I have 8 LED's and I am trying to turn 2 on at a time. My voltage source is 5V and the LED's require up to 200 mA current. I am finding quite a few demultiplex chips that are 2×4:1 but most of them do not operate in this range of voltage and current. Does anyone have a suggestion for a higher current Demultiplex chip or a switch. The reason demultiplex is appealing is because it has control inputs, which I need something similar to control the switch itself. A chip I found that would be ideal, if the voltage and current maximums were larger, is the TS3A5017
These LED's are BJT driven, which I won't go in to, but in order to turn them OFF the voltage source has to be off.
Best Answer
There are some issues with using extremely high frequencies to switch LEDs: The LED junction capacitance becomes a factor, and intensity drops significantly as the LED does not get the required excitation time per pulse.
LEDs have a minimum rise time specified, refer to the datasheet of the LED concerned to determine yours.
In other words, the light will be dimmer than at lower frequencies, and PWM dimming will be much less linear than with lower frequencies.
Assuming that the frequency for controlling the LED can be dropped much lower, an alternative approach is to use a high current rated latching serial-in-parallel-out power shift register like the Texas Instruments TPIC6A595.
This shift register has a high enough current rating, 350 mA per channel, to be able to sink the 200 mA per LED load described. What it lacks is the speed to handle the 120/125 MHz signal rates mentioned in one of OP's comments.
The benefit of this approach is that it requires a small number of control pins from your controller, and since the device is cascadeable, increasing the LED count does not increase required pin count.
If an even higher current drive is required, it is simple to drive two MOSFET arrays like the Hitachi 4AK21 from each shift register. This array is rated at 8 Amperes per channel (so long as per-channel dissipation is under 4 watts across Rdson=0.12 Ohms).