ZHCSJO3A May 2019 – October 2019 LMR34215-Q1
The spread spectrum is a factory option in the select variants.
|ORDERABLE PART NUMBER||OUTPUT VOLTAGE||SPREAD SPECTRUM||FPWM||fSW|
|LMR34215FSC5RNXRQ1||5-V Fixed||Yes||Yes||2.1 MHz|
|LMR34215FSC5RNXTQ1||5-V Fixed||Yes||Yes||2.1 MHz|
|LMR34215SC5QRNXRQ1||5-V Fixed||Yes||No||2.1 MHz|
|LMR34215SC5QRNXTQ1||5-V Fixed||Yes||No||2.1 MHz|
The purpose of the spread spectrum is to eliminate peak emissions at specific frequencies by spreading emissions across a wider range of frequencies than a part with fixed frequency operation. In most systems containing the LMR34215-Q1 low frequency conducted emissions from the first few harmonics of the switching frequency can be easily filtered. A more difficult design criterion is reduction of emissions at higher harmonics which fall in the FM band. These harmonics often couple to the environment through electric fields around the switch node. The LMR34215-Q1 devices with a triangular spread spectrum use typically a ±4% spreading rate with the modulation rate set at 16 kHz (typical). The spread spectrum is only available while the internal clock is free running at its natural frequency. Any of the following conditions overrides spread spectrum, turning it off: