I am trying to match the current I observe the ADP8866 draw versus the expected current (obtained from Register Settings). There are 8 LEDs total connected to the ADP8866. 2 Blue LEDs(D1,D2: Part Number:SMS1105BWC) and 6 white LEDs (D3 to D8, Part Number: NSSW304GT-HG). I am turning ON one LED at a time and measuring the current the ADP8866 draws. (Current is measured by reading the voltage across a 100milliOhm resistor connected between VCC and Vin of the chip).

Observed current values:

SET A:

Register settings: Reg0x06 = 0x04, Reg0x07 = 0x04 (20.8mA), Reg0x08=0xff, Reg0x23 to 0x2B = 0x4F

Observed Currents: Blue LEDs = 15.92mA White LEDs: 9.13 to 9.32mA

SET B:

Register Settings: Same as SET A except: reg0x06 = 0x01

Observed Currents: Blue LEDs = 8.9 or 9.3mA White LEDs: 8.9 or 9.3mA

For SET B I can work out that I set 20.8 mA using LEVEL_SET bits (reg0x07 = 0x04) and using TABLE39 in the datasheet for a DAC Code of 4F and a full scale of 25mA current to be expected should be about 9.67mA. But I cannot figure out SET A

I replied separately to the customer about this. But I want to post the answer, in case it helps anyone else. The customer was measuring the input current and using that to infer the LED current. That can be done, but you must take into account the gain of the charge pump (boost).

So to be clear, the LED current is always very constant (irrespective of the charge pump gain). But the input current is really only equal to the output current (which is the sum of all the active LEDs currents) when the gain is 1x. For the other gains (1.5x and 2x), the input current scales with the gain. This is because the charge pump is a boost type circuit. So since Pout ~ Pin, then Vout*Iout ~ Vin * Iin. And Vout, Iout, and Vin are all relatively constant. So it means that Iin scales with the gain needed to produce the required Vout.

So then the input current = Iq +G*ILED*N. Where Iq is just the Iq of the part (Iq(active) in Table 1), G is the gain (1, 1.5, or 2), ILED is the individual channel LED current (so 25mA), and N is the number of LED channels active (1-9). Now you can measure input current and infer a total LED current measurement.