According to the graph posted by ChiggerPepi:. Does it mean regardless of modes, I am better off getting a light with less chips if I want longer runtimes instead of using one with more chips at medium and low modes? That is not a good way to drive the AMC as the brightness will suddenly decrease in the lower ranges of duty cycle. This can be seen here:. Nah, that can’t be true.
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But that’s just not practical in most cases.
To see how amc77135 relates to brightness, you can approximate by ledd this graph: Sorry to dig up an old thread. Does the qty of chips need to be even or odd numbered or is there an optimum number? It supplies mA per chip as long as the input and output voltage is within the specified range.
That is not a good way to drive the AMC as the brightness will suddenly decrease in the lower ranges of duty cycle.
The light I saw at has different configs available and those I mentioned above has 2 groups and can be switched to 3 modes amcc7135 5 modes. The time to get stable actually depends on the load capacitance and how fast the source can ramp up the current ESR of source, etc matter too.
AMC7135 PWM LED control – works?
Assuming that the supply voltage is under 6V, the setup can drive a single 1W white power LED easily with minimal component count and no current sense resistor.
If you have the space for multiple boards, use them and don’t use more than 8 chips each. Apologies for my terrible drawing skills! Here is the test circuit I used to check how long it takes for the circuit to draw a stable mA through the LED: However, assuming that the AMC is a feedback based current control system, you must consider the time that the device takes to settle to a stable constant current output.
Tag: LED Driver chip AMC 7135
Only high seems affected by the stacking of chips. The time required by the current sink to become stable is about 8us. It partly depends on the programming of the driver.
Many based drivers use pulse width modulation to control the lower modes. Is it recommended to do this?
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Please look at the chart I posted above, and pay attention to what it means. Excellent info for a newbie.
This can be seen here: Starts off very high constant e0 and then decreases more and more rapidly with drive current until it approaches but never reaches zero lumens per watt.
In the scope screenshots shown below, the nice rectangular wave is the signal generator output 3.
Correct, which is inversely exponentially proportional. Heat will be your enemy.
This can be seen here:. According to the graph posted by ChiggerPepi: But keeping amc71355 the things modest… I think this is the right frequency.
AMC – DC LED Driver CC  : Sunrom Electronics/Technologies
Nah, that can’t be true. There’s only lec for each and the ones for LED- are smaller than the ones for the ground planes. As in this screenshot, the duty cycle is at its minimum possible here. PWM control will not be effective over all duty cycles. Why do you say that lower than 5KHz will produce visible flicker? Not caring about the settling time of the current sink will cause loss of total effective power delivered to the LED.
Odd or even number of chips is irrelevant. You can of course go higher, but it will reduce smoothness in brightness control.