CurrentDIG 0-DIG 7 Sink Current..............................................500mASEG A-G, DP Source Current........................................100mA
Another thing caught my eye though. In the MAX7219 datasheet, it says that the resistor between the ISET and V+ pins is for controlling the display brightness. Does this mean that with that single resistor between ISET and V+, I don't even need those 7 resistors on the SEG pins?
Also, the datasheet says that a 10K resistor will limit the current on each SEG pin to about 40mA, what value resistor would be required to get that down to 10 or 20mA?
Selecting RSET Resistor andUsing External DriversThe current per segment is approximately 100 timesthe current in ISET. To select RSET, see Table 11....
And if you wire them in parallel without current limiting resistors, there is nothing to assure that the current is divided equally between them.
Page 10 of the data sheet:QuoteSelecting RSET Resistor andUsing External DriversThe current per segment is approximately 100 timesthe current in ISET. To select RSET, see Table 11.....
BTW, absolute maximum ratings are to be avoided. The rated typical segment drive current is 40mA, but the minimum is 30mA, so that is what should be designed for.
Will this display be ok to use? I believe the 90mA peak forward current means that I can safely put 40mA to it for a very short period of time, like the MAX7219 would as it cycles the digits on/off.
The 30mA is max continuous current and 90mA is a peak current when the display is multiplexed, note the "1/10 duty cycle, 0.1ms pulse width" meaning it would be on for 0.1ms then off for 0.9ms in a multiplexed setup.
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