MAX7219 8x8 LED matrix: specs and pinout
Serially interfaced driver for common-cathode LED displays of up to 8 digits or 64 individual LEDs, with a 10 MHz serial interface.
Specs
| Spec | Value | Source |
|---|---|---|
| Operating supply V+ | 4.0 V to 5.5 V | source Electrical Characteristics (p.2) |
| Absolute maximum V+ | -0.3 V to +6 V | source Absolute Maximum Ratings (p.2) |
| Shutdown supply current | 150 uA (all digital inputs at V+ or GND, 25 C) | source Electrical Characteristics (p.2); features (p.1) |
| Serial interface rate | 10 MHz | source Features (p.1) |
| Logic high input VIH | V+ - 1 V min | source Logic inputs (p.3) |
| Drive capacity | up to 8 digits or 64 individual LEDs | source General description (p.1) |
Power
| Value | Source | |
|---|---|---|
| Supply | V+ 4.0-5.5 V (chip ratings; 8x8 module regulator not covered) | source Electrical Characteristics (p.2) |
| Current | Shutdown 150 uA; operating supply current is not given here | source Electrical Characteristics (p.2) |
Chip pins
These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently. Module header labels come from the Compoden listing, not an official module schematic.
| Pin | Function | Voltage | Notes | Source |
|---|---|---|---|---|
| V+ | Positive supply voltage; connect to +5 V | 4.0-5.5 V operating; absolute max -0.3 to +6 V | Module-level 3.7-5.3 V claim is not in the datasheet. | source Pin Description (p.5); Electrical Characteristics (p.2); Absolute Maximum Ratings |
| GND | Ground; both GND pins must be connected | 0 V | source Pin Description (p.5) | |
| DIN | Serial-data input; loaded into the 16-bit shift register on CLK rising edge | VIH min V+ - 1 V; absolute max -0.3 to +6 V | At V+ = 5 V, VIH is 4 V, which 3.3 V logic does not guarantee. | source Pin Description (p.5); Electrical Characteristics (p.2-3) |
| CLK | Serial-clock input, 10 MHz max | VIH min V+ - 1 V; absolute max -0.3 to +6 V | Same note as DIN. | source Pin Description (p.5); Electrical Characteristics (p.2-3) |
| LOAD (CS) | Load-data input (MAX7219): last 16 bits latched on rising edge; named CS on MAX7221 and on the module | VIH min V+ - 1 V; absolute max -0.3 to +6 V | Same note as DIN. | source Pin Description (p.5); Electrical Characteristics (p.2-3) |
| DOUT | Serial-data output for daisy-chaining; never high-impedance; data valid 16.5 clock cycles later | Module label DOUT on the listing; feeds the next module's DIN. | source Pin Description (p.5) | |
| ISET | Segment current set; connect to V+ through RSET | 9.53 k RSET in the datasheet test conditions. | source Pin Description (p.5) | |
| DIG 0-DIG 7 | Eight digit drive lines (sink current from the display common cathode) | Absolute max -0.3 to V+ + 0.3 V | Internal to the 8x8 board; not on the module header. | source Pin Description (p.5) |
| SEG A-G, DP | Seven-segment and decimal-point drivers (source current) | Absolute max -0.3 to V+ + 0.3 V | Internal to the 8x8 board; not on the module header. | source Pin Description (p.5) |
Common mistakes
- Running V+ below 4.0 V: the operating supply range is 4.0-5.5 V (source)
- Changing or omitting RSET: the peak segment current is set by the RSET resistor (9.53 k in the test conditions) (source)
- Driving DIN, CLK or LOAD from 3.3 V on a 5 V supply: the logic high input is V+ - 1 V minimum, which 3.3 V logic may not reach (source)
What we could not confirm
- Module input voltage and current (3.7-5.3 V; 320 mA) are listing values and not in the datasheet.
- 8x8 matrix board and its header pins are not covered; chip datasheet only.
- The operating supply current row is not given here; only the shutdown current is listed.
- Pin rows are the MAX7219 chip pins; the 8x8 LED matrix board, its regulator and its 5-pin header (listing: VCC, GND, DIN, CS, CLK; DOUT named in the cascade FAQ) are not covered by an official source.
- Listing says any 3.3 V or 5 V microcontroller works; datasheet VIH min is V+ - 1 V (4 V at V+ = 5 V), so 3.3 V logic is not guaranteed at 5 V supply.
Sources
- link (Maxim/ADI MAX7219/MAX7221, 19-4452 Rev 4, 7/03)
- Copy of the Maxim datasheet hosted by a hosted copy: link
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