STPMS2

Theory of operation

Doc ID 16525 Rev 3

19/33

The STPMS2H sigma-delta modulators work in the following mode:

The STPMS2 performs operations in 2 basic modes: Hard mode and Soft mode.

In Hard mode the configuration is set through external pins MS0, MS1, MS2 and MS3.

In Soft mode, 40 configuration bits can be accessed through CFG[39:0], via serial

communication. The pins used for serial communication are: MS0, MS1 and MS2.

Switching between Hard and Soft modes is achieved through pin MS3.

●

Hard mode: In this case the device configuration is bootstrapped at startup and signals

come from VIN and VIP for voltage channels, and CIP and CIN for current channels or

from internal BIST DAC.

●

Soft mode: In this mode all possible settings from Hard mode are accessible, as well

as the additional settings described in Section 8.5.

The STPMS2 sends to the DAT and DATn pins selected signals based on the configuration

used.

Both outputs have cross-current and slew rate limiters to prevent excessive current spikes

on supply lines.

Table 7.

Operating modes

Operating mode

Device

Current

consumption

LP (low power)

LPR (low precision)

STPMS2L

1 MHZ

1,2 mA typ

HP (fast)

HPR (high precision)

STPMS2L

2 MHz – 4MHz

4 mA typ

HHPR (very high precision)

STPMS2H

4 MHz

Figure 17.

Block diagram of the modulator

AM09894v1

-

∫

-

∫

D/A

input

stream out

comparator

dithering