D8 12pin LED Light IC for OPPO A57 R9SK R9plus & Vivo X5SL Y83

When a phone comes in with a dark screen but a working display panel, the backlight driver IC is usually the first place you check — and on OPPO A57, R9SK, R9 Plus, and Vivo X5SL, Y83 boards, that IC is the D8-marked LM3697YFQR. This chip sits between the PMIC and the display connector, and it's the part responsible for boosting the battery rail up to the voltage the LED strings actually need to light.The LM3697 is an 11-bit LED driver built for three-string backlight control, and it runs on a 2.7V to 5.5V input range straight off the board's power rail. Internally it uses an integrated boost converter with a 1-A, 40-V MOSFET, pushing output up to around 41V to drive the LED strings at proper brightness. That boost stage is why a failed D8 IC so often shows up as "backlight dead but display works" — the panel itself is fine, but nothing is supplying the high-voltage current the LEDs need.Configuration runs over an I2C-compatible interface, which lets the phone's software set brightness levels, ramp timing, and dimming curves rather than relying on a fixed analog control. It also supports PWM input for adjustable brightness, and switches between 500kHz and 1MHz operation depending on board design. If you're chasing a backlight issue after a flash or software repair and the screen still won't light, check this IC before assuming a panel fault — a "software mara" fix won't touch a hardware-failed driver.On the bench, this is a straightforward reballing job. The D8 comes in a compact 12-pin DSBGA package, so you'll want a good hot air station, flux, and a microscope or magnifier for placement — pad pitch on these chips is tight enough that eyeballing it without magnification usually ends in a bridge or a cold joint. Preheat the board evenly before hot air to avoid lifting neighboring components, and confirm continuity on the boost output pin after reflow before you close the phone back up.This part gets pulled into a lot of common backlight complaints: screen that stays dark on power-on but takes calls fine, backlight that flickers under load, backlight that dims and won't go back up, or a board that was working until a drop damaged the IC pads. It's also a frequent casualty of liquid damage on these particular OPPO and Vivo boards, since the backlight boost circuit sits close to the charging port flex.Verify the mark under magnification before you commit to a reflow — D8 is the correct marking for LM3697YFQR, and mixing it up with a similar-looking driver IC on a donor board is an easy way to waste a repair cycle. Keep a few in stock if you handle OPPO A-series or Vivo Y-series volume, since backlight IC failure is one of the more predictable repairs on these chassis.