Datasheet

TMS320F28379S

TMS320F28377S

TMS320F28376S, TMS320F28375S, TMS320F28374S

SPRS881C –AUGUST 2014–REVISED MAY 2016

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5.9.5 Sigma-Delta Filter Module (SDFM)

The SDFM is a four-channel digital filter designed specifically for current measurement and resolver

position decoding in motor control applications. Each channel can receive an independent sigma-delta

(ΣΔ) modulated bit stream. The bit streams are processed by four individually programmable digital

decimation filters. The filter set includes a fast comparator for immediate digital threshold comparisons for

overcurrent and undercurrent monitoring. Figure 5-53 shows a block diagram of the SDFMs.

SDFM features include:

• Eight external pins per SDFM module:

– Four sigma-delta data input pins per SDFM module (SDx_Dy, where x = 1 to 2 and y = 1 to 4)

– Four sigma-delta clock input pins per SDFM module (SDx_Cy, where x = 1 to 2 and y = 1 to 4)

• Four different configurable modulator clock modes:

– Modulator clock rate equals modulator data rate

– Modulator clock rate running at half the modulator data rate

– Modulator data is Manchester encoded. Modulator clock not required.

– Modulator clock rate is double that of modulator data rate

• Four independent configurable comparator units:

– Four different filter type selection (Sinc1/Sinc2/Sincfast/Sinc3) options available

– Ability to detect over-value and under-value conditions

– Comparator Over-Sampling Ratio (COSR) value for comparator programmable from 1 to 32

• Four independent configurable data filter units:

– Four different filter type selection (Sinc1/Sinc2/Sincfast/Sinc3) options available

– Data filter Over-Sampling Ratio (DOSR) value for data filter unit programmable from 1 to 256

– Ability to enable or disable individual filter module

– Ability to synchronize all four independent filters of a SDFM module using the Master Filter Enable

(MFE) bit or the PWM signals.

• Filter data can be 16-bit or 32-bit representation

• PWMs can be used to generate modulator clock for sigma-delta modulators