Thanks for your reply!
In fact, I would like to know some control techniques or ways to adjust the brightness of the LED. For example, PWM control, LDO control and digital control or discrete look-up table control.
Normally parallel LEDs are drived by charge pump circuit, and the driver seems like paralleled LDOs. Use resistor to sample the current to keep the current constant. sometimes it is diffuricult to keep the leds the same brightness. current match of 0.006 is quite a commerical value. Some companies such as linear tech provide such products, you can search and have a look.
Normally parallel LEDs are drived by charge pump circuit, and the driver seems like paralleled LDOs. Use resistor to sample the current to keep the current constant. sometimes it is diffuricult to keep the leds the same brightness. current match of 0.006 is quite a commerical value. Some companies such as linear tech provide such products, you can search and have a look.
Thanks for your suggestions!
could you tell me whether LED adjusts the brightness by using different voltage reference(keeping the resistor constant) or by changing the resistance while keeping the voltage reference constant?
Added after 10 minutes:
Thanks for your self-giving help!
I have two questions
For discrete brightness control
whether LED adjusts the brightness by using detect resistor network while keeping voltage reference (voltage drop on the detect resistors) constant or by changing the value fo voltage reference while keeping the detect resistor constant?
For PWM control
how to adjust the brightness of the LED continuously? could you show me some detailed circuit structures and its principles?
Added after 17 minutes:
could someone tell the principle of some parts of MAX1537 shown with PDF?
The most-left part:
the terminal SET connected with a set resistor, could you tell me the role of the two PMOS especially the right PMOS?