All LED drivers such as the IS31FL3246 will affect the power supply rails due to the On/Off nature of the integrated LED current sinks. During a PWM operation, when an LED channel is turned On there is an instant current demand placed on the V_CC power rail resulting in a slight drop in voltage. However, when the LED channel is turned Off, the V_CC rail will overshoot as seen in the diagram here. This constant current On/Off function will result not only in power supply ripple but also in audible hum from the MLCC capacitors. The ‘hum’ is a result of the MLCC capacitors expanding and contracting as they attempt to respond to the instant LED current demand. The IS31FL3246’s programmable staggered outputs and clock phase inversion help minimize both EMI (due to overshoot/undershoot) and audible noise (due to MLCC electrostriction).