I connected one LED between C0 and A0 of HT16K33 and turned it on.
Only 2.2mA flows through that LED. why?
I want to emit light at 20mA.

Connect 60 LEDs to HT16K33.
Only one of them lights up.

void setup() {
HT.begin(0x00);
HT.setLedNow(15); //The brightness is set to maximum.
HT.setLedNow(0);
}

Mod: Added datasheet.E

 

The data sheet attached does not discuss the voltage output to any extent that I see.
Certainly LED illumination is a function of current, but in addition, the current is a function of voltage.
Like every other diode type, an LED is very non-linear. What is not mentioned in the question is either the forward voltage specification of the LED, OR the supply voltage to the driver module assembly. THOSE parameters matter. If the module supply voltage is 3.3 volts and the LED forward voltage is 2.7 volts that leaves only 0.6 volts possible drop in the drive control IC.
In short, we do not have nearly enough information provided.

 

I'm not familiar with the HT code library, but is line 4 turning the LED off immediately after it is turned on at full brightness?