LED Drivers...
For my LED drivers, I probably want a shift register topology so that I can drive them all from a single data line
WarningI need to be careful as I am only using 21 channels per driver, such that the extra 3 channels must be
0when shifting the dataAlso, if most SOP/QFP ICs still require/encourage the thermal solder pad to be soldered for heatsinking, I might as well consider a QFN/other no-lead package—as I will be unable to iron-solder in either case
If the LED driver is handling all the power/brightness control, all my micro will need to do is write the information for the next row to the drivers, latch them, multiplex to the row, and wait until the next scan cycle before repeating
This should be fairly straightforward?
| Part Number | TLC5955DCAR | STP24DP05BTR | LED2472GBTR | TLC6C5724QDAPRQ1 | PCA9956BTWY | TLC5947DAPR | TLC5951DAP | TLC5952DAP |
|---|---|---|---|---|---|---|---|---|
| Image |  |  | |  |  |  | | |
| Supplier Link | DigiKey | DigiKey | DigiKey | DigiKey | DigiKey | DigiKey | DigiKey | DigiKey |
| Input Pins | 4 | 6 | 4 | 8 | 8 | 5 | 10 | 5 |
| Package | 56-HTSSOP | 48-TQFP | 48-TQFP | 38-HTSSOP | 38-HTSSOP | 32-HTSSOP | 38-HTSSOP | 32-HTSSOP |
| Pin Pitch | ||||||||
| Channels | 48 | 24 | 24 | 24 | 24 | 24 | 24 | 24 |
| Protocol | Shift register | Shift register | Shift register | Shift register | I2C | Shift register | Shift register | Shift register |
| Dimming | Analogue global, PWM greyscale | Output enable pins | Output enable pins | Analogue group, PWM greyscale | PWM greyscale, output enable pin | PWM greyscale | Analogue global, PWM greyscale | Analogue global |
| Greyscale Resolution | 16 bit | - | 6 bit and external resistor | 12 bit | 8 bit | 12 bit | 12 bit | - |
| Global Brightness Control | 7 bit | External resistors | External resistors | 8 bit per group, external resistors | 8 bit | External resistors | 8 bit, external resistors | 7 bit |
| Voltage | ||||||||
| Max Current per Channel | ||||||||
| Max GND Current | ||||||||
| Max Frequency | ||||||||
| Cost (for 5) | USD$29.90 | USD$15.60 | USD$15.80 | USD$17.65 | USD$18.40 | USD$19.45 | USD$21.90 | |
| Remarks | Automotive | Has internal oscillator | Has internal oscillator | Best so far |
The best device seems to be the TLC5951DAP due to its maximum output current and brightness/dimming controls/data frequency. If I find that TLC6C5724QDAPRQ1 may be the better choice (the lower speed may actually be desirable from an ease-of-implementation perspective).
- These selections give me the following matrix layout:
