Covers the practical frequency limits and thermal considerations for switching a high-side switch as a PWM output, including why very high frequencies require an external low-side switch instead.
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Device Type |
Question |
Answer |
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HSS |
What is the maximum PWM switching frequency for TI high-side switches? |
TI smart HSS devices are typically rated for PWM up to a recommended maximum of 750Hz to 2000Hz. As this varies by device please refer to the device datasheet to check for a Fmax: Maximum PWM frequency spec. For higher frequencies, use the HSS before the load for protection and a separate low-side switch after the load to generate the PWM signal. At higher frequencies: switching losses scale with frequency. Sources: |
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HSS |
How do I minimize thermal dissipation when using an HSS for PWM switching? |
Power dissipation = conduction loss (I² × Rds(on)) + switching loss (∝ frequency, V², transition times). At 1kHz with resistive load, conduction loss dominates. Use heavy copper weight, maximize exposed thermal pad via array, and place the device close to a copper pour. The PWM app note provides a worked example for calculating total dissipation at a given frequency and duty cycle. Sources: |
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HSS and eFuse |
What HSS devices support PWM? |
TI HSS devices support PWM operation up to a maximum frequency specified in the dataqsheet. For TI standard HSS devices: the PWM operation is achieved by toggling the device EN pin with the desired PWM waveform. TI Efuse HSS devices have an integrated PWM driver that is configurable through SPI register settings. Sources: |