Theory of operation

STPMS2

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Doc ID 16525 Rev 3

In this way it is possible to access 128 different combinations, which are controlled through

pins MS0, MS1, MS2 and MS3.

MS0 sets the operating mode and amplifier gain selection as described in Table 8.

For the STPMS2L:

●

frequency and low power mode is selected.

●

clock frequency and accuracy is enhanced.

For the STPMS2H, LPR mode is not used and the settings should be chosen between

The relative gain of the current channel is selectable between 2 or 16, which defines the

maximum differential voltage on the current channel to ± 300 mV or ± 37.5 mV, respectively.

The voltage channel gain setting is fixed at 2, which defines the maximum differential

voltage on the voltage channel inputs to ± 300 mV.

MS1 defines the temperature compensation (TC) curve of the internal voltage reference of

the STPMS2L, as described in Table 9. This bootstrap function is not used with the

1.23 V. This generator is implemented as a band gap generator, whose temperature

compensation curve can be selected through the MS1 configuration pin.

MS2 defines the outputs of the device:

The STPMS2 sends to the DAT and DATn pins the sigma-delta streams synchronous to the

CLK signal. The output mode can be configured according to Table 10 as follows:

●

The output current channel's sigma-delta stream on DAT and the voltage channel's

sigma-delta stream on DATn

●

Output multiplexed signals, so when CLK = 0, the current channel output sigma-delta

value is set on the DAT pin, and when CLK = 1, the voltage channel output sigma-delta

value is set on the DAT pin. The DATn pin tracks DAT, so DATn = ~DAT.

●

Output current channel's sigma-delta stream on DAT and the current channel's sigma-

delta stream negated on DATn

Table 8.

Precision mode and input amplifier gain selection

MS0

Mode

Description

GND

0

LPR, amplifier GAIN selection g3 = 16

CLK

1

LPR, amplifier GAIN selection g0 = 2

NCLK

2

HPR, amplifier GAIN selection g0 = 2

VCC

3

HPR, amplifier GAIN selection g3 = 16

Table 9.

TC of the band-gap reference

MS1

Mode

Description

GND

0

TC = 60 ppm/°C

CLK

1

Flattest TC = +30 ppm/°C

NCLK

2

TC = +160 ppm/°C

VCC

3

TC = -160 ppm/°C