LM3421MH/NOPB

LM3421MH/NOPB is a high efficiency, boost-buck LED driver with integrated dimming functionalities. It is a members of the LM3421 family of Power Management Integrated Circuit (PMIC) LED Drivers. This chip is designed for battery powered lighting applications.

A simple circuit schematic of the LM3421MH/NOPB can be seen in Figure 1. This is the basic topology of a boost-buck converter – a common architecture used for DC/DC buck and boost converters. The LM3421MH/NOPB features two inputs and one output. The input voltage is supplied to the device through the “VIN” pin, which is connected to the cathode of the battery ordc source. The input voltage for the LM3421MH/NOPB can range from 1.5V to 16V. The LM3421MH/NOPB also has an enable pin, which is connected to the input voltage. Setting this pin to high will enable the device, allowing power to flow through the device from the input to the output.

The LM3421MH/NOPB is designed to convert a DC input voltage into a higher or lower DC output voltage. This is accomplished through the use of a buck-boost circuit, which uses a switch (in this case, the LM3421’s integrated switch) to either step up (boost) or step down (buck) the required output voltage. In the case of the LM3421MH/NOPB, the output voltage can be adjusted through the use of an external voltage divider. Through this voltage divider, the output voltage can be adjusted from 0.6V to 18V.

The LM3421MH/NOPB provides programmability of the output current and dimming functions. To program the output current, the LM3421MH/NOPB utilizes a dedicated current-sensing pin, ISEN. This pin is connected to a sense resistor, which allows the LM3421MH/NOPB to measure the output current. The user can then can select the appropriate sense resistor to limit the total output current to a specific desired value.

The LM3421MH/NOPB also provides dimming functionality. This is achieved through the implementation of Pulse Width Modulation (PWM) on the EN pin. This allows for variable dimming levels, as the duty cycle of the PWM input will determine the output current. The frequency of the PWM can also be adjusted, allowing for greater flexibility in the dimming implementation.

The LM3421MH/NOPB also provides several protections for both the device and the load. These include an overvoltage protection (OVP) circuit, a temperature protection circuit, and a short circuit protection (SCP) circuit. These features help ensure that the device and the load remain safe and operational under certain conditions.

In summary, the LM3421MH/NOPB is a high efficiency, boost-buck LED driver with integrated dimming functions. It is designed for battery powered lighting applications, and provides programmability of output current and dimming functions through the use of a dedicated current-sensing pin and PWM input. The device also provides several protections for both the device and the load.