Texas Instruments is aiming at robot motor control up to 60V with a series of isolated ADCs that include 200V barriers and come in 8pad 3.5 x 2.7mm VSON packaging.

TI AMC0106M05 isolated ADC
Each has a ΣΔ ADC on the hot side, an isolation barrier, then a digital interface on the cool side.

The output is a modulated bit stream synchronised to an externally-provided clock that needs to be processed externally – an external SINC3 filter is suggested with 256 over-sampling.

There are three parts:

AMC0106M05
±50mV input range
16bit resolution
82.5dB dynamic range
78ksample/s
AMC0106M25
±250mV input range
16bit resolution
86dB dynamic range
78ksample/s
AMC0136
±1V input range
14.8 effective bits
89dB dynamic range
at 39ksample/s
The bit-counts and dynamic ranges above are with the suggested 256 SINC3 filter.

Each requires a separate hot-side and cold-side power supplies: 3 to 5.5V and 2.7 to 5.5V respectively.

The high-side power supply (AVDD) is generated from a bootstrap circuit (R4, D1, C2). The low-side supply is shared with circuitry in the signal domain. 

The two AMC0106Mx5 parts are nominally for current sensing, and TI proposes establishing their hot-side power supplies by bootstrapping (R4, D1, C2 in diagram left).

Each part has a pair of inputs across which the differential voltage is converted. Common-mode input range appears to include the hot-side negative supply terminal – but the data sheets differ slightly on this so check if it is important to you.

The ΣΔ modulator is a second-order, switched-capacitor, feed-forward type. An external capacitor is sometimes required across the inputs.

TI AMC0106M05 isolated adc block

The barrier is classed as ‘functional’ by TI, meaning that is has is only there for circuit function and does not bestow any safety characteristics (while ‘basic’ and ‘reinforced’ barriers do add safety).

Internally, on-off keying is used to transmit data through the internal capacitors that cross the isolation barrier.

Despite using capacitors across the barrier to transfer data the ADCs have “a common-mode transient immunity of 150V/ns [which enables] designers to use switching speeds of 50V/ns or more for gallium-nitride motor designs”, said TI.

Cumulatively, the barrier is rated for 60s of 570Vrms ac or 800V dc.

On the microporcessor (or FPGA) interface side, clocking can be between 5 and 21MHz (11MHz max for AMC0136).

At the same time, TI announced similar devices in larger packages rated for higher voltages between hot and colds sides:

AMC0236, 4.9 x 6mm SOIC basic 800Vrms
AMC0386 12.8 x 10.3mm SSOP reinforced 1.5kVac
AMC0386-Q1 12.8 x 10.3mm SSOP reinforced 1.5kVac
AMC3306M05-Q1 10.3 x 10.3mm SOIC reinforced 1.2kVac, includes isolated psu
AMC3306M25-Q1 10.3 x 10.3mm SOIC reinforced 1.2kVac, includes isolated psu
Q1 parts are AEC-Q100 qualified for automotive use