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4-Channel LED Driver with Phase Shift Control and
10-Bit Dimming Resolution
The ISL97687 is a PWM controlled LED driver that supports
4 channels of LED current, for Monitor and TV LCD backlight
applications. It is capable of driving 160mA per channel from a
9V to 32V input supply, with current sources rated up to 75V
The ISL97687’s current sources achieve typical current
matching to ±1%, while dynamically maintaining the
minimum required VOUT necessary for regulation. This adaptive
scheme compensates for the non-uniformity of forward
voltage variance in the LED strings.
The ISL97687 can decode both an incoming PWM signal and
an analog input voltage, for DC-to-PWM dimming applications.
Modes include direct PWM and several modes where the PWM
frequency is synthesized on chip at 10-bit resolution. This can
be either free running, or synchronized with the frame rate to
give both a frequency and a phase lock, minimizing panel to
panel variation and display flicker. Phase shift is supported,
reducing flicker and audio noise, as is multiplication of the
incoming decoded analog and PWM values.
The ISL97687 has an advanced dynamic headroom control
function, which monitors the highest LED forward voltage
string, and regulates the output to the correct level to minimize
power loss. This proprietary regulation scheme also allows for
extremely linear PWM dimming from 0.02% to 100%. The LED
current can also be switched between two current levels, giving
support for 3D applications. The ISL97687 incorporates
extensive protections of string open and short circuit
detections, OVP, and OTP.
• 4x160mA, 75V rated channels with integrated channel
• Channels can be ganged for high current
• 9V~32V input voltage
• Dimming modes:
- Direct PWM dimming from 100Hz~30kHz
- PWM dimming with adjustable output frequency
- 10-bit dimming resolution
- VSYNC function to synchronize PWM signal to frame
- Phase shift
- Analog to PWM dimming with 8-bit resolution
• 2 selectable current levels for 3D applications
• Current matching of ±1%
• Integrated fault protection features such as string open
circuit protection, string short circuit protection, overvoltage
protection, and over-temperature protection
• 28 Ld 5mmx5mm TQFN and 28 Ld 300mil SOIC Packages
• Monitor/TV LED Backlighting
• General/Industrial/Automotive Lighting
• See AN1674 for “ISL97687IRTZ-HEVALZ and ISL97687IRTZ-
LEVALZ Evaluation Board User Guide” for TQFN Application
• See AN1706 for “ISL97687IBZEV1Z Evaluation Board User
Guide” for SOIC Application
D1 160mA MAX PER STRING
FIGURE 1. ISL97687 APPLICATION DIAGRAM
0 20 40 60 80
DIMMING DUTY CYCLE (%)
FIGURE 2. PWM DIMMING LINEARITY
November 13, 2013
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2011, 2013. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
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