Alternative to the TLC5940

piemadd · October 10, 2016

Does anyone know a cheaper alternative to the TLC5940? I am using it to control RGB led's. Thanks!

mariushm · October 10, 2016

Go to any reputable distributor or electronic components and search for a replacement? Keep in mind volume discounts as well. Look at digikey.com , newark.com (Farnell's US website) , Mouser.com etc

TLC5940 is what, a 16 channel 4096 step grayscale pwm driver (linear) ... costs about 2.3$ each if you buy 100: http://www.digikey.com/product-detail/en/texas-instruments/TLC5940PWPR/296-35975-1-ND/4135049

There are 24 channel and 32 channel and even 48 channel ICs out tjhere, it depends on you how flexible your circuit is and how many features of those drivers you actually need (for example a 48 channel led driver may only have 8bit/256 step graycale / brightness control while tlc5940 has 10bit/4096 step) but if your display won't be in very bright areas or won't require fine brightness adjustment, you may not care about this feature and could work with that other led driver.

here's for example TLC5954 with 48 channel for 3.6$ at 100pcs or TLC5955 for 4.3$ in the more classic shape - you get 4 times the number of channels for 1.5x - 2x the price of your older chip, but you lose features and you'd have to be a bit more careful about thermals (heat dissipation for the chip, in extreme cases like when all the leds controlled by the driver are lit)

you could also go with chips like IS31GL3236 which give you 24 channels for about 1.6$ but the downside is they work with i2c so unlike serial shift register type drivers you ca only chain maybe 7 of them, and the bandwidth is more limited (you may not be able to do crazy things like push 100+ updates a second to all leds through i2c when you have several such chips on the same i2c bus, but you only need three wires from a microcontroller to led driver and they have auto increment feature for the i2c address so it makes layout on pcbs much easier if the downsides don't affect your project)

you could also go the other way around and go with smaller ICs that have only 8 channels for example, and by buying bigger number you could get better discounts. For example, you could buy 1000pcs of STP08DP05MTR for 0.36$ each giving you 8000 channels for 363$ , while with 48 channel drivers like TL5954 you would have to buy 167 chips at 3.62$ each (you get the 100pcs break price, but if you negociate with Digikey they may give you the 500pcs price if you buy 200-250 of them) or about 600$.

On one hand, the led driver ICs having more surface for 8 channels can dissipate more power so leds can be driven at higher currents BUT on the other hand the chips take more pcb space, they require additional traces for power and ground to each chip, decoupling capacitors for each chip, the quiescent currents would be higher (each chip will use more power at idle compared to chips with more channels), it will take more time to push a lot of data through all the chips if you chain a lot of them together so you have larger refresh times (less "fps") and if you have big displays it would be harder to control the brightness of each set of 8 leds (or multiple leds driven by channels on chip),led drivers with more channels will match the currents of all channels better and you'd have bigger led areas with same brightness.

there's a huge amount of choice, just go and filter by your needs (number of channels, current per chanel, brightness control , connection type to microcontroller, if multiple ics can be chained and sync'ed and if there's pass through of data like with shift registers etc : http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-led-drivers/2556628

piemadd · October 10, 2016

1 hour ago, mariushm said:

Go to any reputable distributor or electronic components and search for a replacement? Keep in mind volume discounts as well. Look at digikey.com , newark.com (Farnell's US website) , Mouser.com etc

TLC5940 is what, a 16 channel 4096 step grayscale pwm driver (linear) ... costs about 2.3$ each if you buy 100: http://www.digikey.com/product-detail/en/texas-instruments/TLC5940PWPR/296-35975-1-ND/4135049

There are 24 channel and 32 channel and even 48 channel ICs out tjhere, it depends on you how flexible your circuit is and how many features of those drivers you actually need (for example a 48 channel led driver may only have 8bit/256 step graycale / brightness control while tlc5940 has 10bit/4096 step) but if your display won't be in very bright areas or won't require fine brightness adjustment, you may not care about this feature and could work with that other led driver.

here's for example TLC5954 with 48 channel for 3.6$ at 100pcs or TLC5955 for 4.3$ in the more classic shape - you get 4 times the number of channels for 1.5x - 2x the price of your older chip, but you lose features and you'd have to be a bit more careful about thermals (heat dissipation for the chip, in extreme cases like when all the leds controlled by the driver are lit)

you could also go with chips like IS31GL3236 which give you 24 channels for about 1.6$ but the downside is they work with i2c so unlike serial shift register type drivers you ca only chain maybe 7 of them, and the bandwidth is more limited (you may not be able to do crazy things like push 100+ updates a second to all leds through i2c when you have several such chips on the same i2c bus, but you only need three wires from a microcontroller to led driver and they have auto increment feature for the i2c address so it makes layout on pcbs much easier if the downsides don't affect your project)

you could also go the other way around and go with smaller ICs that have only 8 channels for example, and by buying bigger number you could get better discounts. For example, you could buy 1000pcs of STP08DP05MTR for 0.36$ each giving you 8000 channels for 363$ , while with 48 channel drivers like TL5954 you would have to buy 167 chips at 3.62$ each (you get the 100pcs break price, but if you negociate with Digikey they may give you the 500pcs price if you buy 200-250 of them) or about 600$.

On one hand, the led driver ICs having more surface for 8 channels can dissipate more power so leds can be driven at higher currents BUT on the other hand the chips take more pcb space, they require additional traces for power and ground to each chip, decoupling capacitors for each chip, the quiescent currents would be higher (each chip will use more power at idle compared to chips with more channels), it will take more time to push a lot of data through all the chips if you chain a lot of them together so you have larger refresh times (less "fps") and if you have big displays it would be harder to control the brightness of each set of 8 leds (or multiple leds driven by channels on chip),led drivers with more channels will match the currents of all channels better and you'd have bigger led areas with same brightness.

there's a huge amount of choice, just go and filter by your needs (number of channels, current per chanel, brightness control , connection type to microcontroller, if multiple ics can be chained and sync'ed and if there's pass through of data like with shift registers etc : http://www.digikey.com/product-search/en/integrated-circuits-ics/pmic-led-drivers/2556628