STPM32TR datasheet(33/121 Pages) STMICROELECTRONICS

Part #	STPM32TR

Description	ASSP for metering applications with up to four independent 24-bit 2nd order sigma-delta ADCs, 4 MHz OSF and 2 embedded PGLNA

PDF	121 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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33 / 121 page

DS10272 Rev 8

33/121

STPM32, STPM33, STPM34

Theory of operation

121

Figure 23. Temperature compensation typical curves

8.2.2

Analog front end

Analog channel inputs of voltages VIP1, VIN1, VIP2, VIN2 and currents IIP1, IIN1; IIP2, IIN2

are fully differential.

Voltage channels have a preamplification gain of 2, which defines the maximum differential

voltage on voltage channel inputs to ± 300 mV.

Current channels have a programmable gain selectable among 2, 4, 8 and 16, which

defines the maximum differential voltage on current channel to ± 300 mV, 150 mV, 75 mV or

± 37.5 mV respectively. The selection is given by GAINx[1:0] (DFE_CR1, DFE_CR2) bits as

described in Table 10.

The oversampling frequency of the modulators is 4 MHz, the output bitstreams of the 2nd

order sigma-delta modulators relative to the voltage and to the two current channels are

available on INT and LED output pins through the proper configuration (see configuration bit

map).

Table 10. Current channel input preamplifier gain selection

GAINx0

GAINx1

Gain

Differential input

± 300 mV

± 150 mV

± 75 mV

X16

± 37.5 mV

STPM32TR Datasheet(PDF) 33 Page - STMicroelectronics