Free Trial

Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.

Share this Page URL
Help

Chapter 5: Buck-Based LED Drivers > 5.2 Buck Circuits for DC Applications - Pg. 41

Buck-Based LED Drivers 41 The HV9910B has two current sense threshold voltages ­ an internally set 250 mV and an external voltage at the LD pin. The actual threshold voltage used during switching will be the lower of the two. The low value of sense voltage allows the use of low resistor values for the current sense, which means high efficiency. The HV9910B IC operates down to 8 V input, which is required for some automobile applications, and can accept a maximum of 450 V input, which makes it ideal for offline applications. The IC has an internal regulator that supplies 7.5 V to power to the IC's internal circuits from the input voltage, eliminating the need for an external low voltage power supply. The IC is capable of driving the external MOSFET directly, without the need for additional driver circuitry. 5.2 Buck Circuits for DC Applications For DC applications, the schematic shown in Figure 5.3 can be used.