MAX32600 User’s Guide
Analog Front End
8.5 LED
8.5.2.8
Multiple High Voltage LED Control Configuration
Figure 8.18: Multiple High Voltage LED Control Configuration
This configuration provides for the high drive voltage requirements inherent to some LEDs. LEDs, particularly blue and green, often have high forward voltages;
even red LEDs have high drive voltage requirements at high currents due to internal resistances. In these cases, the
MAX32600
3.6V maximum voltage becomes a
limiting factor. However, it is possible to use up to a 5V anode voltage on the LEDs in the multiple LED configuration shown
if the cathode is driven to V
DDIO
to
turn the diode off. When off, the diode still has around 1V on forward bias; however, if that voltage is still on the exponential portion of the diode I-V curve, then the
off current is vanishingly small.
Note
The anode voltage and the main chip supply should be optimized for the particular diode to maintain desired on voltage and off current.
Rev.1.3 April 2015
Maxim Integrated
Page 480
Содержание MAX32600
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