MAX32600 User’s Guide
Analog Front End
8.5 LED
8.5.2.3
H-bridge LED Configuration
Figure 8.13: H-bridge LED Configuration
The H-bridge LED configuration uses a pair of source/sink LED I/O to drive a pair of diodes connected back-to-back. This design only requires two pins on the LED
package and cable; however, it necessitates the use of a pullup device within the
MAX32600
. The onboard pullup devices on the
MAX32600
can usefully source
25mA from diodes with forward voltages as high as 2.5V. Note that capacity is a function of the sense resistor and the minimum available supply voltage. This source
capability is not as high as the sink. In cases when more than 25mA is needed, multiple I/O pairs can be hooked up in parallel.
Note
Overshoot on the control voltage must be prevented. The most reliable and effective way of accomplishing this is to switch the negative op amp input
from the sense resistor to a voltage higher than the command from the DAC using uncommitted switches when enabling the loop.
Rev.1.3 April 2015
Maxim Integrated
Page 475