, ISL97684 are Intersil’s highly integrated 2-3-4-channels LED drivers that are suitable for medium size TFT-LCD backlights. These parts can drive multiple channels of LEDs from inputs as low as 4V to outputs of up to 45V . They can also operate from inputs as low as 3V to outputs of up to 26.5V in bootstrap configuration.

The ISL97682, ISL97683, ISL97684 feature optional channels phase shift control. This feature is used to minimize the input, output ripple characteristics and load transient, which help eliminate or reduce the video and audio noise interference from the backlight driver operation.

The ISL97682, ISL97683, ISL97684 offer 8-bit PWM dimming for systems that need frequency tuning flexibility. With the unique adaptive boost switching architecture, the ISL97682, ISL97683, ISL97684 also offer Direct PWM dimming with output, which follows input and achieves linearity as low as 0.009% at 200Hz or 1.35% at 30kHz.

The drivers incorporate dynamic headroom control that monitors the highest LED forward Voltage string and uses its feedback signal for the minimum output regulation. The ISL97682, ISL97683, ISL97684 incorporate extensive fault protection functions including
string open and short circuit detections, OVP, and OTP. The switching frequency can be selected at either 600kHz or 1.0MHz in PFM or PWM mode. These parts are available in the thin and compact 16 Ld 3mmx3mm TQFN package and operate in ambient temperature from -40℃ to +85℃.

ISL97684 main features:

• ISL97682 – 2 x 100mA Channels

• ISL97683 – 3 x 50mA Channels

• ISL97684 – 4 x 50mA Channels

• Input Voltage 4.0V~26.5V with Max VOUT of 45V

• Input Voltage 3.0V (see Figure 26)~24V with Max VOUT of 26.5V

• PWM Dimming Linearity

– PWM Dimming with Adjustable Dimming Frequency with Duty Cycle Linear from 0.4% to 100% <30kHz

– Direct PWM Dimming with Duty Cycle Linear from 0.009% to 100% at 200Hz

• Current Matching of 0.7% typical from 1%~100% Dimming

• Selectable 600kHz or 1MHz Switching Frequency in PWM/PFM Mode

• Dynamic Headroom Control

• Fault Protection

– String Open/Short Circuit Protections, OVP, OTP

• Thin and Compact TQFN-16 3mmx3mm Package

ISL97684 application:

• Tablet to Notebook PC Displays LED Backlighting

• PMP LED Backlighting
IntersilISL97684 Quad TFT-LCD Display LED Backlight Driving Solution
Figure 1. ISL97684 block diagram
IntersilISL97684 Quad TFT-LCD Display LED Backlight Driving Solution
Figure 2. ISL97684 single-supply 3V application circuit diagram
IntersilISL97684 Quad TFT-LCD Display LED Backlight Driving Solution
Figure 3. ISL97684 Dual Power 2.7V Application Circuit Diagram
IntersilISL97684 Quad TFT-LCD Display LED Backlight Driving Solution
Figure 4. ISL97684 direct PWM dimming application circuit diagram

Figure 4. ISL97684 adopts RFPWM frequency adjustable PWM dimming application circuit diagram

For details, see:
http://www.intersil.com/data/fn/fn7689.pdf

The Links:   RM500UZ-2H LQ065T9DZ03

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